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Semesta Teknika
ISSN : 1411061X     EISSN : 25025481     DOI : https://doi.org/10.18196/st
Core Subject : 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
Kuat Tekan Beton Serat Menggunakan Variasi Fibre Optic dan Pecahan Kaca Sustika Pratiwi; Hakas Prayuda; Fadillawaty Prayuda
Semesta Teknika Vol 19, No 1 (2016): MEI 2016
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v19i1.2033

Abstract

Fibre concrete is one of special concretes which developed from normal concrete by adding fibre into concrete mortar. It aims at preventing crack of loading, heat hydrating as well as depreciation and to increase the stress force, bent force, and tensile force. In this research used the fibre optic which is a synthetic fibre obtained from the inside of optic cable. Glass is a material which is easy to find and has an economic value, beside that glass also has excellent resistance of abrasion, weather or chemical attack. This research uses three variations of fibre grade that are 0,1%; 0,15%; 0,2% with the length 10 cm obtained from concrete weight, while glass fracture that used is 20% of sand weight. Average Compressive strength   of fibre addition consecutively 22,43 MPa; 24,31 MPa and 29,63 MPa. Compressive strength increased with the increasing number of fibre.
Pengeringan Tembakau dengan Sistem Hybrid Dwi Aries Himawanto , Muhammad Nadjib
Semesta Teknika Vol 16, No 1 (2013): MEI 2013
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v16i1.426

Abstract

Productivity of tobacco crop may be affected by several factors, one of which is the weather that can influence the tobacco drying process. Providing a customized tobacco dryer may help solving these problems. The study begins by designing a solar energy and biomass (tobacco stem waste) combustion followed by manufacturing and data collection of dryer performance. It can be concluded that the dryer for 140 minutes can reduce the moisture content of fresh tobacco leaves to  64%.
Prototipe Sistem Monitoring pada Pembangkit Listrik Tenaga Mikrohidro Ramadoni Syahputra; Revi Muhammad Fasha; Anna Nur Nazilah Chamim; Kunnu Purwanto
Semesta Teknika Vol 25, No 1 (2022): MEI 2022
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v25i1.13180

Abstract

Energi potensial hidro, sumber energi baru dan berkelanjutan yang mencakup pembangkit listrik tenaga mikro-hidro, penting untuk dikembangkan sebagai sumber daya alternatif yang sangat bermanfaat bagi lingkungan. Pengaturan inlet air mikro hidro saat ini masih dilakukan secara manual. Hal ini menjadi perhatian karena memerlukan banyak sumber daya manusia dan jika dilakukan secara manual, akurasinya tidak terlalu baik. Sebelumnya, sistem pemantauan hanya dapat diamati di dekat generator dan tidak dari jarak jauh. Dalam penelitian ini dikembangkan sistem monitoring sehingga dapat diakses kapan saja dan dari lokasi manapun menggunakan aplikasi smartphone. Saluran masuk air dirancang untuk diatur secara otomatis menggunakan aplikasi smartphone untuk mengatasi masalah tersebut. Hasil penelitian menunjukkan bahwa sistem yang telah dibangun dapat bekerja dengan baik.
Perencanaan dan Simulasi Jaringan Small Cell Indoor Hotspots Studi Kasus di Gedung Vokasi Universitas Telkom Toha Ardi Nugraha
Semesta Teknika Vol 20, No 1 (2017): MEI 2017
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v20i1.2354

Abstract

Poor signal in indoor celluler network is caused by attentuation of the building  partition. In indoor areas, signal from base station transmitter cannot received perfectly in the receiver part. Therefore, this study discusses about planning of Indoor Hotspot (InH) using Small Cells technology case studi in Vocational Building Telkom University. From the network simulation, the  transmit power of the entire antennas can cover each floor as well with received signal level greater than -80 dBm with SIR level has positive value above 0dB. The lowest floor, the average received signal power values is the best value compare with the others with  received power about -40 dBm using 6 InHs. SIR best quality on the first floor of the building with the average received signal quality value of about -50 dBm using 7 InHs.
Optimalisasi Kerja Tabung Induksi Menggunakan Mekanisme Katup pada Mesin Dua Langkah Jenis Yamaha Force 1 ZR Masy’ari Masy’ari
Semesta Teknika Vol 11, No 2 (2008): NOVEMBER 2008
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v11i2.764

