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Semesta Teknika
Published by Universitas Muhammadiyah Yogyakarta
ISSN : 1411061X     EISSN : 25025481     DOI : https://doi.org/10.18196/st
Core Subject : Engineering,
Engineering
SEMESTA TEKNIKA is a reputable refereed journal devoted to the publication and dissemination of basic and applied research in engineering. SEMESTA TEKNIKA is a forum for publishing high quality papers and references in engineering science and technology. The Journal is published by the Faculty of Engineering, Universitas Muhammadiyah Yogyakarta, INDONESIA. Copyright is by the publisher and the authors. The Journal is issued in electronic form and also issued in printed form as annual volume for the contributors only. The journal contains original research papers, review articles, short notes and letters to the editors. The topics of interest include modeling, experimental, analytical and numerical investigations on the mechanical, physical, chemical and mineralogical properties of material, developing the prototype/instrument, technology and construction process. Topic of management in industry and civil construction is also considered. SEMESTA TEKNIKA receives manuscripts from the contributor written in the Indonesian and English. Manuscripts submitted to the journal for publication must not have been previously published or is under consideration simultaneously by any other publication. Manuscripts submitted to SEMESTA TEKNIKA will be reviewed Peer Reviewers local and foreign.
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Articles 715 Documents
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The Conceptual Design of An Electro-Magnetic Power Generator Azahari, Faiq Taquiddin; Atel, Maxmillain Newman Anak; Samsuri, Siti Salwa; Abdul Aziz, Azunaidi
Semesta Teknika Vol 26, No 2 (2023): NOVEMBER
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v26i2.19404

Abstract

Nowadays, magnetic field induction is a dependable renewable energy source that can convert magnetic fields into electrical power. In this study, our objective is to propose a low-cost free energy generator design based on neodymium. The main problems with existing generators were air pollution, noise pollution, and even fuel price volatility. To begin addressing this issue, we compared 6 currently used generators. We concentrated on 5 criteria in light of this outcome. Our top considerations in this study are cost and maintenance. Then comes the size, weight, and noise. The best electromagnetic power generators for satisfying all the criterion domains are determined using Pugh's matrix. It demonstrates that electromagnetic power generators have a high score of 95 compared to natural gas, portable, and diesel power generators. We have also calculated the resulting voltage from the selected number of permanent magnet coils. This calculation shows 60V resulting in 9600 turns. As a result, we draw the conclusion that the reduction of problems like noise and air pollution makes this power generator look like a very appealing alternative.
Web-Based System Information Certificate Services at Klamono District Offices Arief, Muhammad Nur; Setyawan, Muhammad Rizki; Soekarta, Rendra; Simori, Pascalina Magrice
Semesta Teknika Vol 26, No 2 (2023): NOVEMBER
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v26i2.19573

Abstract

Klamono District Office still relies on manual procedures for delivering certificates to residents, involving steps such as direct submission of certificate requests at the village office, form filling, and physical submission of supporting documents. To overcome this challenge, the proposal of implementing a dedicated information system tailored to streamline the certificate issuance process has emerged. This study proposes a Certificate Service Information System to elevate operational efficiency at the Klamono District Office. The Extreme Programming system development method is utilized, along with testing through Blackbox Testing and Usability Testing. This research indicates that the developed application can improve the effectiveness and efficiency of services in the certificate issuance process. The Blackbox testing results show a system success rate of 100%, while the usability testing report records a user satisfaction level of 93.1%.
Correlation Analysis Between Measured Rain Data with Satellite at Rainfall Station in Merapi Ikhsan, Jazaul; Sari, Amalia Kurnia; Hairani, Ani; Hidayah, Alidina Nurul
Semesta Teknika Vol 27, No 1 (2024): MEI
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v27i1.22180

