Logic : Jurnal Rancang Bangun dan Teknologi

Utilization of Corn Cob Waste as an Alternative Catalyst in Catalytic Converters for Diesel Engine Carbon Emission Reduction

Muhajir Muhamad — 2025-11-30

Catalytic converters function to transform harmful exhaust gases into less hazardous substances through catalytic reactions, primarily oxidation and reduction. This study aims to investigate the potential of corncob waste as an alternative catalytic material in catalytic converters for reducing carbon emissions from diesel engines. The methodology involves synthesizing biochar-based catalysts derived from corncobs via pyrolysis, followed by performance evaluation within a catalytic converter system under varying engine speeds: 700 RPM, 900 RPM, and 1100 RPM. Experimental results demonstrate that catalytic efficiency does not increase monotonically with char content; instead, the 70% char formulation achieved the highest smoke opacity reduction, recording 18.90% at 700 RPM and 14.70% at 900 RPM, outperforming both the 50% and 100% variants at 1100 RPM, where exhaust temperature and flow rate increase substantially, the 100% char catalyst showed comparatively greater stability, achieving a reduction of 5.50%, while the 70% formulation declined to 2.90%. These quantitative outcomes confirm that optimal performance arises from a balanced char loading that maximizes reactive surface area while preserving gas–solid interaction efficiency. Corncob biochar thus represents a viable and sustainable alternative to metal-based catalysts. However, the variability in performance across operating conditions and the need for improved thermal durability underscore the importance of further material optimization for commercial diesel applications.

Analysis of Tensile Strength in a Combination of Recycled HDPE Plastic and Liquid Asphalt

Achmad Bryan Baharrudin Sofan — 2025-11-30

Plastic waste reuse has gained significant attention due to its potential to reduce environmental pollution and provide alternative materials for engineering applications, particularly in the construction sector where durability and maintenance issues are common. One persistent problem in building structures is roof leakage caused by long-term exposure to rainfall, ultraviolet radiation, and extreme temperature changes, which gradually damage conventional waterproofing materials. To improve performance, materials with higher tensile strength and flexibility are needed. High-Density Polyethylene (HDPE), a thermoplastic known for its strength and durability, offers promising reinforcement when combined with liquid asphalt, while also supporting environmentally sustainable practices by reducing plastic waste. In this study, liquid asphalt was heated to 40°C and mixed with HDPE heated at 200°C, 210°C, and 220°C, then stirred for 1.5 hours until homogeneous, cooled to room temperature, and molded according to ASTM D638 for tensile testing. The results show that the 90:10 (HDPE: asphalt) composition at 200°C produced the highest tensile strength of 6.14 MPa, while the 80:20 composition at 220°C showed the lowest value of 3.86 MPa, indicating that higher HDPE content at optimal melting temperatures enhances mechanical properties and provides strong potential for use as a durable, environmentally friendly waterproofing layer in building construction.

Design of Integrated Distillation-Dehydration Prototype for Bioethanol with Flexible Column and Capillary Condenser

Mustofa — 2025-11-30

The production of high-purity bioethanol remains a challenge, particularly when the feedstock originates from traditional fermentation processes such as cap tikus. This study presents an integrated distillation–dehydration prototype that enables simultaneous vapor separation and moisture removal within a single columnn – an innovation that combines a flexible dual-layer adsorbent chamber and a capillary-type condenser tio improve mass and heat transfer performance. The prototype consists of three main components: a boiler with a diameter and height of 500 mm, a distillation–dehydration column with a diameter of 101.6 mm and a height of 1000 mm designed for flexibility to accommodate various adsorbents, and a shell-and-tube condenser 1200 mm long equipped with 19 capillary tubes of 8 mm diameter. Heat is supplied by a “1000-eye” gas burner that ensures uniform thermal distribution at the boiler base. Preliminary testing with 10.8 L of cap tikus (25% alcohol) produced 94 mL of distillate in 3 hours, with a stable of 5 °C temperature gradient along the column. The resulting distillate reached alcohol 87% purity, demonstrating the capability of the integrated system to enhance dehydration performance. Despite performance limitations caused by heat losses in the boiler and vapor-flow resistance witihn the zeolite-packed column, theprototype shows promising thermal and separation characteristics and is ready for futher optimization to increase distillation rate and energy efficiency.

