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181	Mathematics Education	ABS-219
Analysis of the Didactic Situasion in Mathematical Problem Solving of Equations for Tangent Cicles Nanang Diana(a)*, Didi Suryadi(b), Jarnawi Afgani Dahlan(b), Husnul Khatimah(c), Arnasari Merdekawati Hadi(d) a,c) Mathematic Education, STKIP Taman Siswa Bima a,b) Mathematic Education, Universitas Pendidikan Indonesia d) Mathematic Education, STKIP Bima Abstract This study aims to describe (1) the knowledge that students already have, (2) strategies for solving problems of tangent circles, and (3) didactic situations of students on material tangent circles. The methodology in this study is a qualitative research of phenomenology and the subject taken is a third semester student who is taking analytic geometry courses by giving problem solving questions then conducting interviews with three students. The results of this study are to explore the knowledge students have and problem solving strategies by analysis the theory of didactic situations consisting of action situations, formulation situations, and institutional situations. In the action situation, students develop their own solutions to find a solution to the problem and are given more specific information to be able to determine the equation of the circle tangent. The situation of the student formulation generalizes the problem to determine the equations of tangents of a circle. The validation situation on students^ understanding obtained from the formulation activities is further validated by giving problems that determine tangent equations in circles and in institutional situations that allow students to change their previous knowledge into new knowledge through reinforcement by lecturers who give them the value of truth and allow new knowledge to be obtained to solve the problem given. Keywords: Didactic Situation, Problem Solving, Equation of Tangent Circle. Share Link | Plain Format | Corresponding Author (Nanang Diana)

182	Mathematics Education	ABS-223
Assessing Pre-service Mathematics Teachers^ Problem Solving Ability: The Case of School Geometry Al Jupri Universitas Pendidikan Indonesia Abstract This study aims to analyze pre-service mathematics teachers^ problem solving ability for the case of school geometry. To this end, this study used a qualitative case study involving 31 pre-service mathematics teachers attending the school mathematics course, for the topic of school geometry, from one of the state universities in Bandung, Indonesia. In this study, pre-service mathematics teachers^ written work retrieved from the formative assessment was analyzed using Polya^s problem solving model. The results showed that the step of devising a plan in problem solving is the key to success in the solution process and is influenced by the step of understanding the problem. In devising the plan, pre-service teachers need to transform the geometric problem into symbolic algebraic models through for instance constructing appropriate geometric figures. The step of checking or looking back seems to lack attention for most of participants. Two representative examples are addressed to illustrate these findings. Keywords: School geometry, preservice mathematics teacher, Polya^s problem solving model Share Link | Plain Format | Corresponding Author (Al Jupri)

183	Mathematics Education	ABS-225
PROBLEM-BASED STUDENT WORKSHEETS FOR ONLINE MATHEMATICS LEARNING IN ELEMENTARY SCHOOL DURING THE COVID-19 PANDEMIC Melva Zainil (a*), Ary Kiswanto Kenedi (b), Yullys Helsa (a) (a) Universitas Negeri Padang (b) Universitas Samudra Abstract A motivating factor for this study was the need for innovation in online mathematics learning during the Covid-19 pandemics. The innovation aimed to boost the learning motivation of elementary school students. The purpose of this study was to develop valid, practical, and effective problem-based student worksheets for online mathematics learning in elementary school during the Covid- 19 pandemics to increase students^ willingness to learn. This study was a development study that follows a 4-D model that includes stages of define, design, development, and dissemination. The results showed that (1) the validation test score of problem-based student worksheet was 87% with a highly valid category (2) the practicality test score of the problem-based student worksheet from teacher and students aspects was 88% with a highly practical category (3) the effectiveness test showed an increase in student learning motivation from 68.00 to 86.50. This study concluded that problem-based student worksheets for online mathematics learning can boost elementary school students^ motivation to learn in a valid, practical, and effective way during the Covid-19 pandemics. Educational practitioners might utilize the findings of this study as a guide to design an online learning innovation during the COVID-19 pandemic. Keywords: student worksheets, mathematics, online, elementary school Share Link | Plain Format | Corresponding Author (Melva Zainil)

184	Mathematics Education	ABS-229
Means-Ends-Analysis Model with Didactical Engineering to Enhance Junior High School Students HOTS Ability and Mathematical Habits of Mind Wahid Umar FKIP Universitas Khairun, Ternate Indonesia Abstract This article presents the results of research on how to construct a Means-Ends-Analysis (MEA) model with Didactical Engineering (DE) to enhance students^ high order thinking skill (HOTS) ability. This study uses Research & Development Method, lasting for one Year, which is divided into two stages. The first stage used the research design of one group of students without control, and the second stage used two groups of students with quasi-experimental methods of pretest-posttest. The sample involved 158 eighth grade students from two junior high schools at the high and medium levels in Ternate City. The sample for the experimental group and control group was randomly selected on the basis of grades. Instruments used were tests of prior mathematical ability (PMA), HOTS ablity test, and MHM of students. Research data of students^ pretest, posttest, and normalized gain scores for HOTS ability were analyzed using mix-methods, i.e. a combination of quantitative and qualitative analyses adapted to the existing data. The results showed that there is a significant difference in the enhancement of students^ HOTS ability between the experimental and control groups. The enhancement of HOTS ability of the experimental group students who were taught with the MEA model with DE is significantly greater in each category of their PMA both in the schools of the high and medium levels compared to the enhancement of the students who were taught with conventional learning model. In addition, there is no interaction effect between the learning model and the students^ PMA on the mathematical habits of mind (MHM). Keywords: HOTS ability, mathematical habits of mind, MEA, didactical engineering Share Link | Plain Format | Corresponding Author (Wahid Umar)

