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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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Perancangan Database Pada Sistem Asessmen Dan Pemetaan Hasil Asessmen Berbasis Tag Sebagai Pembantu Penyusunan Strategi Pembelajaran Apriliya Kurnianti; Angguningtyas Angguningtyas; Reza Giga Isnanda
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.v20i2.3292

Abstract

The Assessment and Mapping System of Tag-Based Assessment Results is an online-based system that aims to assist teachers and students in recording and mapping the assessment results for college admission. Information from the recording and mapping is very useful in helping the preparation of learning strategies and strategies to face the next exam. To support this assessment system required a database design. In the design of the database, the design is divided into 4 stages of Data Collection and Analysis, Conceptual Database Design, Logical database design, and Physical Database Design. The design of a conceptual database includes anyone involved in the system, what inputs are required, and what information (output) is desired from the database. While in logical database design, including the determination of Entities and attributes, determination of primary key, Entity Relationship Diagram (ERD). In the physical design, including ERD conversion to table form, normalization and implementation into the form of tables created on MS SQL Server. From the design of the database produces tables without anomalies, ie Eye, Student, Teacher, Testing, Problem, StandardValues, Tags, Groups, GrupMember, Member, EventUjian, Nilai, NomorSoal, PesertaUjian, Clipbooard, and OnGoingExam tables.
Studi Optimasi Waktu dan Biaya dengan Metode Time Cost Trade Off pada Proyek Konstruksi Pembangunan Gedung Olah Raga (Gor) Mandiyo Priyo; Meiki Risa Anggriani Paridi
Semesta Teknika Vol 21, No 1 (2018): MEI 2018
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.211213

Abstract

Cost and time analysis are most important on the contruction project. Optimal Time and minimal cost become standart to make profit benchmarks on a project. Therefore, it is necessary to optimize the cost and time by looking for work items that are included in the critical path. The purpose of this study is to know the change of cost and time due to the addition of working time, change of cost and time due to the addition of employee, as well as cost that needed if the projects experienced delays and penalty.. So it will be compared from all three to get the minimum cost with the optimum duration.The data used in this study is secondary data obtained from contractor implementing. Data analysis using time cost trade off method with microsoft project 2010 program. The results of the study, From the time cost trade off with the addition of 1 hours of work per day conducted on first day on critical jobs during the project, obtained the reduction in the cost of Rp 39,552,394,71 and the reduction in the duration of 36.18 days. Addition of 2 hours of work per day obtained the reduction in the cost of Rp 57,532,834.66 and and the reduction in the duration of 62.61 days. Addition of 3 hours of work per day obtained the reduction in the cost of Rp 69,392,147,01 and and the reduction in the duration of 82.48 days. Meanwhile, for the addition of employee for 1 hours obtained the reduction in the cost of Rp 52.497.085,35 and the reduction in the duration of 36.18 days. Addition of employee for 2 hours obtained the reduction in the cost of Rp 91,349,394.80 and the reduction in the duration of 62.61 days. Addition of employee for 3 hours obtained the reduction in the cost of Rp 120,645,301,55 and the reduction in the duration of 82,48 days. So that, the optimal time and cost occur when addition employee is incurred for 3 hours, compared to overtime and overdue. Namely with the optimal cost of the project of Rp 2,418,408,305.45 and the optimal duration of the project for 57.52 days.
Simulasi CFD Aliran Stratified Air-Udara pada Pipa Horisontal Sukamta Sukamta; Thoharudin Thoharudin; Dedy Melianto Nugroho
Semesta Teknika Vol 21, No 2 (2018): NOVEMBER 2018
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.212227

