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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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Efek Variasi Beban Pendinginan Terhadap Coefficient Of Performance (Cop) Alat Uji Pengukuran Koefisien Evaporasi Menggunakan Refrigeran R-134A Santosa, Tito Hadji Agung; Nadjib, Muhammad; Thoharuddin, Thoharuddin; Riza, Muhammad Akhid
Semesta Teknika Vol 20, No 2 (2017): NOVEMBER 2017
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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.
Studi Kerentanan Bangunan Akibat Gempa : Studi Kasus Perumahan Di Bantul Bawono, Adi Setiabudi
Semesta Teknika Vol 19, No 1 (2016): MEI 2016
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One of earthquake mitigation activities is to know the probability of damage to buildings and the estimated loss caused by the earthquake on each typical building in an area. In developed countries attempt to predict the probability of damage to buildings caused by the earthquake have been found. One method used is a method of HAZUS (Hazard United States). In evaluating damage to buildings, one of the methods HAZUS by assessing the probability of damage to each building in an area using Fragility curve. In Indonesia, research on the Fragility Curve is still less. This study is an initial study to develop a Fragility curve which in turn will be compared with the version HAZUS Fragility curve building, so that it can be seen a typical residential buildings in Bantul, near the type of building whether in the United States. This study uses data reference damage to housing caused by the Yogyakarta earthquake May 27, 2006. Studied housing is housing that has the same type of building, which houses tembokan with retrofitting. Map data used mikrozonasi Bantul is a map Pariatmono (2008). The data collected includes data characteristic of houses and damage. House defects studied using media images or interviews with houseowners. To determine the probability of damage using FAHP (Fuzzy Analytic Hierarchy Process). Conclusions obtained from this study is that housing in Bantul are studied when compared with the type of building types URML tembokan HAZUS approach (Unreinforced Masonry Bearing Walls)
Pengaruh Cuaca Terhadap Perilaku Pengendara Sepeda Motor di Daerah Istimewa Yogyakarta Ismaili, Abul Fida
Semesta Teknika Vol 20, No 2 (2017): NOVEMBER 2017
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Indonesia as a developing country has a considerable growth in motor vehicles. Unlike other countries, the growth of motor vehicles is quite large motorcycle. In the last few years, the study of the relationship between weather and transportation is mostly done in the region or country with four seasons different in climate condition or in developed countries with good public transport conditions. It is still few to do research in developing countries, with poor public transport conditions and other problems. Yogyakarta is a city with tropical climate that it only has two types of weather conditions, namely dry and rainy seasons, which the both  will affect motorcyclists in Yogyakarta becoming the majority. In this study,  the author used a qualitative and quantitative approach to find the impact of weather changes on motorcyclists travel behavior. From the results of the study, it was found that the number of motor users was reduced by more than 30% when the weather changed. Broadly speaking, there are three behaviors of motorcyclists when the weather changes namely, wait until the weather back to normal, cancel the trip and continue the journey however in the conditions due to some reasons.
Analisis Percepatan Waktu Dan Biaya Proyek Konstruksi Dengan Penambahan Jam Kerja (Lembur) Menggunakan Metode Time Cost Trade Off : Studi Kasus Proyek Pembangunan Prasarana Pengendali Banjir Priyo, Mandiyo; Sumanto, Adi
Semesta Teknika Vol 19, No 1 (2016): MEI 2016
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Abstract

Time and cost have significanteffect on the success and failure of the projects.Thebenchmark for the success project is usually seen by short finishing time with theminimum cost without leaving the quality.Project management systematically isrequired to ensure the project implementation time in accordance with the contractor even faster so the cost can provide benefits, and also avoid the penalty due todelay in the completion of project. The aim of this research is to calculate thechanges of the cost and (overtime) and to compare the results between the cost ofpenalty cost with the changes after adding the overtime.The secondary dataobtained from the contractor.Data analysis in this research is using MicrosoftProject 2007 program and methods of time cost trade off. The results of theprogram Microsoft Project 2007 is the critical path and the results of the method oftime cost trade off is duration acceleration and cost increases due to the accelerationof the duration in any activities that increased.The results of this study indicate that:(1) From the time cost trade off with the addition of 1 hours of work per dayconducted on first day on critical jobs during the project, obtained the reduction inthe duration of 57 days, from the normal duration of 196 days to 139 days with atotal project cost changes from the normal cost of Rp 16,371,654,833.56 to Rp 16133 .588.292,57 (the difference between the cost of Rp. 238,096,540.99) as well ascausing an increase in the direct cost of Rp 15,469,452,846.76 to Rp15,493,731,373.36 (the difference between the cost of Rp. 24,278,526.60) andindirect costs experienced a decrease of US $ 902,201,986.80 to Rp 639,826,919.21(the difference between the cost of Rp. 262,375,067.59), (2) cost of accelerating theduration of the project with overtime is cheaper than the cost to be incurred ifprojects experienced delays and penalty.