185	Mathematics Education	ABS-233
Analysis of Algebraic Thinking Skills in Seventh Grade Students Riane Nurismawati (a*), Kusnandi (b) a) Departemen Pendidikan Matematika, Universitas Pendidikan Indonesia Jl. Dr. Setiabudi No. 229, Bandung 40154, Indonesia *rianenurismawati[at]upi.edu b) Departemen Pendidikan Matematika, Universitas Pendidikan Indonesia Jl. Dr. Setiabudi No. 229, Bandung 40154, Indonesia Abstract Algebra is quite a difficult subject for most students because there is a transition from arithmetic to algebraic thinking. However, there are several studies showing activities that support algebraic thinking skills that are not always related to formal algebra, therefore exercises to develop algebraic thinking skills can be studied before students learn formal algebra and are even expected to reduce students^ difficulties in understanding formal algebra in junior high school. This study analyzed the algebraic thinking skills of seventh grade junior high school students before being introduced to formal algebra using descriptive method with a qualitative approach. The algebraic thinking ability test instrument questions were given to several students who represented students with high, medium and low mathematical abilities. The results showed that the ability to think algebraically for the initial level was quite good, but in general only showed a little generational activity and did not show transformational activity. Keywords: algebraic thinking ability- early algebra Share Link | Plain Format | Corresponding Author (Riane Nurismawati)

186	Mathematics Education	ABS-236
Mathematics learning loss due to distance learning during pandemic covid19 A Systematic Literature Review Nindya Langen Luthfiani (a*), Nurjanah (b) a) Universitas Pendidikan Indonesia, Jalan Dr Setiabudhi 229, Bandung 40154, Indonesia *nindyalangenluthfiani[at]student.upi.edu b) Universitas Pendidikan Indonesia, Jalan Dr Setiabudhi 229, Bandung 40154, Indonesia Abstract The Covid19 pandemic has affected lives, including the education sector. There has been an adjustment to online learning. It is therefore pointed out that students have learning disabilities in various subjects, one of which is mathematics. And in this study will discuss the loss of learning in mathematics. This is done so that it can provide alternative prevention and knowledge regarding the learning loss that students experience when learning math. For this reason, it is necessary to conduct related studies, to find out whether it is true that students are lost in learning mathematics. This study used a systematic literature review approach, including planning, implementation and reporting. Data were analyzed based on inclusion criteria and then data was extracted, creating 12 studies. The results show that skills scores in 2020 are slightly lower than three years earlier, due to the lack of an opportunity to study mathematics with peers. Students entering first grade in fall 2020 performed better in September than in March. Disability claims during COVID19 have also been made by researchers from different countries Thus, a loss of math during the pandemic has occurred. Keywords: Mathematics Learning Loss- Learning loss- Distance learning Share Link | Plain Format | Corresponding Author (Nindya Langen Luthfiani)

187	Mathematics Education	ABS-241
THE ANALYSIS OF UNIVERSITY STUDENT^S MOTIVATION IN LEARNING BY USING E-BOOK WITH MAGAZINE DISPLAY IN THE TIME OF COVID-19 PANDEMIC Novferma1,a), Mujahidawati2, b), Febbry Romundza3, c), Ari Frianto4, d) 1,2 Program Studi Pendidikan Matematika, Universitas Jambi, 3 Program Studi Pendidikan Kimia, Universitas Negeri Jakarta 4 Guru SD Al Azhar 57 Jambi Abstract Abstract . For a year, Indonesia was hit by an outbreak of the COVID-19 virus which made the learning process unstable, both in elementary schools and universities. The current learning system is carried out online or offline, but for the learning process in higher education, it is mandatory to go online using i-LMS or zoom meetings. This change in the learning process can cause most students to lack motivation, especially in the learning process in economics mathematics courses. Therefore, it is necessary to have media or teaching materials that can support students^ online learning processes, one of which is in developing student reading materials that are initially unattractive to become more interesting. This study aims to describe students^ learning motivation towards the use of teaching materials in the form of e-books with magazine displays during the covid-19 pandemic. This research is a qualitative descriptive study. The research subjects were students who took a randomly selected contract economics mathematics course. The instruments used were motivation questionnaire test sheets, interview test sheets, and learning process observation questionnaires. The data analysis technique used is quantitative descriptive analysis. The results showed that the percentage of student learning motivation as a whole was 86.5% with a very high category. The results of the percentage of each indicator of motivation are the desire and desire to succeed, the drive and the need to learn, and perseverance in facing tasks of 82.5%, 84.5%, and 85% with very high categories. Furthermore, the percentage of each indicator of student learning motivation is tenacity to face difficulties, interesting activities in learning, and pleasure in finding and solving problems by 80%, 78.5%, and 83% with high categories. Therefore, it can be concluded that e-book teaching materials with magazine displays are very effective in being used as teaching materials for students of economics mathematic Keywords: analysis, motivation in learning, e-book with magazine display, covid-19 pandemic Share Link | Plain Format | Corresponding Author (Novferma Novferma)

188	Mathematics Education	ABS-248
Implementation Digital Literacy of Textbook of Statistics I for Islamic Religious Education Students Sari Herlina a) Mathematics Education Department, Universitas Islam Riau Jl. Kaharuddin Nasution No. 113, Pekanbaru-Riau, Indonesia (a*) sariherlina99[at]edu.uir.ac.id b) Mathematics Education Department, Universitas Islam Riau Jl. Kaharuddin Nasution No. 113, Pekanbaru-Riau, Indonesia Abstract This research was motivated by differences in the ability of students in Islamic Religious Education in understanding various statistical concepts. So that the research has the aim of knowing the impact of using digital literacy of Textbook of Statitics I on Mathematics Understanding Ability of Islamic Religious Education Students at Universitas Islam Riau. This type of research is a quasi-experimental research. The population is 4th semester Islamic Religious Education students at the Universitas Islam Riau. The sampling method was purposive sampling with a sample of 91 students for two classes. The instrument and data collection technique used was the result of Mathematical Understanding Ability test on Statistics Material. The data analysis was the analysis of result of Mathematical Understanding Ability test after using Digital Literacy of textbook of statistics in the learning process using the one sample t-test. The results showed that Digital literacy of Textbook of Statistics I has effect on the mathematical understanding ability of Islamic Religious Education students at Universitas Islam Riau (Islamic University of Riau). Keywords: Literacy Digital- Textbook of Statistics I- Mathematical Understanding Ability Share Link | Plain Format | Corresponding Author (Sari Herlina)