Abstract

Two-phase flow can be found in industries, such as petroleum, electricity generation. In geothermal power plants, two-phase flow occurs from a mixture of water and steam which should be avoided in the piping system because it can cause equipment damage in the operating system. Therefore, an operator and engineer need a knowledge of flow patterns, phenomena and characteristics of the two-phase flow. One of the methods to predict the flow pattern is ud\sing the Computational Fluid Dynamic (CFD). This CFD simulation was modeled using Ansys Fluent 15.0 software to determine the changes of Stratified flow characteristics. The model used is Volume of Fluid (VOF). The fluid type is water and air. The variation of superficial water velocity JL of 0.025 m/s - 0.1 m/s while the superficial air velocity (JG) of 0.05 m/s - 1 m/s. The pipe used is an acrylic of 19 mm diameter and length of 1000 mm. The simulation results show that: (1). Stratified flow occurred for the low velocity of the liquid and gas phases. It was shown by the water and air are clearly separated. (2). Flow patterns are not stable, but it can change depending on the superficial velocity of gas and water. (3). The larger of JG causes the wave height because of Bernoulli’s effect so that it will make the stratified wavy or ripple flow pattern. (4). The frequency of stratified-wavy and ripple waves will tend to decrease when the JL increases, while the effect of JG is insignificant. Furthermore, it can be concluded that the speed of gas must be regulated so as not too large to the speed of water.
Perkuatan Struktur Jembatan Kereta Api Rangka Baja Tipe Warren bentang 42 Meter soebandono, Bagus; Nugroho, Bintang Noorohmad Wahyu; Anam, Ariq Naufal; Ismayana, Raka Putra; Maulana, Taufiq Ilham
Semesta Teknika Vol 22, No 2 (2019): NOVEMBER 2019
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.222244

Abstract

Jembatan kereta api merupakan salah satu prasarana transportasi penting dalam memenuhi kebutuhan manusia. Seiring dengan bertambahnya usia suatu struktur, maka jembatan kereta api juga akan mengalami penurunan kapasitas yang disebabkan oleh faktor internal maupun faktor eksternal. Melihat dari kegunaan jembatan kereta api yang sangat penting, maka dibutuhkan struktur yang kuat serta mampu menjamin keamanan dan keselamatan. Perkuatan merupakan salah satu usaha untuk mengembalikan kapasitas muat suatu struktur sehingga mampu menahan beban yang terjadi. Dalam penelitian ini jembatan kereta api rangka baja tipe warren mengalami penurunan mutu baja sebesar 30%. Analisis dan pemodelan struktur rangka baja menggunakan software SAP2000 V.20 yang kemudian dilakukan perkuatan dengan mengganti elemen-elemen lemah pada struktur rangka baja. Hasil penelitian menunjukan bahwa, nilai mode shapes maksimum setelah dilakukan perkuatan pada arah perpindahan sumbu global X ( UX ) memiliki nilai yang lebih besar 0,072% dari sebelum dilakukan perkuatan yaitu dari 0,825365 menjadi 0,825962. Nilai periode (T) juga mengalami peningkatan sebesar 1,603% dari 0,370023 detik menjadi 0,375957 detik. Lendutan pada tengah bentang jembatan sumbu lokal horizontal searah bidang XY ( U3 ) mengalami penurunan sebesar 32,85% dari 36,437377 mm menjadi 24,467447 mm. Pada evaluasi tegangan, terdapat 25 batang yang mengalami field capacity yang kemudian dilakukan perkuatan dengan mengganti 17 batang dengan memperbesar dimensi profil sehingga seluruh batang tidak mengalami field capacity. Nilai tahanan maksimum pada batang yang tidak aman setelah dilakukan perkuatan menjadi lebih kecil dari 25,324 ton menjadi 23,861 ton dengan kapasitas yang meningkat dari 12,612 ton menjadi 34,824 ton.The railway bridge is one of the important transportation infrastructures in meeting human needs. As a structured age, the railway bridge will also experience a decrease in capacity caused by internal and external factors. Seeing from the use of the railway bridges which is very important, it takes a strong structure and can guarantee security and safety. Reinforcement is an effort to restore the load capacity of a structure so that it can withstand the burden that occurs. In this study, the warren type steel frame railroad bridge experienced a 30% decline in steel quality. Analysis and modeling of steel frame structure using SAP2000 V.20 software which is then performed strengthening by replacing the weak elements in the steel frame structure. The results showed that the value of the maximum mode shapes after the reinforcement in the direction of global X-axis displacement (UX) has a greater value of 0.072% than before the reinforcement is from 0.825365 to 0.825962. Period value (T) also increased by 1.603% from 0.370023 seconds to 0.375957 seconds. Deflection in the middle of the horizontal local axis bridge spread in the direction of the XY (U3) plane decreased by 32.85% from 36.437377 mm to 24.467447 mm. In the stress evaluation, there is 25 frames that experience field capacity which is then strengthened by replacing 17 frames by enlarging the profile dimensions so that all the bars do not experience field capacity. The maximum resistance value on the unsafe stem after reinforcement is smaller than 25,324 tons to 23,861 tons with capacity increasing from 12,612 tons to 34,824 tons. 
Faktor Penyebab Terjadinya Keterlambatan dan Waste Time pada Proyek Pembangunan Konstruksi Turbine Hall PLTU Tambak Lorok Block 3 Semarang Yoga Aprianto Harsoyo; Muhammad Reza Arkan
Semesta Teknika Vol 23, No 2 (2020): NOVEMBER 2020
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v23i2.6842