Abstract

Manual and automatic rain gauges often need to be revised in measuring rainfall due to various constraints. Therefore, using rain data from satellites will be a promising alternative. The rain data used is measured hourly rainfall data 20mm in 2012, 2017, and 2022. In addition, rain data from the PERSIANN and GPM satellites were also used. The analysis was carried out using the correlation coefficient (r) method, which aims to find the correlation between measured rain data and satellite rain data. The results show that the PERSIANN satellite has the highest correlation value in rain duration in two years, while the GPM satellite has the highest total depth and intensity correlation value in two years. Therefore, it can be concluded that the GPM satellite has better accuracy than the PERSIANN satellite in monitoring rain.
Classification of Brain Image Tumor using EfficientNet B1-B2 Deep Learning Hastomo, Widi; Karno, Adhitio Satyo Bayangkari; Sestri, Ellya; Terisia, Vany; Yusuf, Diana; Arman, Shevty Arbekti; Arif, Dodi
Semesta Teknika Vol 27, No 1 (2024): MEI
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v27i1.19691

Abstract

In this study, a new neural network model (EfficientNet B1-B2) was sought for the detection of brain tumors in magnetic resonance imaging (MRI) images. The primary objective was to achieve high accuracy rates so as to classify the images. The deep learning techniques meticulously processed and increased the data augmentation as much as possible for the EfficientNet B1-B2 models. Our experimental results show an accuracy of 98% in the B1 version in Table II. This provides a potentially optimistic view of the application of artificial intelligence technology to disease diagnosis based on medical image analysis. Nonetheless, we must remind ourselves that the dataset we used has limitations in terms of the challenges it can pose. Although the number of potential variations of actual medical images constitutes a major challenge, it is not the only one. Most medical datasets are unbalanced, contain highly variable noise, have a slow internal structure, and are often small in size. Hence, our end goal is to help stimulate not only the field of brain tumor detection and treatment but also the development of more sophisticated classification models in the health context.
The Effect of Rotational Tool Speed on Dissimilar Joint Aluminum-Copper Plate Friction Stir Welded Joint Nugroho, Aris Widyo; Rahman, Khukuh Aulia; Rahman, Muhammad Budi Nur
Semesta Teknika Vol 26, No 2 (2023): NOVEMBER
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v26i2.20477

Abstract

The study investigates the impact of rotational tool speed on the mechanical properties and microstructure of aluminum-cooper friction stir-welded joints. It found that higher rotational speed leads to increased grain size, possibly due to increased heat production. Higher hardness values in the stir zone result from uniform dispersion of smaller copper particles. The study found that 540 rpm yields the maximum hardness value in the stir zone, measuring 67 VHN. However, higher speed results in defects like voids, cracks, and intermetallic compounds (IMCs), which are linked to the formation of IMCs at elevated temperatures. The optimal welding conditions at 550 rpm balance grain refinement, hardness enhancement, and defect mitigation, contributing to the understanding of welding process parameters.
Effect of Friction Pressure on the Mechanical Properties of CDFW Dissimilar Aluminium 6061-T6 and Stainless steel 304 Welding Joints Suwanda, Totok; Yulianto, Tri; Nugroho, Aris Widyo; Ardiyansyah, Nur
Semesta Teknika Vol 27, No 1 (2024): MEI
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v27i1.18534

Abstract

Welding technology has significantly developed in the industrial sector along with advances in manufacturing technology. The demand for joining methods combining dissimilar metals is increasing in the industrial sector. However, joining dissimilar metals is challenging because of differences in physical and mechanical properties. Continuous drive friction welding is a solid-state joining method widely used to join dissimilar metals. The research aimed to determine the effect of variations in friction pressure on the mechanical properties of continuous drive friction welding joints with dissimilar materials, Aluminum 6061 T6 and Stainless Steel 304. The process parameters used in this welding were the friction pressures used were 30 MPa, 35 MPa, and 45 MPa. The friction time is 2 seconds, the rotation speed is 1000 rpm, and the upset pressure is 50 MPa. Then, welded joints were evaluated for Vickers microhardness and microstructure observations. Based on the research results, it shows that the temperature distribution and microstructure results show that there is a change in the hardness value of the aluminum material. In contrast, the 304 stainless steel material experiences an insignificant change in the hardness value.
Properties of Concrete Containing Type-C Fly Ash Under Elevated Temperature Kencanawati, Ni Nyoman; Murtiadi, Suryawan; Qomari, Lina Sabrina; Zaki, Ahmad
Semesta Teknika Vol 26, No 2 (2023): NOVEMBER
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v26i2.19732

