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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.
Arjuna Subject : -
Articles 715 Documents
 41   42   43   44   45 
Kajian Eksperimen Kuat Tekan Beton Ringan Menggunakan Agregat Bambu dan Bahan Tambah Beton Muhammad Riang Endarto; Muhammad Heri Zulfiar
Semesta Teknika Vol 13, No 1 (2010): MEI 2010
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v13i1.721

Abstract

The use bamboo as a substitute aggregate is an effort to reduce the density and static load of structural elements. This reseach focuses on the problem related to the specific gravity and compressive strength of the use of bamboo as a lightweight concrete aggregate. Specimens were produced using additive and 10 mm maximum grain size of bamboo agregate as a substitute for split aggregate, in a lightweight concrete composite systems. Variation of bamboo content as a substitute aggregate were selected being 0% (normal), 20%, 40%, 60%, 80% and 100% by weight of split aggregate. The samples are in the form of cylinder (of 15 cm diameter and 30 cm height), while the compression testing were performed after 14 days of treatment. The results showed that the lightweight concrete containing 80% of bamboo aggregate possessing compressive strength 5,86 MPa, which is below the minimum standard of ACI of 17,2 MPa.
Efek Variasi Beban Pendinginan Terhadap Coefficient Of Performance (Cop) Alat Uji Pengukuran Koefisien Evaporasi Menggunakan Refrigeran R-134A Tito Hadji Agung Santosa; Muhammad Nadjib; Thoharuddin Thoharuddin; Muhammad Akhid Riza
Semesta Teknika Vol 20, No 2 (2017): NOVEMBER 2017
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v20i2.3412

Abstract

Investigation of the cooling load effect toward Coefficient of Performance (COP) is important to conduct. The Coefficient of Performance (COP) is related with compressor work and refrigeration capacity in order to produce a refrigeration system which have a high COP. The high COP value can be reached with minimum compressor work, however it has a maximum refrigeration capacity. This research is to know the effect of cooling load variation toward the performance of experimental device of evaporation heat transfer measurement. By knowing the changing of performance toward cooling load variation, it can be useful in design of an effective and efficient air conditioning system.The method of coolecting data is by experimental method that is by varying water mass flowrate (cooling load) which is flowed to evaporator. An evaporator is soak in a 30 xm x 15 cm x 20 cm water box. Water flowrate can be varied and be masured by a water rotameter. Refrigerant is using Freon R-134a. Experiment is conducted with an evaporation heat transfer coefficient device. The device is a model of modified refrigeration system by adding instruments : an orifice, a test section, and an electric heater. Thermocouple and some pressure gauges is installed at some points which has been determined. Thermocouple and pressure gauges is used to collect temperature and pressure data. After conducting an experiment by evaporator cooling load variation, temperature and pressure data is got. Furthermore based on the temperature and pressure data, the enthalpy is got and can be used to counting the compressor power. Refrigeration capacity can be counted from total heat absorbed by evaporator from water and is divided refrigerant mass flowrate. In this research is got results that cooling load given in evaporator enfluences the COP of the experiment device. By increasing in cooling load at the determined variation, the Coefficient of Performance (COP) of the device is increase. In this research it get results increasing of COP at some refrigerant mass flowrate. The maximum result is get at minimum range inverter variation, that is 16 Hz (ṁr = 9,4 g/s - 10,26 g/s) and the maximum cooling load variation is 2 LPM with COP of 4,96. Whereas the minimum results is get at the maximum inverter range variation, that is 24 Hz (ṁr = 11,83 g/s - 12,25 g/s) and the minimum cooling load variation is 1 LPM with COP of 1,98. This research give some information, if a cooling load of an air conditioning room is chanhing, then it will change the parameter (temperature and pressure) and COP of the air conditioning system in a room.
Robust Canonical Correlation Analysis on Leakage Current Behaviors of Geothermal Polluted Porcelain Insulators Waluyo, Waluyo; Sinisuka, Ngapuli Irmea; Suwarno, Suwarno
Semesta Teknika Vol 12, No 2 (2009): NOVEMBER 2009
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v12i2.732

Abstract

This study presents the leakage current measurements results of three natural geothermal polluted porcelain insulators. The insulators consisted of one new-clean insulator, as reference, and three polluted insulators. The carried out measurements were leakage current and applied high voltage waveforms, used a two-channel storage digital oscilloscope, in a hermetically sealed chamber, where temperature, humidity, pressure and applied voltage amplitude could be adjusted and measured simultaneously. The leakage current waveforms were analyzed using the FFT and the statistical concerns were analyzed by the Fast-Minimum Covariance Determinant (FMCD) of robust multivariate statistical tools, and canonical correlation analysis (CCA). The result indicated that after the fundament, the second highest of harmonics leakage current were fifth harmonics. The leakage current waveforms were significantly influenced by humidity, besides pollution. The dependent or output variables are linear functions of independent or input variables. Based on CCA, the dependent parameters depended on input parameters tightly, with the canonical correlations were more than 0.99. The leakage current  amplitudes were still predominantly influenced by applied voltage amplitudes, where the phase angles and THD were slightly influenced by relative humidity. On these experimental measurements, the insulators were still in normal operation. 
Kajian Kadar Lumpur pada Model Infiltrasi Buatan dengan Variasi Kemiringan Tanah dan Tanaman Usep Supriatna
Semesta Teknika Vol 16, No 2 (2013): NOVEMBER 2013
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v16i2.4897

