INVOTEK: Jurnal Inovasi Vokasional dan Teknologi

Application of Job Safety Analysis (JSA) to Mitigate Ergonomic Risks in Visual Communication Design Vocational High School

Dwi Septiani — 2026-04-11

This study aimed to identify ergonomic hazards and assess occupational health risk levels among Vocational High School students in the Visual Communication Design program. Using a qualitative approach with 32 Grade XII participants, data were collected through participatory observation of 10 critical work steps and workstation measurements. The analysis, mapped into a Job Safety Analysis (JSA) matrix, revealed significant facility dimensional gaps that forced postural compensation. Results indicated that 60% of work steps were classified as High Risk, with the highest risk scores (R=15) identified in repetitive mouse usage and long-duration static work. These risks were driven by an "almost certain" frequency of exposure, confirming the existence of chronic "silent hazards" within computer laboratories. While limited to a case study in Tangerang City, the findings implied that vocational environments harbour cumulative musculoskeletal risks often overlooked compared to acute safety issues. Consequently, the study recommended administrative controls, specifically disciplined micro-breaks and the 20-20-20 visual rule as the most effective and economical mitigation strategies compared to overhauling physical facilities. This research emphasized the urgency of establishing a healthy work culture for the future creative workforce. Its novelty lay in adapting JSA methodology to detect preventive health risks in non-technical Vocational High School settings, distinct from the conventional focus on physical safety in heavy industries.

Effect of Temperature and Catalyst Concentration on the Quality of Biodiesel Oil Extracted From Black Soldier Fly Larvae (Hermetia Illucens)

Dafit Ari Prasetyo — 2026-04-12

Biodiesel is a renewable and environmentally friendly energy source that can be produced from lipid-rich materials through the transesterification process. Black soldier fly (BSF) larvae (Hermetia Illucens) contain approximately 30–40% fat, making them a potential alternative feedstock for biodiesel production. This study aimed to evaluate the effect of reaction temperature and KOH catalyst concentration on the yield and quality of biodiesel derived from BSF larvae oil. Oil extraction was conducted using the Soxhlet method with n-hexane, where 15 g of dried larvae powder extracted for 240 minutes produced the highest oil yield of 97% (w/w). The extracted oil was then converted into biodiesel through transesterification at two temperatures (65°C and 70°C) and two catalyst concentrations (1% and 2% w/v KOH). Biodiesel quality was analyzed based on SNI 7182:2015. The highest biodiesel yield, 60.19% (v/v), was obtained at 70°C and 1% KOH (A2B1). The resulting biodiesel met major SNI requirements, including density (869.59 kg/m³), kinematic viscosity (4.75 cSt), cetane number (44.25), acid number (0.32 mg KOH/g), iodine number (16.8 g-I?/100 g), and FAME content (97.45%). These findings confirm that BSF larvae oil is a viable non-conventional feedstock for biodiesel production. This study is limited by the narrow range of reaction variables tested, suggesting that broader optimization—such as variations in alcohol ratio, reaction time, and pretreatment—may further improve yields. Practically, biodiesel production from BSF larvae supports waste valorization because larvae can be cultivated using organic waste streams. Socially, this approach reduces dependence on edible vegetable oils and supports circular economy initiatives. The originality of this research lies in its systematic evaluation of transesterification conditions for BSF-derived oil, providing new insights into the development of insect-based biodiesel technology.

Numerical Structural Response Analysis of Savonius Wind Turbine Blades with Geometric Variation under Aerodynamic Loads

Aldo Alfattah Sudjono — 2026-05-09

Rising demand for electrical energy has accelerated the development of renewable energy technologies, including wind turbines designed to operate at low wind speeds. The savonius vertical-axis wind turbine is a promising option due to its simple configuration and insensitivity to wind direction. Nevertheless, the structural reliability of its blades is strongly affected by their geometry and the material selected. This study focuses on evaluating the structural response of savonius turbine blades under aerodynamic loading using the finite element analysis (FEA) method. Simulations were carried out in ANSYS Workbench R2 2025, considering geometric variations in blade thickness (1.2 mm, 1.5 mm, and 2 mm), aspect ratio (0.8, 1.0, and 1.3), and arc angle (120°, 150°, and 180°). The blades were modeled using AISI 304 stainless steel. The analysis examined von mises equivalent stress, total deformation, and safety factor. The analysis results show that all geometric variations are structurally safe with a safety factor value of 15. The highest maximum von mises stress of 0.081 MPa occurs at a thickness of 1.2 mm, while the lowest value of 0.017 MPa is obtained at an arc angle of 180°. The maximum deformation of 3.38 × 10?³ mm occurred at an arc angle of 150°, while the lowest deformation of 6.77 × 10?? mm was obtained at an arc angle of 180°, which indicates the most structurally stable configuration.

