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All Journal ASEAN Journal of Systems Engineering Jurnal Teknosains Journal of Engineering and Management in Industrial System Indonesian Journal of Life Cycle Assessment and Sustainability Jurnal Logistik Indonesia JURNAL Al-AZHAR INDONESIA SERI SAINS DAN TEKNOLOGI Journal of Applied Engineering and Technological Science (JAETS) TIERS Information Technology Journal JOCHAC
Bertha Maya Sopha
Universitas Gadjah Mada
Biochemistry, Genetics & Molecular Biology Civil Engineering, Building, Construction & Architecture Computer Science & IT Decision Sciences, Operations Research & Management Electrical & Electronics Engineering Engineering Industrial & Manufacturing Engineering Mechanical Engineering Public Health Social Sciences Other

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HYBRID POWER SYSTEM MODELING FOR ELECTRICITY SYSTEM IN SUMBAWA DISTRICT (HYBRID POWER SYSTEM MODELING) sumartono -; Ahmad Agus Setiawan; Bertha Maya Sopha
ASEAN Journal of Systems Engineering Vol 3, No 1 (2015): ASEAN Journal of Systems Engineering
Publisher : Master in Systems Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1190.425 KB)

Abstract

Include the provision of energy management, utilization and enterprise shall be done justice, sustainability and so can not give optimal benefits for the greater welfare of the people. Sumbawa has a variety of potential sources of renewable energy such as; water energy, solar energy, wind energy, geothermal energy and biomass. From a variety of renewable energy potential can be made a model of hybrid power system design for the electrical system in Sumbawa is based on renewable energy in the region.             The purpose of this study was to determine the magnitude of the potential of renewable energy for power generation, knowing large share of renewable energy to the electrical energy needs and design a model of hybrid power system for electrical system in Sumbawa by using HOMER (Hybrid Optimisation Model for Electric Renewables).             The results of this study recommend a model of hybrid power system that is optimum for a total net present cost (NPC) US $ 144,954,400, operating cost of US $ 1,801,515 / year, the cost of electric (COE) US $ 0.090 / kWh of excess electricity and 99,072,760 (kWh / year) and the contribution of each component of the capacity modeling results are; PV Array 4.4%; wind turbine 20.3%; hydro turbine 74.4%; biomass generator 0.8%; G1 and G2 diesel generator as a back-up system by 0.1%. The results of model simulations also show that the model of hybrid power system that is recommended to have much lower levels of emissions than conventional systems where there is a reduction in the level of emissions into the environment by 99.75%. Thus the hybrid power system for electrical system in Sumbawa considered feasible as an alternative solution to meet the electrical energy needs in Sumbawa
ENERGY MODELLING AND FORECASTING OF DAERAH ISTIMEWA YOGYAKARTA 2025 Eko Haryono; Deendarlianto -; Bertha Maya Sopha
ASEAN Journal of Systems Engineering Vol 2, No 2 (2014): ASEAN Journal of Systems Engineering
Publisher : Master in Systems Engineering