Abstract

From various soil conditions, there are need some efforts to restore soil functions as a water absorbent that is expected to reduce the excessive surface runoff indirectly and to increase infiltration. The purpose of this study was to calculate Total Suspended Solid (TSS) level on artificial infiltration model using the three media (grassland, krokot land, and vacant land) with the variation slope of 5°, 10°, 15° and 20°. This research also to understand the influence of soil media variety and land slope on TSS of artificial infiltration model. This research was carried out by preparing an artificial wood model with size 200 cm x 150 cm x 100 cm, which was then divided into three parts with each of them is 200 cm x 50 cm x 100 cm and used for soil media placement. The discharged water used in all three media was the same that is equal to 0.237ℓ/sec. For the results representative in each study, 100 mℓ of water samples can be taken in the runoff on the model for each soil media and then immediately examined the levels of TSS in the laboratory. According to the variation slope, the results of the research showed that the TSS on the grass soil media was 4700 mg/ℓ, 9200 mg/ℓ, 9500 mg/ℓ and 10 000 mg/ℓ. For krokot soil, the TSS was 6500 mg/ℓ, 66000 mg/ℓ, 126000 mg/ℓ and 273 900 mg/ℓ, while for vacant land was 5100 mg/ℓ, 101500 mg/ℓ, 109500 mg/ℓ and 243600 mg/ℓ. Furthermore, the steeper the lands slope, the higher TSS.
Analisis Arus Jenuh dan Panjang Antrian pada Simpang Bersinyal: Studi Kasus di Jalan Dr. Sutomo-Suryopranoto, Yogyakarta Rahayu, Gati; Rosyidi, Sri Atmaja P; Munawar, Ahmad
Semesta Teknika Vol 12, No 1 (2009): MEI 2009
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v12i1.759

Abstract

The aim of this paper is to analyse the delay length based on MKJI (1997). A case study was conducted on a signalized junction of Dr.Sutomo-Suryopranoto road, Yogyakarta. The correction was carried out on coefficient of basic saturation flow in ranging from 600 to 2200. Therefore, the predicted (from MKJI 1997) and measured delay length was compared. The results show that the coefficient on basic saturation flow calculation needs to be modified in the range of 600 to 2200 in order to find the similar length of the delay between prediction and field measurement. Passenger car unit (PCU) unit for motorcycle from MKJI (1997) was also corrected from 0.2 to 0.15. 
Pengaruh Penambahan Limbah Peternakan Pada Karakteristik Pembakaran Batubara Wahyudi, Wahyudi; Santosa, Tito Haji Agung
Semesta Teknika Vol 11, No 1 (2008): MEI 2008
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v11i1.788

Abstract

Using coal as a fuel is often obstacled  in harding of ignition. Waste of farming which is seldom used as  fuel possible to mix with coal. Research on solid fuel characteristic of combustion of  mixture between coal and waste of farming has been conducted to know the effect of mixture composisition toward rate of combustion. Experiment was conducted in a cylindrical combustion chamber which was heated and flowed with hot air. The content of volatile matter is higher in farming waste than in coal. In combustion of fuel mixture with higher content of farming waste, decreasing of mass of fuel mixture will more rapidly. The maximum combustion rate will higher in fuel mixture consisting more the waste of farming. 
Klasifikasi Wajah Kambing Peranakan Ettawa (PE) Jantan Berbasis Perseptron Chamim, Anna Nur Nazilah; Soesanto, Adhi; Soesanti, Indah
Semesta Teknika Vol 17, No 2 (2014): NOVEMBER 2014
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v17i2.420

Abstract

Goat Peranakan Ettawa ( PE ) is a kind of superior goat derived from goat crosses, between Ettawa (Jamnapari ) from India and Kambing Kacang (Bean Goat) from Java. A factor to determine quality of goat PE is it’s face. More than 30 cm ears length and the head color is black represents good quality. More better the quality of goat face, means higher selling price. In this study, male goat face is classified into class good quality, less good, and not good at data such as photo / image In the market, classification done by visual observation, so many farmers have difficulty in classifying the face of a goat. For that purpose, a system is needed that capable for classifying a goat face to facilitate farmers in classifying.This classification system uses Perceptron Method, is a method of guided learning using characteristic as input those are ears length, black value and brown face value. Images are used as training images as much as 9 images, and test images are 20 images. This system could classificating PE goat face with success rate of 95% and 1 error from 20 testing images. Error occured because the background was detected as black and image taking that not precise.
Perubahan Kecepatan Aliran Sungai Akibat Perubahan Pelurusan Sungai Barid, Burhan; Yacob, Muhammad
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.v10i1.850