189	Mathematics Education	ABS-254
Development of Number Pattern Teacing Materials in Mastering Maths Application Oriented to The Mathematical Reasoning Ability Poppy Yaniawati (a), In In Supianti (a*), Dahlia Fisher (a), Nurhayati Fitrie (b) (a) Universitas Pasundan, Jl. Sumatera No. 41 Bandung, Indonesia *supianti[at]unpas.ac.id (b) SMPN 23 Bandung, Jl. Arjuna 20-22 Bandung, Indonesia Abstract Mastering Maths is a mathematics learning application with mobile learning-based teaching materials that can assist teachers and students in doing distance learning. The purpose of this study was to develop an effective number pattern teaching material for improving the mathematical reasoning ability of junior high school students. This research method is R & D with ADDIE steps consisting of five stages, namely analysis, design, development, implementation, and evaluation. The subjects of this study were class VIII students in one of the public junior high schools in Bandung. The research instruments used were material and media expert validation sheets, student response questionnaires, interview sheets, observation sheets, and reasoning ability test questions. The data analysis technique used is triangulation to see the effectiveness of the teaching materials developed to improve students^ mathematical reasoning abilities. The results of the reasoning ability test were analyzed using the difference test of two averages with the help of SPSS 23. The results showed that the teaching materials developed were suitable for use in learning and could improve students^ mathematical reasoning abilities Keywords: mobile learning- mathematical reasoning ability, number pattern Share Link | Plain Format | Corresponding Author (InIn Supianti)

190	Mathematics Education	ABS-255
The impact of online learning assisted by Ms. Teams and videos on understanding group concepts in Abstract Algebra courses Yumiati and Saleh Haji Universitas Terbuka Universitas Bengkulu Abstract The purpose of this study was to determine the impact of online learning assisted by Ms. Teams and videos on understanding group concepts in the Abstract Algebra course. This type of research is experimental research with one group pretest-posttest design. Participants of this study were 13 students of the Bengkulu University Mathematics Education undergraduate program in the even semester of the 2020-2021 academic year. The instrument used is a written test in the form of an essay consisting of 3 questions. The novelty of this research is the application of online learning with the help of Ms. Teams combined with the use of video media. The results showed that 1) Students^ understanding of the group concept increased from 2.74 to 7.03 on a scale of 10- 2) Statistical test shows that the difference in pretest and posttest scores is very significant- 3) Based on the N-Gain calculation, an increase in understanding of the group concept of 0.57 is in the medium category. Keywords: Online learning, Ms. Teams, video, group concept Share Link | Plain Format | Corresponding Author (Yumiati Yumiati)

191	Physics	ABS-277
The Effect of Quasi-solid State Electrolytes used on The Efficiency of Curcuma longa Dye-sensitized Solar Cell Prima Fitri Rusliani (a), Eka Cahya Prima (b*), Endi Suhendi (a), Wiendartun (a) a. Department of Physics Education, Faculty of Mathematics and Science Education, Universitas Pendidikan Indonesia, Bandung, Indonesia. b. Departement of Science Education, Faculty of Mathematics and Science Education, Universitas Pendidikan Indonesia, Bandung, Indonesia. *ekacahyaprima[at]upi.edu Abstract Energy scarcity is a challenge for humans to determine cheap, abundant, and environmentally friendly renewable energy. Renewable energy alternatives can develop in Dye-sensitized Solar Cells with photosensitizers extracted from natural materials. This study aims to determine the effect of quasi-solid state electrolytes on the efficiency of DSSC. The DSSC was fabricated using thin-film layer TiO2 as semiconductor photoelectrode, a photosensitizer Curcuma longa (turmeric), and two different electrolytes such as liquid electrolyte and quasi-solid state electrolyte that was made of 0.1 M lithium oxide, 0.05 iodine, 0.6 M 1-butyl-3-methylimidazolium iodine, 0.5 M 4-tetra-butyl pyridine, polyethylene oxide. Sample characterization had carried out using a UV-Vis Spectrophotometer to determine the absorbance spectrum of dye and a standard solar simulator AM 1.5 filter 100 mWcm2 to determine curve J-V and its electrical properties. The absorbance spectrum of Curcuma longa lies at a wavelength of 419 nm. The efficiency of DSSC using liquid and quasi-solid state electrolytes are 2.27% and 4.30%, respectively. The reason for that is the instability of the liquid electrolyte that causes the electron transfer cycle in the process of converting solar energy into electrical energy to be disrupted. Therefore, the use of quasi-solid state electrolytes that possess a high conductivity and material stability can improve the performance of DSSC as an alternative to renewable. Keywords: Dye-sensitized Solar Cells (DSSC)- Curcuma longa- Electrolytes- Quasi-solid State. Share Link | Plain Format | Corresponding Author (Prima Fitri Rusliani)

192	Physics	ABS-30
Calculation of Quantum Harmonic Oscillator Energies Using Path Integral Monte Carlo Nowo Riveli Universitas Padjadjaran Abstract Energy eigenvalues up to the second excited state of quantum harmonic oscillator are calculated by means of Path Integral Monte Carlo method. Application of the path integral method in simple problem serve as a demonstration of the principal and numerical technique of this important subject in quantum mechanics. This is particularly important for university students whom familiar only with the Schrodinger equation approach. The importance came from the fact that path integral is the foundation of the more advance theories in molecular to particle physics. In this paper, the explanation of path integral formulation for quantum harmonic oscillator will be given, along with the numerical Monte Carlo procedure to perform the calculation. The energies eigenvalues from the ground state up to the second excited states are obtained, with results that matches the analytic solutions. Keywords: quantum mechanics, harmonic oscillator, path integral, Monte Carlo Share Link | Plain Format | Corresponding Author (Nowo Riveli)

