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Jurnal Semesta Teknika
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Articles 285 Documents
Perkiraan Masa Tunggu Alumni Mendapatkan Pekerjaan Menggunakan Metode Prediksi Data Mining Dengan Algoritma Naive Bayes Classifier Asroni, Asroni; Ali, Nadiyah Maharty; Riyadi, Slamet
Semesta Teknika Vol 21, No 2 (2018): NOVEMBER 2018
Publisher : Semesta Teknika

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (747.881 KB) | DOI: 10.18196/st.212225

Abstract

Student and Alumni data Universitas Muhammadiyah Yogyakarta is very common, and one of these is the alumni data obtained from work after the completion of undergraduate studies. Former students are given jobs caused or influenced by a range of factors. This research aims to have the grace period Classification or old alumni gain positions by triggering a process of data extraction and using the Bayes naïve classification algorithm. The algorithms used later succeeded in predicting sooner or later to get a job, the predictive results alumni can be used to make decisions to improve the quality of a university. Research on the support system using several parameters, i.e., gender, faculty, GPA, year of graduation, and job status. The data used are as much as 435, including seven years of 2011-2014 volume. The results of this study have the accuracy level of former students having the grace period come to 71% and of the calculated results of the predictions of the former students obtaining a job at Universitas Muhammadiyah Yogyakarta of the year 2011-2014 the Ensure that the work is carried out more quickly with the status of the slow to deliver the work
Pemeriksaan Material pada Pembangunan Rumah Non-Engineered di Daerah Rawan Gempa Dusun Serut, Palbapang Kabupaten Bantul, Yogyakarta Zulfiar, Muhammad Heri
Semesta Teknika Vol 21, No 2 (2018): NOVEMBER 2018
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Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (682.372 KB) | DOI: 10.18196/st.212224

Abstract

Bantul Regency is a region with high level of seismic activity in Indonesia. Buildings that have the highest risk of collapse to earthquake are non-engineered buildings or residential buildings built without planning or not according regulation. This study aims to know contruction practices and material examination on non-engineered buildings in earthquake prone areas in accordance with the Indonesian National Standard. The object research is the construction of non-engineered building in Serut Village, Palbapang, Bantul Regency. The testing of material construction materials include: concrete test, reinforcing steel test and bricks test. the material are tested on the laboratory of Universitas Muhammadiyah Yogyakarta.  The observations and measurements to the practices of construction consist of: concrete sloof with size 15 × 20 cm with the main reinforcement 4Ø12 and beugel reinforcement Ø6-150; column with size 10 × 15 cm with main reinforcement 4Ø10 and beugel reinforcement Ø6-150; the concrete mixture is made manually with a composition 1 cement: 3 sand: 2 gravel; Brick size 4.35 cm x 12.036 cm x 23.902 cm class criteria M-6 module. Laboratory material test results showed: steel reinforcement diameter Ø 10 mm obtained tensile strength (fy) 401.52 Mpa; Ø12 mm diameter obtained tensile strength (fy) 393,736 M.Pa; concrete have average compressive strength of 181 kg/cm2; brick test have average compressive strength of 20.03 kg/cm2. The conclusion of contruction practices on non-engineered buildings in earthquake prone areas are adequate on major earthquake, the quality of construction concrete and reinforcing steel are fulfilling the criteria and requirements of the Indonesian National Standard, but quality of material brick is not adequate standar. 
Worldwide Hot Mix Asphalt Layer Application and Scrap Rubber and Bitumen Emulsion Studies on Railway Track-Bed Setiawan, Dian M
Semesta Teknika Vol 21, No 2 (2018): NOVEMBER 2018
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Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (936.214 KB) | DOI: 10.18196/st.212223

Abstract

Researchers around the world have performed various studies on reinforcement of track-bed and mitigation of ballast deterioration. This paper objective is to conduct a literature review comprehensively to analyse and discuss the development of rubber, bitumen emulsion, and asphaltic layer usage on railway track-bed to study the proposed alternative of Indonesian unconventional rail track design concept. Various asphalt track-bed concept around the world have been reviewed (Germany, USA, Italia, Japanese, France, Spain, and Austria). Research on scrap rubber and bitumen emulsion in railway track-bed also examined in this paper. There are no researchers’ uses these three methods together in their study. In fact, each design has its benefits and limitations, so if these three methods are combined, then they will complete each other and will produce better output. The author suggests developing a new track structural components design that combined asphalt layer, scrap rubber, and bitumen emulsion. This new design expected to have capabilities to serve high-speed railway and existing railway track corridors more cost-effectively compare to the conventional tracks in consequence of their potential to have greater structural stability, considerably lower maintenance works, and more service-life. It can serve the train journey with higher speed and higher axle load.
Penyusunan Model Elemen Hingga Interaksi Persamaan Aliran dengan Persamaan Sebaran Udara Adam Pamudji Rahardjo, Jazaul Ikhsan ,
Jurnal Semesta Teknika Vol 15, No 1 (2012): MEI 2012
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Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (682.391 KB)

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) Nuri, Sigit Hidayat; Suwanda, Totok; Diharjo, Kuncoro
Jurnal Semesta Teknika Vol 9, No 2 (2006): NOVEMBER 2006
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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.
Analisa Kegagalan Sambungan Las Pada Tiang Penyangga Dermaga Syahputra, Koko Nusyi; Nugroho, Aris Widyo
Semesta Teknika Vol 18, No 1 (2015): MEI 2015
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Abstract

