KURVATEK

NICKEL LATERITE POTENTIAL OF THE PUU NUNU PROSPECT, SOUTH KABAENA DISTRICT, BOMBANA REGENCY, SOUTHEAST SULAWESI PROVINC

Dava Saliham Qoyyibi, Oky Sugarbo, Hill Gendoet Hartono — Thu, 30 Apr 2026 00:00:00 +0700

Nickel occurrences in Indonesia are generally found as lateritic nickel deposits derived from the
residual weathering of bedrock from ophiolite or ultramafic complexes. Sulawesi Island and the surrounding
smaller islands possess significant nickel potential due to their complex geological setting. Therefore, a
geological study is necessary to assess this potential by conducting surface mapping. The study area is
located in Southeast Sulawesi and falls within the mining business license (IUP) area of PT. Tambang Bumi
Sulawesi. This research aims to carry out surface geological mapping, with the objective of identifying
geological conditions, including geomorphology, stratigraphy, geological structures, and resource estimation
in areas with lateritic nickel potential. The results of the study indicate that the geomorphological units
consist of strongly undulating-denudational hills and weakly to strongly undulating-denudational areas. The
stratigraphy of the study area, from oldest to youngest, comprises lherzolite and hornblende pyroxenite of the
Ultramafic Complex, which are unconformably overlain by mica schist and marble of the Pompangeo
Complex. The geological structure is characterized by a sinistral (left-lateral) left slip fault trending
northwest-southeast. Resource estimation using the ordinary kriging method yielded a total measured
resource volume of 518,855 m³, with an estimated tonnage of 778,283 tons in the lateritic potential area.

EVALUATION OF OPEN CHANNEL DRAINAGE IN THE MINING AREA OF BLOK SAWIT PT PPA AT PT ABC JOBSITE USING HEC-RAS SIMULATION

Thu, 30 Apr 2026 00:00:00 +0700

The mining area of PT PPA site PT MLP, specifically in the Sawit Block, has flooding on the road. This problem is supported by the fact that the rainfall intensity at the research site is classified as heavy (25.61 mm/hour). Open channels are one of the most important infrastructures for draining runoff water. However, there are areas without open channels and channels with insufficient capacity. This indicates that the existing mining drainage system is not optimal. Therefore, a study and design of open channels in the Sawit Block area are required. This research estimates surface water flow using the rational method, considering rainfall intensity (Mononobe), DTH characteristics, and runoff coefficients (Gautama). The runoff flow rate values are used as a reference in assessing and designing the dimensions of the open channel (Manning equation). A simulation of potential flooding in HEC-RAS is then conducted as a form of validation for the channel dimensions obtained from the calculations. The rainfall intensity value obtained is 25.61 mm/hour with a 2-year return period, and a hydrological risk of 88%. Based on calculations using the Manning equation and simulations in HEC-RAS, design modifications are required for open channel 1 at DTH 4 and an expansion of open channel 4 at DTH 6. However, the actual capacity of open channels 2 and 3 is already sufficient.

WETLAND CONSTRUCTION DESIGN FOR ACID MINE DRAINAGE MANAGEMENT IN POST-COAL MINING VOIDS

Bantar Tyas Suksmawati Rukmana, Shofa Rijalul Haq, Oktarian Wisnu Lusantono — Thu, 30 Apr 2026 00:00:00 +0700

Acid mine drainage (AMD) was one of the major environmental problems commonly encountered in mining activities, including in Kutai Barat, East Kalimantan. The presence of AMD reduced environmental quality. This study aimed to design a constructed wetland as a passive treatment solution for AMD by utilizing Typha sp. and microalgae. The methods applied included geochemical characterization of rocks, hydrological analysis, and a pilot project experiment using five compartments. The results indicated that most rocks in the low wall area were classified as acid-forming, while creek water around the void had a pH of 2–3.5. The pilot project showed that the application of lime and organic fertilizer on planting media with Typha sp. increased water pH to 6.91, reduced dissolved metals below the quality standards, and improved soil quality. This study concluded that constructed wetlands had potential as a passive, environmentally friendly, and sustainable solution for acid mine drainage management.