Grouping of Research Interests of Final Project of Computer Science Students at UINSU Using the Fuzzy C-Means Approach

Harun Al Rasyid — 2026-05-17

Determining research topics for final projects that align with students' competencies and interests remains a challenge in academic management because the process is often influenced by subjective factors. This situation can lead to various impacts, such as inappropriate research topics, delays in study completion, and imbalances in the guidance workload among supervisors. This study aims to cluster the research interests of students preparing their final projects in the Computer Science Study Program at the State Islamic University of North Sumatra (UINSU) using the Fuzzy C-Means (FCM) algorithm. The data used were obtained from a student interest questionnaire from the 2020–2022 intake and historical data on final project titles. Furthermore, the text data underwent preprocessing and was converted into numerical form using the Term Frequency–Inverse Document Frequency (TF-IDF) method. The FCM algorithm was then used to form research interest clusters with fuzzy membership degrees. Based on the results of the cluster quality evaluation, it was found that the most optimal number of clusters was six, with a Silhouette Index value of 0.6311 and a Davies–Bouldin Index of 0.5505, which indicates that the cluster structure formed is classified as good. The clustering results indicated that student interests were dominated by Software Engineering and Artificial Intelligence, with a fairly high degree of overlap. This study combines student interest questionnaire data and historical final project title data, represented using TF-IDF and clustered using the Fuzzy C-Means algorithm to map multidimensional research interests. The results suggest that this approach provides a more objective basis for identifying students’ research tendencies and can support topic recommendation systems and academic supervision planning.

Relationship Between CBR Value and Soil Compaction Under Various Number of Blows

Nadra Mutiara Sari — 2026-06-22

Subgrade is one of the essential components in road pavement construction, particularly in flexible pavement. This is because the subgrade serves as the foundation that supports the overall load above it. Therefore, it must have a high bearing capacity with a minimum California Bearing Ratio (CBR) value of 6%. To achieve this requirement, efforts to increase the CBR value are needed, one of which is through soil embankment and compaction. In this study, soil compaction was carried out to obtain the desired CBR value. The sample consists of 18 samples with each impact variation (25, 35, 45, 55, 65, and 75 times) being three samples. The fill soil comes from the Gandus area, Palembang city. The test results showed the lowest CBR value of 2.79% at 25 blows with a dry density of 1.51 g/cm³, and the highest value of 14.23% at 75 blows with a dry density of 1.95 g/cm³. At 45 blows, a CBR value of 8.05% with a dry density of 1.78 g/cm³ was obtained, which already meets the subgrade requirement. It can thus be concluded that the greater the number of blows, the higher the CBR value. However, the dry density did not significantly increase beyond 55 blows, indicating that the soil had reached a sufficient level of compaction with minimal air voids, and further compaction was unnecessary since the standard CBR value had been achieved.

Investigated of Zn-1Mg Alloy Using Potentiodynamic Polarization and Weight Loss Methods in Kokubo’s Solution

Andril Arafat — 2026-06-26

Zinc alloys are considered as candidates for bioabsorbable implant materials due to their corrosion rates and their outstanding combination of biodegradability and biofunctionality. This study compares the corrosion behavior of Zn-1Mg alloys prepared in as-cast, as-rolled, and as-extruded forms using two main methods: immersion testing (weight loss) in Kokubo's Simulated Body Fluid at 37 °C for up to 14 days, and potentiodynamic polarization (PDP). Microstructure characterization was performed using SEM/EDS to identify corrosion products after the corrosion test. The weight loss method showed the highest corrosion rate in the as-rolled sample 0.56 mm/year and the lowest in the as-cast sample 0.35 mm/year. In contrast, the potentiodynamic method showed the lowest corrosion rate in the as-extruded sample 0.019 mm/year. These results indicate that the extrusion process produces a refined and uniform grain microstructure, which contributes to improved electrochemical corrosion resistance. Overall, the corrosion rates of all samples were still within the safe daily intake limits of Zn allowed in the human body. It were concluded that mechanically processed Zn-1Mg alloys (rolling for plates and extrusion for pins) are suitable and promising for use as bioabsorbable metals for non-load-bearing applications such as craniofacial implant applications.