Abstract

Penanganan run off dengan secepat cepatnya cenderung hanya menyelesaikan masalah pada sub DAS tersebut dalam jangka  pendek dan akan memberikan resiko banjir pada daerah yang lebih hilir. Dalam jangka panjang dimungkinkan banjir juga akan bergeser pula pada sub DAS tersebut juga.   Penyelesaian banjir yang sekarang sering dilakukan adalah normalisasi sungai. Salahsatu unsur normalisasi sungai adalah pemberian tanggul sungai. Tujuan. penelitian ini adalah mengetahui perubahan kecepatan akibat pembuatan tanggul.Tanggul berguna untuk memperlancar aliran sungai dan mengganti fungsi bantaran sungai menjadi lahan pemukiman. Dinding tanggul umumnya terbuat dari bahan yang lebih halus daripada dinding alam sungai. Perubahan kekasaran sungai ini  menjadikan berubahnya kedalaman, radius hidraulik dan kecepatan aliran. Penghitungan kecepatan secara teoritis dilakukan dengan persamaan manning pada sungai sebelum dan sesudah ada tanggul. Besarnya perubahan diperoleh dengan membandingkan kedalaman, radius hidraulik, dan kecepatan sebelum dan sesudah ada tanggul.Hasil analisis yang telah dilakukan dari kondisi tanpa tanggul menjadi dengan tanggul untuk Q5 tahun : di P 394 tinggi muka air naik 5,861%, radius hidraulik naik 6,947% dan kecepatan air naik 19,523%. Pada P 249  tinggi muka air naik 4,327%, radius hidraulik naik 7,405% dan  kecepatan air naik 19,808%. Pada P 170 tinggi muka air naik 7,657%, radius hidraulik naik  9,708% dan kecepatan air naik 21,527%. 
Comparison of Interpretation Between CPT and Res-2d Methods for Geostratigraphic Profiling Determination of Kota Depok Putera Agung Maha Agung , et.al
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.v15i1.438

Abstract

In its simplest application, the cone penetrometer offers a quick, expedient, and economical way to profiling a subsurface soil layering at a particular site. No drilling, soil samples, or spoils are generated, therefore, cone penetration test CPT is less disruptive from an environmental standpoint. The continuous nature of CPT reading permits clear delineations of various soil strata, their depths, thicknesses, and extent, perhaps better than conventional rotary drilling operations that use a standard drive sampler at 5-ft vertical intervals. The cone penetrometer is instrumented with load cells to measure point stress and friction during a constant rate of advancement. The results can be interpreted within different theoretical frameworks or by using empirical methods, or both. RES-2D (resistivity – two dimension) completed by Geoscanner devices is applicable to interpret the soil profiling from soil exploration works. Generally, the geoscanner is used to assess the geological subsurface condition for mining works. This paper is addressed to compare the results for soil classification in Kota Depok, West Java using a cone penetration test and RES-2D. From both methods, the result of soil strata shows the soft soil in study area can be classified as clay layers from ground surface to the depth of 15.0 m. However, the CPT is less applicable to measure exactly the elevation of ground water table than RES-2D. In addition, RES-2D is also less applicable to predict the soil properties of the soil type than CPT. In general application, both devices can be applied to soil investigation for geotechnical works.   
Optimalisasi Tekanan Kompaksi, Temperatur Dan Waktu Sintering Terhadap Kekerasan Dan Berat Jenis Aluminium Pada Proses Pencetakan Dengan Metalurgi Serbuk Totok Suwanda
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.v9i2.873

Abstract

Powder metallurgy is one of the manufacturing processes. Upon the process, melting process is not necessary to carry out. The powder is subsequently compacted then sintered. These processes can be conducted either separately or simultaneously.  However metallurgy processes have not been commonly developed in Indonesia yet. Therefore it is necessary to carry out preliminary research that serves as a basis for developing of further process. The effect of the independent variables of the process on mechanical and physical properties of the product will be examined. The research was conducted by arranging the independent variables which consist of pressure, temperature and sintering period whereas hardness and density of product are the dependent variables.  Aluminum will be water atomized for obtaining the powder. Response surface method is used as the experimental design method.  The method can show the effect of the independent variables individually and the interaction among the variables. Data analysis will result mathematic formula showing the functional relation. The research concludes that 170 MPa compaction pressure and 500 0C sintering temperature and 40 to 50 minutes range period of sintering produces the maximum Brinell hardness number of 47 BHN. On the other hand, the effect of the independent variables to the density has not been able to be formulated. 

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