2D GEOELECTRIC DATA ANALYSIS FOR COAL LAYER DETERMINATION AND COAL RESOURCE ESTIMATION

Yuni Elfrina Siringoringo — Thu, 30 Apr 2026 00:00:00 +0700

Potensi batubara terdapat di Lapangan Neira Kalimantan Utara, meskipun eksplorasi geofisika di daerah tersebut masih terbatas . Penelitian ini bertujuan untuk mengidentifikasi lapisan batubara berdasarkan nilai resistivitas batuan dan memperkirakan sumber dayanya. Metode yang digunakan adalah geolistrik resistivitas 2D dengan konfigurasi Wenner-Schlumberger dan analisis geostatistik menggunakan kriging biasa pada perangkat lunak SGeMS. Hasil pengolahan data geolistrik resistivitas 2D menunjukkan bahwa lapisan batubara tersebut memiliki nilai resistivitas 90–150 Ωm yang secara umum menunjukkan batubara jenis lignit. Perkiraan sumber daya yang diperoleh melalui pemodelan resistivitas dan interpolasi spasial berjumlah 2.124.510,323 ton, dan setelah koreksi faktor geologi menjadi 650.951,016 ton. Hasil penelitian ini diharapkan dapat menjadi acuan dalam eksplorasi dan pengelolaan batubara berkelanjutan di Kalimantan Utara.

Kata Kunci : Batubara, Estimasi sumber daya, Geolistrik resistivitas 2D, Kriging biasa, Wenner-Schlumberger.

EXPERIMENTAL STUDY ON THE EFFECT OF IGNITION ANGLE VARIATIONS AND FUEL OCTANE NUMBER ON THE PERFORMANCE OF 110CC UNDERBONE MOTORCYCLES

Mustakim Mustakim, Sigit Gunawan, Dandung Rudy Hartana — Thu, 30 Apr 2026 00:00:00 +0700

Improving motorcycle performance is a primary focus in efforts to enhance energy efficiency. Motorcycle performance is strongly influenced by ignition timing and fuel octane rating, as the standard ignition timing of most motorcycles is designed for RON 88 fuel. This study aims to examine the effect of ignition timing variation using a programmable CDI and different fuel types on the performance of a 110 cc underbone motorcycle engine. The research variables include ignition timing and fuel types with different octane ratings (Pertalite RON 90, Pertamax RON 92 and Pertamax Turbo RON 98). An experimental method was employed by conducting tests on a chassis dynamometer to obtain power and torque data. The results show that adjusting the ignition timing using a programmable CDI and increasing the fuel octane rating significantly improve engine power and torque, particularly at medium and high engine speeds. The highest standard ignition timing—32° before top dead center using regular fuel—produced a maximum power of 7.8 HP at 7500–8000 RPM and a peak torque of 8.41 Nm at 4000 RPM. Meanwhile, with the programmable CDI, the highest power was achieved at an ignition timing of 34° before top dead center on map 2 using Pertamax Turbo (RON 98), generating a maximum power of 8 HP at 7500 RPM and a peak torque of 8.66 Nm at 4500 RPM.

A MULTI-STAGE VALIDATION OF AN INTERIOR DESIGN MODEL FOR PSYCHOLOGICAL WELL-BEING

Ahmad Dananjaya — Thu, 30 Apr 2026 00:00:00 +0700

Abstract Traditional interior design often prioritizes aesthetics over users' psychological needs, while existing Human-Centered Design (HCD) approaches remain intuitive. This research proposes and validates a "human as an element" design paradigm focused on personalization, flexibility, and autonomy. A multi-stage mixed-methods methodology was used to test its impact on psychological well-being. The first stage, a Virtual Reality (VR) experiment (N=180), found that the "human as an element" design significantly increased psychological well-being compared to a minimalist (control) design, providing causal evidence. The second stage, a pre-test/post-test field case study (N=46), implemented these principles in a real-world setting. Results showed a dramatic increase in psychological comfort, validating the model's practical effectiveness. This study bridges the gap between internal (VR) and external (field) validity, culminating in an empirically tested "Integrative Psycho-Behavioral Interior Design Model" for evidence-based practice.

