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All Journal CAUCHY: Jurnal Matematika Murni dan Aplikasi AdMathEdu : Jurnal Ilmiah Pendidikan Matematika, Ilmu Matematika dan Matematika Terapan Kubik Jurnal Sains Matematika dan Statistika Edumatsains NUMERICAL (Jurnal Matematika dan Pendidikan Matematika) Sinkron : Jurnal dan Penelitian Teknik Informatika Desimal: Jurnal Matematika BAREKENG: Jurnal Ilmu Matematika dan Terapan Justek : Jurnal Sains Dan Teknologi JURNAL TEKNIK INFORMATIKA DAN SISTEM INFORMASI Zeta - Math Journal Jurnal Pendidikan Matematika (JUDIKA EDUCATION) NUSANTARA : Jurnal Ilmu Pengetahuan Sosial Zero : Jurnal Sains, Matematika, dan Terapan AXIOM : Jurnal Pendidikan dan Matematika JURNAL MathEdu (Mathematic Education Journal) JOURNAL OF SCIENCE AND SOCIAL RESEARCH Saintifik : Jurnal Matematika, Sains, dan Pembelajarannya M A T H L I N E : Jurnal Matematika dan Pendidikan Matematika Math Educa Journal Progresif: Jurnal Ilmiah Komputer JURNAL PEMBELAJARAN DAN MATEMATIKA SIGMA (JPMS) Proximal: Jurnal Penelitian Matematika dan Pendidikan Matematika JOURNAL OF INFORMATION SYSTEM RESEARCH (JOSH) SEPREN: Journal of Mathematics Education and Applied Community Development Journal: Jurnal Pengabdian Masyarakat Theta : Jurnal Pendidikan Matematika Jurnal Lebesgue : Jurnal Ilmiah Pendidikan Matematika, Matematika dan Statistika Jurnal Pengabdian kepada Masyarakat Nusantara KUBIK: Jurnal Publikasi Ilmiah Matematika FARABI: Jurnal Matematika dan Pendidikan Matematika Algebra : Jurnal Pendidikan, Sosial, dan Sains Mathematics and Applications (MAp) Journal Humantech : Jurnal Ilmiah Multidisiplin Indonesia Jurnal IPTEK Bagi Masyarakat Journal of Mathematics and Scientific Computing With Applications Relevan Jurnal Informatika Teknologi dan Sains (Jinteks) Edu Society: Jurnal Pendidikan, Ilmu Sosial dan Pengabdian Kepada Masyarakat Prisma Sains: Jurnal Pengkajian Ilmu dan Pembelajaran Matematika dan IPA IKIP Mataram Abdimas Indonesian Journal Bulletin of Applied Mathematics and Mathematics Education International Conference on Sciences Development and Technology JS (Jurnal Sekolah) Jurnal Bayesian : Jurnal Ilmiah Statistika dan Ekonometrika JME APPA : Jurnal Pengabdian Kepada Masyarakat Faedah: Jurnal Hasil Kegiatan Pengabdian Masyarakat Indonesia Jurnal Pengabdian Masyarakat Algebra Indonesia Bergerak: Jurnal Hasil Kegiatan Pengabdian Masyarakat Relevan : Jurnal Pendidikan Matematika
Riri Syafitri Lubis
Universitas Islam Negeri Sumatera Utara, Medan, Indonesia
Religion Agriculture, Biological Sciences & Forestry Humanities Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Engineering Environmental Science Health Professions Industrial & Manufacturing Engineering Languange, Linguistic, Communication & Media Law, Crime, Criminology & Criminal Justice Library & Information Science Materials Science & Nanotechnology Mathematics Mechanical Engineering Medicine & Pharmacology Physics Public Health Social Sciences Transportation Other

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Probabilistic Model of Back Order Policy on Dodol Pulut Raw Material Inventory Control With Linear Programming Br Siahaan, Erika Handayani; Riri Syafitri Lubis
KUBIK Vol 10 No 1 (2025): IN PRESS
Publisher : Jurusan Matematika, Fakultas Sains dan Teknologi, UIN Sunan Gunung Djati Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15575/kubik.v10i1.49121