193	Physics	ABS-46
Meteor Flux Determination Using USG Fireball Data Judhistira Aria Utama (a*), Taufiq Hidayat (b), Lala Septem Riza (c) a) Department of Physics Education, Faculty of Mathematics and Natural Sciences Education, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudhi 229, Bandung 40154, Indonesia *j.aria.utama[at]upi.edu b) Astronomy Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia c) Department of Computer Science Education, Faculty of Mathematics and Natural Sciences Education, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudhi 229, Bandung 40154, Indonesia Abstract Every time the Earth is impacted by celestial bodies of various sizes, some produce bright meteors known as fireballs. This study utilizes observational data from USG sensors. From 871 fireball data, we selected 249 events accompanied by pre-impact velocity information. Using the available velocity information and calculated total impact energy, we have calculated the impact velocity, photometric mass, radius (assuming a density value that complies with the PE criteria), and an estimate of the absolute magnitude of the parent body outside the atmosphere. Based on the cumulative number of events with meteoroid masses equal to or bigger than m, the fireball flux value has been obtained. Keywords: Fireball flux, large meteoroid, small asteroid Share Link | Plain Format | Corresponding Author (Judhistira Aria Utama)

194	Physics	ABS-52
Groundwater Level Fluctuation and Prediction in The Jakarta Groundwater Basin Using Non Linear Autoregressive Exogenous (NARX) Dani Ruswandi (a*), Selly Feranie (a), Gumilar Utamas Nugraha (b) a) Physics Study Program, Indonesian University of Education Jl. Dr. Setiabudhi No. 229 Bandung 40154, Indonesia b) Research Center For Geotechnology, Indonesian Institute of Sciences Jl. Cisitu, Sangkuriang, Bandung 40135, Indonesia Abstract Groundwater in the Jakarta Groundwater Basin is the focus of Jakarta residents in meeting their clean water needs, therefore it is necessary to monitor the quantity of groundwater in the Jakarta Groundwater Basin. Accurate groundwater level prediction provides important information about groundwater quantitatively and provides an overview of the condition of the aquifer. One of the models that can be used to predict groundwater level is Neural Network Non Linear Autoregressive Exogenous (NARX). In this NARX model, there are several modeling parameters that must be optimized to produce accurate model predictions. These parameters include: Exogenous input, time delay and optimization algorithm. The results of the prediction of the output of the model will be tested for accuracy using the value of Root Mean Square Error (RMSE) and Coefficient of Determination (R2). The hydrological factors that will be used as exogenous input variables are potential evaporation, precipitation and humidity. The groundwater level that will be predicted is a monitoring well located at Citra Grand Cibubur, Jalan Alternative Cibubur Km. 4 Bekasi City, West Java Province, located at 6.38 South Latitude and 106.92 East Longitude. The modeling results show that the Bayesian Regularization (BR) optimization algorithm has the most optimal results with the time delay value being dominated by a value of 50, only the exogenous humidity input has a time delay of 100. The most optimal prediction results for each NARX model are: potential evaporation exogenous input with RMSE = 1.02 x 10-6 and R2 = 0.999632- input precipitation RMSE = 2.79 x 10-5 and R2 = 0.999426 - Input humidity with RMSE = 2.46 x 10-5 and R2 = 0.99952 - input humidity RMSE = 6.74 x 10-7 and R2 = 0.999726. From the results of forecasting the depth of the groundwater level of the 4 models have a value different depths but, all prediction models experiencing a trend graph down or to say the depth of ground water getting inside Keywords: Groundwater Level, Humidity, NARX, Potential Evaporation, Precipitation, Prediction Share Link | Plain Format | Corresponding Author (Dani Ruswandi)

195	Physics	ABS-56
GROUNDWATER BASIN CHARACTERISTICS BASED ON SATELLITE GRAVITY DATA Ariq A. Naufal (a*), Gumilar Utamas Nugraha (b), Selly Feranie (a) a) Department of Physics Education, Indonesia University of Education Jalan Dr. Setiabudi 229, Bandung 40154, Indonesia *ariqnaufal[at]upi.edu b) Geotechnology research and development, Lembaga Ilmu Pengetahuan Indonesia (LIPI) Jalan Sangkuriang, Kompleks LIPI, 40135, Dago, Kecamatan Coblong, Kota Bandung, Jawa Barat 40135 Abstract Groundwater Basin on Lombok Island is 3,490 km2 or 36.83% of the total area of the groundwater basin in Nusa Tenggara Barat Province (9,475 km2). Information of Groundwater Basin characteristics is very important in planning and development of an area in order to avoid groundwater degradation and environmental damage. The objective of this study is to examine the basement characteristics of Lombok Groundwater Basin by satellite gravimetry data using gravity methode. Complete Bouguer Anomaly (CBA) map, regional and residual anomaly maps and 2D models were created using Oasis Montaj version 8.3 software. Complete Bouguer Anomaly (CBA) values in the study area were in the range of 45.0 to 208.5 mGal. The average regional gravity anomaly response is at a depth of 43856.83 m, while the average residual gravity anomaly response is at a depth of 301.73 m. In forward modeling, there are seven rock formations found in the study area, namely, the Alluvium (Qa) formation with a density value of 2.29 gr/cc, the inseparable volcanic rock formation (Qhv) has a density value in the range of 1.67 - 2 ,5 gr/cc, the Lekopiko formation (Qvl) has a density value in the range of 2.04 - 2.84 gr/cc, the breccia and lava groups consist of the Kalibabak formation (TQb) and the Kalipalung formation (TQp) with a density value are in the range of 2.06 - 2.84 gr/cc, the Ekas formation (Tme) with a density value of 2.56 gr/cc, and basement rocks formed in the tertiary period with a density value of 2.44 gr/cc. Keywords: Gravity Data, Groundwater Basin, Lombok Groundwater Basin Share Link | Plain Format | Corresponding Author (ARIQ ABDURAHMAN NAUFAL)

