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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
 63   64   65   66   67 
Uses Of Lime -Rice Husk Ash And Plastic Fibers As Mixtures-Material In High-Plasticity Clayey Subgrade: A Preliminary Study Ario Muhammad; Agus Setyo Muntohar
Semesta Teknika Vol 10, No 2 (2007): NOVEMBER 2007
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v10i2.841

Abstract

Silica produced from rice husk ashes have investigated successfully as a pozzolanic material in soil stabilization. However, rice husk ash cannot be used solely since the materials lack in calcium element. As a result, rice husk ash shall be mixed with other cementitious materials such as lime and cement to have a solid chemical reaction in stabilization process. The main objective of this study focused on bearing capacity of the stabilized clayey subgrade with lime-rice husk ash and fibers. The main laboratory test shall be compaction and CBR tests. The investigation results revealed that the inclusion of lime-rice husk ash-fiber into the soil decreased MDD and OMC. On the other hand, stabilization and reinforcement with lime-rice husk ash and fibers waste improved significantly the CBR values 
Pemetaan Batimetri dan Analisis Pasang Surut untuk Menentukan Elevasi Lantai dan Panjang Dermaga 136 di Muara Sungai Mahakam, Sanga-Sanga, Kalimantan Timur Adiguna Rahmat Nugrahav, Siddhi Saputro, Purwanto
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.v16i1.429

Abstract

Mahakam River estuary water located in East Kalimantan is territorial water that often traversed by ships transporting coal and passengers. A dock is needed in order to support such transportation activities. Sanga-Sanga Unit of Pertamina was planning to rebuild the dock that has been existed since the 1980s in the waters of the Mahakam River estuary, thus bathymetry mapping and tidal behavior analysis are needed. Bathymetry mapping and tidal behavior analysis are two important parameters in determining the elevation of the dock floor. The purpose of this study is to obtain information on the bathymetry condition and the tidal  behavior that will be used as reference of boundary conditions in determining floor elevation and dock length of the Mahakam River estuary water. Field data collection was conducted on 18 to 21 September 2012 in the water Mahakam River estuary, Sanga - Sanga, East Kalimantan. The method being used is a quantitative method, and analysis using statistical or model. Mahakam River estuary waters depth was found being between -1,3 to - 8,6 meters. It was mixed with tidal type with prominent double type, where MSL 82 cm to 260 cm interval tides, MLWL (- 28,60 cm), LLWL (- 90 cm) and HHWL (+167 cm). Dock floor elevation was obtained being +2.76 m with a value of Zo as a point of ± 0,00 m and + 2,04 with MSL as a point of ± 0,00 m, while the length of the dock is recommended to serve one boat with Loa 95,70 m is 114,84 m. With the water depth in front of the dock is needed to serve the largest ships draft is - 5 m in order to dock the ship safely.
Penyusunan Model Elemen Hingga Interaksi Persamaan Aliran dengan Persamaan Sebaran Udara Jazaul Ikhsan , Adam Pamudji Rahardjo
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.v15i1.439

Abstract

Aeration process is one of water treatment processes. The process consists of two physical phenomena, flow, and spreading of air bubble. This research has developed a finite element model for three-dimensional flow and spreading of air bubble. The flow equation employs Navier-Stokes equation. The spreading of air bubble is modeled as convection-diffusion equation. The Navier-Stokes and the spreading of air bubble equation are combined by Navier-Stokes equation with additional new term, which shows the accelerated flow caused by the air bubble moves. The Navier-Stokes equation was solved in four stages, i.e., Taylor Galerkin convection approximation, viscous prediction, pressure correction and velocity correction stages. Galerkin Standard method was used to solve the spreading of air bubble equation. Quadratic brick finite elements with 20 nodes were used on the geometry. To show performance model, comparison to the result of air bubble investigation was carried out. The numerical model that has been obtained is capable of simulating the phenomena of air bubble spreading and flow. The numerical stability analyses showed that the numerical scheme of convection and diffusion equation based on Galerkin is stable for Courant Number £ 0.01 and Peclet Number 125.
Kajian Komprehensif Pengaruh Perlakuan Alkali Terhadap Kekuatan Komposit Berpenguat Serat Nanas-Nanasan (Bromeliaceae) Sigit Hidayat Nuri; Totok Suwanda; Kuncoro Diharjo
Semesta Teknika Vol 9, No 2 (2006): NOVEMBER 2006
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v9i2.874