Abstract

The high production costs of Dodol Pulut Raya further emphasize the importance of implementing a systematic, measurable, and effective inventory control strategy to maintain profitability, operational efficiency, and long-term business stability. This study applies the Probabilistic Back Order Policy Model combined with the Simplex Linear Programming method to determine the most optimal raw material management policy, taking into account demand uncertainty, supply variability, and the risk of stock shortages that could disrupt production smoothness. This approach comprehensively integrates precise safety stock calculations to minimize stockouts, reduce production delays, and ensure raw material availability so that customer needs can be consistently, timely, and sustainably met. The analysis results show that the implementation of this model can significantly reduce annual production costs from IDR 509,941,040 to IDR 338,719,300, resulting in cost efficiency of IDR 171,221,740 per year. This finding demonstrates the model's effectiveness in minimizing total inventory costs while enhancing competitiveness and operational sustainability. Additionally, this study provides a practical framework for small and medium-sized enterprises facing fluctuating demand, balancing service levels, safety stock, and overall cost optimization.
Optimizing the use of sewing materials to maximize production output Rakhmawati, Fibri; Rifki, Mhd Ikhsan; Husein, Ismail; Cipta, Hendra; Lubis, Riri Syafitri; Sari, Rina Filia
Abdimas Indonesian Journal Vol. 5 No. 2 (2025)
Publisher : Civiliza Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59525/aij.v5i2.1043

Abstract

This Community Service Program aims to optimize the use of sewing materials to maximize production output at Rumah Jahit Nila through the application of a linear programming model in the allocation and use of sewing materials in planning and maximizing production output. The implementation methods include mapping processes and data requirements and formulating a linear programming model relevant to the scale of Nila Sewing House MSMEs, as well as training and live demonstrations using QM as software to determine optimization solutions. The evaluation was conducted on 15 participants using a 1–4 Likert scale instrument with four assessment indicators, namely, training content, presenter's subject-matter expertise, event facilities, and benefits of the program. Descriptive analysis showed an overall average of 3.43 on a scale of 4, with a percentage level of 85.8%, which is in the Very Good category. In order, the indicator achievements are Presenter’s Subject-Matter Expertise = 3.53 (88.33%), Benefits of the Program = 3.47 ( 86.67%), Training Content = 3.40 (85.00%), and Event Facilities = 3.33 (83.33%). These results confirm that the competence of the speakers and the relevance of the benefits are the main strengths, while the content and facilities of the activities are areas for priority improvement. This program has successfully improved participants' technical capacity in modeling and implementing linear program-based raw material optimization, while also providing a foundation for operational implementation to reduce waste and increase throughput.
Penerapan Logika Fuzzy Pada Pengendalian Mutu Minyak Kelapa Sawit dengan Metode Statistical Quality Control di PKS Ptpn II Pagar Merbau Auliya Ramadhani, Dhea; Lubis, Riri Syafitri; Widyasari, Rina
Proximal: Jurnal Penelitian Matematika dan Pendidikan Matematika Vol. 8 No. 4 (2025): Volume 8 Nomor 4 Tahun 2025
Publisher : Universitas Cokroaminoto Palopo

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30605/proximal.v8i4.7151

Abstract

Pengendalian mutu Crude Palm Oil (CPO) merupakan faktor krusial untuk menjaga standar kualitas dan daya saing PKS PTPN II Pagar Merbau. Metode konvensional seperti Statistical Quality Control (SQC) umum digunakan untuk memantau stabilitas proses produksi melalui peta kendali. Namun, SQC memiliki keterbatasan dalam menangani data yang bersifat ambigu atau samar (ketidakpastian) karena pendekatannya yang crisp (tegas), yang hanya mengklasifikasikan status proses sebagai "terkendali" atau "di luar kendali". Penelitian ini bertujuan untuk merancang dan mengimplementasikan sistem pengendalian mutu CPO dengan mengintegrasikan metode SQC dan Logika Fuzzy. Penelitian ini menggunakan data parameter mutu utama CPO, seperti Asam Lemak Bebas (ALB), Kadar Air , dan Kadar Kotoran yang dianalisis terlebih dahulu menggunakan peta kendali SQC untuk menentukan batas-batas kontrol statistik. Selanjutnya, data tersebut dijadikan variabel input untuk Sistem Inferensi Fuzzy (FIS). Logika Fuzzy digunakan untuk memetakan data input yang ambigu ke dalam himpunan fuzzy (misalnya: Rendah, Normal, Tinggi) dan memprosesnya melalui basis aturan (IF-THEN) untuk menghasilkan output kualitatif berupa status mutu CPO (misalnya: Sangat Baik, Baik, Cukup, Buruk). Hasil penelitian menunjukkan bahwa penerapan Logika Fuzzy mampu memberikan penilaian status mutu yang lebih fleksibel, adaptif, dan informatif dibandingkan metode SQC murni. Sistem ini dapat memberikan peringatan dini yang lebih sensitif terhadap pergeseran kecil dalam proses, sehingga membantu manajemen PKS PTPN II Pagar Merbau dalam mengambil keputusan korektif yang lebih cepat dan tepat untuk menjaga konsistensi mutu CPO.
BLACK TEA GRADE CLASSIFICATION USING PROBABILISTIC NEURAL NETWORK (PNN) Sari, Evi Indah; Prasetya, Nurul Huda; Lubis, Riri Syafitri
Journal of Mathematics and Scientific Computing With Applications Vol. 2 No. 1 (2021)
Publisher : Pena Cendekia Insani

