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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 19 Documents
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Search results for , issue "Vol 15, No 1 (2012): MEI 2012" : 19 Documents clear
Pengaruh Jumlah Lapisan dan Spasi Perkuatan Geosintetik terhadap Kuat Dukung dan Penurunan Tanah Lempung Lunak Anita Widianti
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.v15i1.447

Abstract

One of the ways to improve the mechanical characteristics of soft soil is to provide soil reinforcement which is a geosynthetic sheet overlaid on the soft soil. Previous studies show that the installation of geosynthetic layers in soft soil proved to increase the bearing capacity and reduce the settlement. Theoretically, if more layers of reinforcement are given, the support will be stronger, while the soil of settlement will be reduced even greater. In this study, the influence of the number of layers and vertical distance between geosynthetic layers on the magnitude of bearing capacity, and the settlement in base soil will be assessed. The primary research is a load test on each clay included in model boxes of 120 cm x 120 cm x 100 cm size. Water was added to the soil to achieve the liquid limit conditions, then the soil was strengthened by inserting 60 x 60cm2 HRX200 woven geotextile layers whose tensile strength is 20 kN/m2 with various distances and number of layers among different boxes. The bottom of loading foundation on the top side of the samples is square whose side (B) is of 10 cm. The loading process were done until the soil collapse indicated by visual observation or by the condition of no increase of the load magnitude causing settlement. The results showed that 1 layer, 2 layers and 3 layers geosynthetic correspond to the bearing capacity increase of 60.57%, 213.00% and 402.64%, respectively, and experienced a reduction in soil settlement by 40%, 60% and 70%, respectively, compared to that without any reinforcement. Geosynthetic being placed at a distance of 0.4 B and 0.6 B gives the greatest bearing capacity increase, in the amount of 402.64%. Geosynthetic mounted on distance more than 0.6 B resulted in bearing capacity increase of diminishing percentages.
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.   
Perpindahan Kalor pada Penukar Kalor Selongsong dan Pipa Memakai Sekat Miring Tidak Sejajar Muhammad Nadjib
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.v15i1.441

Abstract

Generally speaking, baffle installation of a shell-and-tube heat exchanger is in straight-standing with respect to shell axis. A common problem of this arrangement is that there will be found a stagnant fluid condition in the death-zone. The impact is the heat transfer coefficient could not reach an optimum value. Based on baffle configuration, the death-zone effect can be minimized by installing an un-parallel tilted baffle. The purpose of this research is to investigate the effect of using non-parallel tilted baffle on heat transfer coefficient. The heat exchanger model was made with single pass fluids. Hot water is going through inside the tube bundles and cold water pass is in the shell. The baffle was installed in various angle of 0°, 15°, 30°, and 45° with respect to shell axis. The cold water flow rates were varied from 75 l/hr, 100 l/hr, 125 l/hr, 150 l/hr, 175 l/hr, to 200 l/hr. The hot water flow rate was fixed at 150 l/hr. Temperature of the hot and cold water at inlet and outlet was recorded by means of K type thermocouple and data logger. The data was then analyzed to obtain the convection heat transfer coefficient. The data were also used to determine the empirical correlation of Nusselt number and Reynolds number. The results indicate that baffle in angle 0° produce the highest convection heat transfer coefficient. Installing the baffle at tilted position is not significant in convection heat transfer coefficient. The empirical correlation of Nusselt number and Reynolds number is influenced by angle function of the baffle.
Uji Model Fisik Water Treatment Bentuk Pipa dengan Media Aerasi Baling-Baling Surya Budi Lesmana , Indah Nurfathin
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.v15i1.444

