Jurnal Riset Ilmu Teknik

Performance of Pineapple Leaf Fiber-Based Composite Bearing Thermofluids in Evaporative Cooling: A CFD Study with the Taguchi L9 Design

Joel Mangasi Tua Purba — 2026-08-31

The use of synthetic materials in evaporative cooling pads has prompted the exploration of pineapple leaf fiber (PALF)-based composites; however, the sensitivity of their thermophysical properties regarding thermofluid performance remains unquantified. This study aims to examine the sensitivity of material density, porosity, and thermal conductivity to temperature drop (ΔT), cooling effectiveness, and pressure drop (ΔP). Steady-state, fully wetted, homogeneous porous zone Computational Fluid Dynamics (CFD) simulations were conducted using a Taguchi L9 orthogonal array (3 factors × 3 levels). Inlet air conditions were set at a temperature of 21°C, a relative humidity of 79.2%, and a velocity of 1 m/s. A "larger-the-better" Signal-to-Noise (S/N) ratio analysis was applied to evaluate factor sensitivity rankings across the tested levels. Based on delta S/N values, porosity ranked highest in sensitivity regarding its influence on ΔT, followed by thermal conductivity and density. Combination S5 (porosity 0.9198, density 953.3 kg/m³, and thermal conductivity 0.0489 W/m·K) yielded a ΔT of 0.147°C, cooling effectiveness of 5.627%, and ΔP of 0.172 Pa. The theoretical temperature drop is limited by the inlet air's wet-bulb temperature. This study did not involve physical sample fabrication, testing of absorption or durability, or direct experimental comparison with commercial pads. The results present numerical sensitivity trends under the tested simulation conditions to serve as a guide for pore architecture design, rather than a physical validation of replacing commercial materials.

Design of Waste-Wood Pendant Ceiling Lamps Based on Circular Economy Principles through Quality Function Deployment

Rahul Salmansyah Pasaribu — 2026-08-31

The growing volume of wood waste from the wood-processing industry creates environmental pressure when not optimally utilized. This study proposes a circular-economy-based conceptual design for a decorative pendant ceiling lamp made from wood waste using Quality Function Deployment (QFD). Customer preferences were obtained from 68 millennial respondents in Lhokseumawe City through open and closed questionnaires. Closed-questionnaire data were analyzed using the House of Quality (HOQ) to determine technical priorities for the proposed product. Of 20 customer attributes, 19 passed validity testing, with r-count values exceeding the r-table value of 0.244. The diffuser-color attribute was excluded because its r-count was 0.214. The retained instrument showed acceptable reliability, with Cronbach’s Alpha of 0.900. However, this value does not prove that all attributes form a single construct because they represent different dimensions, including materials, lighting, safety, and sustainability. After correcting an arithmetic transcription error and recalculating technical priorities from normalized HOQ contributions, the priorities were water-based matte finish (19.95%), teak wood-waste frame (17.32%), knock-down connection system (13.10%), E27 LED filament lamp (12.00%), adjustable textile cable with an SNI-compliant E27 ceramic socket (11.41%), translucent plastic-fiber diffuser (11.19%), dimensions of Ø60 × 28 cm (10.30%), and adjustable hanging height up to 120 cm (4.78%). These characteristics were subsequently mapped to five 9R circular-economy strategies: reduce, reuse, repair, recycle, and remanufacture. The result is a conceptual design, not a fabricated or tested prototype. Structural, electrical, thermal, lighting, environmental, and user-acceptance tests were not conducted. Estimated production cost is IDR 447,000 per unit, with a planned price of IDR 970,000 and an illustrative gross margin of 53.9% before overhead and tax. The estimate excludes wood-waste collection, selection, and drying. Prototype testing, named competitor benchmarking, and life-cycle evidence are therefore required before environmental or market readiness can be claimed.

Efficiency Analysis of the Analysis of Diesel Fuel Refilling Queue Efficiency Using Queueing Theory at the Hawai Sentani Gas Station, Jayapura Regency

