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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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Pengaruh Perlakuan Panas Terhadap Struktur Mikro Logam St 60 Rina Dwi Yani; Tri Pratomo; Hendro Cahyono
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.v11i1.797

Abstract

This research aim to know the transformation of microstructure and it influence to ST 60 when its heated by heat treatment process. Specimen heated and arrested at temperature 800°C during 30 minutes, then is cooled with water coolant. Hardness of test piece is measured [by] before and after heat treatment by using method Rockwell C. Microstructure of metal photograph take by using special camera, and it presenting in millimeter block to calculate ferrite and pearlite content percentage. Result of research indicates that heat treatment to metal ST 60 causing microstructure change and percentage of ferrite was increase, directly causes material hardness value  increase too.
Pengaruh Penambahan Plastik High Density Polyetilene (HDPE) dalam Campuran Hot Rolled Sheet Wearing Course (HRS-WC) terhadap Parameter Marshall, Kuat Tekan dan Kuat Tarik Belah Pepi Nega Akmus
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.v16i2.4895

Abstract

In this study, plastics High-Density Polyethylene (HDPE) were used as an additional ingredient of asphalt for HRS-WC mixtures by using a variation of the plastic content of 0%, 2%, 4%, 6% to the asphalt weight. Bitumen content obtained from the optimum bitumen content of 7.5%. The purpose of this research is to examine and to compare the Marshall characteristics, compressive strength and split tensile of HRS-WC mixture. The results showed that the addition of HDPE plastic provide a significant influence on the marshall characteristic, split tensile strength and compressive strength. Asphalt stability with the addition of HDPE by 2%, 4% and 6% compliant with the specifications of marshall stability results respectively amounted to 2589.40 kg, 2257.13 kg and 2385.16 kg.
Kekuatan Geser Campuran Tanah-Kapur-Abu Sekam Padi Dengan Inklusi Kadar Serat Karung Plastik Yang Bervariasi Anita Widianti; Edi Hartono; Agus Setyo Muntohar
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.v10i1.849

Abstract

Stabilisasi tanah secara kimia yaitu dengan penambahan kapur dan abu sekam padi mampu meningkatkan kekuatan gesernya, namun campuran tersebut cenderung berperilaku getas (brittle). Keadaan ini kurang memuaskan bila digunakan sebagai bahan konstruksi yang lebih menginginkan bahan berkekuatan tinggi tetapi berperilaku ductile. Kombinasi dari teknik perbaikan tanah secara kimia dan secara mekanis (yaitu dengan perkuatan serat-serat plastik) diharapkan akan memberikan hasil yang lebih baik. Tujuan dari penelitian ini adalah untuk mengkaji kuat geser tanah yang distabilisasi dengan kapur-abu sekam padi-serat plastik dengan berbagai variasi kadar serat  dan masa perawatan. Dalam penelitian ini digunakan tanah yang dicampur 12% kapur, 24% abu sekam padi dan serat karung plastik sebanyak 0,1%, 0,2%, 0,4%, 0,8%, dan 1,2% dari berat total campuran. Uji yang dilakukan adalah uji geser langsung pada saat benda uji berumur 7 dan 14 hari. Secara umum dengan adanya penambahan serat karung plastik dan masa perawatan, nilai kohesi, sudut gesek dalam, dan kuat geser mengalami peningkatan dibandingkan nilai pada tanah asli dan tanah yang hanya dicampur dengan kapur-abu sekam padi saja. Campuran tanah - kapur-abu sekam padi dan 0,4 % serat untuk masa perawatan 14 hari memberikan peningkatan nilai kuat geser tertinggi, yaitu sebesar 178,63 % dari nilai kuat geser tanah asli (pada σ = 12,59 kN/m2).
Pengaruh Ukuran dan Kedalaman Geotekstil Teranyam Tipe HRX 200 terhadap Daya Dukung Ultimit dan Penurunan Tanah Lempung Lunak Anita Widianti , Azmania , Budi Kurniawan Thirayo
Semesta Teknika Vol 16, No 1 (2013): MEI 2013
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v16i1.437