196	Physics	ABS-58
ANALYSIS OF GROUNDWATER RECHARGE USING HYDROGRAPH SEPARATION AND WATER BUDGET: A CASE STUDY IN THE RIVER FLOW REGION OF CIUJUNG, PANOSONGAN VILLAGE, PAMAYARAN SUB DISTRICT, SERANG REGENCY Felia Nur Rohata(a*), Selly Feranie(b), Gumilar Utamas Nugraha(b) Departement of Physics Education, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudi No. 229, Bandung 40154, Indonesia Abstract Groundwater has been used in many countries to meet the needs of both the household, industrial, and agricultural sectors. The availability of groundwater is very dependent on how much recharge. The Ciujung Watershed as the largest river in Banten Province passes through Lebak, Pandeglang, and Serang Regencies. The increase in population in the Serang area demands adequate water supply, it is necessary to know the estimated quantity of groundwater recharge in the area. In this study, to obtain the estimated value of groundwater recharge using the water budget method and the hydrograph separation method, the researchers used the ESPERE software. The groundwater recharge value in the water bugdet for the Thornthwaite method is 443 mm/year, the Dingman method has an recharge of 446 mm/year and the Edijatno-Michel method has an recharge value of 444 mm/year. Meanwhile, the hydrograph separation method for the Wallingford method has an recharge of 459 mm/year and the Chapman method has an recharge of 558 mm/year. The groundwater recharge value is different from previous research, this is because there are several things related to the hydrological cycle and the hydrogeological cycle such as land use at the research location, slope conditions at the research site. Keywords: Groundwater, water budget, hydrograph separation method, ESPERE software, Thornthwaite, Dingman, Edjatno-Michel, Chapman, Wallingford, evapotranspiration, the river flow region of Ciujung, Serang Share Link | Plain Format | Corresponding Author (Felia Nur Rohata)

197	Physics	ABS-63
Characterization of Slope Movement Hazard at Sukatani-Ciganea Railway Section Using Slope Stability Analysis and Center of Mass Approaches Agrie Sri Yulia Fuji (a*), Selly Feranie (a), Adrin Tohari (b) a) Laboratory of Earth and Space Science, Department of Physics Education, Indonesia University of Education (UPI), Bandung, Indonesia *agriesriyf[at]upi.edu b) Research Center for Geotechnology, National Research and Innovation Agency (BRIN), Bandung, Indonesia Abstract The occurrence of rapid slope movements is common in man-made slopes during heavy rainfall in West Java Province, Indonesia, and may pose a risk to transportation infrastructures such as railways and highways. Mitigation of such a landslide risk requires an understanding of the characterization of the hazard. The study presented in this paper aims to characterize a slope failure hazard at a railway section located between Sukatani and Ciganea stations in Purwakarta Regency. The objectives of this study were to determine the sliding surface within the man-made slope using Slope/W and PyBIMstab software and to predict the run-out distance and the velocity of the slope movement using the center of mass approach. Both slope stability software shows a good agreement in determining the slip surface location within the slope at critical safety factors. Based on the center of mass approach, the slope failure is characterized by a run-out distance of about 24.5 m and a movement of more than 6.3 m/s. Therefore, the combination of long run-out and extremely rapid movement indicators would suggest a high risk to the railway traffic. Keywords: Centre of Mass- Landslide Hazard- Run-Out Distance- Landslide Velocity- Safety Factor- Slope Stability Analysis Share Link | Plain Format | Corresponding Author (Agrie Sri Yulia Fuji)

198	Physics	ABS-65
Prediction of Landslide Run-Out Distance and Velocity at Sidamukti Landslide Using Slope Stability and Center of Mass Approaches Afshih Lisaan Auliya (*a), Selly Feranie (a), Adrin Tohari (b) a)Laboratoy of Earth and Space Science, Department of Physics Education, Indonesia University of Education (UPI), Jl. Dr. Setiabudhi No. 229, Bandung, Indonesia *afshihlisaanauliya[at]upi.edu b)Research Center for Geotechnology, National Research and Innovation Agency (BRIN), Bandung, Indonesia Abstract A landslide occurrence may involve a rapid movement and poses a substantial risk to a densely populated area. Thus, an effort to reduce the substantial landslide risk requires knowledge of landslide velocity and run-out distance. The study presented in this paper attempts to predict the velocity and run-out distance of a potential landslide movement in the Sidamukti area, Bandung Regency, using two different slope stability analysis software and the center of mass approach. Results of slope stability analysis show that the estimated potential landslide masses obtained from PyBimstab software show a good agreement with those obtained by Geostudio software. Accordingly, the results of the center of mass analysis of both estimated landslide masses resulted in a run-out distance of approximately 60 m and a velocity of more than 5 m/s. Thus, the landslide in the study area can be classified as an extremely rapid landslide. Keywords: Center of mass, landslide, run-out distance, slope stability, velocity Share Link | Plain Format | Corresponding Author (Afshih Lisaan Auliya)

199	Physics	ABS-66
Application of Slope Stability Analysis and Center of Mass Approach to Predict Landslide Run-out Distance and Velocity at Cibitung Landslide, Bandung Regency Ghina Almira Salsabila (a*) , Selly Feranie (a), Adrin Tohari (b) a) Laboratoy of Earth and Space Science, Department of physics education, Indonesia University of Education (UPI), Jl. Dr. Setiabudhi No. 229, Bandung, Indonesia b) Research Center for Geotechnology, National Research and Innovation Agency (BRIN), Jl. Sangkuring, Cisitu Bandung, Indonesia Abstract A pre-existing landslide mass may be unstable and pose a hazard to critical infrastructures during heavy rainfall. Proper understanding of such a risk is predicated on an accurate characterization of the hazard. This paper presents the application of slope stability analysis and the center of mass approach to predict run-out distance and velocity of the unstable pre-existing landslide mass in Cibitung, Bandung Regency. The slope stability analysis was performed using the Pybimstab and Slope/W software. The results of the slope stability analysis using both software resulted in a nearly similar location of the sliding plane within the Cibitung landslide mass. Based on calculations using the center of mass approach, the Cibitung landslide may be classified as an extremely rapid movement with a velocity of up to 7.7 m/s and a run-out distance of up to 38 m. Thus, the landslide risk is still prominent in the study area. Keywords: Center of mass, landslide hazard, landslide velocity, run-out distance, slope stability Share Link | Plain Format | Corresponding Author (Ghina Almira Salsabila)