Saul Weipsa — 2026-08-31

The diesel-fuel line at SPBU Hawai Sentani, Jayapura Regency, reportedly experiences heavy queuing, although its operating characteristics had not been quantitatively established. This study evaluates the existing single-server queue and an analytical two-server scenario. Vehicle arrivals were recorded on seven observation days—August 5–10 and 12, 2026—during the 07:00–17:00 WIT operating period. August 11 was not observed for an undocumented reason. A total of 2,680 arrivals produced an average arrival rate of 38.29 vehicles per hour. Based on 10 timed observations, mean service time was 1.35 minutes (SD = 0.158), corresponding to a service rate of 44.44 vehicles per hour. The existing system was modeled as M/M/1, while the two-server configuration was evaluated analytically as M/M/2. Because the observed service-time coefficient of variation was only 11.7%, substantially below the 100% implied by an exponential distribution, an M/G/1 Pollaczek–Khinchine calculation using empirical variance was included as a cross-check. Under M/M/1, utilization was 0.8616, average queue length was 5.36 vehicles, and average waiting time was 8.41 minutes. Under M/M/2, per-server utilization was 43.08%, P0 was 0.398, average queue length was 0.196 vehicles, waiting time was 0.31 minutes, and the Erlang-C probability of waiting was 0.259. The M/G/1 model predicted a 4.25-minute wait, approximately half the M/M/1 estimate. Sensitivity analysis showed waiting time increasing sharply as arrivals approached service capacity. Limitations include the small service-time sample, absence of hourly arrival data, untested distributional assumptions, and unresolved discrepancies between modeled averages and reported multi-hour waits. Thus, the two-server scenario conditionally predicts shorter waits but does not establish that adding a service line is the optimal investment. Decisions also require analysis of costs, available land, staffing, fuel supply, operational disruptions, and direct field validation.

Experimental Comparison of Compressive Strength, Flexural Strength, and Splitting Tensile Strength of a Single Normal Concrete Mixture with Empirical Predictions from SNI 2847:2019

Ninik Paryati — 2026-08-31

Concrete has three principal mechanical properties: compressive, tensile, and flexural strength. In reinforced-concrete design, compressive strength (f’c) is the primary indicator of concrete quality, while tensile and flexural strengths indicate its ability to resist tensile and bending loads. SNI 2847:2019 provides empirical expressions relating splitting tensile and flexural strengths to compressive strength. This study compares the measured mechanical properties of one normal-concrete mixture from a single batch with values predicted using the applicable SNI expressions. It does not establish a general relationship among these properties because that would require multiple strength levels and independent batches. The concrete mixture was designed according to SNI 03-2834-2000 for a target 28-day compressive strength of 20 MPa. Eighteen specimens were produced: six cylinders measuring 150 × 300 mm for compressive testing, six cylinders of identical dimensions for splitting tensile testing, and six beams measuring 150 × 150 × 500 mm for flexural testing. After recalculating the results from recorded loads and cross-sectional areas, mean compressive strength was 20.65 MPa (SD 0.58 MPa; CV 2.79%), flexural strength was 1.91 MPa (SD 0.05 MPa; CV 2.59%), and splitting tensile strength was 1.77 MPa (SD 0.15 MPa; CV 8.29%). The measured flexural and splitting tensile strengths were approximately 39.8% and 37.3% below the SNI-predicted values of 3.18 MPa and 2.82 MPa, respectively. Inadequate compaction is only one unverified explanation because supporting air-content, density, porosity, ultrasonic, or microscopic evidence was unavailable. Conversion errors, loading rates, fracture locations, and specimen alignment are also plausible factors. Therefore, SNI 2847:2019 overestimated both strengths for the investigated mixture under controlled laboratory conditions. However, this finding cannot be generalized because it represents only one mixture, batch, and testing age. Confirmation requires independent batches, multiple strength levels, repeated testing, and regression analysis.

Analysis of Crude Palm Oil (CPO) Production Quality Control Using the Seven Tools

Saul Weipsa — 2026-08-31

Crude palm oil (CPO) quality is affected by free fatty acid (FFA/ALB), moisture, and dirt content, which can reduce product quality and economic value. This study analyzes quality-control implementation at PT Tandan Sawit Papua, Arso Timur, using the Seven Tools and identifies dominant quality problems and potential causes requiring verification. A quantitative case-study design used daily quality records from 15 days in January 2026, divided into two shifts. The dataset comprised 30 shift-level observations, 1,500 samples, and 3,826 tons of CPO production. Analyses included check sheets, shift stratification, Pareto diagrams, p-control charts, scatter diagrams, flowcharts, and fishbone diagrams. Results showed 148 parameter-level off-specification occurrences, equivalent to 9.87% of tested samples, although this represents an occurrence rate because individual samples could fail multiple parameters. FFA/ALB was dominant with 92 occurrences (62.16%), followed by moisture with 37 (25.00%) and dirt with 19 (12.84%). The pooled p-chart initially identified one special-cause signal; however, shift-specific limits showed that the observation remained within Shift 2 limits. Shift 1 recorded a 4.93% occurrence rate, while Shift 2 reached 14.80%. The pooled production–defect correlation (r = −0.675) was confounded by shift differences, whereas within-shift correlations were weak and insignificant. Shift-adjusted regression confirmed shift as the dominant predictor. The 5.00% FFA limit followed SNI 01-2901-2006, while moisture and dirt limits were stricter than commonly cited national limits. Fishbone analysis identified material, method, machine, personnel, environment, and measurement as candidate causes. However, these remain hypotheses. Verification of unique defective samples, continuous laboratory results, applicable specifications, and shift-specific process records is required before corrective actions and statistical-control baselines are established.