CHARACTERISTICS OF MARBLE ROCK DENSITY BASED ON MICROTREMOR DATA IN TOTOGAN FORMATION, KARANGSAMBUNG, KEBUMEN

Nugroho Budi Wibowo — Thu, 30 Apr 2026 00:00:00 +0700

In Totogan Village, there is an outcrop of the Totogan Formation which is composed of white, red and green marble. The marble stones in the Totogan Formation are part of the Karangsambung Geopark nature reserve, so its existence is one of the important sites. This study aims to determine the distribution of the presence of marble stones in the Totogan Formation using the microtremor method. Identification of the presence of marble stones was carried out using rock density parameters based on microtremor data. The density value at the measurement site varies between 400 – 2600 kg/m3. The density of rocks with a value of <1000 kg/m3 is interpreted as a surface soil layer, a density of 1000 – 1400 kg/m3 is interpreted as weathered Marble and a density of >1400 kg/m3 is fresh marble.

LITHOLOGY OF THE COMPOSITION AND DISTRIBUTION OF GEOLOGICAL STRUCTURES ON CUMBRI HILL, BITING DISTRICT, PONOROGO REGENCY, EAST JAVA

Al Hussein Flowers Rizqi, Fanssyah Widianto — Thu, 30 Apr 2026 00:00:00 +0700

Cumbri Hill, situated on the boundary of Ponorogo and Wonogiri, is a narrow ridge trending northeast-southwest, formed by regional structures and variations in lithological resistance; however, comprehensive geological investigations remain scarce. This study seeks to determine the constituent lithology and examine the geological structural factors that affect the morphology of Cumbri Hill. The methodologies employed encompass geological mapping, petrographic and micropaleontological analyses, and stereonet analysis of fracture and fault data. The findings reveal that the lithology comprises rudstone limestone from the Middle Miocene (N16) within a Middle Neritic setting, which is subsequently overlain by shallow trachyte intrusions exhibiting porphyritic-vesicular textures. The geological structure is characterized by NE-SW oriented left-lateral strike-slip faults, with one site indicating a reverse left-slip mechanism attributed to a localized compressional component. This structural pattern governs the orientation of the ridge, linear valleys, and the location of the intrusion. The research findings significantly enhance the comprehension of the local magmatic and tectonic evolution of Ponorogo and act as a reference for advancing geological studies and geotourism in the area.

SETTLING POND DESIGN IN OPEN PIT MINES

Arie Inung — Thu, 30 Apr 2026 00:00:00 +0700

Kegiatan penambangan terbuka selalu berkaitan dengan air hujan. Air hujan yang jatuh ke permukaan tanah dapat mengikis tanah, sehingga menyebabkan erosi tanah. Dengan adanya erosi tanah, banyak partikel tanah yang dapat mengganggu kualitas air, yaitu total padatan tersuspensi (TSS), sehingga diperlukan kolam pengendapan. Tujuan dari penelitian ini adalah untuk mendapatkan desain yang ideal untuk pengelolaan air limbah. Data yang digunakan adalah curah hujan, luas daerah tangkapan hujan, nilai TSS, dan dimensi aktual kolam pengendapan. Hasil analisis menunjukkan bahwa nilai debit pencucian bijih bauksit dan material sebesar 0,389 m3/detik dengan jam kerja 19,86 jam, sedangkan debit limpasan sebesar 1,45 m3/detik dengan jam hujan 3,51 jam, sehingga total debit air dan padatan yang masuk ke kolam pengendapan sebesar 1,84 m3/detik atau 46.179,43 m3/hari. Rancangan kolam pengendapan dengan target produksi 2.300.000 ton bauksit tercuci per tahun memiliki luas total kolam 18.542 m², jumlah kompartemen yang dibutuhkan sebanyak 6, dan volume kolam pengendapan sebesar 46.305,9 m³. Persentase pengendapan adalah 86,46%, dengan volume pengendapan sebesar 1.137,08 m³ per hari. Rancangan ini dapat menjadi dasar bagi kolam pengendapan yang efektif untuk mendukung pencapaian standar kualitas air.