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.53806/jmscowa.v2i1.42

Abstract

North Sumatera tea is known as black tea, one which is produced by PT Perkebunan Nusantara IV Unit Bah Butong which produce 16 types of black tea. This research aims to classify black tea grades using Probabilistic Neural Network method and determine the accuracy value of black tea classification using Probabilistic Neural Network method. Data used are data of characteristics of 16 black tea types with the attributes id, types of tea, colour density, particel weight, particel size and particel shape. To get the best accuracy result, training data and testing data are divided using K-Means Clustering. Futhermore, classificy the testing data using Probabilistik the result obtained a grade 1 classification class totaling 7 records with a brownish black appearance and granutes particel, grade 2 totalling 7 record with a beownish appearance and grade 3 totaling 2 records with reddish appearance and not determine its shape and obtain an accuracy value of 80,00%.
ANALYSIS OF THE VISIT RATE AT THE IRIAN MARELAN SUPERMARKET DURING THE COVID-19 PANDEMIC Kartika , Dinda; Lubis, Riri Syafitri; Widyasari, Rina
Journal of Mathematics and Scientific Computing With Applications Vol. 2 No. 1 (2021)
Publisher : Pena Cendekia Insani

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.53806/jmscowa.v2i1.44

Abstract

Currently our country is experiencing a disaster due to a very dangerous virus that has claimed many lives or commonly referred to as COVID-19. The government had limited the operating hours of public places to prevent the spread of the virus. This has resulted in disruption of economic activities, one of which is the Irian Supermarket & Dept Store. This research was conducted to determine how the level of visits to Irian with the Spearman Rank Correlation method. From the results of the Spearman Rank correlation analysis carried out, the calculated value is 0.307 with a positive sign which indicates a low level of relationship and it is concluded that the level of visits is not influenced by the application of health protocols but is influenced by facilities and sales techniques, This can also be seen in the results of the t-test. The result of count obtained is 3.20 shows that the variable level of visits has a significant correlation with purchasing decisions.
M/G/1 QUEUE WITH SINGLE WORKING VACATION AND VACATION INTERRUPTION TO THE EXPECTED VALUE OF MANY CUSTOMERSAT BANK MUAMALAT SUKARAMAI SUB-BRANCH OFFICE Susilowati, Rahmi; Lubis, Riri Syafitri; Widyasari, Rina
Journal of Mathematics and Scientific Computing With Applications Vol. 2 No. 1 (2021)
Publisher : Pena Cendekia Insani

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.53806/jmscowa.v2i1.46

Abstract

Queuing occurs because the number of customers who arrive exceeds the service capacity, so customers have to queue to be served. A working vacation is a server serving at a slower speed. The server can return to a busy period with a (vacation interruption) opportunity or continue a vacation with a opportunity, with the single working vacation and vacation interruption method. The objective of this study is to obtain the effect of service rate and the expected value of the number of customers in the system after the departure of one customer and minimize operating costs during the vacation period (pause). The M / G / 1 queue study with Single Working Vacation and Vacation Interruption found that the average arrival rate (?) was 0.069 and the average service rate was 1.5 with the average vacation time (?) was 0, 41 and the average value of the expected number of customers in the system is 0,19 and for operating costs it can also be drunk to -16,38. This means that the queuing system is not efficient, due to the low level of server activity and the expected value of the number of customers in the system is 0 or there are no customers waiting in the system.
POPULATION PROJECTION AND FACTOR ANALYSIS AFFECTING POPULATION GROWTH IN THE CITY MEDAN USING NON LINEAR TRENDS POLYNOMIC METHOD Pertiwi, Fina Nur; Lubis, Riri Syafitri; Widyasari, Rina
Journal of Mathematics and Scientific Computing With Applications Vol. 2 No. 1 (2021)
Publisher : Pena Cendekia Insani

