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Journal : Journal Of Engineering Sciences (Improsci)

Determination of Maintenance Intervals Using Multi-Criteria Approach to Increase Machine Availability at a Cement Company M. Taufik, Ilham; Prasetyaningsih, Endang; P. A. Hidayat, Nita
Jurnal Improsci Vol 1 No 2 (2023): Vol 1 No 2 October 2023
Publisher : Ann Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.62885/improsci.v1i2.66

Abstract

A downtime will decrease machine availability that will affect reliability and maintainability. If interval time between two consecutive machine failures is approach to zero, it shows that the machine reliability is low, and so the availability. In the other hand, if interval time between is high, the machine availability and reliability are high. However, the procuring cost of the machine components is expensive. The problem is what is the maintenance interval time in order to optimize machine availability and reliability. In this study, the downtime is minimized by determining maintenance intervals using a multicriteria, i.e. reliability, availability, and maintainability (RAM). The model used in this research is the Age Replacement Model. A case study of a cement company is taken to show the determination of the maintenance interval. The observation shows that the Kiln Division has the longest total downtime of 1,846 hours/year although the Kiln Division has implemented overhaul during 15 days and maintenance one times. The total downtime of the Kiln Division was caused by failure to the Grate Cooler machine by 56.582%. A maintenance interval is proposed, and the result shows that the proposed maintenance intervals reduce total downtime by 86.6% and improve machine availability by 1,8%.
Model of Start-Up Business with Considering Household Spending using System Dynamics Approach Renosori, Puti; Prasetyaningsih, Endang; Satori, Mohamad
Jurnal Improsci Vol 2 No 3 (2024): Vol 2 No 3 December 2024
Publisher : Ann Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.62885/improsci.v2i3.537

Abstract

This study investigates a family-run start-up business in which the company's finances are not separate from the family’s finances. The start-up business owner relies on the company's finances to cover the household spending from the beginning because the owner is not paid by the company. As a result, the company fails to grow and is on the verge of bankruptcy. This study focuses on developing a start-up business model that considers household spending as a decision variable allowing it to grow and develop. The System Dynamics approach was chosen due to the complexity of the trade-offs between variables in a start-up business model. The Cassava meatball start-up business run by Madrasah is used as an example. The developed model simulates a variety of treatments, including giving debt to develop start-up businesses. However, this debt can be burdensome because the company must pay it. The findings indicate that the use of income to cover household spending at the beginning is inappropriate while providing debt to revive the startup must be sufficient and timely. The developed model is expected to assist start-up business owners in selecting a variety of alternative policies that will allow the business to grow, develop, and be sustainable.
System Dynamics Model of Technology Transition under Resource Constraints: A Catfish Farming Case Prasetyaningsih, Endang; Renosori, Puti; Selamat, Selamat; Wahyudi, Dadan
Jurnal Improsci Vol 3 No 2 (2025): Vol 3 No 2 October 2025
Publisher : Ann Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.62885/improsci.v3i2.1050

Abstract

Background. This study deals with a System Dynamics (SD) model to investigate technology transition under resource constraints, using small-scale catfish farming as a case study. In this context, land availability constitutes the resource constraint. To address this constraint, it is necessary to achieve catfish productivity gains through technological intensification, such as the use of aquaponics. Methods. The SD model captures feedback interactions among production, operating costs, revenue, profit, and reinvestment by setting aside a portion of profits. The SD model's behavior is analyzed by generating six scenarios over 25 years to examine the effects of feed price fluctuations, fingerling price fluctuations, and alternative reinvestment rates. Model outcomes were evaluated using production, profitability, and the benefit–cost ratio (BCR) as an economic performance indicator. Result. The results show that feed and fingerling price fluctuation exerts a strong negative effect on profitability and economic feasibility, while higher reinvestment rates accelerate aquaponics adoption and improve long-term performance. Conclusion. BCR analysis indicates that technology transition in land-limited catfish farming is feasible only when BCR remains above unity, supporting sustained reinvestment. Implementation. The study highlights the importance of reinvestment strategies and feed and fingerling costs management in enabling resilient technological upgrading in spatially constrained aquaculture systems.