Abstract

Penelitian ini bertujuan untuk menyelidiki pengaruh perlakuan alkali (5% NaOH) terhadap sifat tarik (tegangan, regangan, modulus elastisitas) bahan komposit berpenguat serat nanas-nanasan (bromiliaceae) dengan matrik unsaturated polyester. Karakteristik penampang patahan diselidiki dengan pengamatan menggunakan foto makro. Bahan utama penelitian adalah serat nanas-nanasan kontinyu, NaOH, dan resin unsaturated polyester. Serat yang digunakan dikenai perlakuan alkali (5% NaOH) selama 0, 2, 4, 6, dan 8 jam. Pembuatan komposit dengan metode cetak tekan pada kisaran fraksi massa serat 15% - 50. Pembuatan spesimen uji komposit dan prosedur pengujiannya mengacu pada standar ASTM D 638. Hasil penelitian menunjukkan bahwa perlakuan alkali (5% NaOH) mampu menghilangkan lapisan seperti lilin di permukaan serat sehingga serat dan resin memiliki ikatan (mechanical bonding) yang kuat. Komposit yang diperkuat serat yang dikenai perlakuan alkali memiliki kekuatan yang lebih tinggi dibandingkan dengan komposit yang diperkuat serat tanpa perlakuan.  Semakin tinggi fraksi massa serat (Wf)  maka kekuatan tariknya juga semakin besar. Pada di atas 30%, kekuatan tarik paling besar terjadi pada komposit yang diperkuat serat dengan perendaman alkali selama 4 jam, dan selanjutnya disusul oleh komposit yang diperkuat serat dengan perendaman alkali selama 2 jam pada (Wf). Komposit yang diperkuat serat perlakuan alkali selama 4 dan 2 jam juga memiliki modulus elastisitas yang lebih tinggi, yaitu masing-masing 40.71 GPa dan 50.65 GPa pada Wf sekitar 38%. Jenis patahan splitting in multiple area terjadi pada komposit yang diperkuat serat dengan perlakuan NaOH selama 4 jam, 2 jam, dan tanpa perlakuan. Namun, komposit yang diperkuat serat dengan perlakuan NaOH selama 8 jam memiliki jenis patahan patah tunggal. Berhubung penampang patahan komposit yang diperkuat serat tanpa perlakuan mempunyai mekanisme kegagalan fiber full out, maka kekuatan komposit ini pun menjadi rendah karena memiliki ikatan antara serat dan matrik yang lemah.
Tranduser Ultrasonik Sebagai Pendeteksi Gerak Pada Sistem Keamanan Rumah Fathul Qodir; Juniardi A Putra
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.v8i1.913

Abstract

Ruangan yang penuh barang-barang berharga memerlukan sistem keamanan  elektronis yang bisa langsung dipantau.Transduser ultrasonik dapat menjadi alternatif solusi untuk mengamankan suatu ruangan yang butuh pengawasan secara otomatis. Transduser bisa dilengkapi buzzer atau sirane yang berbunyi sebagai alarm atau terkoneksi dengan telepon rumah, sehingga akan men-dial up telepon rumah jika ada seseorang yang tanpa ijin memasuki ruangan tersebut. Jadi, selama didalam ruangan tersebut tidak ada benda yang bergerak maka alarm tidak akan berfungsi. Hasilnya berupa jangkauan sistem yang dipengaruhi sudut antara pemancar dan penerima pada jarak pancar 1 sampai 9 meter,  relai pada rangkaian penerima akan aktif (on) mulai sudut 800 keatas, sedangkan mulai dari jarak pancar 10 sampai 15 meter, sudut pengaktifan relai berkurang 100   setiap penambahan jarak pancar 1 meter, misalnya pada jarak pancar 10 meter sudut pengaktifan relainya mulai sudut 700 keatas, sedangkan pada jarak pancar 11 meter sudut pengaktifan relainya mulai  sudut 600 keatas begitu seterusnya sampai dengan jarak pancar 15 meter 
Karakteristik Kecelakaan Lalu Lintas dan Pendidikan Keselamatan Berlalulintas Sejak Usia Dini: Studi Kasus di Kabupaten Purbalingga Gito Sugiyanto; Mina Yumei Santi
Semesta Teknika Vol 18, No 1 (2015): MEI 2015
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v18i1.707