Efektivitas Zona Selamat Sekolah (ZoSS) di Sekolah Dasar(Studi Kasus di Kabupaten Banyumas, Provinsi Jawa Tengah) Indriyati, Eva Wahyu; Santi, Mina Yumei; Tanjung, Mega Zahara; Sugiyanto, Gito
Semesta Teknika Vol 18, No 2 (2015): NOVEMBER 2015
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Many elementary schools in a city or district in Indonesia located on the edge of the highway (arterial road or collector road), with many vehicles are driving at high speed. In these circumstances it is very dangerous for school children as a pedestrian or vulnerable road user. In response, the government implemented a program like School Safety Zone (Zona Selamat Sekolah ” ZoSS”) to anticipate the movement of school children who are spontaneous and unpredictable. School Safety Zone, as an instrument to reduce traffic speed in a school area, has been implemented in Indonesia from 2006. The aim of this study tried to evaluate the effectiveness of the School Safety Zone in elementary school based on the behaviour of its users, including students, parents, and travelers around the school. The approach taken with analyzes the effectiveness of ZoSS, by the research at three public elementary school in Banyumas District. The analysis was done by observing pedestrian behavior, the behavior of the parent then analyzed with reference to the guidelines issued by ZoSS General Directorate of Land Transportation Decree No. 3236/AJ 403/DRJD/2006. Based on the analysis, the behavior of pedestrians and parent were unsaved with percentage average of unsaved pedestrian behavior is 84.92% and unsaved parent behavior is 74.52%. Percentage of the average pedestrian crossing procedure 4-T is 33.16%, crossing road by walking 87.87%, facility using the zebra cross 58.90%. Direction of arrival of the vehicle in front of the school 80.26%, stopping in the spot 63.33% and putting up/down child of the vehicle on the curb side of 72.97% . It’s still not effective as many pedestrians and parent don’t have good traffic behavior.
Implementasi Sistem Monitoring Deteksi Hujan dan Suhu Berbasis Sensor Secara Real Time Mustar, Muhamad Yusvin; Wiyagi, Rama Okta
Semesta Teknika Vol 20, No 1 (2017): MEI 2017
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The aim of this research is to provide the design and implementation of a monitoring system which is able to detect rain and temperature based on real time sensor. This system focuses on the results of raindrop detection sensor as a rain detector and NTC thermistor as a temperature detector. Both of the sensors have an analog output. Therefore, they require an Analog Data Converter (ADC) to measure. Several tools are used to build this monitoring system, including microcontroller Arduino NANO for input sensor value readings, data processing and programming. Real Time Clock (RTC) is used to provide time information when the sensor works, as well as the telemetry as the wireless communication device. An interface based on Graphical User Interface (GUI) using JAVA as the monitoring software which can be operated on a PC or laptop. Based on the analysis and evaluation, this tool can detect rain and temperatures in real time.
Optimalisasi Sink Mark Index Pada Produk Plastik Dengan Variasi Ketebalan Ekstrim Menggunakan Simulasi Moldflow Budiyantoro, Cahyo
Semesta Teknika Vol 19, No 2 (2016): NOVEMBER 2016
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Injection Molding Process is a closed cycle process involving 4 important factors that influencing product quality such as: process setting parameter, plastic material selection, product design and mold design. Ideally a plastic product is designed with uniform wall thickness since the thickness variation brought about negative effect on the final product. Those negative effects are warpage, sink mark or voids. Warpage is a bending failure of product, void cannot be observed as unfilled or holes on the cross section of the part, whereas sink mark is a deflected mark that can directly be seen on the surface of the part. Those 3 failures are normally caused by material accumulation and thermal rate differentiation. This research was a computerized based simulation using Autodesk MoldFlow Plastic Insight software to predict the 3 failures and to optimize the product quality by Sink Mark Index reduction, minimizing sink mark estimation and volumetric shrinkage  due to extreem thickness variation. The selected specimen was a brush handle, a real product that can easily be found in the market. The errors of brush handle in fact was caused by poor design and the only way to improve its quality is from process parameters point of view. There are 5 possible factors in fixing the failures, each factor possessed 3 level of values, then according to the Taguchi approach of design experiment, there must be 27 experiments to be done. After having 27 times experiments with combination of level and factors, it can be summerized that by combining low melting temperature, high injection pressure and high holding pressure, a sink mark index of 2.642% and a volumetric shrinkage of 19.28% can be obtained, and those were the minimum values representing the best results of product. The extension of holding time did not give a significant influence on the target quality.