Optimization of Pineapple Leaf Fiber-Reinforced ABS Waste Filaments for FDM: Effect of Mesh Size and Volume Fraction

Wahyu Sipahutar — 2025-11-30

Acrylonitrile Butadiene Styrene (ABS) plastic waste presents significant potential for upcycling into environmentally friendly materials, particularly as feedstock for 3D printing filaments in Fused Deposition Modeling (FDM). This study investigates the influence of pineapple leaf fiber (PALF) reinforcement at two weight fractions (3% and 5%) and two mesh sizes (200 and 300) on the dimensional stability, printability, and mechanical properties of ABS waste-based composite filaments. Comprehensive evaluations were conducted, including filament diameter consistency, surface morphology, and uniaxial tensile testing. The 5% fiber content with 300-mesh PALF yielded the most stable filament diameter (average 1.73 mm, CV 2%), while the same formulation also achieved the highest ultimate tensile strength (UTS) of 8.873 MPa and elongation at break of 0.197%. Interestingly, the highest Young’s modulus (0.139 GPa) was observed in the 3%–300 mesh variant, although it exhibited more brittle behavior. Overall, the 5%–300 mesh formulation was identified as optimal, striking a favorable balance between tensile strength, flexibility, and dimensional consistency, thereby validating its suitability as a sustainable FDM filament derived from post-consumer ABS waste.

Redesign of Patient Wheelchair Type SM-8018 Based on Ergo-Total Function Deployment (ETFD) Integration

Heri Setiawan — 2025-11-30

Manual wheelchairs remain widely used in Indonesian health-care facilities, yet their design often does not fully accommodate local anthropometric characteristics and work patterns. The SM-8018 patient wheelchair used at PT SPU is operated by caregivers, exposing both patients and caregivers to potential ergonomic risks. This study aims to evaluate and redesign the SM-8018 wheelchair using an integrated Ergo-Total Function Deployment (ETFD) and House of Ergonomics (HoE) approach within a Total Ergonomics framework. A pre–post experimental design was applied involving 32 adult users and caregivers with at least six months of experience using or pushing the SM-8018. Data collection included anthropometric measurements, musculoskeletal complaints using the Nordic Body Map (NBM), subjective fatigue using the Japan Association of Industrial Health (JAIH) questionnaire, boredom scores, satisfaction using the Minnesota Satisfaction Questionnaire (MSQ) and voice of customers (VoC). VoC and ergonomic findings were mapped into a HoE matrix to derive priority design specifications through ETFD. Results showed notable mismatches between user anthropometry and key wheelchair dimensions, particularly seat depth and width, backrest and headrest height and angle, and push-handle height, which were associated with high levels of discomfort in the lower back, buttocks, shoulders and upper arms and with considerable fatigue. The ETFD–HoE analysis identified four primary redesign priorities: adjustment of push-handle height, optimisation of backrest and headrest geometry, refinement of seat dimensions and improvement of front-wheel stability. Pre–post comparisons indicated that musculoskeletal complaints and fatigue remained relatively high and in some cases increased, whereas boredom and satisfaction tended to change in a more favourable direction. These findings suggest that the first iteration of the SM-8018 redesign, although guided by Total Ergonomics principles, requires further refinement and system-level support. Nonetheless, the study demonstrates the feasibility of integrating ETFD, HoE and Total Ergonomics to systematically guide the improvement of low-cost hospital wheelchairs in the Indonesian context.