200	Physics	ABS-67
Run-Out Distance and Velocity Prediction of Landslide Movement in Pasirjambu, Bandung with pyBIMstab and GeoStudio Modelling Fuji Lestari (a*), Selly Feranie (a), Adrin Tohari (b) a) Laboratory of Earth and Space Science, Department of Physics Education, Indonesia University of Education (UPI), Bandung, Indonesia *fujilestari26[at]upi.edu b) Research Center for Geotechnology, National Research and Innovation Agency (BRIN), Bandung, Indonesia Abstract Rainfall-induced landslides are a very common occurrence in hilly regions in West Java Province. Efforts to mitigate the landslide hazard require knowledge about the landslide hazard characteristics. This paper presents the results of an analytical study aimed to determine the sliding surface and to predict the run-out distance and velocity of the Pasirjambu landslide, Bandung Regency. For these objectives, the slope stability analysis was performed using pyBIMstab and Slope/W software, and the run-out distance and velocity were predicted using the center of the mass approach. The results of slope stability analysis show that a good agreement of sliding surface location for a critical safety factor was obtained using both slope stability software. The predicted run-out distance and velocity indicate that the Pasirjambu landslide is likely to exhibit a long run-out of 87 m and move at a velocity of about 8.3 m/s. Thus, the Pasirjambu landslide hazard would pose a significant risk to the residents below the landslide zone. Keywords: Landslide Hazard- Landslide Velocity- Run-Out Distance- Slope Stability Analysis Share Link | Plain Format | Corresponding Author (Fuji Lestari)

201	Physics	ABS-111
Determination of Geohydraulic Parameter Values Through Empirical Approach Analysis of Geoelectrical Methods Study Case in Cikole Lembang Bandung Aisyah Dewi Rulyadi (a*), Gumilar Utamas Nugraha (b), Selly Feranie (a) a) Department of Physics Education, University Indonesia of Education, Jl. Dr. Setiabudi No. 229, Isola, Kec. Sukasari, Kota Bandung, 40154 b) Geotechnology Research and Development, Lembaga Ilmu Pengetahuan Indonesia Jl. Cisitu Sangkuriang Bandung, Jawa Barat, 40135 Abstract Measurement of hydraulic parameters is essential in and groundwater resources. The hydraulic parameters consist of hydraulic conductivity and transmissivity. Hydraulic conductivity can be interpreted as the potential for rocks to channel the water in units of length per time. While hydraulic transmissivity is the capacity of the aquifer to drain water throughout the rock in unit time. Hydraulic parameters are usually obtained using the conventional steps which called pumping test. This method caused more expensive and took days to observe. This paper presents a study to find best method from value of hydraulic parameters with and empirical in Cikole Lembang Bandung and compare the result with the reference value of the direct pumping test. Based on the result hydraulic conductivity and transmissivity data obtained by method of Niwas and Singhal was 323.20 until 1661.21 m/day. Meanwhile through the Heigold Approach, the result of hydraulic conductivity were 0.57 until 2.65 m/day. And the result of hydraulic transmissivity obtained by Niwas and Singhal method was 396.68 until 25175.71 m2/day. and Heigold method were 1.98 until 46.23 m2/day. From the data that has bees obtained using an empirical approach, compared with the pumping test it can be seen that Heigold method has a value with a range that is relatively closer to the value of the pumping test result. so it can conclude that Heigold method are more accurate to obtained the hydraulic parameter values. Keywords: Hydraulic parameters- hydraulic conductivity- transmissivity- Niwas and Singhal method- Heigold method Share Link | Plain Format | Corresponding Author (Aisyah Dewi Rulyadi)

202	Physics	ABS-113
Delineation of Saline Water Using the Geoelectric Method. Case Study : Rusun Damkar Cengkareng Iswi Dwi Nurvita*, Mimin Iryanti, Waslaluddin Pyhsics Program, Universitas Pendidikan Indonesia, Bandung, Indonesia *Coressponding author^s email: iswidnrvta[at]student.upi.edu Abstract Decreasing water quality is a serious problem because water that has decreased in quality can no longer be used to meet water needs for humans. Recovery of water quality degradation takes quite a long time. The migration of seawater to land is one of the factors that can disrupt the quality of groundwater. In the research area, there has been a decrease in the groundwater level with saline water. The purpose of this study was to determine the delineation and depth of the saline water table in the study area. The method used in this study is the resistivity geoelectric method with the Wenner-Schlumberger configuration. Data acquisition using ARES geoelectric tools. Measurements were carried out with 3 passes. Data processing was carried out using RES2DINV and Voxler software with the results in the form of subsurface resistivity images. The results obtained from processing and interpretation are the resistivity values in the study area ranging from 0.16 to 19.8 ohm.m. In the 2-D subsurface resistivity cross-section, the distribution of saline groundwater below the surface is estimated to a depth of 43.6 meters with a resistivity value of 0.16-5.76 ohm.m. The resistivity value of 8.56-14.2 ohm.m was identified as sandy silt soil, and the resistivity value in the range of 17-19.8 ohm.m was a material of fine to medium sand, gravel, and clay. It could be concluded that saline water was suspected as a result of seawater intrusion. The amount of saline water content in the aquifer, where freshwater has been contaminated by saline water. Keywords: Geoelectric Method, Resistivity, Saline Water, Wenner-Schlumberger Share Link | Plain Format | Corresponding Author (Iswi Dwi Nurvita)

