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Show Abstract | Download PDF | DOI: 10.31004/jestm.v6i2.431 | Check in Google Scholar
Series tank systems are vital in chemical industries but susceptible to mass and thermal disturbances, making stability analysis essential. This study models the level and temperature dynamics of a non-interacting two-tank system equipped with a heater in Tank-01, analyzing its stability via Nyquist plots. The methodology involves laboratory step-response experiments validated against mathematical models derived using Laplace Transforms and Explicit Euler methods. Results demonstrate the model closely matches experimental data; Tank-01 exhibits first-order characteristics, while Tank-02 functions as a second-order system. The physical system successfully handled +52% and -35% step disturbances within liquid height limits of 3–24 cm and feed flow rates of 40.33–136.5 cm³/s. Furthermore, Nyquist analysis confirms the open-loop thermal process is inherently stable across all tested capacities. Maximum level and thermal process gains were 0.3787 and 0.0062, respectively. Ultimately, this study confirms the non-interacting two-tank system possesses stable, self-regulating characteristics against load disturbances within operational limits.
Show Abstract | Download PDF | DOI: 10.31004/jestm.v6i2.410 | Check in Google Scholar
This study investigates the factors contributing to electrical voltage instability in Auxiliary Engine No. 2 aboard MV. Hanglima. The research was motivated by operational disruptions where the voltage output dropped significantly from the standard 440V to 290V, leading to blackouts when the generator operated independently. Employing a qualitative research method utilizing the Fishbone (Ishikawa) diagram for root cause analysis, data was collected through onboard observation, documentation, and interviews with the engineering crew. The analysis revealed that the instability was primarily caused by mechanical failure in the alternator bearings, which had approached their operational limit, leading to an unbalanced rotor rotation. This mechanical imbalance caused friction between the rotor and stator, resulting in insulation leakage (short circuits) within the windings. Corrective measures implemented included a comprehensive overhaul, re-insulating the rotor and stator windings using insulating varnish, and replacing the worn bearings. These actions successfully restored the voltage output to a stable 445V, ensuring the safety and efficiency of the vessel's electrical system.
Show Abstract | Download PDF | DOI: 10.31004/jestm.v6i2.414 | Check in Google Scholar
The ship engine cooling system is critical for maintaining the operational stability of main and auxiliary machinery. However, biofouling within sea chests and seawater pipelines remains a prevalent issue, leading to flow obstruction, reduced heat transfer efficiency, and potential engine malfunction. While the Marine Growth Prevention System (MGPS) is designed to mitigate this via electrolysis, marine growth persisted on MV Ever Clear, indicating suboptimal system performance. This study aims to analyze the effectiveness of the MGPS in preventing biofouling and to identify factors contributing to its performance degradation. Using a qualitative descriptive method with a case study approach, data were collected through direct onboard observation, interviews with the engineering crew, and document analysis. Results indicate that the decreased effectiveness was primarily caused by insufficient electrode maintenance, unstable electrical parameters (current and voltage), and inadequate operational monitoring. These deficiencies compromised the electrolysis process, preventing sufficient ion release. It is concluded that MGPS efficacy is contingent upon stable electrical parameters, rigorous preventive maintenance, and consistent operational supervision in accordance with established procedures.