Rice Farmers' Knowledge Regarding Pesticide Use in Larompong Urban Village, Larompong District, Luwu Regency

Nurul Fadillah — 2026-08-31

Pesticides are widely used by smallholder rice farmers to control plant pest organisms, but unsafe use can carry risks for farmer health and the environment. This study explores the understanding and reported practices of rice farmers. A qualitative descriptive design was used, involving nine male rice farmers recruited by purposive sampling from a population of about 150 rice farmers in the village; the sample was bounded by the depth of information obtained across participants rather than by statistical representativeness or a documented saturation assessment. Data were collected through in-depth interviews, field observation, and documentation covering books, journals, and regulatory sources, and analyzed using the Miles and Huberman interactive model of data reduction, data display, and conclusion drawing and verification. All nine participants described a consistent, functional understanding of pesticide definitions, purposes, product types, and weather-dependent spraying timing, drawing mainly on farming experience, alongside agricultural extension, peer farmers, retailers, and product labels; extension visits in this village were reportedly not conducted on a regular schedule, which may partly explain the emphasis on experience. Two divergent practices qualify this otherwise consistent picture: at least one participant's account indicates that some farmers have occasionally used a pesticide dose exceeding the label recommendation, and participants reported protective measures during spraying fall short of complete personal protective equipment, since boots and eye protection were not mentioned and the group's practice was not consistently complete. These findings are specific to the nine participating men in this single setting and season and should not be generalized to all rice farmers in Larompong Urban Village or Luwu Regency, nor to women or non-landowning pesticide handlers, who were not included. Targeted, participatory extension addressing dosage adherence and complete PPE use is suggested, rather than a general claim that farmers' knowledge is already good.

The Effect of Satisfaction on Switching Intention Public Transportation Users Among Bekasi ASN

Fahmi Istkhori — 2026-08-31

Dependence on private vehicles remains a major challenge for public transportation development in the Bekasi metropolitan area. This study examines the associations between five perceived service-quality dimensions; tangible, reliability, assurance, responsiveness, and empathy and user satisfaction, as well as the association between satisfaction and intention to increase public-transport use among State Civil Apparatus (ASN) in Bekasi. An explanatory quantitative design using Partial Least Squares Structural Equation Modeling (PLS-SEM) was applied. Data were collected through a five-point Likert-scale questionnaire from 374 ASN in Bekasi City and Bekasi Regency selected using purposive, non-probability sampling. All respondents had experience using public transportation and evaluated the mode they used most frequently. Because only 135 respondents (36.1%) used private vehicles as their primary commuting mode, the outcome was interpreted as intention to increase public-transport use and reduce private-vehicle dependence, rather than a literal switching decision. The results show that tangible, reliability, assurance, responsiveness, and empathy were positively and significantly associated with user satisfaction. Tangible demonstrated the strongest association with satisfaction (β = 0.482; p < 0.001). Satisfaction was also positively and significantly associated with intended public-transport use (β = 0.551; p < 0.001). The model explained 67.3% of the variance in satisfaction and 30.4% of the variance in intention. Bootstrapping results revealed significant specific indirect associations of assurance, reliability, responsiveness, and tangible with intended use through satisfaction, whereas empathy’s indirect association was not significant (p = 0.058). These findings suggest that perceived service quality and satisfaction are important factors associated with ASN’s intention to use public transportation. However, the results do not establish causal relationships due to the cross-sectional design, self-reported data, heterogeneous commuting modes, and purposive sampling. Future studies should employ probability sampling, longitudinal designs, and objective travel-behavior data to evaluate actual changes in public-transport use.