Abstract

Traffic accidents increased along with the increase in road traffic violations. One of the victims of traffic accidents is children. Road safety awareness and culture of children can be improved by doing the traffic safety education from an early age and promotion of the importance of road safety for children. Pedestrian is one of the vulnerable road users. The aim of this study is to investigate the characteristics of traffic accident in Purbalingga District, Central Java Province and the characteristics of the vehicle speed on arterial roads without median and introduces the principle of crossing the road by using 4-T procedure that is (Tunggu sejenak, Tengok kanan, Tengok kiri, dan Tengok kanan lagi) or waiting for a moment, look right, look left, and look right again to children from an early age. Based on the analysisof an accident data from 2010 till 2013, motorcycles are vehicles most involved accident followed by truck.Characteristics of speed in arterial roads without median with the function as a school district obtained a mean of the speed is 56.80 km/h. The probability of a pedestrian who was hit motorcycle or car passengers with this speed (56.80 km/h) will die is 90%.
Pengaruh Penambahan Dinding Geser (Shear Wall) pada Waktu Getar Alami Fundamental Struktur Gedung Pinta Astuti
Semesta Teknika Vol 18, No 2 (2015): NOVEMBER 2015
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v18i2.1815

Abstract

The structure of high-rise buildings should have sufficient stiffness so that no damage could harm users when earthquake occurred. The addition of shear wall structure is one way to increase stiffness of the building. This research is analyzing the capacity of structural elements and the influence of shear walls in high rise buildings, taking a case study at Mataram City Apartments and Condominium, Yogyakarta. The building consists of two towers. Analytical calculations in this research based on technical data field, quality of materials, and the results of structural analysis with SAP2000. After that, this research will calculate strength of the structure. The analysis based on SNI 03-2847-2002, SNI 03-1726-2002, and the Uniform Building Code (UBC) 1997 Chapter 16 on Requirements Design Structure. Three modification of the shear wall layouts in this research are use to understanding about the effect of adding shear walls to the natural vibration time.   Based on the analysis and calculation, the structure has adequate capacity to support the load with the natural vibration period of 1.831 seconds. Maximum allowable vibration time by SNI 03-1726-2002 is 3.24 seconds, while the Uniform Building Code (UBC) is 1.698 seconds. First model can decrease the natural vibration period of 1.53 % to 1.80 seconds with a drift reduction of 11.35 % in the x axis and 35.27 % in y axis. The second model can decrease the natural vibration period by 5.08 % to be 1.73 seconds with drift reduction is 20.73 % the x axis, 39.31 % and y axis. The merged models have the natural vibration structure of 1.66 seconds
Analisis Kekuatan Mekanik pada Struktur Cooling Tank Section Untai FASSIP-03 NT Berbasis Simulasi Software Dedy Haryanto; Giarno Giarno; Adhika Enggar Pamungkas; Ainur Rosidi; Gregorius Bambang Heru Kusnugroho; Mulya Juarsa
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.v25i1.13470