203	Physics	ABS-114
Earthquake Hypocenter Relocation Using Double-Difference Method in Central Java Muhammad Alif Fauzan Aolindar (a*), Kartika Hajar Kirana (a), Pepen Supendi (b), Mia Uswatun Hasanah (a), Rayi Purbayanti (c) a) Departement of Geophysics, Universitas Padjadjaran, Jatinangor 45363, Indonesia *mfauzan.aolindar[at]gmail.com b) Agency for Meteorology, Climatology, and Geophysics (BMKG), Jakarta, 10720, Indonesia c)Junior High School Satu Atap 3 Sobang, Banten 42365, Indonesia Abstract Central Java is one of the areas with high seismic activity caused by the subduction of the Indo-Australian and Eurasian plates. The tectonic setting of this area needs to be known by determining the hypocenter location of the earthquakes. To produce an accurate hypocenter, the relocation of the hypocenter was carried out using the Double-difference (DD) method. The data used in this study consist of P- and S-waves arrival-time taken from the Agency for Meteorology, Climatology, and Geophysics (BMKG) for the time period January 2010 to December 2018. Totally, 755 out of 780 earthquakes were successfully relocated and the travel-time residuals are close to zero. Based on the relocated seismicity pattern, there are shows the presence of a back-thrust fault beneath the southern part of central Java. We also identified a seismicity gap beneath this area in agreement with previous study as a hole in the subducted slab in the upper mantle. In addition, we found the earthquakes cluster in eastern part of the Opak fault with a lineament in the southwest-northeast direction which is estimated to be a ^new fault^. Keywords: Earthquake, Hypocenter Relocation, Double-Difference, Central Java. Share Link | Plain Format | Corresponding Author (muhammad alif fauzan aolindar)

204	Physics	ABS-126
Deep learning application in Earthquake related studies in Indonesia: A review Lina Handayani Indonesian Institute of Sciences Abstract The basic of deep learning in earth sciences is statistics and geophysics. And recently, the studies in this area have been increasing, for the availability of a high volume of open access data. DL is applicable in all geophysical methods, which is one of the approaches to simplify or to accelerate some processes, or to have more elaborate results. The application for ^artificial intelligence^ approaches in earthquakes has been used since the computation was available. Two or three decades ago, we approach the problem with fuzzy logic and neural networks. Recently, we used deep learning, which has at least three layers of neural networks. In this paper, we review the advance of the usability in several Earthquake related studies. Earthquake prediction is one of the most desired results. With advanced methods and more data, we expected better results. However, decades of studies indicate small advancement. The closest outcome is forecasting the aftershocks. However, some studies offered good results in speedy and more accurate seismic arrival waves processing. In addition, one applicable ready result is the study of hazard and risk assessment. Keywords: deep learning, earthquake, prediction Share Link | Plain Format | Corresponding Author (Lina Handayani)

205	Physics	ABS-133
Study of Phase Purity and Magnetic Properties of Eu1.86Ce0.14CuO4 Synthesized by Solid-State Method without Annealing Process Yuyu R. Tayubi, Selly Feranie, Wiendartun Department of Physics Education, Faculty of Mathematics and Natural Sciences, Universitas Pendidikan Indonesia Abstract The samples of Eu2-xCexCuO4 (ECCO) with x=0.14 (Eu1.86Ce0.14CuO4) has been synthesized by the solid reaction method without annealing in order to study the purity and magnetic properties of ECCO samples. The sample is covered with CuO to prevent excess oxygen entering the sample. The purity and magnetic propertirs were investigated by x-ray Diffraction (XRD) and susecptibility measurements. From the XRD analysis, it was found that the purity of ECCO phase was 84.8% with tetragonal structure of T^ for x = 0.14. These results show that the synthesis method with CuO covering has succeeded in synthesizing materials with high purity. From the susceptibility measurements, the trace of superconductors was not observed in sample. It shows that the Eu1.86Ce0.14CuO4 material has paramagnetic properties. It is probably the existence of excess oxygen, which was not fully absorbed by CuO Covering. Keywords: Crystal structure, CuO covering, Eu1.86Ce0.14CuO4, Magnetic susceptibilitas, Phase purity. Share Link | Plain Format | Corresponding Author (Yuyu Rachmat Tayubi)

206	Physics	ABS-188
Novel Study on Bone-Plate Finite Element Analysis: Which Software Produce the Truest number? Talitha Asmaria(a*)- Richard Lee(b)- Andy Daniswara(b)- Dita Mayasari (c)Yudi Nugraha(a)- Fendy Rokhmanto(a)- Ika Kartika(a) a) Research Center for Metallurgy and Materials, Indonesian Institute of Sciences, Building 470, Puspiptek Area, Setu, South Tangerang 15314, Indonesia b)Biomedical Engineering Study Program, International University of Liaison Indonesia, The Breeze BSD, South Tangerang 15345, Indonesia c) Department of Biomedical Engineering, University of Dian Nuswantara, Jalan Imam Bonjol 207, Semarang 50131, Indonesia Abstract Finite element analysis (FEA) have been widely and effectively used to predict the behavior of a part or assembly prior to manufacturing process. Several software is good for computerizing the FEA process. However, based on FEA running in types of software, the difference comes in huge number. Until today, there is no one literature discussing which software that close to the real number on physical tests. The accuracy of prior computational prediction, particularly in medical devices manufactures including bone-plate, is highly needed to minimize mistakes and reduce expenditure. This paper aims to verify the most accurate one from the finite element analysis that has been run in four software. Researcher conducted two methods of using mathematical approach and the hardness Rockwell C test. A three-dimensional (3D) model, allocates for bone-plate implant, was made and printed using Ti6Al4V. FEA of a bone plate cut performed in COMSOL, Ansys, Abaqus, and Inventor using a precise constrained and load number of 1471 N. The average von Mises stress (VMS) for each software is 1.625e-03 GPa for COMSOL, 1.98865e-01 GPa for ANSYS, 1.0895e-6 GPa for Abaqus, and 2.071e-02 GPa for Inventor. The hardness Rockwell C test shows in five iterations using 150 Kgf and produces 1.595 GPa. Among all software, in this experiment, Ansys presents as the closest result compared to manual calculations and the hardness Rockwell C test. Besides giving an authentic FEA software option, a claim that Ansys can produce the truest number need further confirmation using different models and methods. Keywords: Finite Element Analyis- COMSOL- Ansys- Abaqus- Inventor- Hardness Rockwell C Share Link | Plain Format | Corresponding Author (Talitha Asmaria)