Abstract

Rapid development of the automotive world, especially in the two-wheel motor vehicles, must also be compensated with fuel efficiency. Many ways has been used to save fuel for vehicles, particularly for two strokes (2t) gasoline motor, that uses YEIS (Yamaha Energy Induction System) technology, or known as tube Induction. This technology in general is used in Yamaha motorcycle engine with cylinder volume ranging from 155 cc, 135 cc, 150 cc to 250 cc. However the application of YEIS tube is not optimal. The goal of this research is to optimize the performance of the system by creating a system with valve mechanism to regulate incoming and outgoing flow of the mixture of fuel-air into the YEIS system. Induction tube acts as a buffer for fuel-air mixture preventing the mixture from returning to the carburetor during process strokes and then dispose of the rinse proceed with steps, so that the remaining fuel is not futile. The research was started with constructing induction tube, valves and valve housing, assembling and testing. The results of this research indicates that two-wheeled vehicles using an induction tube efficiency has better fuel efficiency than two-wheeled vehicle without induction tube and two-wheeled vehicle equipped with induction tube without the valve mechanism. The result also indicates that the acceleration of the vehicle is not reduced.
Evaluasi Pengaruh Fungsi Aktifasi Dan Parameter Kemiringannya Terhadap Unjukkerja Pengenalan Jaringan Syaraf Tiruan (Studi Kasus Pada Pengenalan Karakter Angka Tulisan Tangan) Irwan Suhardi
Semesta Teknika Vol 10, No 1 (2007): MEI 2007
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v10i1.854

Abstract

Jaringan syaraf tiruan merupakan salah satu topik baru yang menarik untuk dikaji dikarenakan mampu menangani permasalahan yang sangat kompleks.  Salah satu variabel yang berperan pokok untuk menghasilkan unjukkerja jaringan syaraf tiruan yaitu pemilihan parameter  fungsi aktifasinya. Tulisan ini mencoba menganalisis pengaruh fungsi aktivasi terhadap unjukkerja jaringan syaraf tiruan terutama parameter kemiringannya. Sebagai studi kasus dalam penelitian ini yaitu sejauh mana jaringan syaraf tiruan mampu mengenali pola karakter tulisan tangan. Pola karakter yang akan dicoba untuk dikenali yaitu karakter angka (dari 0 sampai 9). Permasalahan yang dihadapi dalam pengenalan pola tulisan tangan sangat kompleks, antara lain bervariasinya model tulisan tangan, pena untuk menulis, dan ukuran tulisan tangan. Didapatkan kesimpulan bahwa parameter kemiringan fungsi aktivasi untuk menghasilkan unjukkerja pengenalan terbaik didapatkan pada nilai kemiringan  0,8 dengan menggunakan sigmoid bipolar.
Kuat Geser Tanah Pasir yang Distabilisasi Menggunakan Aspal Cair SC60-70 Willis Diana , Elfira Resti Mulya
Semesta Teknika Vol 15, No 1 (2012): MEI 2012
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v15i1.442

Abstract

Soil is one of the most important parts in construction work. Soil being found in the field are vary in terms of its properties, and its quality usually does not meet the specified requirements for building construction on it including sandy soil. Sandy soil does not have cohesion value (c), so its shear strength is very low and can lead to collapse. Because of that, it needs to be stabilized to improve the parameter of soil shear strength which are friction angle value (φ) and cohesion value (c). Stabilizing material being used in this research is asphalt, in order to improve cohesion and soil density. Asphalt being used in this research is emulsified asphalt SC 60-70 which is Asphalt Cement (AC) dissolved in diesel oil. In this research, the shear-strength of  sandy soil stabilized with emulsified asphalt SC 60-70 was analyzed by means of direct shear-strength testing. It can be concluded from the result that friction angle tends to increase with the increase of the asphalt content. It can also be shown that the lowest friction angle value was found being at 0% asphalt content, 35,753°, while the biggest friction angle value was found being at 5% asphalt content,  38,970° (increased 10,169%).
Rancang Bangun Model Turbin Pelton Mini Sebagai Media Simulasi/Praktikum Mata Kuliah Konversi Energi Dan Mekanika Fluida Hadimi Hadimi; Supandi Supandi; Agus Rohermanto
Semesta Teknika Vol 9, No 1 (2006): MEI 2006
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v9i1.877