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.53806/jmscowa.v2i1.47

Abstract

Non-linear trend is a measure of trend that has a model with quadratic equations, cubic and so on. The purpose of this research is to determine the population projection in Medan using a non-linear trend of the polynomial method (parabolic trend / quadratic trend) and to determine the factors that influence population growth in the city of Medan. From the results of data processing using the non-linear trend of the polynomial method, it is obtained that the projected number of population in 2029 will be 2645501 people, with The total male population is 1314713 and the female population is 1330788. When compared with the population in previous years, it can be seen that until 2029 the population in Medan will increase. Based on the research results from the factor analysis, it is known that the factors that are formed from the factor analysis process can be concluded that all the factors formed affect the population growth rate of Medan. The factors formed are birth (fertility), death (mortality) and migration.
IMPLEMENTATION OF THE GENERALIZED SPACE TIME AUTOREGRESSIVE (GSTAR) MODEL IN THE CASE OF THE SPREAD OF CORONAVIRUS IN THE DISTRICT CITY OF NORTH SUMATRA Nasution, Alfina Febriani; Lubis, Riri Syafitri; Widyasari, Rina
ZERO: Jurnal Sains, Matematika dan Terapan Vol 6, No 2 (2022): Zero: Jurnal Sains Matematika dan Terapan
Publisher : UIN Sumatera Utara

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30829/zero.v6i2.14785

Abstract

Corona Virus Disease 2019 (COVID-19) is a new virus that can be transmitted and the worst impact is death. Covid-19 first appeared in Wuhan, China and eventually spread throughout the world, one of which was North Sumatra Province. The spread of Covid-19 cases was quite rapid, until finally the World Health Organization (WHO) declared the Covid-19 case a pandemic. Based on the conditions that occurred, this final project discusses the prediction of positive cases of Covid-19 in five locations in North Sumatra using the Generalized Space Time Autoregressive (GSTAR) model. Considering that Covid-19 spreads very easily, it does not only depend on time but also the proximity between locations, so the GSTAR model is quite good to use in predicting it, assuming the parameters between locations are heterogeneous. The estimation used is OLS with inverse distance weight. This study aims to determine the best GSTAR model and forecast positive cases of Covid-19 at five locations in North Sumatra. The results show that the best GSTAR model in this study is -OLS with an inverse weight of distance with forecasting results for the next 10 days in May 2022.
Solusi Numerik Model Verhulst Pada Estimasi Hasil Panen Melalui Perkembangan Produksi Padi dan Beras dengan Metode Milne-Simpson Arjuna, Dimas Bagus; Lubis, Riri Syafitri
Journal of Information System Research (JOSH) Vol 5 No 2 (2024): Januari 2024
Publisher : Forum Kerjasama Pendidikan Tinggi (FKPT)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47065/josh.v5i2.4857

Abstract

The aim of this research is to develop a numerical solution using the Verhulst model to estimate paddy and rice production in North Sumatra. The Milne-Simpson method is used in this research to provide an efficient numerical approach in solving the model, with the aim of increasing the accuracy and effectiveness of estimating rice plant growth and rice production in the North Sumatra region through a systematic and computational approach. In this research, the Milne-Simpson method is used to estimate paddy and rice production results in the following year. The results show that the estimated rice production in North Sumatra Province is 2,086,590.76 tons in 2023 and 2,098,149 tons in 2024. Meanwhile, the estimated rice production in North Sumatra Province is 1,198,678.38 tons in 2023 and 1,207,384 tons in 2024. The results of this research also show that every year rice production increases by an average of 13,430 and rice production increases by an average of 8,254. Therefore, it can be seen that the estimated paddy and rice production in North Sumatra Province for 2023-2024 has increased.
Probabilistic Model of Back Order Policy on Dodol Pulut Raw Material Inventory Control With Linear Programming Br Siahaan, Erika Handayani; Riri Syafitri Lubis
KUBIK Vol 10 No 1 (2025): IN PRESS
Publisher : Jurusan Matematika, Fakultas Sains dan Teknologi, UIN Sunan Gunung Djati Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15575/kubik.v10i1.49121

