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INDONESIA
Jurnal Sains dan Teknologi
Published by Universitas Pendidikan Ganesha
ISSN : 23033142     EISSN : 25488570     DOI : -
Core Subject : Science, Education,
Computer Science & IT Education
Jurnal Sains dan Teknologi(JST) is a journal aims to be a peer-reviewed platform and an authoritative source of information. We publish original research papers, review articles and case studies focused on Mathematic, Biology, Physic, Chemistry, Informatic, Electronic and Machine as well as related topics. All papers are peer-reviewed by at least two referees. JST is managed to be issued twice in every volume.
Arjuna Subject : -
Articles 694 Documents
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Comparison of Text Classification Performance Using Manhattan Distance and Jaccard Distance in the KNN Algorithm Ni Ketut Tari Tastrawati; Luh Sukma Mulyani; I Komang Gde Sukarsa; I Putu Eka Nila Kencana
JST (Jurnal Sains dan Teknologi) Vol. 15 No. 1 (2026): April
Publisher : Universitas Pendidikan Ganesha

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23887/jst-undiksha.v15i1.111518

Abstract

The rapid growth of short user-generated content has created significant challenges in accurately classifying sparse and high-dimensional text data, particularly in distinguishing spam from legitimate comments. Inappropriate selection of distance metrics and feature representations often leads to unstable and suboptimal classification performance. This study aims to analyze the effectiveness of Jaccard distance with Binary Bag of Words and Manhattan distance with TF-IDF in improving text classification performance. This research employs a quantitative approach with a comparative experimental design. The research subjects consist of 1,956 labeled text data points, including spam and non-spam comments. Data were collected using documentation techniques from a publicly available dataset, with the instrument in the form of labeled text data and a preprocessing pipeline to ensure data quality. Data analysis was conducted through K-Nearest Neighbors classification, performance evaluation using accuracy, precision, recall, and F1-score, and inferential statistical testing supported by effect size analysis. The results show that Jaccard distance consistently provides more stable and effective classification performance compared to Manhattan distance in handling sparse text data. This finding indicates that set-theoretic approaches are more suitable for high-dimensional text representations than geometric approaches. In conclusion, the alignment between distance metrics and feature representations plays a crucial role in optimizing classification performance. The implications of this study suggest that developers and researchers should prioritize appropriate metric-representation combinations to enhance the effectiveness and reliability of text classification systems.
Physical and Organoleptic Characteristics of Cowpea Yogurt (Vigna unguiculata L.) with the Addition of Roselle Flower Extract (Hibiscus sabdariffa L.) Ika Dyah Kumalasari; Aisyah Putri Muharami; Wahidah Mahanani Rahayu
JST (Jurnal Sains dan Teknologi) Vol. 15 No. 1 (2026): April
Publisher : Universitas Pendidikan Ganesha

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23887/jst-undiksha.v15i1.111696

Abstract

Yoghurt is not only produced from cow’s milk, but can also be made from high protein plant based ingredients such as legumes, one of which is cowpea. However, cowpea has a disadvantage in the form of a bitter and unpleasant aroma and taste caused by lipoxygenase enzyme activity. These undesirable characteristics could be reduced by combining cowpea with other food ingredients. The addition of dates as a natural sweetener and rosella flower extract, which has a distinctive fragrance and refreshing sour taste, was expected to improve the physical and organoleptic properties of cowpea yoghurt. The purpose of this study was to determine the physical and organoleptic characteristics of cowpea yoghurt with the addition of rosella flower extract. This study used four formulations of cowpea milk with different concentrations of rosella flower extract, namely F0 (100%:0%), F1 (98%:2%), F2 (96%:4%), and F3 (94%:6%), each formulation was added with 30 g of date juice as a natural sweetener. The study was conducted in four stages, including yoghurt production, viscosity testing, product acceptance testing (scoring), and organoleptic testing (hedonic and descriptive). The results showed that rosella flower extract significantly affected the viscosity and organoleptic acceptance of cowpea yoghurt. Viscosity values and hedonic test showed significant effects (p<0.05) on colour, aroma, thickness, texture, taste, and overall acceptance. Formulation F3 was the most preferred, while F0 showed the highest viscosity value. Yoghurt F3 showed dark brown colour, soft texture, moderate thickness, sour-sweet taste. Roselle flower extract improved the physical and organoleptic characteristics of jackfruit yoghurt.
Information System Quality Using Webqual 4.0 Method, Importance Performance Analysis (IPA) and Usability Testing Gemara Adhiyasa Parahita Nurgraha; Gede Rasben Dantes; I Made Gede Sunarya
JST (Jurnal Sains dan Teknologi) Vol. 15 No. 1 (2026): April
Publisher : Universitas Pendidikan Ganesha

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23887/jst-undiksha.v15i1.112440

Abstract

The Academic Information System (SIAKAD), as the primary digital service in higher education, has not fully met user expectations regarding ease of use, information quality, and service security. This study aims to analyze the suboptimal service quality of the SIAKAD website resulting from a gap between user expectations and system performance. The method used is a quantitative survey. The population in this study comprised all users of the Academic Information System (SIAKAD), including students, lecturers, and administrative staff. The sampling technique was carried out in two stages: purposive sampling and accidental sampling. The number of respondents in this study was 65 for the WebQual 4.0 and IPA analyses, and 20 for usability testing. Data collection methods in this study were closed questionnaires, interviews, observations, and usability testing. The research instrument used a questionnaire. The analysis assessed the dimensions of usability, information quality, and service interaction quality and mapped the level of importance and performance to determine improvement priorities. The results showed that all aspects of SIAKAD were highly important, but the actual quality fell short of user expectations. The system performed well in display clarity, information relevance, and academic communication, but was less than optimal in information updates, data security, and user experience. IPA prioritizes user experience, information accuracy, data security, and communication effectiveness for improvement. Usability testing showed that the system effectively supports academic functions but remains inefficient and not yet fully satisfying to users.
Performance Evaluation of Tungsten-Based Composites as Lead-Free X-Ray and Gamma Radiation Shielding Materials Across Medical Photon Energy Ranges Mahmoud Suleiman Dahoud
JST (Jurnal Sains dan Teknologi) Vol. 15 No. 1 (2026): April
Publisher : Universitas Pendidikan Ganesha

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23887/jst-undiksha.v15i1.112441

Abstract

Lead-based radiation shielding has limitations in the form of high toxicity and high density, making it less safe and efficient for medical applications. Therefore, alternative radiation shielding materials are needed that are lighter, non-toxic, and remain effective across a wide range of photon energies. This study aims to evaluate the performance of tungsten-based composites as lead-free radiation shielding materials through a systematic review and numerical simulation of 110 scientific articles from 2025 to 2026, focusing on 18 tungsten composites (S1–S18). Data were collected from the literature and the Phy-X/PSD database using half-value layer (HVL) and effective atomic number (Zeff) parameters, then analyzed comparatively with lead shielding. The results show that composites with high tungsten content, especially S5, have better HVL values than lead. At low energies, non-linear behavior occurs due to the K-edge effect and the dominance of the photoelectric effect. In contrast, at high energies, the HVL increase is influenced by Compton scattering. Material density also affects the effectiveness of the shielding. It is concluded that tungsten composites have the potential to be safer and more sustainable radiation shielding materials, with the implication that optimizing composition and density is key to developing effective materials.

Page 70 of 70 | Total Record : 694

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