Abstract

This Research is conducted in Pontianak state Polytechnic using test-drive method based on literature. The step are scheme/ turbine design, making and repairing in order to get a better pelton turbine. The main objective of this research is to provide facility for energy conversion and fluid mechanism practice which is limited in Mechanical Engineering Department so that it is hoped that it will contribute positive effects on students ability in that field. The construction and specification of pelton turbine model resulted of this research as follows; ( 1) Type Pump: Jet propulsion Pump, with the energy input 500 Watt, head pump 55 m, and debit 30 L / minute. ( 2) Generator energy 500 VA and Rpm 1500 rpm, 50 Hz. ( 3) Runner specification: The sum of buckets / sudu is 8 ( single and double), runner diameter 17 cm, out side diameter 44 cm, the width of bucket 6 cm, the length is 14 cm, and pitch pelton wheel diameter is 30 cm. ( 4) Nozzle diameter is 20 mm. The result of research on this pelton turbine model shows of water kinetic energy into electrical energy resulted by pelton turbine, and the bucket type design as well as the sum influence the rpm and voltage gained.
Interpretasi Letak Bidang Longsor dan Faktor Aman Lereng dengan Bahasa Pemrograman MATLAB Joko Supriyadi , Anita Widianti
Semesta Teknika Vol 14, No 2 (2011): NOVEMBER 2011
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v14i2.552

Abstract

Slope stability analyses can be performed using computer program, such as Matrix Laboratory (MATLAB). In the current work, a computer program for slope stability analysis named JOZLOPE based on MATLAB and using Bishop simplified analysis method was used to determine the location of a slip surface and its safety factor. The validation is carried out by analyzing three simple slope models and comparing their results by JOZLOPE and some comparator slope stability analysis programs. It is found that the variations between JOZLOPE’s results and those of the comparators are less than 1% for bottom circle-slope geometry intersection, less than 7% for top circle-slope geometry intersection  and less than 4% for Safety Factor. These findings demonstrates  that the a MATLAB program is successfully compiled and it produced measured values that agree with those of their respective comparator.  
Pengaruh Beban Pada Permukaan Tanah Dan Frekuensi Gempa Terhadap Respon Seismik Linier Elastis Lapisan Tanah As’at Pujianto
Semesta Teknika Vol 8, No 1 (2005): MEI 2005
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v8i1.909

Abstract

Respon seismik lapisan tanah akibat gempa merupakan suatu parameter gerakan tanah akibat gempa. Selama getaran merambat dari pusat gempa sampai ke permukaan tanah, maka faktor tanah sebagai penghantar getaran mempunyai peran yang sangat penting. Berbagai parameter penting mengenai jenis tanah tersebut meliputi keadaan geologi secara lokal dan kondisi tanah itu sendiri. Di samping itu juga ada beberapa faktor yang berpengaruh terhadap respon tanah, di antaranya adalah indeks plastisitas (PI), kandungan frekwensi gempa serta keadaan beban diatas permukaan lapisan tanah. Beban pada permukaan lapisan tanah akan berpengaruh terhadap kekakuannya. Kekakuan tanah yang mempunyai beban lebih kecil akan berbeda dengan tanah yang mempunyai beban lebih besar. Dengan keadaan seperti itu maka tanah yang mempunyai berat beban bangunan berbeda akan menghasilkan respon yang berbeda juga. Penelitian dengan menggunakan satu data profil tanah tanpa beban dan lima variasi pembebanan telah dilakukan, akibat gempa Koyna dan Bucharets yang telah dinormalisai, sehingga hanya mempunyai perbedaan frekuensi. Analisis hitungan menggunakan program sederhana dengan dasar metode analisis dinamika struktur “Multi Degree of Freedom” dan pemodelan matematis lapisan tanah berupa model “Shear Building” serta penyelesaian problema dinamik dengan metode numerik “Central Difference”. Hasil analisis menunjukan bahwa Semakin besar beban mengakibatkan simpangan semakin kecil. Dengan percepatan maksimum sama akibat gempa Koyna dan Bucharest, namun mempunyai frekuensi yang berbeda,  mengakibatkan respon yang tidak sama besar. Parameter percepatan tanah bukan satu-satunya parameter yang dapat dipakai untuk mengetahui damage potential suatu gempa tetapi terdapat parameter lain yang harus diperhatikan. Kandungan frekuensi gempa Koyna maupun Bucharest terhadap frekuensi struktur masih cukup jauh (tidak berimpit), sehingga jika terjadi gempa dengan frekuensi tersebut struktur tanah tidak akan mengalami resonansi.  

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