Abstract

The high production costs of Dodol Pulut Raya further emphasize the importance of implementing a systematic, measurable, and effective inventory control strategy to maintain profitability, operational efficiency, and long-term business stability. This study applies the Probabilistic Back Order Policy Model combined with the Simplex Linear Programming method to determine the most optimal raw material management policy, taking into account demand uncertainty, supply variability, and the risk of stock shortages that could disrupt production smoothness. This approach comprehensively integrates precise safety stock calculations to minimize stockouts, reduce production delays, and ensure raw material availability so that customer needs can be consistently, timely, and sustainably met. The analysis results show that the implementation of this model can significantly reduce annual production costs from IDR 509,941,040 to IDR 338,719,300, resulting in cost efficiency of IDR 171,221,740 per year. This finding demonstrates the model's effectiveness in minimizing total inventory costs while enhancing competitiveness and operational sustainability. Additionally, this study provides a practical framework for small and medium-sized enterprises facing fluctuating demand, balancing service levels, safety stock, and overall cost optimization.
Co-Authors Adisty, Fahliza Ahmad Sugarda Ainun Palihah Ananda, Lyra Anggi Pranata Annisa, Nur Alvi Aprilia, Rima Arjuna, Dimas Bagus Aslam, Fazri Aulia Turrizqiya Auliya Ramadhani, Dhea Batu, Annisa Rajaq Lumban Batubara, Fikri Husin Bella Syahrani Nasution Blaster, Irena Br Siahaan, Erika Handayani Cynthia, Mayang Modelina Dara Nurul Hasnah dewi, mutia hatina Dian Darmawan Didik Santoso Didik Santoso Dinda Renata Cecilia Dwi Haprida Ningsih Elma Dwi Ariana Aprilia Zam Fachrur Rozi Fadhliyah, Annisa Fadilatus Sahraini Siregar Fadillah, Yanna Rezki Fajriana, Fajriana Farwansyah, Mhd Rio Fatmawati, Ayu Isnaini Fernando, Anjas Fuja Nauli Pasaribu Giawa, Freddy Gishela Agra Moukia Gurusinga, Ditha Aulia Harleni, Harleni Harleni, Silvia Hasibuan, Elpita Sari Hazizah, Salsabillah Hendra Cipta Heni Pujiastuti Ilham Salim Siregar Ilham Syaputra Indah Kholila Indah, Windi Rezeki Ir Zulkarnain, Ayu Najmita Binti Irena Blaster Ismail Husein, Ismail Kartika , Dinda Khairun Nikmah Lisa Setia Ningsih M Agung Pradana Manurung, Silvi Khairiyah Maudya Nur Azura Mhd Ikhsan Rifki Mohammad Badri Muhammad Arfie Munawar Muhammad Farhan Mingka Muliawan, Hari Nadhila, Nurul Nasution, Alfina Febriani Nasution, Dafa Al Qifti Nasution, Hamidah . Neliwati Neliwati Nenna Irsa Syahputri Nina Amanda nova audry utami Nurmadani Nurmawati Nurmawati Nurmawati Nurul Nadhila Nusantara, Badai Charamsar Oktaviana Oktaviana Palihah, Ainun Pertiwi, Fina Nur Pohan, Siti Rolizah Pradana, M Agung Prasetya, Nurul Huda Pratiwi, Miftah Pulungan, Ahmad Fauzan Putri Harahap, Rahmelia Rahmat Darmawan, Rahmat Rakhmawati, Fibri Rambe, Muhammad Vikry Rezky Riani Dwi Lestari Ricka Afriani Rima Aprilia Rima Aprilia Rina Filia Sari Rina Filia Sari, Rina Filia Rina Sari Filia Rina Widyasari Ritonga, Nurhalimah Rivani Kabrina Br Surbakti Rizkina, Ayu Rizky Mulyani Ropiqoh, Ropiqoh Ropiqoh, Ropiqoh Rusydi Ananda Ruth Mayasari Simanjuntak Sahraini Siregar, Fadilatus Sajaratud Dur Samsudin, Samsudin Sari, Evi Indah Serdano, Akbar Sintia Agustina Siregar Siregar, Evi Borliana Siregar, Evi Borliana Siregar, Fadilatus Sahraini Siregar, Tanti Jumaisyaroh Siti Jubaidah Siti Zunaida Nasution Suci Permata Sari Suendri, Suendri Sulaiman Ananda Harahap Supiah Supiah Susanti, Komaria Susilowati, Rahmi Suzana, Yenny Syafitri, Ellysa Syahfitri, Fatharani Syahputra, Bayu Teza Syahputri, Linna Syahputri, Nenna Irsa Syarah, Fatmah Tanti Jumaisyaroh Siregar Tri Handayani Tri Lutfiah Wardah Turrizqiya, Aulia Utami, Ristika Dian Vani Hajari Wenny Marta Dolok Saribu Widyasari, Rina Widyasari, Rina Windi Rezeki Indah Wulandari Wulandari Wulandari, Mitha Yahfizham Yahfizham Yoffa Sunita Yulanda Novita Zebua Yulinda, Jeni Zakaria Alfikri Sirait