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Abstract

Daerah Istimewa Yogyakarta (DIY) is one of the provinces in Indonesia which does not have a backup or potential sources of non-renewable primary energy. The non-renewable energy demand until this time, such as oil,coal and gas is supplied from the outside. DIY is in Java Madura Bali (JAMALI) interconnerction system and has not had a large-scale power systems. While DIY has renewable energy sources such as hydro, solar, wind, wave and biomass energy. These renewable energy sources are alternative energy that have not been optimally used. The lack of reserve energy resources that resulting dependence of energy supply from other areas should receive special attention from DIY government. To meet energy demand, the energy resources development is required. Due to the energy resources development requires a long time and high cost, it is necessary to be supported by good planning in energy policy.The purpose of this study is to determine the balance of energy demand and supply of  DIY until 2025. Furthermore, the purpose of this study is to find out a mix number of renewable energy. The Indonesian government has launched a vision of 25/25 which expection in 2025, the mix number of renewable energy will be 25%.The results of this study indicate that in 2025, the Transportion Sector is the largest energy user sector in DIY at 52.37%, followed by Household Sector (32.70%), Commercial Sector (8.26%), Other Sector (4.64%), and Industrial Sector (2.04%). The high level of energy consumption in the Transportation Sector is caused by the increasing number of vehicles especially motorcycles and passenger cars considering DIY is a student and tourism city. In term of the type of energy used, in 2025, the gasoline is the greatest type of energy demand (41.8%), followed by LPG (23.97%), electricity (18.14%) and diesel oil (11, 74%). This indicates that the fuel oil is still the main energy source for the DIY community activities. When viewed from supply side, most of the energy needs in DIY are supplied from outside. If the development of enewable energy targets DIY reached, the renewable energy mix is obtained by 0.53 %.
SOLAR AND WIND ENERGY MODELLING FOR CENTRAL BANGKA REGENCY, BANGKA BELITUNG PROVINCE Wahyu Edifikar; Bertha Maya Sopha; Ahmad Agus Setiawan
ASEAN Journal of Systems Engineering Vol 4, No 1 (2020): ASEAN Journal of Systems Engineering
Publisher : Master in Systems Engineering

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Abstract

Central Bangka is a developing regency in Bangka Belitung Island Province. Geographically Bangka Belitung Islands is not far from the equator. The development of human resources and infrastructure for the energy sector is an integral part of regional development efforts. To fulfill the district's energy, we need to look at the potential of renewable energy such as wind power and solar power within the district. This research also provides the potential renewable energy capacity configuration through a simulation.This research used the simulation approach method to map the energy demand over the district and renewable energy available in the region. Energy demand data received from the National Electrical Company (PLN) of Bangka Belitung Province, and potential renewable energy data were obtained from the Ministry of Energy and Mineral Resources of The Republic of Indonesia and the NASA website. Software HOMER is used to analyze electrical energy potential from renewable energy sources.The simulation shows wind energy could provide 0.15 – 0.19 kW and solar power at 3.99 – 4.96 kW/m2/day. The optimum configuration of energy supply consists of 61.4% solar energy and 38.6% wind energy. The hybrid configuration above using the solar photovoltaic (PV) output of 286,981 kWh/year and wind generator output of 180,758 kWh/year and an estimated value of $1,663,598.53 for capital cost, $134,548.34 of operational cost, and cost of energy generated at $0.43/kWh. 
OPTIMIZATION OF MUNICIPAL WASTE COLLECTION POINTS IN YOGYAKARTA CITY- INDONESIA Bertha Maya Sopha; Alditya Perkasa Sri Haryoto
Jurnal Teknosains Vol 5, No 2 (2016): June
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/teknosains.27581

Abstract

Uneven capacity utilization seems to be a constant problem in Yogyakarta waste management system. The problem is worsen by lack of a decision tool to evaluate the system and formulate appropriate strategy.This present study therefore aims atevaluatingthe performance of existing waste management systemandoptimizingmunicipal waste collection points. A mathematical model of MixedIntegerLinearProgramming was developed and implemented inLingo 9. Findings show that the current waste management system is associated to daily total cost of about IDR 10 million and capacity utilization of 88%. Scenarios are developed to examine the optimized system. Findings suggest that current municipal waste can be handled with 35 collection points involving 15 depots and 20 containers. The optimized system is corresponding to IDR 6.3 millionand the capacity utilization of 99%, which makes a reduced cost of 37% and an increasedcapacity utilization of 13% in comparison to the performance of the existing system. Based on sensitivity analysis,volume of municipal waste appears to be influential factor toward the total cost and network structure. Limitation of the model is also discussed. 
Environmental Assessment of Motorcycle using a Life-Cycle Perspective Bertha Maya Sopha; Setiowati Setiowati; Sholeh Ma’mun
Indonesian Journal of Life Cycle Assessment and Sustainability Vol. 1 No. 1 (2017)
Publisher : Indonesian Life Cycle Assessment Network (ILCAN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (401.035 KB) | DOI: 10.52394/ijolcas.v1i1.3