Welded join failure analysis of broken jetty head strut has been carried out to find out the root cause of the failure which was obverved at the ring welding. Specimens being made of unbroken and broken struts were characterized and analyzed. The results show that the chemical composition of the based metal and the strut welded  joins especially their phosporus content were close to that of the ASTM A 252 grade 2 standard.   A common phenomenon was noted on the hardness testing result where the hardness numbers of the weld metal zone were found being higher than those of the base metal. The Widmanstatens stucture was noticed on both the weld metal and the coarse grain zone.  Further examination of the macrostructures revealed that blow holes and incomplete fusions were detected on the weld metal of the broken struts.  These flaws may the root cause of the failure because they acted as an initial crack that may propagate until fracture.
Aplikasi Metode Nilai Hasil (Earned Value Method) pada Sistem Pengendalian Proyek Pujihastuti, Siti Yuliani; Priyo, Mandiyo
Jurnal Semesta Teknika Vol 15, No 2 (2012): NOVEMBER 2012
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Abstract

In a project implementation, the project implementer wants the project completed on time as efficient as possible while the produced quality is in accordance with the initial plan. Therefore, in order to meet the requirements for controlling process and to minimize any deviations that can occur during the project, the earned value method is considered accurate. The aim of this study was to identify the final result of the project which will be achieved in the aspect of cost (whether the project experience gains, losses, or within budget) and time (whether the project is delayed, ended early, or on time as scheduled). The study was conducted on the 4th, 8th, 12th, 16th, and 20th weeks by using the earned value. Earned Value Method, or often called the Concept of Earned Value, is the concept of calculating project costs in accordance with the budget and the scope of job which have been completed or implemented (budgeted cost of works performed). This method combines the cost, schedule, and work performance of a project. Therefore, this method is considered effective in monitoring and controlling project activities.
Extensive Geotechnical Instrumentation Program to Control Dike Raising Constructed on Soft Clay Tabbal, Mahmoud; Mansour, Ziad
Jurnal Semesta Teknika Vol 12, No 2 (2009): NOVEMBER 2009
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Abstract

In its quest of increasing potash production, Arab Potash Company (APC) decided to increase the size of their salt evaporation pans. The Dike 18 which is spanning a length of 13km and enclosing a pan area of 16.5km2 was built between January 1996 and December 1997 as part of APCs expansion scheme. The foundation soils were predominantly varies from soft to very soft silty clay. From laboratory and field test results the undrained shear strength of the clay was between 28 to 40 kPa. An extensive instrumentation program was designed and implemented in order to control the dike raising during construction as well as to monitor the performance of the dike foundation during and after the construction. Instrumentations being installed included settlement spider magnets, level stations, standpipe and pneumatic piezometers. The major constraints of the instrumentation program were the large vertical settlements (2-3m) of the very soft clays, artesian conditions where sand and salt layers were present, high salinity of the groundwater and the development of sinkholes. Special installation and protection measures were developed to overcome these constraints. The performance aspects of the instruments were discussed and typical plots were presented. 
Pengaruh Pemodelan Kotak Resapan Buatan di Saluran Drainase terhadap Debit Limpasan Adinda, Sabarani; Barid, Burhan
Jurnal Semesta Teknika Vol 17, No 1 (2014): MEI 2014
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Abstract

Drainage isasewer system in an areathat serves todrain excess rainfall. Initially, an artificial drainage channel could absorb water because the drainage channel is made from landorland with grass. Negative impacts frequently occurrence on the channel walls that are eroded by water see page. While the current drainage channel is impermeable, making direct runoff flows rapidly into water bodies. Land use is increasingly impermeable resulting bigger runoff and causing negative impacts, such as floods and decreasing groundwater savings due to rainfall directly flows into water bodies orriver nearby. In this paper, authortried tomake adrainage channel innovation by making boxes infiltration along the concrete channel. The aim of the study is to determine the effect of artificial recharge box modeling along drainage channels in reducing runoff using wastel and and grintinggrass(Cynodondactylon) media, determine the ratio of absorptionability between box wastel and media and Grinting grassmedia in reducing runoff using concrete channel/watertight as a reference. The model is made of wood with the size of 750×30×20cm and 5catchment box made every distance of 100cm along the channel, then the water flowed into the channel for an hour, and velocity data taken every five minutes before and after the flow through the box and also water level data taken every five minutes. The result shows that artificial recharge box with wasteland media can reduce runoff entering the channel, with the ability to reduce runoff at first hour about of 38.322% and it will decrease every hour, on it is smallest on the fourth hour 4 about of 28.038%. Also, a model with grintinggrass media can reduce runoff and the largestefficiency value is about 49.744% in first hour. Channel modeling with artificial recharges box using grinting grass media is better than only using wasteland for reducing.
Pemilihan Mesin Welding Otomatis Dengan Penerapan Value Engineering Dan Analitical Hierarchy Process Nuruddin, Moch; Andesta, Deny
Jurnal Semesta Teknika Vol 11, No 1 (2008): MEI 2008
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Abstract

By chosening machine of welding automatic with Value Engineering, hence company can know which machine is which have high value and can improve production process specially to part of welding. With quality, quality of product which different each other hence consumer have to be clever in assessing and chosening reliable product. Because many company promoting its product with advertisements, so that make consumer interest to buying. This research aim to look for and analyse some alternative which can be made size measure in chosening machine of welding reliable automatic. Election of merk here there is three merk type for example Panasonic, Daihen, and Hitachi. From third this merk type will be selected which merk which have best quality. Result of got calculation, hence machine merk the selected is merk of Hitachi because this machine have high value and difference is expense of Rp 35 million compared to two other alternative. this Volts machine Pri equal to 380V, input pri 42,5KVA 23,5KW and current output 500A. If compared to this machine alternatives have value of Vn equal to 2,1.

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