Show Abstract | Download PDF | DOI: 10.31004/jestm.v6i2.452 | Check in Google Scholar
Safety of life at sea is a paramount operational priority that heavily relies on crew preparedness in managing maritime emergencies. This study evaluates the effectiveness of abandon ship drills in improving crew readiness on the commercial tanker MT. Pagerungan. Using a qualitative case-study design, data were collected over a 12-month period through direct participant observations, structured interviews with six key personnel, and documentary analysis. Effectiveness was measured using specific operational indicators: alarm response time, correct usage of life-saving appliances (LSAs), compliance with muster list duties, and communication efficiency. The results indicate a significant gap between administrative compliance and practical readiness. Drills were conducted only four times annually, violating the monthly requirement stipulated by the Safety of Life at Sea (SOLAS) Convention. Observations revealed critical deficiencies, including the inability of junior and catering crew members to correctly don lifejackets and a lack of role awareness among specific deck ratings. Furthermore, commercial pressures and a tendency to view drills as bureaucratic formalities hindered the development of a robust safety culture. The study concludes that while incremental improvements were observed across repeated drills, overall effectiveness remains structurally fragile. Recommendations include the rigorous implementation of monthly drills, integration of pre-drill toolbox meetings, station-specific compliance checklists, and documented competency assessments to bridge the gap between regulatory mandates and actual emergency preparedness
Show Abstract | Download PDF | DOI: 10.31004/jestm.v6i2.385 | Check in Google Scholar
The selection process for new student admissions in secondary schools is often manual and error-prone, so a web-based decision support system (DSS) is needed to improve objectivity and efficiency. This study aims to design and implement a DSS using the Simple Additive Weighting (SAW) method at SMK Negeri 1 Tanjung Lubuk. An applied quantitative approach with the Waterfall model was used; the population was all prospective students through three admission pathways, a sample of 23 purposive applicants. Instruments included academic data documents, interviews, and web input; data analysis via SAW (matrix normalization, criteria weighting, preference values). The results showed an accurate ranking with the highest score of 1.84 (Muhamad Angga Prayitno) based on five criteria (exam scores, report cards, KIP, achievement, distance). The conclusion states that the system increases transparency and speed of selection, and replication in other schools with broader testing is recommended.
Show Abstract | Download PDF | DOI: 10.31004/jestm.v6i2.480 | Check in Google Scholar
This study aims to determine the effect of liquid organic fertilizer (LOF) made from a mixture of cattle urine and fruit waste on plant height growth, leaf length, and fresh weight of elephant grass (Pennisetum purpureum). The study used a Completely Randomized Design (CRD) with 4 treatment levels and 5 replications, namely P0 (control / without LOF), P1 (50 ml LOF/liter of water), P2 (100 ml LOF/liter of water), and P3 (150 ml LOF/liter of water). The results showed that the application of cattle urine and fruit waste liquid organic fertilizer significantly affected plant height, leaf length, and fresh weight production of elephant grass. The treatment with the highest concentration, namely 150 ml LOF/liter of water (P3), yielded the best results for plant height growth (140.60 cm), leaf length (130.20 cm), and fresh weight of elephant grass (3,637.00 grams).
Show Abstract | Download PDF | DOI: 10.31004/jestm.v6i2.460 | Check in Google Scholar
Occupational Safety and Health (OSH) management in Liquified Natural Gas (LNG) terminals requires stringent alignment with both general workplace safety and process safety protocols. This study evaluates the implementation of the OSH Management System (SMK3) at PT X, an LNG logistics terminal in Indonesia, focusing on employee Personal Protective Equipment (PPE) compliance and visitor safety controls. Utilizing a qualitative case study design, data were collected through field observations, document reviews, and semi-structured interviews with nine key informants across operational and safety divisions. The data were analyzed using a formal SWOT/TOWS matrix to develop strategic interventions. The findings indicate that while PT X’s institutional procedures—such as mandatory safety inductions, daily toolbox meetings, and medical fit-to-work screenings—are consistent with ISO 45001 standards, critical field execution gaps remain. Empirical evidence highlights recurring PPE non-compliance driven by human factors (e.g., thermal discomfort), visitor violations of electronic device restrictions in hazardous explosive zones, and logistical bottlenecks due to insufficient visitor PPE inventory during peak periods. The study concludes that achieving optimal safety compliance requires moving beyond bureaucratic procedures. Practical implications include the necessity for risk-based PPE procurement, the enforcement of a controlled intrinsically-safe device management policy, and enhanced human-centric safety supervision.
LPPM Universitas Pahlawan Tuanku Tambusai
Jalan Tuanku Tambusai No. 23, Bangkinang Kota
Kabupaten Kampar, Riau, Indonesia
Publisher: LPPM Universitas Pahlawan Tuanku Tambusai
e-ISSN 2828-7886
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