Abstract

Dalam suatu pembangunan proyek konstruksi hampir selalu dipastikan terdapat permasalahan yang dapat menimbulkan keterlambatan dan pemborosan waktu. Baik dari proses perencanaan, pengadaan hingga proses instalasi akan dihadapkan pada berbagai permasalahan teknis dan nonteknis yang harus dapat diminimalisir dengan sebaik-baiknya oleh semua pihak dalam proyek konstruksi. Pekerja pada proyek konstruksi seperti Kontraktor Utama dan Kontraktor SUB merupakan pekerja yang sering menghadapi masalah langsung dalam proyek konstruksi. Begitu pula pada proyek pembangunan Turbine Hall di PLTU Tambak Lorok Blok 3 Semarang ditemukan beberapa kendala yang menjadi faktor keterlambatan dan pemborosan waktu. Penelitian ini dilakukan untuk mengetahui faktor-faktor penyebab keterlambatan dan pemborosan waktu menurut beberapa elemen pekerja kontraktor utama dan sub kontraktor yang mengerjakan proyek dengan cara penyebaran kuisioner. Hasil yang diperoleh dari kedua elemen pekerja tersebut kemudian dianalisis menggunakan analisis deskriptif dengan SPSS untuk penyebab keterlambatan dan analisis dengan metode Borda untuk faktor penyebab waste time. Dari faktor-faktor penyebab keterlambatan dan pemborosan waktu yang didapat dari beberapa elemen pekerja, akan dilakukan analisis perangkingan dan diketahui faktor-faktor utama.In a construction project development is almost always sure to always have problems that can cause delay and waste time. Both of the planning process, procurement even until the installation process will be faced with various technical and nontechnical problems that must be able to be minimized as well as possible by all sides of the construction project. Workers in construction projects such as Main contractors and SUB contractors are workers who often face problems directly in the construction project. Similarly, the Turbine Hall construction project at PLTU Tambak Lorok Block 3 Semarang was found in the project a few obstacles which became a factor of delay and waste time. This research was conducted to determine the factors of the cause of delays and waste time according to some elements of the workers ' main contractors and sub-contractors working on the project by the dissemination of the questionnaire. The results obtained from all two elements of the worker are then analyzed using the descriptive analysis with SPSS for the cause of delays and analysis by Borda method to cause waste time factors. From the factors that cause delays and waste time gained from some elements of the worker, there will be a ranking analysis and known major factors. 
Model Bangkitan Perjalanan Kerja dan Faktor Aksesibilitas pada Zona Perumahan di Yogyakarta Yuswendra Ersandi; Ahmad Munawar; Sri Atmaja P Rosyidi
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.v12i1.747

Abstract

The aim of this paper is to develop the mathematical model of home based work-trip generation and to obtain its trip variables influencing the model. Factors of trip accessibility i.e. distance to work, travel time, cost for public transport and cost for private vehicle were also observed in the model. In this study, several households in Griya Taman Asri, Sleman Yogyakarta were chosen for questioner sample in home interview survey. Mathematical model was generated using the multi-linear regression with the dependent variable is work-trip which is affected by nine independent variables. The generated model was then validated by VIF and Anova test. The result shows that the work-trip generation model for Griya Taman Asri was influenced by parameter of the car ownership (X2) and the worker in household (X5). However, all trip accessibility factors considered in this study do not influence to work-trips.
Analisis Nyala Torch Oksidasi Pada Oxy-Acetylene Terhadap Sifat Fisik Dan Mekanik Sambungan Las Pelat Baja Karbon Rendah Andika Wisnujati; Rivaldy M Kartika
Semesta Teknika Vol 20, No 1 (2017): MEI 2017
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v20i1.3063