Abstract

Transportation sector contributes as the second largest polluter of the air pollution in Indonesia. Of the transportation sector, road transport has generated 70% of the air pollution, 81% of which is attributable to motorcycles. The motorcycles are currently accounting for 79% of the total motor vehicles. It is predicted that the number of motorcycles will continue to grow at an annual rate of 9-26%. However, due to little attention to the motorcycle’s environmental impacts, this present study, therefore, aims to assess and report the environmental impacts of using motorcycles based on life-cycle perspective. Using a functional unit of one passenger per kilometer (pkm), resource consumption and emissions through the entire life-cycle of a motorcycle were estimated. The foreground Life Cycle Inventory (LCI) was compiled through observation, interview, and secondary data, while the background LCI was based on ecoinvent data v.2.0. Results show that the environmental impacts of the chosen function unit constitute Abiotic Resource Depletion Potential (ADP) of 0.515 g Sb-eq., Global Warming Potential (GWP) of 176 g CO2-eq, Human Toxicity Potential (HTP) of 1.1 g 1.4-DCB-eq, and Acidification Potential (AP) of 0.544 g SO2-eq, respectively. Operation (usage stage) of the motorcycle has been the most contributor to GWP and AP, while manufacturing stage has been the most contributor to HTP. Potential interventions related to the manufacturing process, fuel, and usage of the motorcycle to reduce the environmental impacts are also discussed.
Pengembangan Model dan Simulasi Berbasis Agen untuk Adopsi Layanan Bank Sampah di Kota Semarang Halim Qista Karima; Bertha Maya Sopha
JURNAL Al-AZHAR INDONESIA SERI SAINS DAN TEKNOLOGI Vol 5, No 3 (2020)
Publisher : Universitas Al Azhar Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36722/sst.v5i3.371

Abstract

Abstrak - Pemerintah Kota Semarang melakukan pembentukan bank sampah untuk menekan jumlah sampah di tempat pembuangan akhir. Masih bayak masyarakat di Kota Semarang yang belum mengikuti program tersebut. Pada penelitian ini dilakukan pemodelan untuk meningkatkan partisipasi masyarakat dalam mengelola sampah. Keikutsertaan masyarakat dipengaruhi oleh beberapa faktor yaitu intention, sosial norm, jarak menuju recyclingsiteagent dan outcome. Intention seseorang dalam melakukan pengelolaan sampah secara signifikan dipengaruhi oleh awareness of consequences, ascription of responsibility dan personal norm. Pemodelan dan skenario menggunakan metode agent based modeling, menghasilkan usulan kebijakan yaitu dengan mendirikan empat bank sampah. Melalui keputusan tersebut mampu menghasilkan 93% partisipasi rumah tangga dalam mengelola sampah dan 2,4 ton sampah yang dikumpulkan hingga periode ke 60 minggu.Abstract - Semarang government has established a Waste Bank to reduce the amount of waste in landfills. There are still many people in Semarang who have not participated in this program. This research modeling aims to increase public participation in managing waste. Public participation is influenced by intention, social norm, and distance to recycling site agents as well as the outcome. An intention to of managing waste is significantly influenced by awareness of consequences, the ascription of responsibility and personal norm. In this study using agent-based modeling. The results obtained from this model and scenarios are the intervention to establishing four Waste Bank. It produced 93% of households participating in managing waste and 2.4 tons of garbage collected in the 60 weeks.Keywords – Agent-based modeling, Norm Activation Model, Waste Separation Behavior, Bank Sampah, 
Analisis potensi penerapan teknologi produksi bersih pada c-maxi alloycast, Yogyakarta Dewi Masri; Wagiman Wagiman; Bertha Maya Sopha
Jurnal Teknosains Vol 12, No 1 (2022): December
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/teknosains.67962