Abstract

Both water and health are inter-connected things. Water is used for many daily needs. In Universitas Muhammadiyah Yogyakarta, water needs are quite big, such as for bathroom needs, laboratory, mosque and other places. Because of that, water quality in campus need to be examined in order to fulfill requirement of Indonesia Health Ministry (KepMenKes No. 907/2002). That requirement is about water conditions and supervision. This study aimed to analyze the ability of water treatment equipment used by doing analysis of Fe and DO parameters.
Kaji Eksperimental Efektifitas Penyerapan Limbah Cair Industri Batik Taman Sari Yogyakarta Menggunakan Arang Aktif Mesh 80 dari Limbah Gergaji Kayu Jati Sudarja , Novi Caroko
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.v15i1.443

Abstract

Utilization of teak wood saw scratches can be optimized by processing it becomes active charcoal which possesses higher economic value. The purpose of this study is to obtain mesh 80 activated charcoal made from teak sawing industrial waste and to determine it’s effectiveness in adsorbing heavy metals pollutant Cd, Pb, Cr, and colouring agent in liquid waste of batik industries. The charcoal is produced at ~5000 oC retort either for 4 hours or until white colour smoke does not appear. Charcoal was activated using H2SO4 at temperature of 5000 oC for 30 minutes in a furnace. There were 2 variables in this study, i.e weight of the activated charcoal (10, 15, 20 grams) and duration of the stirring (5, 10,15 minutes). Result of the research shows that activated charcoal made from teak wood saw scratches can be used as adsorbent in the liquid waste of batik industries such as heavy metals Cd, Pb, Cr, and dark colour. The colour gradation was found to decrease from 12600 TCU to 198 TCU, Pb content decrease from 0,189 mg/l to less than 0,0093 mg/L, Cd content decrease from 0,213 mg/l to less than  0,0093 mg/L, while Cr content decrease from 2,03 mg/l to 0,4205 mg/l.
Penghitungan Tebal Setara Metode Boussinesq-Exel dan FWD-ELMOD pada Perkerasan Lentur Hardwiyono, Sentot
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.v15i1.446

Abstract

Calculating the Flexible Pavement System (FPS) response has initiated by Boussinesq, Burmister, Huang and more scientists around the world. Determining modulus elasticity each stratum FPS very important to note to designing the Flexible Pavement. The purpose of this study is to determine the elastic modulus of each layer in the profile Flexible Pavement Systems (FPS) with a thickness equivalent method Boussinesq-Exel and FWD-ELMOD. Tests were run on the Soekarno-Hatta Cikampek-Purwakarta-Bandung and West Java highways, Indonesia. The test results showed a good correlation between the modulus of each layer in the FWD testing with those of Boussinesq-Exel test.
Optimalisasi Energi Terbarukan pada Pembangkit Tenaga Listrik dalam Menghadapi Desa Mandiri Energi di Margajaya Arif Febriansyah Juwito , Sasongko Pramonohadi , T. Haryono
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.v15i1.440

Abstract

The Energy Self-Sufficient Village is one of main programs from goverment about the village ability to produce energy. This program has been launched in 2007 by the President of the Republic of Indonesia, to enhance energy security in rural areas by harnessing local energy potential. The criteria of Energy Self-Sufficient Village is village capability to produce at least 60% of the total amount of required energy, using renewable energy. Geographically, Margajaya village has solar and microhydro resource which is very potential for being developed. Furthermore, Margajaya also produces agricultural commodities such as palm oil, in which it also produces waste like palm bunches which is a very potential biomass. The optimization of renewable energy for electrical power generation which has annual power peak of 65kW and daily energy consumtion of 415kWh/day in Margajaya village has been designed using HOMER. The result from simulation of Hybrid renewable system in HOMER showed that Hydro, Biomass and grid is the most economical solution over hydro-biomass-PV with battery, to design hybrid system with minimum total net present cost (NPC) and cost of electricity. The system can serve annual 100% of load in Margajaya and have surplus of electricity, and could sell to grid with amount of 124.827kWh/years. Economically, the electricity of the system costs US$ 0,013/kWh.
Kuat Geser Tanah Pasir yang Distabilisasi Menggunakan Aspal Cair SC60-70 Willis Diana , Elfira Resti Mulya
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.v15i1.442

Abstract

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%).
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.

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