INTEGRATION OF TAM AND UTAUT MODELS IN ANALYZING USER SATISFACTION OF ONLINE TRANSPORTATION MODES

Sudiana Sudiana, Trie Handayani — Thu, 30 Apr 2026 00:00:00 +0700

The development of information technology and digitalization has significantly transformed the transportation sector. The presence of online transportation services such as Gojek, Grab, Maxim, and Shopee in Yogyakarta has increased accessibility, convenience, and efficiency for urban communities. However, user satisfaction remains a challenge due to unmet expectations, long waiting times, and various technical issues within the applications [1]. Therefore, an in-depth examination of the factors influencing user satisfaction is necessary. This study aims to identify and analyze the determinants of user satisfaction with online transportation services in Yogyakarta by integrating the Technology Acceptance Model (TAM) and the Unified Theory of Acceptance and Use of Technology (UTAUT). This integrative approach is used because it provides a comprehensive explanation of user perceptions and behavioral responses to technology. This study adopted a quantitative method with an exploratory sequential mixed methods design. The population consisted of active users of online transportation applications in Yogyakarta, selected through stratified proportional random sampling. Data were collected using a Likert-scale questionnaire and semi-structured interviews. Data analysis was conducted using Structural Equation Modeling (SEM) with AMOS to examine the relationship between the TAM and UTAUT variables. The results of the hypothesis testing, which included 13 hypotheses, showed that 9 hypotheses were accepted (significant) and 4 were rejected (insignificant). Overall, the integrated TAM–UTAUT model successfully explained most of the factors influencing user satisfaction and behavioral intention, particularly through the significant roles of Attitude Toward Using (ATU), Social Influence (SI), Perceived Ease of Use (PEOU), Effort Expectancy (EE), Behavioral Intention (BI), and Performance Expectancy (PE). The findings indicate that emotional factors, perceived ease of use, user experience, and social pressure exert a stronger influence on user satisfaction and intention than rational considerations such as functional benefits or infrastructure readiness. Therefore, service providers are encouraged to prioritize interface simplification, expectation management, and social influence-based marketing strategies rather than simply adding technical features or emphasizing operational efficiency.

LAND POTENTIAL IDENTIFICATION FOR RESIDENTIAL AREA DEVELOPMENT IN CIANJUR REGENCY

Janthy Trilusianthy Hidayat, Novida Waskitaningsih, Muhammad Alif Dhiya Ulhaq — Thu, 30 Apr 2026 00:00:00 +0700

Natural population growth and in-migration opportunities in Cianjur Regency have the potential to stimulate the expansion of residential activities into areas that are not intended for such development. This study aims to identify the extent of land suitable to support residential area development in Cianjur Regency based on physical condition criteria and land-use policy considerations. The research employs a residential land suitability analysis using a Multi-Criteria Evaluation (MCE) approach, complemented by an analysis of residential land availability conducted through a comparison of existing land use, spatial pattern planning policies, and policies on Sustainable Food Agricultural Land (LP2B) in Cianjur Regency. The results indicate that 7,038.651 ha (1.94%) of land area has potential for residential development. This area comprises land with very high suitability (S1) covering 123.841 ha (0.03%), moderately suitable land (S2) covering 6,481.492 ha (1.79%), and marginally suitable land (S3) covering 433.318 ha (0.12%).