Abstract

High temperatures affect the properties of the concrete material. The changes generally depend on the quality of the concrete and the content of added ingredients during concrete mixing. This article examines the strength, weight, and visual changes of normal and high-strength concrete with the addition of class C fly ash (FA) under elevated temperature. FA was added as much as 15% by cement weight in each concrete type. The specimens consisted of four types concrete: normal concrete, normal concrete + FA, high-strength concrete, and high-strength concrete + FA. The fire test was carried out after 45 days curing time for 3 hours with variations in combustion temperature of 500ºC and 1000ºC. Visually, the concrete changes color to yellow-white with micro-cracks after being exposed to a temperature of 500ºC, while at 1000ºC, the surfaces of the concrete turns white, and there are larger and more apparent cracks. Furthermore, adding class C FA to high-strength concrete does affect the fire resistance level because it showed almost the same residual compressive strength after exposure to both elevated temperature of 500°C and 1000°C.
Editorial Preface for May 2024 Issue Sudarisman, Sudarisman
Semesta Teknika Vol 27, No 1 (2024): MEI
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v27i1.22499

Abstract

Thermal Stratification Characteristics of Storage Tanks on Solar Water Heater Inserted with Latent Heat Material Nadjib, Muhammad; Wahyudi, Wahyudi; Santosa, Tito Hadji Agung; Hidayat, Yaafi
Semesta Teknika Vol 27, No 1 (2024): MEI
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v27i1.21753

Abstract

As a latent heat medium, phase change material (PCM) can be applied to heat storage for solar water heaters (SWH). The method used to place PCM is to put it in a capsule. Thermal stratification is critical in generating SWH thermal efficiency. Installation of horizontal capsules in the tank has no known effect on thermal stratification. This paper aims to study the thermal stratification in active-type SWH incorporating PCM. A cylindrical capsule containing the PCM was placed inside the tank. The thermocouple was installed on both the water and PCM sides. The charging process was conducted indoors, and the water flow rate varied from 1, 2, and 3 LPM. Water temperature data for each variation was analyzed to evaluate the thermal stratification. Richardson number analysis proved that thermal stratification was formed in all water flow rates. It was found that a low water flow rate results in high thermal stratification.
Evaluation of Satellite-based Rainfall Data in Flood Prediction Wisnulingga, Bayu Krisna; Sujono, Joko; Jayadi, Rachmad
Semesta Teknika Vol 26, No 2 (2023): NOVEMBER
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v26i2.19036

Abstract

Rainfall-runoff transformation is a solution to the difficulty of obtaining observed discharge data in flood prediction analysis. Rainfall-runoff transformation requires observed rainfall data with a high rate of accuracy spatially. However, observed rainfall data is also often not available. Satellite rainfall data is commonly used to replace observed rainfall data. However, the accuracy of satellite rainfall data still needs to be tested. This study applied rainfall-runoff transformation to the observed rainfall data and the PERSIANN, GPM, and GSMaP satellite rainfall data in the Opak Watershed using GAMA I SUH method, which were then compared with the observed hydrograph at the AWLR Kretek during the flood event that occurred in Yogyakarta Province due to Cyclone Cempaka to evaluate their accuracy. The results showed that the GPM data generated a hydrograph that is the closest to the observed hydrograph, both the shape and the peak of the hydrograph.

Page 70 of 72 | Total Record : 715

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