Abstract

Oxy-acetylene welding is widely used in small workshops for car body repair, automobile and motorcycle exhaust, and other improvements using a maximum temperature of 3000oC that can not be done through another process. The purpose of this study was to analyze the effect of torque oxy-acetylene flame on the physical-mechanical properties in welding connection low carbon steel plates . The method used by using a low carbon steel plate 2 (two) pairs in a butt weld dimmension of  300 mm x 75 mm x 1 mm. After welding with oxy-acetylene in torch oxidation flame, the specimens were  examined through physical observation including microstructure and mechanical properties. Micro hardness vickers was used to evaluate the hardness. Tensile properties was determine using the universal testing machine. In the microstructure testing, there is a pearlite and ferrite whose become different dimensions as it is affected by the heat and air pressure of the weld. Mechanical testing that is tensile test obtained yieldpoint of the specimen A 125,17 N/mm2 and specimen B 126,55 N/mm2. The result of tensile strength specimen A 166,35 N/mm2 and specimen B 169,76 N/mm2. While the vickers test obtained the highest hardness that is 152.5 VHN in the welding area, and the lowest hardness number is 124,9 VHN in the heat affected zone.
Respon Model Gedung Beton Bertulang dengan Penambahan Dinding Pengisi terhadap Beban Gempa Muhammad Ibnu Syamsi
Semesta Teknika Vol 21, No 1 (2018): MEI 2018
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.211208

Abstract

Earthquake-resistant building structures designs usually are not considering the influence of non-structural walls. In fact, non-structural walls could give additional strength for building especially to help retaining seismic loads. The Influence of masonry walls on infill frame building structure model to the open frame model became the objective in this study. Spectrum response and time history are applied to both types of model to know and compare the behavior of those two samples. The observed building is an educational facility and located in an area prone to earthquakes. The parameters used in this research are based on natural periods, shear forces, and drift ratios. After performing linear analysis, the drift ratio on each floor of the building could be categorized as safe condition because it has not exceeded its limit. Structural models with masonry walls have larger stiffness than open frames. Moreover, the greater structure stiffness in the infill frame model is able to narrow the drifts that occur from the inter-story drift ratio to be smaller. Due to higher stiffness, the base shear results from structures with infill frame system models are also larger than structures modeled with open frames system.
Worldwide Hot Mix Asphalt Layer Application and Scrap Rubber and Bitumen Emulsion Studies on Railway Track-Bed Dian M Setiawan
Semesta Teknika Vol 21, No 2 (2018): NOVEMBER 2018
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | 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.
Recommendation of Knockdown Building Design at Yogyakarta Sand Dunes (Restricted and Heritage Areas) Adwitya Bhaskara; Fitri Nugraheni; N. Faried Hanafi
Semesta Teknika Vol 22, No 1 (2019): MEI 2019
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.221239

Abstract

Sand dunes located in Special Region of Yogyakarta Indonesia is a restricted caused by the heritage and there only four spread in hemisphere one of them in Yogyakara, Indonesia. To build in sand dunes area building could not be built arbitrarily. Portable and knockdown is the character of the building that could be adjust to the conditions in Sand dunes. By the observation results compact building design with cold formed steel material for the main building material is the recommendation of this case. The design is then consulted with sub-contractors who are expert in their expertise as the validation stage, it is feasible to be transformed into a real building for the specific needs. Output of this research is recommendation of portable building model in modular form, where the design recommendation has been adjusted with building requirement in heritage and restricted area, which is also an area prone to tsunamis and wind disasters, therefore the recommended building are; easy to remove, easy to disassemble (knockdown), forward tsunami load, efficient cost and time (using cold formed steel material and prefabricated GRC), eco friendly (zero waste), does not require many workers (less man power).

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