Abstract

Untai Fasilitas Simulasi Sistem Pasif-03 Nanobubble Transparent (FASSIP-03 NT) mulai didesain pada tahun 2021. Komponen pada untai FASSIP-03 NT terdiri dari Heating Tank Section (HTS) dan Cooling Tank Section (CTS) yang dilengkapi dengan Helical Heat Exchanger, Pyrex Glass Tube dan sistem pemipaan. CTS berfungsi sebagai komponen untuk mensimulasikan penukar kalor dari teras reaktor nuklir. Pengujian secara simulasi dan analisisnya dilakukan untuk mengetahui kekuatan mekanik terdiri dari tegangan mekanik dan translational displacement pada desain komponen CTS. Hasil pengujian secara simulasi diperoleh tegangan mekanik maksimal sebesar 1,61 x 108 N/m2 lebih kecil daripada yield strength material stainless steel 304 sebesar 1,73 x 108 N/m2. Translational displacement yang terjadi sebesar 3,04 mm pada bagian sisi belakang CTS. Hasil pengujian secara simulasi dan analisisnya menunjukkan bahwa desain CTS dapat dipabrikasi dan aman digunakan sebagai penukar kalor pada untai FASSIP-03 NT.
Pengaruh Fraksi Udara Terhadap Koefisien Perpindahan Kalor Kondensasi Refrigeran Petrozon Rossy-22 Di Dalam Pipa Tegak Sudarja Sudarja; Purnomo Purnomo; Prajitno Prajitno
Semesta Teknika Vol 10, No 2 (2007): NOVEMBER 2007
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v10i2.840

Abstract

Petrozon Rossy-22 is one of hydrocarbon refrigerants which environmentally safe, since there is no effect on either ozone depletion or global warming. In the refrigeration cycle, imperfect vacuuming process or other factors that permit circulation of air taken place in the system predicted influencing heat transfer rate in condenser. Therefore, research on the influence of air fraction against condensation heat transfer coefficient of Petrozon Rossy-22 inside vertical pipe to be done. A modified refrigeration system of vapor compression was applied in this research, where the condensation was done in the 2 meters straight vertical condenser (double pipe heat exchanger, that further called as test section). The diameter of internal and external pipe were ¾” and 1 ¼” respectively. Electric heater was installed on upstream of the test section. Mixture of air- refrigerant was flowed downward inside internal pipe, while cooling water was flowed upward through annulus. The varied parameters were: air fraction, air-refrigerant and cooling water flow rate. The result of the research indicated that condensation heat transfer coefficient significantly decreased when air fraction increased. The proposed empiric equation is :       Nu = 0.0138. (1-w)8.8198. Re0.7941. Pr4.7315with determination coefficient of 0.6927 and average absolute deviation of 17.65 %. The equation was for Re= 6.922-12.953, Pr= 2,008-2,696, and w= (0,25-1)%.
Pengaruh Penambahan Biopolimer Xanthan Gum untuk Mengurangi Konsumsi Energi pada Sistem Perpipaan Sealtial Mau; Crisyamor Daniel Pada
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.v25i1.13701

Abstract

Drag merupakan salah satu hambatan yang terjadi pada sistem transportasi fluida dimana hal ini merupakan hal yang menarik untuk dikaji. Pada penelitian ini fluida kerja yang digunakan untuk disirkulasikan adalah campuran air dan xanthan gum. Tujuannya adalah untuk mengetahui pengaruh penambahan xanthan gum terhadap penurunan tahanan gesek pada sistem perpipaan. Penambahan xanthan gum sebagai biopolimer termasuk dalam kategori kontrol aktif yang digunakan dalam kajian ini. Pada penelitian ini dirancang rangkaian sistem perpipaan secara horizontal dengan panjang pipa uji utama 0,8 m dengan diameter 0,015 m dan campuran fluida kerja yang divariasikan masing-masing 100 ppm, 300 ppm dan 500 ppm. Dari ketiga konsentrasi tersebut nilai tahanan gesek terendah pada fluida kerja dengan campuran 100 ppm pada kecepatan ± 1,5 m/s dengan nilai koefisien gesek sebesar 0,0053. Konsentrasi fluida kerja 300 ppm dan 500 ppm tidak memberikan keuntungan karena memiliki koefisien gesekan di atas air murni masing-masing yaitu 0,1578 dan 0,3276.

Page 65 of 72 | Total Record : 715

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