Abstract

CV C-Maxi Alloycast is an industry engaged in the manufacture of household appliances (pans) made of aluminum which is located in Yogyakarta. The aim of the study was to identify the potential application of clean production principles in CV C-Maxi Alloycast. The methods used were production process mapping, waste analysis through liquid waste testing and potential analysis of clean production principles. The results obtained for the production process were smelting aluminum and scrap, pouring molten metal into molds, lifting molds and providing coolant, lifting castings, turning, filing, quality control, storage and distribution. Based on the laboratory test, the characteristics of the liquid waste produced by the CV C-Maxi Alloycast  were pH 8.9; COD 52.1 mg/L; BOD 21.4 mg/L; TSS 6660 mg/L; Fe 4,2440 mg/L; Cu 0.0130 mg/L; and Zn 0.0893 mg/L. All parameters indicate that the value meets the quality standard, but the TSS content did not meet the NAB (Threshold Value) which refers to the Regulation of the Minister of the Environment of the Republic of Indonesia No. 5 of 2014 and the Regulation of the Special Region of Yogyakarta (DIY) No. 7 of 2016. Clean production opportunities were: good housekeeping, application of 3R (Reduce, Reuse, Recycle) on solid waste, construction of B3 Waste TPS and capacity building of human resources. Environmental performance had increased based on the Green Industry Standard (SIH) from level 1 to level 2 with a value of 53% to 65% with the implementation of clean production. The economic performance of implementing clean production gains a profit of Rp. 77,412,000,-/year, then the second alternative, namely recycling aluminum scrap is an economical alternative to clean technology with a 5-year NPV value of Rp. 37,853,056,558,- Implementing clean production can have a positive impact on the environment and the economy.
A FRAMEWORK FOR OBSERVATIONAL DATA-BASED RESPONSE SURFACE METHODOLOGY Hadiyat, Mochammad Arbi; Sopha, Bertha Maya; Wibowo, Budhi Sholeh
JEMIS (Journal of Engineering & Management in Industrial System) Vol 12, No 2 (2024): (in process)
Publisher : Industrial Engineering Department, Faculty of Engineering, Universitas Brawijaya

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Abstract

Response Surface Methodology (RSM) is an integrated tool for optimization purposes based on an experiment; it consists of three stages of analysis, i.e., the design of experiment (DoE), causality modeling, and response optimization. The designed experiment ensures the researcher fully controls all factors that potentially influence the response and simultaneously fulfills the orthogonal assumption among factors. On the other side, conducting DoE for a continuous production process raises difficulties since it should be interrupted during experiment runs. Meanwhile, the rapid development of production data acquisition systems provides stored records or observational data with potentially useful information for supporting process optimization. This paper proposes an alternative framework for adopting observational data for RSM analysis. Referring to three stages of classic RSM and adopting the instance selection concept in the data mining context, the proposed framework aimed to achieve an observational data condition similar to an orthogonal D-optimal DoE based on criteria of Variance Inflation Factor (VIF) and determinant of matrix containing factor levels. It starts by applying a genetic algorithm for iteratively selecting an orthogonal subset of observational data and generating new actual experiment points to satisfy an orthogonality criterion. Then, a linear RSM model is fitted and continued by adding new experiment points. Then a standard numerical optimization method is applied to search among factor levels that optimize the response. A simulated data-based case study was taken in this paper, aiming to maximize a response of a production process with some pre-determined factors. The proposed framework has been implemented successfully, orthogonality of the data subset is achieved, and an optimal solution is found. Both criteria show the acceptable result and raise some improvement opportunities
SENSITIVITY ANALYSIS OF HYPERPARAMETER IN SOLAR ENERGY PREDICTION MODEL USING GRADIENT BOOSTING METHOD Ramadhan, Aska; Sopha, Bertha Maya; Ridwan, Mohammad Kholid
ASEAN Journal of Systems Engineering Vol 9, No 1 (2025): ASEAN Journal of Systems Engineering
Publisher : Master in Systems Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ajse.v9i1.78322

