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Rekayasa: Jurnal Penerapan Teknologi dan Pembelajaran
Published by Universitas Negeri Semarang
ISSN : -     EISSN : 25276964     DOI : https://doi.org/10.15294/rekayasa
Core Subject : Education,
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REKAYASA journal publishes exciting articles from all fields of research and Engineering Science. The journals primary focus is on research practice and engineering processes utilizing biomass or factory waste. The engineering journal is an open-access peer-reviewed journal that publishes articles from all areas of Engineering and Science research.
Arjuna Subject : Umum - Umum
Articles 5 Documents
 1 
Search results for , issue "Vol. 21 No. 1 (2023)" : 5 Documents clear
Sustainable Dyeing: Utilizing Natural Ketapang Colors for Shibori Products Widowati; Atika; Sholikhah, Roudlotus; Nurmasitah, Sita; Wahyuningsih, Sri Endah; Apriliana, Luthfiyah; Ayudianisa, Nadhifa Luthfihasna; Mutiara, Alma
Rekayasa Vol. 21 No. 1 (2023)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/rekayasa.v20i2.897

Abstract

The use of synthetic dyes in the textile industry produces wastewater with high potential for environmental pollution. Utilizing natural dyes from Ketapang leaves offers an alternative for reducing such wastewater and can be considered a sustainable dyeing method. According to data from the UNNES Conservation Development Agency, there are 5,170 Ketapang trees around the UNNES campus, indicating a plentiful supply for natural dye production. The purpose of this study is to explore the potential of Ketapang leaf dye in enhancing the aesthetic quality of Shibori products, specifically in terms of motif aesthetics and color direction. The research employs a quantitative approach with an experimental design, using a single variable. Data analysis was conducted through descriptive percentage statistics. The Shibori with the highest aesthetic value was produced using lime as a fixative, achieving a 95% rating (highly quality). Color direction analysis showed that each fixative produced different color outcomes: lime resulted in a Dijon color, alum produced a Corn color, and ferrous sulfate yielded a Seaweed color. Based on these findings, it can be concluded that natural dyes from Ketapang leaves contribute significantly to both motif aesthetics and color direction in Shibori dyeing, offering a sustainable and environmentally friendly alternative for textile production.
Site Effect Analysis in Prambanan District and Surroundings Using Shear Wave Velocity and Ellipticity Curve Method from Microtremor Data Rahmania Sofyana Ulya, Rahmania Sofyana Ulya; Adhi, Mochamad Aryono; Budi Wibowo, Nugroho; Desi Mustami Limayukha, Desi Mustami Limayukha; Elsa Fadlika Widyantari, Elsa Fadlika Widyantari; Bilqis El Farsiyyi, Billqis El Farsiyyi; Ilqia Rahma, Ilqia Rahma
Rekayasa Vol. 21 No. 1 (2023)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/rekayasa.v20i2.9962

Abstract

The shear wave velocity (Vs) is a crucial parameter for determining subsurface layers by averaging the Vs value to a depth of 30 meters, known as Vs30. This study aims to analyze the subsurface soil layers, calculate the Vs30 value, and assess the potential seismic site classifications in Kapanewon Prambanan and its surrounding areas. The research utilizes secondary microtremor data from 27 observation points in the form of MSD files. The microtremor data was processed using Geopsy software with the HVSR method to generate an H/V curve. This curve was further analyzed with the Ellipticity Curve method via Dinver software to obtain the Vs profile at various depths. The findings suggest that the subsurface layers in Kapanewon Prambanan are predominantly composed of hard, very dense soil, soft rocks, and solid rocks, based on the Vs30 values. The Vs30 distribution across the region ranges from 267.857 m/s to 1675.977 m/s, classified into site categories A, B, C, and D. However, the majority of the area falls under site classes B and C. These classifications indicate that the regions under B and C have a relatively lower potential for significant earthquake wave amplification. Nonetheless, attention should still be given to areas categorized under sites D and E, particularly for earthquake disaster mitigation efforts. This detailed Vs30 analysis provides critical insights for seismic assessments, regional planning, and mitigation strategies in Kapanewon Prambanan.
Strategies for Clean Production in Methyl Isocyanate Synthesis for Pesticide Raw Materials Faisal, Deni; Sulaiman, Fatah; Pramudita, Marta
Rekayasa Vol. 21 No. 1 (2023)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/rekayasa.v21i1.15782

