Clean Energy and Smart Technology

COST AND ON-SITE DURATION COMPARISON OF CONVENTIONAL AND PRECAST FLOOR SLAB METHODS: A TWO-STORY BOARDING HOUSE CASE STUDY IN YOGYAKARTA

2026-07-31T06:40:23+07:00

Floor slab construction strongly affects both the cost and the on-site duration of low-rise buildings, yet transparent project-level comparisons for small boarding houses remain scarce. This study compares the direct cost and on-site construction duration of conventional cast-in-place and precast floor slab methods for the 50.36 m² second-floor slab of a two-story type-135 boarding house in Pugeran, Yogyakarta. A quantitative comparative case study was applied using project drawings, an itemized quantity take-off, the Indonesian Unit Price Analysis (AHSP), documented local price bases, a supplier quotation, and labor-based duration calculations. The conventional alternative cost IDR 35,746,962.53 and the supplier-inclusive precast alternative IDR 30,216,000.00, a project-specific saving of IDR 5,530,962.53 (15.47%), while the calculated on-site duration fell from 11 days to 2 days, a reduction of 9 days (81.82%). A sensitivity analysis shows that the cost advantage reverses once the precast price rises by about 18%, identifying the condition under which the conventional method becomes cheaper. The reported savings apply only to the prices, crew composition, and work scope adopted in this case study; they exclude factory lead time and curing, and they do not constitute structural verification of the precast system.

QUANTITY TAKE-OFF AND UNIT PRICE ANALYSIS FOR THE ESTATE SEPAKU HOUSING PROJECT, PENAJAM PASER UTARA REGENCY

2026-07-08T12:33:20+07:00

Housing development in the buffer area of Indonesia's Nusantara Capital City (IKN) requires accurate, location-sensitive cost estimates, yet the cost structure of such projects remains poorly documented. This study analyzes the Cost Budget Plan (Rencana Anggaran Biaya/RAB) of the Estate Sepaku Housing Project in Penajam Paser Utara Regency using quantity take-off and Unit Price Analysis (Analisis Harga Satuan Pekerjaan/AHSP). A quantitative descriptive case study was applied to a work package of 20 housing units and supporting site infrastructure on a 2,211 m² site with 1,055 m² of building floor area, using working drawings, technical specifications, PUPR Regulation No. 8 of 2023, and the 2023 regional Standard Price List of Goods and Services (SHBJ). Work items were identified, quantities were calculated and reconciled against the cost recapitulation, AHSP-based unit prices were applied, and costs were recapitulated by work group. The total construction cost was Rp4,240,234,957, equivalent to Rp212,011,748 per housing unit and Rp4,019,180 per m² of building floor area, excluding taxes and other non-construction cost components. Wall work dominated at Rp1,202,854,210 (28.37%), followed by roofing work (18.62%), door and window frame work (11.57%), and structural work (11.12%); together these four groups accounted for 69.67% of the total. The novelty of this study lies in mapping the cost drivers of repetitive housing construction in the IKN buffer area, providing normalized cost benchmarks and identifying the work groups that should receive priority in procurement planning and budget control.

THERMAL AND GEOMETRIC CHARACTERIZATION OF A PLASMA TORCH: A STUDY ON THE EFFECT OF ELECTRICAL CURRENT VARIATION

2026-10-02T10:51:22+07:00

Plasma gasification is a technology that utilizes high plasma energy to convert organic and inorganic materials into syngas. In hot plasma gasification, a plasma torch heats and decomposes waste into synthetic gas (syngas). This study is expected to improve understanding of efficient and effective plasma gasification operating parameters. The experimental method in this study uses variations of DC electric currents of 30 A, 40 A, 50 A, and 60 A, with three replicates conducted for each experimental condition at a constant operating pressure of 5 bar and a gas flow rate of 21 L/min. The highest arc length and temperature were obtained at 60A with argon as the plasma gas (20 mm, 563.67ºC) and with air as the plasma gas (25 mm, 215ºC). Electric current and plasma gas type can affect the efficiency of gasification using a plasma torch; higher electric current increases arc length and temperature. Air can be used as a plasma gas alternative to other plasma gases. This research can serve as a reference for developing gasification technology using a plasma torch.

SCHEDULE DEVIATION EVALUATION OF A THREE-STORY BOARDING HOUSE PROJECT USING EARNED VALUE MANAGEMENT

2026-07-13T09:02:40+07:00

Delays in construction projects affect the achievement of completion targets, so a control method that evaluates schedule performance effectively is required. This study evaluates the schedule performance of a three-story boarding house project at Gg. Menur, Ngropoh, Condongcatur, Depok, Sleman using a schedule-based Earned Value Management (EVM) approach. Because the project Bill of Quantities (BoQ) was not available, Planned Value (PV) and Earned Value (EV) are represented by cumulative percentages of physical progress rather than by budgeted cost values. The approach is therefore a modified, schedule-only application of EVM: it measures schedule performance alone, and cost indicators such as Cost Variance (CV) and Cost Performance Index (CPI) are outside its scope. A quantitative descriptive approach was applied to the project time schedule and weekly progress reports, and performance was analyzed through Schedule Variance (SV) and Schedule Performance Index (SPI), with weeks classified using a predetermined tolerance band of SPI = 1.00 ± 0.05. At the end of week 35 the PV reached 100% while the EV reached only 76.224%, giving an SV of −23.776 percentage points and an SPI of 0.76. Of the 35 weeks, 60% were ahead of schedule, 14.29% within tolerance, and 25.71% delayed, with sustained delay from week 27. The actual progress rate remained almost constant at about 2.2 percentage points per week throughout, whereas the plan required it to double after week 25, indicating that the deviation arose from a back-loaded baseline rather than from a decline in site productivity. An Earned Schedule analysis gives an estimated duration of approximately 42.6 weeks, about 7.6 weeks beyond the plan.

ATTENTION ENHANCED HYBRID VGG19 CNN MODEL FOR ROBUST SUGARCANE DISEASE CLASSIFICATION

2026-06-12T10:15:00+07:00

Accurate and timely identification of sugarcane diseases is essential for improving crop productivity and supporting sustainable agricultural practices. This study proposes an attention-enhanced hybrid deep learning framework that integrates VGG19-based transfer learning with custom convolutional neural network (CNN) layers for robust disease classification. To address the challenge of high inter-class similarity among sugarcane diseases, a lightweight attention mechanism is incorporated to selectively emphasize disease-relevant regions and enhance discriminative feature learning. A dataset comprising 2000 labeled sugarcane leaf images across five disease classes—Cercospora Leaf Spot, Helminthosporium Leaf Disease, Rust, Red Dot, and Yellow Leaf Disease—was used for training and evaluation. The proposed model was assessed using standard performance metrics, including accuracy, precision, recall, and F1-score. Experimental results demonstrate that the proposed approach achieves an accuracy of 94.6%, outperforming baseline CNN and conventional VGG19 models. Furthermore, the model is benchmarked against state-of-the-art architectures such as ResNet50, EfficientNet-B0, and MobileNetV2, demonstrating superior performance in feature discrimination and classification robustness. The integration of attention-based feature refinement with transfer learning significantly improves localization of disease-specific patterns and reduces misclassification among visually similar classes. The proposed framework offers a scalable and efficient solution for real-time crop disease detection and precision agriculture applications. Future work will focus on optimizing the model for edge deployment and extending the framework to multi-crop disease classification