Abstract

Solar energy prediction is one alternative to handling unpredicted conditions of weather and solar radiation intensity. It could be the most important factor in achieving stability in electricity generation using solar energy resources. In making predictions, the use of machine learning models has been carried out by various methods, and in this study, the method used for the algorithm model is gradient boosting. In the modeling process using gradient boosting, several hyperparameter settings are needed. Hyperparameters have an important role in producing stable predictive patterns and can avoid overfitting or underfitting conditions. In this study, the accuracy and speed of prediction of the machine learning model with the gradient boosting approach, namely XGBoost and LightGBM, were analyzed in relation to setting the hyperparameter learning rate and max depth of the model's prediction pattern. The dataset used spans 6 months at a data resolution rate of every 5 minutes and includes meteorological data at the location point of Energy Laboratory UKRIM Yogyakarta as well as the output value of PLTS power and temperature panels onsite. Setting the hyperparameter learning rate in the highest and lowest conditions generates accuracy values with a difference of 2% and about the same prediction speed. With nMAE values of 2.84% and 1.35% and nRMSE values of 6.11% and 3.68%, respectively, the higher learning rate results in lower error values for both models. The XGBoost model shown tendency for overfitting and slower prediction speeds with the highest max depth setting. The prediction speed is faster at the lowest max depth condition, but the XGBoost and LightGBM models both exhibit underfitting.
Hydrogen Supply Chain Network Optimization for Supporting Urban Hydrogen Vehicle Infrastructure Development Anasrul, Rahmad Fajri; Sopha, Bertha Maya
TIERS Information Technology Journal Vol. 6 No. 1 (2025)
Publisher : Universitas Pendidikan Nasional

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.38043/tiers.v6i1.6453

Abstract

This study addressed the rising concerns regarding greenhouse gas emissions and the depletion of fossil fuel resources by exploring hydrogen as a clean energy alternative. The Indonesian government established a national roadmap that prioritized the transportation sector as a starting point for hydrogen deployment. The objective of this research was to design and optimize a hydrogen supply chain network in Jakarta, a densely populated urban area considered strategic for early adoption. The study applied a two-stage approach. First, potential locations for Hydrogen Refueling Stations (HRS) were pre-selected based on spatial and demographic scoring using a modified gravity model. Then the second, the optimal placement of HRS and hydrogen suppliers was determined through a Mixed-Integer Linear Programming (MILP) method. The entire modeling and optimization process was implemented in Python, with MILP solved using the Gurobi optimizer. A total of 216 existing gas stations were assessed and grouped into five priority levels. The optimization was conducted for three planning periods: 2026-2030, 2031-2035, and 2036-2040. The results showed that integrating new HRS into existing infrastructure reduced land use and investment costs. Sensitivity analysis indicated that daily HRS capacity, hydrogen demand, and capital cost were the most influential factors. The study concluded that this integrated approach provides an efficient, flexible, and sustainable foundation for future hydrogen infrastructure development in urban regions.
Co-Authors Abd. Rasyid Syamsuri Ahmad Agus Setiawan Ahmad Agus Setiawan Alditya Perkasa Sri Haryoto Anak Agung Ngurah Perwira Redi Anasrul, Rahmad Fajri Anna Maria Sri Asih Budhi Sholeh Wibowo Deendarlianto Dewi Masri Ho, Hwi-Chie hyldan Natawiguna Karima, Halim Qista Liperda, Rahmad Inca Mochammad Arbi Hadiyat Mohammad Kholid Ridwan Ramadhan, Aska Rinaldy, Ravi Prananda Setiowati Setiowati Sholeh Ma’mun Sumartono - Sunyoto Usman Venessa, Venessa Wagiman Wagiman Wahyu Edifikar