Keywords: Development, Land, Residential

ACID MINE DRAINAGE TREATMENT

Rifki Naufal — Thu, 30 Apr 2026 00:00:00 +0700

Acid mine drainage is one of the main environmental problems in coal mining activities, especially open pit mining methods. This study aims to analyze the characteristics of acid mine drainage in settling pond 39 inlet of PT Indominco Mandiri and analyze the effectiveness of the combination of active (addition of quicklime) and passive (phytoremediation using Pistia stratiotes) treatment in increasing pH and reducing Mn levels. The research methods include field surveys, laboratory tests, and laboratory-scale experiments with four treatment variations: P1 without treatment or treatment (control), P2 addition of lime (active), P3 addition of lime and pistia stratiotes plants (active-passive combination), and P4 addition of plants only (passive) using a static phytoremediation system for 7 days per periode Mn parameters were tested until the 28th day, while pH were analyzed every 3 days until the 30th day. The results showed that the initial pH was 3 and Mn 13.95 mg/L and the P3 treatment was the most effective, increasing pH by 138.67% and reducing Mn by 99.15% at the end of the experiment.

UTILIZATION OF BLACK SOLDIER FLY LARVAL SHELLS AND FRASS FOR THE PRODUCTION OF SOLID AND LIQUID FERTILIZERS AND THEIR APPLICATION TO CHILI CULTIVATION

Ani Purwanti, Mukasi Wahyu Kurniawati — Thu, 30 Apr 2026 00:00:00 +0700

This research explores the utilization of Black Soldier Fly (BSF) frass and larval shells (exuviae) as primary materials for producing both solid and liquid organic fertilizers, and assesses their influence on the growth and productivity of chili plants (Capsicum annuum L.). The experiment was carried out under greenhouse conditions using a Completely Randomized Design (CRD) consisting of four treatments: control (P0), NPK fertilizer (P1), solid BSF frass fertilizer (P2), and fermented liquid fertilizer made from BSF frass and larval shells (P3). Observed parameters included plant height, leaf number, fresh fruit weight, and post-harvest soil nitrogen content. Results revealed that the P3 treatment substantially improved plant performance compared to the other treatments, showing an average increase of 61,9% in height and 128% in fruit weight relative to the control (p<0.05). Additionally, soil nitrogen levels rose by 68%, indicating that BSF-based fertilizers enhance nutrient availability and promote soil microbial activity. Overall, the findings demonstrate that integrating BSF frass and larval shells into fertilizer formulations presents an environmentally friendly and effective alternative to conventional chemical fertilizers for sustainable chili cultivation.

PROBABILISTIC SEISMIC HAZARD ANALYSIS BALI: FOCUS ON LOCAL EARTHQUAKE SOURCES AND SHALLOW BACKGROUND

Riski Kurniawan, Adistina Lailia Fajar Dewi, Ajimas Pascaning Setiahadiwibowo — Thu, 30 Apr 2026 00:00:00 +0700

This study evaluates seismic hazard in Bali Island by considering local fault sources and shallow background seismicity using Probabilistic Seismic Hazard Analysis (PSHA). Peak Ground Acceleration (PGA) was estimated using Ground Motion Prediction Equations (GMPEs) for shallow crustal earthquakes, adjusted to the characteristics of local fault and shallow background sources. The results show that PGA values from local fault sources range from 0.02–0.20 g for a 500-year return period and 0.05–0.30 g for a 2500-year return period. Meanwhile, shallow background sources produce PGA values of 0.02–0.30 g for 500 years and 0.30–0.60 g for 2500 years. Southern Bali shows the highest PGA values, while central and northern Bali exhibit moderate to low values. The integration of both seismic sources provides a more representative hazard map to support risk mitigation, spatial planning, and earthquake-resistant building design.