Abstract

The increasing demand for pesticides in agriculture has led to a rise in the production of methyl isocyanate, a key intermediate in carbamate pesticide manufacturing. However, this process generates sodium sulfate as a by-product, dissolved in an aromatic solvent, which, if not adequately managed, contributes to environmental pollution and resource inefficiency. Chemical and environmental engineering are crucial in addressing this issue by developing effective separation and recovery methods. One potential solution is the distillation process, which separates sodium sulfate based on boiling point differences with water. However, the effectiveness of this method depends on operational conditions, particularly pressure and sulfuric acid concentration. This research focuses on optimising the recovery of sodium sulfate from methyl isocyanate production waste by investigating different operating pressures (atmospheric, vacuum, and combined) and sulfuric acid concentrations (0 M, 0.07 M, 0.15 M, 0.22 M, and 0.30 M). A recovery efficiency of sodium sulfate as high as 92.5% using vacuum distillation at a 0.22 M sulfuric acid concentration. Additionally, the condensate water contained 98.7% purity, making it suitable as a precursor for struvite fertiliser. Sodium sulfate is used as a raw material in producing insecticidal pesticides, with a purity level of 97.3%. This study demonstrates that an optimised distillation process can enhance the efficiency of pesticide production by minimising waste and maximising resource utilisation, contributing to cost efficiency and environmental in industrial pesticides.
Seismic Interpretation Using RMS Amplitude and Envelope Attributes to Identify Hydrocarbon Prospects in the “CAT” Field, Central Sumatra Basin Sulaiman, Ryan; Adhi, M. Aryono; Nurcahya, Budi Eka
Rekayasa Vol. 21 No. 1 (2023)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/rekayasa.v21i1.19597

Abstract

To enhance oil production rates, optimising idle wells with reserve potential and continuing exploration efforts to discover new hydrocarbon resources are necessary. The CAT Field in the Central Sumatra Basin is one of Indonesia's prospective oil and gas-producing areas. This study aims to identify and map the distribution of sandstone reservoirs through 3D seismic data interpretation using RMS Amplitude and Envelope seismic attributes. The data used are secondary data from a reflection seismic survey processed at the Energy Study Centre. The interpretation stages include well-to-seismic tie, horizon picking, time structure mapping, and seismic attribute analysis. The interpretation results show that RMS Amplitude values in the Duri Formation range from 0.80 to 5.60, while in the Bekasap Formation, they range from 0.00 to 4.00. The Envelope attribute values in the Duri Formation range from 0.60 to 8.40, and from 0.50 to 6.00 in the Bekasap Formation. High attribute value zones are consistently detected around wells CAT_01, CAT_03, and northwest of CAT_02, corresponding to elevated topography based on the time structure map. These findings indicate potential hydrocarbon accumulation in the area, making it a prime target for field development and revitalisation. Seismic attribute interpretation offers an efficient exploration approach and supports future sustainable exploration efforts.
Evaluation of Seismic Vulnerability Index and Soil Classification in Sleman Regency Based on Microtremor Analysis and the HVSR Method Fadlika Widyantari, Elsa; Aryono Adhi, Mochamad; Rahma, Ilqia; Budi Wibowo, Nugroho; Mustami' Limayukha, Desi; El Farsiyyi, Bilqis; Sofyana Ulya, Rahmania
Rekayasa Vol. 21 No. 1 (2023)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/rekayasa.v21i1.9959

Abstract

Kalasan District and Ngemplak District, located in Sleman Regency, Yogyakarta, are areas with significant seismic risk due to the subduction of the Indo-Australian and Eurasian plates south of Java Island. To support disaster mitigation and land-use planning, it is essential to understand the local geological structure and soil dynamic response. This study aims to evaluate the seismic vulnerability and soil classification using the Horizontal to Vertical Spectral Ratio (HVSR) method and Rayleigh wave ellipticity inversion modeling. Microtremor measurements were conducted at 27 points distributed across both districts. The HVSR method was used to obtain the dominant frequency and amplification values, while the ellipticity inversion of Rayleigh waves was employed to estimate the shear-wave velocity profile and calculate Vs₃₀ values. The results show that the dominant frequency ranges from 0.713 Hz to 18.006 Hz, amplification values range from 0.569 to 4.193, and the seismic vulnerability index ranges from 0.010 to 12.060. Based on these parameters, Sleman Regency is generally categorized as having low to moderate seismic damage potential due to the relatively low amplification and vulnerability index. The Vs₃₀ values indicate a variation in soil site classes, namely medium-density soil (SD) and very dense soil (SC). These findings provide essential data for seismic microzonation, contributing to more resilient urban development strategies. 

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