Development of Quality Performance Index for Quality Evaluation of High-End Residential Projects

Rakhmat Syah Rizal Siregar — 2026-08-31

High-end residential construction requires a quality evaluation approach that can combine physical technical quality, managerial process quality, and user perception in a single, traceable measure. This study reports a cross-sectional, single-project pilot study that developed a preliminary Quality Performance Index (QPI) as a project-specific diagnostic tool for the construction implementation stage. A mixed methods case study was applied to the Widya Chandra Residence Project in Jakarta. Five main criteria and 25 subcriteria were compiled from a structured literature review and construction-quality practice, then validated by seven experts through focused discussion before being used in the Analytic Hierarchy Process (AHP); the same seven experts subsequently supplied pairwise-comparison judgments used to derive criterion and subcriterion weights. Actual performance was rated by 47 project stakeholders using a 1-5 Likert scale. Item-total correlations of the instrument ranged from 0.388 to 0.845, above the r-table value of 0.288, and Cronbach's Alpha reached 0.955; these results indicate acceptable item discrimination and high internal-consistency reliability, but they are not by themselves evidence of content or construct validity, which were not separately tested in this study. AHP results placed Technical Quality of Construction Work at 31.7%, Perception and Satisfaction of Users/Owners at 27.1%, Material Quality at 16.7%, Quality Management System at 12.6%, and Implementation and Control Process at 12.0%. Because these rounded weights summed to 1.001, they were normalized before being multiplied by the actual scores; the resulting Quality Performance Index is 4.212, which falls in the Excellent band of a corrected four-band rating scale (Excellent, Good, Fair, Poor) spanning the 1-5 measurement range. The QPI framework is proposed as a preliminary internal diagnostic tool for periodic evaluation and identification of improvement priorities on a single project; benchmarking across different high-end residential projects is not yet supported and requires calibration on independent samples.

Analysis of Quality Control Using Quality Control Circle & Plan-Do-Check-Act to Improve The Quality of KTMY Joint Brake Products

Alikha Choirunnisa Syafrina — 2026-08-31

Joint Brake KTMY is a safety-critical connector within the motorcycle braking system, yet quality control efforts on this component have received limited attention compared with non-safety-critical automotive parts. This study used a single-site before-and-after case study to evaluate an implemented Quality Control Circle (QCC) integrated with the Plan-Do-Check-Act (PDCA) cycle for Joint Brake KTMY products at PT Ciptaunggul Karya Abadi. Baseline records comprised 30,500 production units and 1,200 targeted defective units; the post-improvement dataset comprised 5,500 production units and 24 targeted defective units. The actions included replacement of worn dies and tapping tools, standardized machine settings, material and hole checks, operator briefings, and inspection check sheets. The targeted-defect proportion decreased from 3.93% to 0.44%, an observed absolute reduction of approximately 3.50 percentage points. Because the comparison had no control group, unequal periods, and possible confounding factors, the result is interpreted as a lower observed post-improvement proportion, not definitive proof of causation or process stability. These findings suggest that standardizing the implemented QCC-PDCA actions into routine work instructions and periodic audits could help sustain quality improvement in safety-critical brake components.

Design and Evaluation of an Android Educational Game for Respiratory-System Learning in Grade V

Meisyah Safira Putri — 2026-08-31

Elementary science instruction at SD Negeri 85 Palembang primarily used lectures, textbooks, and board-based explanations, indicating the need for a more interactive supplementary learning medium. This study aimed to develop an Android educational game, Oxygen: Petualangan Oksigen, for Grade V learning about respiratory systems in plants, animals, and humans, and to evaluate its functional performance, media validity, and student responses. The study employed a research-and-development method using a modified Game Development Life Cycle consisting of initiation, pre-production, production, testing, and release. Developed with Unity, the game integrates learning materials, platformer gameplay, multiple-choice questions, and drag-and-drop activities. Evaluation included Black Box Testing, media validation by six experts, and classroom administration involving 119 of 129 Grade V students, representing a participation rate of 92.25%. Two separate five-item questionnaires were used to identify students’ initial learning needs and gather their responses after using the game. Black Box Testing showed that all documented application functions operated as intended. Media-expert assessments produced scores of 95.00%, 88.33%, 93.33%, 90.00%, 86.67%, and 93.33%, with an aggregate score of 328 out of 360 (91.11%), categorized as Very Valid for presentation, navigation, and graphical design. The comparatively lower ratings concerned character and asset design (79.17%) and quiz presentation (83.33%). Students also provided favorable immediate responses regarding the game’s appearance, ease of use, and attractiveness. However, the initial and post-use questionnaires measured different constructs and therefore cannot demonstrate improved understanding or learning effectiveness. Moreover, content accuracy and instructional quality were not separately validated. Thus, Oxygen: Petualangan Oksigen is functionally operational and considered highly valid in terms of media presentation. These findings support its use as a supplementary classroom prototype. Further studies should involve content and pedagogical experts, equivalent pretest–posttest achievement measures, and a comparison group to determine its educational effectiveness.