Pengaruh Diameter Elemen Bara Api Terhadap Peningkatan Efisiensi Kompor LPG Fadelan, Fadelan; Sudarno, Sudarno
Semesta Teknika Vol 20, No 2 (2017): NOVEMBER 2017
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 The addition of embers is an effort to improve the efficiency of LPG stoves. Fire-embossed element of woven pattern is made of wire nikelin. The device when is burned with LPG cooker fire will incite to form a high-temperature fire, so as to burn the unperfectly burned fuel vapor around the wire. Previous research has shown that the element of fire can improve the efficiency of 8.32%. The efficiency test is done by boiling water test. The diameter of the embers element is varied, 20 mm, 30 mm, and 40 mm. The performance of the appliance is compared to the LPG stove without the use of embers. Temperature distribution at each treatment was also examined. It was found that the use of fire element with diameter of 0.20 mm resulted in the highest efficiency of 61.71%, with an increase of 8.32%. Temperature distribution test results show that the use of fire diameter element 0.20 mm produce the most optimal adult fire areas.
Kajian Pola Operasi Jalur Ganda Kereta Api Muara Enim - Lahat Setiawan M, Dian
Semesta Teknika Vol 19, No 1 (2016): MEI 2016
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Muara Enim – Lahat railway double track construction can optimise the passenger and freight transportation in South Sumatera. The objective of this study is to conduct railway double track operation concept analysis in order to obtain full concept of railway operation on this line. The result of this study become so important since it can be used for maintaining the optimisation steps of railway double track operation between Muara Enim – Lahat. This research was conducted by doing field survey and instantional survey to obtain primary and secondary data that is used as basic analysis of Muara Enim – Lahat railway track line operation. The key points included on this railway operation concept analysis are number of train per day, train length, maximum speed, station location, station function, station category, station type and activity, line capacity, and station layout. 
Studi Literatur Tentang Program Pump System Improvement Modeling Tool Untuk Penyempurnaan Kinerja Sistem Pompa Sukamta, Sukamta; Husda, Syamsul Muarif; Caroko, Novi
Semesta Teknika Vol 20, No 1 (2017): MEI 2017
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In the industrial world often encountered actual loads do not match the design load.  These differences lead to energy wastage. Pumping system is one of the systems that always exist in the industry. Improving of pumping system performance is an important step in saving energy. Impeller trimming is one method to improve the performance of the pump system. One of the obstacles in performing the impeller trimming method is to determine the magnitude of the impeller diameter reduction to be performed. Currently, many software developed to improve the performance of pumps and pumping systems. One of the softwares is Pump System Improvement Modeling Tool (PSIM). Imprimer trimming method is one of the features in PSIM. To be optimal in the use of PSIM in the improvement of the pump system it is necessary to conduct a literature study on PSIM to improve the performance of the pump system. In this article has been studied PSIM literature on the process of perfection of centrifugal pump system with impeller trimmer method by taking case study on hot water provider system. The method used in this literature study is by comparing the results of PSIM calculations on case studies with the pump theory of the impeller trimming method. Through this comparison will be known the advantages of PSIM and weaknesses, PSIM calculation margin error compared to the theoretical calculations. By knowing these things then it can be determined the limits of the use of PSIM in the improvement of pump system performance. The result of analysis shows that PSIM trimming impeller calculation is based more on the calculation according to affinity law than any other theory, even in the calculation there is error margin. The tendency of data is the greater the value of the reduction the greater the deviation. If based on the theory then the calculation of PSIM which can be used as a guide in calculating the reduction of diameter is a maximum reduction of 15% or 85% of the original diameter. A larger reduction of the value needs to be re-measured to the characteristics of the pump system.

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