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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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Identifikasi Titik Api Lilin Berbasis Nilai HSV , Threshold dan Momen Citra untuk Aplikasi Robot Pemadam Api Wiyagi, Rama Okta; Soesanti, Indah; Susanto, Adhi
Jurnal Semesta Teknika Vol 17, No 1 (2014): MEI 2014
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Abstract

Fire fighting robot is robot that has function to find and extinguish a candle flame in the space arena. To be able carry out their duties then the robot is equipped with sensors, controllers and drivers. Phototransistor, thermopile arrays, or UVTron is sensors that usually used in fire fighting robot. These sensors have some drawbacks. Phototransistor has a relatively close distance readings. While TPA81 thermopile array has a narrow field of reading only 41 ° x 6 ° from sensor. UVtron only limited to determine whether there is any point of the fire and was unable to determine absolute position or angle of the hotspots and vulnerable to damage if the jar is touched by the hand. Additionally TPA81 sensors and sensor UVtron is relatively expensive. This research aims to build a candle light detection alternative better in terms of specification, performance, price, reliability and ease of development. As the input of the system identification using webcams camera types. The webcam running on Raspberry Pi single-board computer. Image information is converted to HSV color space (Hue, Saturation, Value) and applied threshold processing. Thresholding HSV performed on the range of values contained in the object candle flame. To get the absolute position of a candle flame using moments analysis. Identification system can identify candle flame spot with the farthest distance is 225cm. Angle readings in the horizontal plane by 60 ˚ and the vertical plane by 40 ˚. The achievement of the highest FPS obtained in image resolution size of 320 x 240 pixels which is 8.129 FPS.
Pengaruh Lokasi Ketebalan Maksimum Airfoil Simetris Terhadap Koefisien Angkat Aerodinamisnya Nurcahyadi, Teddy; Sudarja, Sudarja
Jurnal Semesta Teknika Vol 11, No 1 (2008): MEI 2008
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Abstract