207	Physics	ABS-193
Synthesis and Characterization of Activated Carbon from Candlenut Shells Using Various Types of Activators Sahrul Hidayat, Sarifah Mudaim, Otong Nurhilal and Risdiana Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang km 21 Jatinangor, Sumedang, West Java, Indonesia 45363. Abstract In this research, the synthesis of porous carbon from candlenut shell has been carried out using various types of activators in the chemical activation process. From SEM (Scanning Electron Microscope) images can be observed that the carbon activation process has occurred which was indicated by the appearance of many pores on the surface of carbon. Characterization of BET (Brunauer-Emmett-Teller) which clarified with the International Union of Pure and Applied Chemistry (IUPAC) isotherm curves was indicated that the porous carbon is dominated by mesoporous with a pore size around 2-50 nm. From BET characterization also can be determined the surface area of activated carbon using activator of H3PO4 was around 636 m2/g, activator of ZnCl2 was around 477 m2/g and activator of KOH was around 681 m2/g. Based on this research can be observed that the activator of KOH produces a larger carbon surface area than the other types of activators. Keywords: Activated Carbon, Candlenut Shells, Mesoporous Share Link | Plain Format | Corresponding Author (Sahrul Hidayat)

208	Physics	ABS-221
Estimation of the Characteristics of Cikareteg Landslide Based on Electric Resistivity Tomography Rofiq Fadillah Awal(a*), Selly Feranie(a), Adrin Tohari(b), Dadan Dani Wardhana (a) Laboratory of Earth and Space Science, Physics Department FPMIPA UPI, Jl. Dr. Setiabudhi No. 229, Bandung (b) Research Center for Geotechnology (P2G-LIPI), Komplek LIPI Jl. Sangkuriang, Bandung *Rofiqawal7[at]gmail.com Abstract A toll road segment in Bogor, West Java, was constructed in an old landslide zone in the Cikareteg area. Knowledge of the slip surface is necessary to mitigate the hazard associated with the possible reactivation of the landslide. This paper presents the results of the resistivity tomography survey to estimate the depth and geometry of the landslide slip surface using dipole-dipole configuration. Based on the resistivity tomography, the landslide is estimated to involve a non-circular sliding plane located within a thick soil layer with low resistivity at a depth of less than 10 m below the slope surface. Thus, a thick landslide material still exists in the vicinity of the bridge, posing an imminent hazard to the toll road. Keywords: landslide, sliding plane, resistivity tomography, dipole-dipole Share Link | Plain Format | Corresponding Author (Rofiq Fadillah Awal)

209	Physics	ABS-235
An Investigation Into Reverse Engineering Process and Fabrication for Fenestrated Aneurysm Clip Talitha Asmaria(a*)- Made Subekti Dwijaya(a)- Joko Triwardono(a)- Andika Widya Pramono (a)- Eka Julianta Wahjoepramono(b)- Fendy Rokhmanto(a)- Ika Kartika(a) a) Research Center for Metallurgy and Materials, Indonesian Institute of Sciences. Building 470, Puspiptek Area, South Tangerang 15314, Indonesia *talitha.asmaria[at]lipi.go.id b) Faculty of Medicine, Pelita Harapan University, MH Thamrin Boulevard 1100, Tangerang 15811, Indonesia c) Neurosurgery Department, Siloam Hospital Karawaci, Jl. Siloam No.6, Bencongan, Kelapa Dua, Tangerang 15811, Indonesia Abstract Surgical treatment of aneurysms requires special instrumentation. Fenestrated clips are useful in cases of limited approach angles and tight workspaces. This paper presents the design concept of a fenestrated titanium aneurysm clip using reverse engineering and specific fabrication techniques. It is starting with obtaining a 3D model of the fenestrated titanium aneurysm clip which is then used to determine the torsional spring parameters. Based on the dimensions of the clip model obtained, it is planned to develop a fabrication technology in the form of jig design, dies, selection of production machines and tools. Reverse engineering models of aneurism clip shows a high similarity in geometrical and mechanical testing. The weakness of this study is the inability to mimicking the blade tip surface. In future work, exploration about blade tip surface machining needs to be improved. Keywords: Fenestrated Aneurysm Clip- Reverse Engineering- Neurosurgery- Share Link | Plain Format | Corresponding Author (Talitha Asmaria)

210	Physics Education	ABS-1
Analysis of students^ critical thinking skill on optical instruments through worksheet-based inductive learning model A Suparman (a*), A Samsudin(a), I Kaniawati (a), Fakhruddin (b), and V Lantik (b) a) Departemen S2 Pendidikan Fisika, Universitas Pendidikan Indonesia, Jl. Dr. Setia Budhi No. 229, Bandung 40154, Indonesia b) Departemen Pendidikan Fisika, Universitas Nusa Cendana, Jl. Adi Sucipto, Penfui, Klp. Lima, Kota Kupang, Nusa Tenggara Timur, 85001, Indonesia Abstract Physics learning in the class has not been able to improve student^s 21st skills due to the learning process still focusing on teachers and the lack of using innovative and variative teaching models. Critical thinking skill is one of the 21st skills which will be analysed in this study after utilizing the Inductive learning model by assisting student worksheet towards Student^s critical thinking skill. This study employed a quasi-experimental with non-equivalent control group design at State Senior High School in Kupang, Nusa Tenggara Timur, Indonesia. The research subjects consisted of 26 students on experimental class and 29 students on control class. Student^s critical thinking skill was measured through 7 essay question items which had been measured their validity and reliability on the Optic Tools of 11th grade students. The data were firstly analysed by Bartlett^s test and Chi Square test to show that they were qualified for further test. Furthermore, the hypothetical test results were conducted by comparing n-gain values of student^s critical thinking skills before and after conducting inductive learning model with student work sheet which were different. Therefore, it seems that the application of the model on experimental class could effectively and significantly enhance student^s critical thinking skills. Keywords: critical thinking- Innovative models- Inductive Learning Model- worksheet Share Link | Plain Format | Corresponding Author (Andreas Suparman)

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