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All Journal Jurnal PEKA (Pendidikan Matematika) Inkubis: Jurnal Ekonomi dan Bisnis
Dina Agustina, Dina
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Economics, Econometrics & Finance Education Mathematics Social Sciences

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Kemampuan Komunikasi Matematis Siswa SMP pada Materi Bilangan Bulat ditinjau dari Gaya Belajar Auditori Agustina, Dina; Setiani, Ana; Saefuloh, Nandang Arif
Jurnal PEKA (Pendidikan Matematika) Vol. 9 No. 2 (2026): Jurnal PEKA (Pendidikan Matematika)
Publisher : Program Studi Pendidikan Matematika Universitas Muhammadiyah Sukabumi (UMMI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37150/t6k47531

Abstract

ABSTRACT: This study aims to investigate students’ mathematical communication skills based on their learning styles. The research adopts a qualitative approach with a case study design. The subjects of this study were nine 7th-grade junior high school students, selected through purposive sampling. Data collection techniques included test instruments (a learning style questionnaire and mathematical communication skill test sheets) and non-test instruments (interviews). Based on the result and discussion, the findings of the study show that students with a visual learning style experience difficulties when the learning process relies solely on lecture-based methods. These students also tend to feel nervous when asked to explain or present their work, and their mathematical communication skills fall into the moderate category. Students with an auditory learning style tend to lose focus due to frequent noise during task completion. However, they are more confident when explaining or presenting the results of their work, placing them in the high category. Students with a kinesthetic learning style prefer hands-on activities using learning aids or studying outdoors. However, they often lack confidence and feel very nervous during presentations, resulting in their mathematical communication skills being classified in the low category.   ABSTRAK: Penelitian ini bertujuan untuk mengetahui kemampuan komunikasi matematis siswa yang ditinjau dari gaya belajar. Metode yang digunakan yaitu metode pendekatan kualitatif. Desain penelitian yang digunakan yaitu   studi kasus. Subjek yang digunakan dalam penelitian ini yaitu 9 siswa SMP kelas VII dan teknik pengambilan subjek tersebut menggunakan purposive sampling. Teknik pengumpulan data yang digunakan yaitu instrumen tes (angket gaya belajar dan lembar soal kemampuan komunikasi matematis) dan instrumen non tes (wawancara). Berdasarkan hasil penelitian dan pembahasan, hasil dari penelitian tersebut adalah siswa dengan gaya belajar visual itu memiliki kesulitan disaat pembelajaran hanya menggunakan metode ceramah saja dan siswa tersebut merasa gugup saat melakukan penjelasan ulang dan siswa dengan gaya belajar visual berada di kategori sedang, siswa dengan gaya belajar auditori merasa kehilangan fokus karena selalu berisik pada saat mengerjakan soal dan siswa dengan gaya belajar auditori lebih percaya diri ketika melakukan penjelasan ulang atau presentasi hasil pengerjaannya sehingga gaya belajar auditori ada pada kategori tinggi, siswa dengan gaya belajar kinestetik yaitu siswa yang ketika belajar itu selalu ingin praktek menggunakan alat peraga atau belajar di luar ruangan namun ketika melakukan presentasi siswa dengan gaya belajar kinestetik merasa tidak percaya diri dan sangat gugup sehingga gaya belajar kinestetik ada pada kategori rendah.
Economic Feasibility & Carbon Emission Reduction of EV Haul Truck Implementation: A Case Study of Pongkeru Nickel Mining Concession Agustina, Dina; Koesrindartoto, Deddy Priatmodjo
Inkubis : Jurnal Ekonomi dan Bisnis Vol. 8 No. 3 (2026): INKUBIS Jurnal Ekonomi Dan Bisnis
Publisher : Politeknik Siber Cerdika Internasional

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59261/inkubis.v8i3.270

Abstract

Background: Indonesia's nickel mining supports the global EV battery supply chain but relies on diesel haul trucks, causing high fuel consumption, emissions, and exposure to fuel-price volatility. Electrifying hauling can improve efficiency, reduce direct emissions, and strengthen resilience to energy-price and transition risks. Objective: This study analyzes the economic feasibility, environmental impact, and energy-efficiency gains of replacing diesel haul trucks with EV hauling at the Pongkeru Block nickel mine, Indonesia. Methods: A Discounted Cash Flow (DCF) approach using Net Present Value (NPV), Internal Rate of Return (IRR), and Payback Period (PBP) was applied under Conservative, Base Case, and Optimistic scenarios. The scenarios were combined into a probability-weighted expected NPV. The analysis was complemented by activity-based carbon accounting, ESG-integrated valuation with carbon-price scenarios, energy-efficiency analysis, and one-way sensitivity analysis. Results: EV hauling yields NPVs of USD 87.85, 116.99, and 138.70 million under the Conservative, Base Case, and Optimistic scenarios, respectively, versus USD 25.15, 52.57, and 85.18 million for diesel. The expected NPV is USD 112.59 million for EV versus USD 50.86 million for diesel. EV payback is two to three years versus three to five years for diesel. Direct diesel-related emissions are estimated at 142,697.48 tCO₂e over the mine life. EV hauling shows 2.1–3.2 times higher energy-conversion efficiency and 49%–65% lower input-energy requirements. Conclusion: EV-based hauling is economically favorable across all scenarios and delivers substantial environmental and energy-efficiency benefits. Its long-term value depends on reliable electricity supply, adequate charging infrastructure, lower-carbon power sources, effective transition-risk management, and access to sustainable financing.
Co-Authors Deddy P Koesrindartoto Saefuloh, Nandang Arif Setiani, Ana