Airfoil performance data is regarded as highly valuable data in its wide area of application since it will help the designer, for examples; to predict the influence of rear spoiler mounting to the maneuverability and top speed of racing car, the thrust and fuel consumption needed for an aircraft to take off and cruise, or the power delivered by a wind turbine rotor at certain wind speed. The performance of airfoil, which is measured with its lift and drag coefficient, is greatly affected by its geometry and operating condition. The influence of various geometric and operational parameters to the airfoil performance is needed to be studied experimentally and the airfoil performance data obtained can be added to enrich the airfoil performance data base. The experiment was done by testing airfoil models by lift force direct measurements in a sub-sonic wind tunnel.  The type of airfoil used in this experiment is the symmetric airfoil with maximum thickness location as the geometric parameter and angle of attack with wind speed as the operational parameter being investigated for their influence to the lift and drag coefficient. The maximum thickness location was varied in 30%, 40%, and 50% of chord length measured from leading edge. The angle of attack was varied from 0o to 20o with 4o increments. The wind speed was varied from 10 m/s to 20 m/s with 2 m/s increments.  Parameters being measured were the free stream velocity, and the lift force. The result of the research shows that the best airfoil performance with lift coefficient 3,16 is achieved by the airfoil that has maximum thickness location in 40% of its chord length measured from its leading edge and operates at 20o angle of attack and 8,9  m/s free stream velocity.
Kuat Geser Tanah Pasir yang Distabilisasi Menggunakan Aspal Cair SC60-70 Elfira Resti Mulya, Willis Diana ,
Jurnal Semesta Teknika Vol 15, No 1 (2012): MEI 2012
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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; Rohermanto, Agus
Jurnal Semesta Teknika Vol 9, No 1 (2006): MEI 2006
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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.
Aplikasi Metode Time Cost Trade Off Pada Proyek Konstruksi: Studi Kasus Proyek Pembangunan Gedung Indonesia Priyo, Mandiyo; Aulia, Muhamad Raa’uf
Semesta Teknika Vol 18, No 1 (2015): MEI 2015
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Time and cost are very infuential to the success and failure of a project. The measurement of project can be seen by the short time arrangment and minimum cost without denying the quality of project result. Systematically project management is very needed to make sure the time of project realization appropriate with the contract or it can be done faster so the cost will be able to be pressed. Moreover it is also to avoid paying the fine caused by the project lateness. The purpose of this research is to calculate the cost change and time project arrangment by adding work time variation and employed increment, then compare the result between fine cost and cost changing after the overtime and employee increment. Data in this research is secondary data from implementer contractor. Data analysis is used Microsoft Project 2007 program and time cost trade off method. The result from Microsoft Project 2007 program is critical path and result from time cost trade off method is duration velocity and increment cost in every activity that fasten. The result of this research indicated that (1) Time and cost optimum result of the adding work time (overtime) obtained at the age of project 242 days of work with total cost of project Rp. 10.481.732.644,58 with time efficiency project 24 days (9,02%) and cost efficiency project Rp. 43.019.556,39 (0,41%). (2) Time and cost optimum result of the employee increment obtained at the age of project 243 days of work with total cost project  Rp. 10.482.934.084,43 with time efficiency project 23 days (8,65%) and cost efficiency project Rp. 41.818.116,54 (0,40%). (3) The best choise is with adding work time (overtime), because it produces time and cost efficiency highest with time efficiency project 24 days (9,02%) and cost efficiency project Rp. 43.019.556,39 (0,41%). (4) Cost expedite duration project (adding overtime or employee increment) cheaper than the cost that should be paid if the project failed and have to pay the fine.
Measurement of Elastic Strain Wave Propagation Velocity Using FRSGs along Metallic Rods Subjected to Impact Load Sudarisman, Sudarisman
Jurnal Semesta Teknika Vol 13, No 1 (2010): MEI 2010
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The accuracy of foil resistance strain gauge (FRSG) for strain wave propagation measurement along metallic rods, i.e. aluminium, brass, copper and steel rods, subjected to impact load has been investigated. Hexagonal cross section of 5/8” sides × 6’ long metallic rods have been selected for specimens. At a distance of 8” from one end of each rod, an EA-09-125AD-120 type foil resistance strain gauge with gauge factor of 2.105 and resistance of 120W was installed. The rods were then placed on a pair of supports and loaded at the other end surface with an impact loading generated using an impulse hammer. The set up was also instrumented with a typical potentiometer circuit as a signal transducer, and an oscilloscope for signal acquisition. The output signals were then analysed by comparing with their respective theoretical values. The result showed that these FRSGs had demonstrated high accuracy in signal sensing indicated by negligible discrepancies between experimental values on one hand and their respective theor etical values on the other hand.
Pengaruh Perubahan Kecepatan Pemakanan Terhadap Kekasaran Permukaan Pada Proses Pembubutan Hadimi, Hadimi
Jurnal Semesta Teknika Vol 11, No 1 (2008): MEI 2008
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 This research done to know existence of transformation influence of feeding speed at turning process to surface roughness of work substance. Specimen material is ST 37 with Ø 30, 40, 50 and 70 mm, with transformation of feeding speed 0,05, 0,069, 0,088, 0,125 and 0,17(mm/rev), depth of feed 0,2 mm, and speed of revolution of engine 950 rpm. Then the several assaying of surface roughness level of the specimen and calculation statistic by using one way variant analytical method based on data result of assaying. Result of research indicates that existence of influence significant to surface roughness value caused by transformation of feeding speed at specimen turning process Ø 30, 40, 50 and 70 mm, ST 37 material with depth of feed 0,25 mm and revolution of engine 950 rpm. Average of smallest roughness value is at Ø 30 mm yielding best surface roughness. This thing indicates that feeding speed and substance diameter lathed influential to surface roughness value.
Pengaruh Hujan terhadap Perubahan Elevasi Muka Air Tanah pada Model Unit Resapan dengan Media Tanah Pasir Wahyunika Sari, Burhan Barid ,
Jurnal Semesta Teknika Vol 16, No 1 (2013): MEI 2013
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This study aimed to determine changes in ground water level against time to recharge the unit models with medium sand soil in cloudburst conditions, to determine the effect of changes in humidity land in heavy rain conditions and for the efficiency of the model unit catchment .. By using the model infiltration unit made from box 170x170x200 cm3 and infiltration well with dimensions of 30x30x100 cm3 filled with 90 cm thick layer of sandy soil . The results showed that changes in ground water level is 18.8 % , 22.4 % and 24 % for the test I, II, III , respectively .. Soil moisture for the test I ran to saturation at 110 minutes , while for II and III trials in the 90th minute . Unit efficiency filtration models in improving the soil surface water is 3.6 % . This suggests that these filtration units of the model can reduce surface water runoff and increasing groundwater levels. 
Pengaruh Bentuk Pilar Jembatan Terhadap Potensi Gerusan Lokal Ikhsan, Jazaul; Hidayat, Wahyudi
Jurnal Semesta Teknika Vol 9, No 2 (2006): NOVEMBER 2006
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Pilar merupakan bagian dari struktur bawah jembatan. Keberadaan pilar pada aliran sungai menyebabkan perubahan pola aliran sungai. Perubahan pola aliran tersebut akan mengakibatkan terjadinya gerusan lokal di sekitar pilar. Penelitian ini bertujuan untuk mengetahui pengaruh bentuk pilar terhadap potensi gerusan lokal yang terjadi di sekitar pilar tersebut.Penelitian ini dilakukan pada kondisi aliran seragam permanen (steady uniform flow) dengan tiga variasi debit. Model fisik pilar yang digunakan adalah bentuk pilar persegi, bentuk pilar bulat dan bentuk pilar jajaran genjang. Hasil yang didapat dari rangkaian penelitian ini adalah semakin besar debit yang mengalir pada suatu penampang saluran maka gerusan lokal di sekitar pilar juga akan semakin dalam dan bentuk yang terbaik pada penelitian ini adalah bentuk bulat karena mempunyai potensi kedalaman gerusan yang terkecil.
Peranan Teknologi Solar Cell dalam Peningkatan Daya Saing Usaha Kecil dan Menengah Iswanto, Rif’an Tsaqif As Sadad ,
Jurnal Semesta Teknika Vol 14, No 1 (2011): MEI 2011
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Rolling blackouts or blackouts caused by technical errors making people uncomfortable, one of those affected are Micro, Small and Medium Enterprises (MSMEs), due to power outages in various regions in Indonesia made a number of MSMEs to be losers. In addition to the problems faced by MSMEs is the occurrence of the peak load at night cause they can not work in the evenings (overtime). For that alternative energy is necessary for the SMEs in order to work, when electricity from PLN is susceptible to interference (fault) or in the repair process. With the considerations above, this study attempted to apply the technology Solarcell Home System (SHS) to be implemented as an energy reserve and secondary in the industrial sector, particularly in the MSMEs. The results showed that the use of technology can enhance business transformation solarcell through speed, and accuracy in producing goods. The SME entrepreneurs can increase production by using solarcell home system.

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