SERVQUAL–QFD-Based Service Improvement Framework for Smart Public Service Implementation in Subdistrict Administrative Services

Muhamad Engkos Kosim — 2026-08-31

Public administrative services at the subdistrict level require continuous evaluation to ensure service delivery meets community expectations. This study evaluated administrative service quality at the Conggeang Subdistrict Office, identified critical service gaps, and translated citizen requirements into technical improvement priorities to support Smart Public Service development. A quantitative cross-sectional survey was conducted with 104 residents who had used administrative services at the subdistrict office. Data were collected using a questionnaire containing 16 attributes across five SERVQUAL dimensions: tangibles, reliability, responsiveness, assurance, and empathy. Instrument testing demonstrated strong internal consistency, with Cronbach's Alpha values of 0.900 for expectation, 0.934 for perception, and 0.885 for importance. SERVQUAL analysis revealed that 14 of the 16 attributes yielded negative gap scores. The largest negative gaps occurred in facility cleanliness and comfort (−0.16), digital information media availability (−0.14), fair and non-discriminatory service (−0.13), and service completion timeframe (−0.12). Quality Function Deployment (QFD) was then applied to map customer requirements into technical responses via the House of Quality. The Technical Matrix identified three primary priorities: consistent implementation of service SOPs (8.43%), establishment of clear completion-time standards (8.04%), and optimization of digital information media (7.65%). These priorities offer practical guidelines for service enhancement prior to full pilot implementation.

Web-Based Sales Performance Information System Using K-Means

Inayah Ainina Mawardi — 2026-08-31

PT FAN Integrasi Teknologi is a company in the field of information technology that has sales activities as the basis for recording and evaluating sales performance. The sales performance appraisal process is still carried out manually using spreadsheets and separate documents, causing the recapitulation process to take time and make it difficult for management to evaluate performance. This research aims to develop and build a web-based sales performance information system that can integrate data management and help the sales performance evaluation process. The system development method used to classify sales performance is based on the variables of total score, number of projects, and win rate, applied to a dataset of seven historical sales records at the company. The results of the research are in the form of a sales performance information system that provides data management, dashboards, performance analysis, and reports. The clustering process grouped sales into three exploratory categories, namely High Performer, Medium Performer, and Low Performer, based on similarity in the selected variables rather than an independently validated performance standard. A beta test involving eight respondents obtained an initial satisfaction score of 84.5%. These preliminary results indicate that, as a company-specific prototype, the system has potential as a tool for monitoring and supporting the evaluation of sales performance at PT FAN Integrasi Teknologi, pending further validation with a larger dataset.

Analysis of Land-Cover Change Patterns and Their Temporal Association with Flood Occurrence in West Kendari District

Muh. Agung Apri Mars — 2026-08-31

Urban expansion can alter land cover and reduce the land's capacity to absorb rainfall, thereby increasing surface runoff and flood potential. West Kendari District, part of Kendari City, Southeast Sulawesi Province, experienced substantial land cover change over the past decade and suffered severe flooding in 2024. This study aimed to analyze land cover change patterns in the district between 2014 and 2024 and to describe the temporal relationship between these changes and reported flood occurrences, without quantifying economic losses. Land cover was classified from Landsat 8 OLI/TIRS imagery for 2014 and 2019 and Landsat 9 OLI2/TIRS2 imagery for 2024, all at 30 meter spatial resolution and obtained from the USGS EarthExplorer archive, using the Maximum Likelihood Classification method into six classes. Classification accuracy was evaluated through a confusion matrix, with field validation using 26 reference points available only for the 2024 map, yielding an overall accuracy of 88.46 percent and a corrected Kappa coefficient of 0.851, indicating almost perfect agreement. The spatial analysis showed that forest cover declined by 412.47 hectares (36.8 percent), settlement area increased by 235.91 hectares (52.1 percent), and shrubland expanded by 362.51 hectares (502.6 percent), with the dominant transitions occurring from forest to shrubland and mixed garden, and from mixed garden to settlement. Flood events recorded by the Kendari City Regional Disaster Management Agency rose from none in 2014 to three in 2019 and five in 2024, coinciding in time with forest loss and settlement expansion, although a causal relationship could not be confirmed due to other contributing factors such as rainfall, drainage capacity, river conditions, sedimentation, and tidal influence. Further research incorporating rainfall data and economic loss assessment is recommended.