Influence of Workplace Environment and Ergonomic Posture on Musculoskeletal Disorders in Traditional Gamelan Craft Workers in Bali

Juli Suarbawa I Ketut Gde — 2025-11-30

This study investigates the effect of work posture and workplace environmental conditions on musculoskeletal disorders (MSDs) and fatigue among traditional gamelan craftsmen in Bali, Indonesia. Using a pre-experimental one-group pretest–posttest design, fifty-one male workers were assessed using the Nordic Body Map (NBM), the EORTC QLQ-C30 fatigue scale, and the Rapid Upper Limb Assessment (RULA). The results showed a significant increase in MSD scores from 29.72 to 48.90 and fatigue scores from 31.06 to 44.26 after a single four-hour work session (p < 0.001). RULA analysis indicated that 100% of workers performed tasks in moderate- to high-risk postures, with 36.8% requiring immediate ergonomic intervention. The most affected anatomical regions included the lower back, upper back, neck, and thighs. These findings suggest that prolonged static postures, floor-level working positions, and suboptimal workplace environmental conditions substantially contribute to physical strain. The results highlight the urgent need for ergonomic interventions tailored to traditional craft industries to reduce cumulative trauma risks and improve worker well-being.

Thermal Performance Analysis Of TiO₂ and Paraffin as Phase Change Materials

I Made Arsawan — 2025-11-30

Phase change materials (PCMs) are materials that can store and release thermal energy through phase changes from solid to liquid at specific temperatures. This study aims to analyze the effect of TiO₂ concentration in paraffin as a phase change material for thermal energy storage applications. TiO₂ is used as an additive to paraffin to enhance thermal conductivity and accelerate heat transfer, thus improving the performance of the phase change material (PCM). This research investigates the thermal characteristics of the paraffin and TiO₂ mixture by measuring thermal properties such as melting point, heat capacity, thermal stability, and the energy storage capability of the material using techniques such as Differential Scanning Calorimetry (DSC). The results show that the addition of TiO₂ can enhance the thermal performance of pure paraffin as a phase change material. A concentration of 10% TiO₂ can absorb thermal energy up to 94.58 kJ/kg. This study is expected to contribute to the development of more efficient energy storage materials.

Comprehensive Analysis on the Influence of Flap Width on the Hydrodynamic Parameters of OWSC Devices

Rasya Aulia Nathania Nisa — 2025-11-30

The growing need for renewable energy has driven significant interest in harnessing ocean wave power, particularly through Oscillating Wave Surge Converters (OWSCs). This study focuses on examining the effect of flap width on the hydrodynamic capacity of an OWSC, as flap geometry plays a crucial role in energy capture efficiency. A numerical methodology utilizing the Boundary Element Method (BEM) was employed to assess hydrodynamic parameters across both temporal and frequency domains. Five flap width variations were tested under regular wave conditions with different periods, while mesh independence and validation against experimental data ensured accuracy. The results in the time domain revealed a direct correlation between flap width and angular deviation, velocity, torque, and power output, although wider flaps exhibited less stability due to increased inertia. Frequency domain analysis indicated that each flap width had a distinct resonant peak, with narrower flaps performing best at shorter periods and wider flaps at longer ones. Notably, moderately sized flaps (W2 and W3) achieved the highest efficiency, with Capture Width Ratios exceeding 70%, outperforming wider flaps despite their larger surface area. These findings highlight the importance of optimized flap width for efficient and reliable OWSC design.

Thermal Performance of a Branching-Channel Liquid Cooling System for Cylindrical Li-Ion 18650 Batteries

Anggie Topan Wijaya — 2025-11-30

Lithium-ion batteries need effective thermal management to avoid safety risks like thermal runaway. This study analyzes and optimizes a liquid cooling system. Battery Thermal Management System (BTMS) using a branching mini-channel cold plate design for eight Li-ion 18650 batteries. A Computational Fluid Dynamics model was developed to simulate performance at a 2C discharge rate with configurations of 3 (N3), 5 (N5), and 7 (N7) branches. The results, validated against experimental data, showed that all configurations kept maximum temperatures below 37°C and maintained temperature uniformity (ΔT) below 5°C. Increasing branches reduced pressure drop, with the N7 design showing the lowest ΔP of 5.16 Pa. Although it had a lower heat transfer coefficient, N7 achieved the highest J/F factor, indicating optimal thermo-hydraulic performance for liquid-cooled battery systems.