Abstract

Geotextile as one of improvement material in soft clay soil has been widely used.  This study aims to examine the effect of geotextile dimention and placement depth on ultimate bearing capacity, settlement and Bearing Capacity Ratio of soft clay soil. This test was conducted on a series of square plate foundation loading of 10 cm width on clay soil sample and installing one layer of geotextile-improvement inside with several dimention variations and geotextile depth. Clay soil is on soft condition taken into a box model made of steel plate with the dimention of 120 cm x 120 cm x 100 cm. The result of this research shows that dimension and depth of geotextile affected the bearing capacity and settlement of soft clay soil. There were improvement in ultimate bearing capacity of as high as 3 times higher for geotextile 3Bx3B; 4 times higher for geotextile 4Bx4B; 5 times higher for geotextile 5Bx5B and 6 times higher for geotextile 6Bx6B comparing with bearing capacity of non supported-clay soil. Decreasing of settlement on clay soil was observed on the 3Bx3B improvement (twice lower), and 3 times lower, 4 times lower and 5 times lower for 4Bx4B, 5Bx5B, 6Bx6B, respectively. Geotextile which placed at a depth of 0.4 B and 0.8 B resulted in increased ultimate bearing capacity by 3.13 times. Dimension and depth geoxtile also affect the value of BCR. The highest BCR was on the dimention 6Bx6B on the depth of 0.6 B.
Implementation Of Neurofuzzy Controller To Robot Manipulator Sabat Anwari
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.v9i2.872

Abstract

This paper presents a neurofuzzy controller that is applied to robotic manipulators. Robotic manipulators are highly nonlinear, coupled multivariable dynamical system, and may contain uncertain elements such as friction and load. Many efforts have been made in developing control schemes to achieve the precise tracking control of robot manipulators. For this reason, classical linear controller, such as PID (Proportional, Integral, and Derivative) controller, will provide robustness only over relatively small range operation because of complexity and nonlinearity of the system. Neurofuzzy employed in this system to increase the range operation without lack of robustness. Before considering the actual control system, a neurofuzzy controller must be trained. Two strategies of training are presented in this paper : generalized training and specialized training. In generalized training a neurofuzzy controller is trained off-line. The objective of this training is the controller should performed the ability to follow an input signal over the wide range operation even the transient response is poor. Specialized training is on-line procedure learning. Based on the result of generalized training a neurofuzzy controller is trained to achieve the desired transient response.The results proved the potency of the neurofuzzy in robotic manipulators control systems. Neurofuzzy control systems are essentially nonlinear systems, due to the nature of the nonlinear neurofuzzy controller. Mostly, the nonlinear system is so difficult to be solved. Consequently, the analysis of such systems is complicated, particularly, when a neurofuzzy controller is involved. This is because of the absence of a universal mathematical model.
Model Power System Stabilizer Berbasis Neuro-Fuzzy Adaptif Agus Jamal , Ramadoni Syahputra
Semesta Teknika Vol 14, No 2 (2011): NOVEMBER 2011
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v14i2.543

Abstract

Low frequency oscillations are detrimental to the goals of maximum power transfer and optimal power system security. A contemporary solution to this problem is the addition of power system stabilizers (PSS) to the automatic voltage regulators on the generators in the power system. For large scale power systems comprising of many interconnected machines, the PSS parameter tuning is a complex exercise due to the presence of several poorly damped modes of oscillation. The problem is further being complicated by continuous variation in power system operating conditions. This research proposes the PSS model based on adaptive neuro-fuzzy for designing robust power system stabilizers for a multi machine system. Simulations were carried out using several fault tests at transmission line on a Two-Area Multimachine Power System. Simulation is done by using Matlab-Simulink software. The result shows that power transfer response using the model is more robust than Delta w PSS, especially for single phase to ground fault.
In Situ Determination Of Layer Thickness And Elastic Moduli Of Asphalt Pavement Systems By Spectral Analysis Of Surface Waves (Sasw) Method Sri Atmaja P Rosyidi; Mohd Azmi Ismail; Abdul Rahim Samsudin; Mohd Raihan Taha; Abdul Ghani Rafek; Khairul Anuar Mohd Nayan
Semesta Teknika Vol 8, No 2 (2005): NOVEMBER 2005
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v8i2.904

Abstract

Spectral analysis of surface waves (SASW) is a non-destructive and in situ method for determining the stiffness profile of soil and pavement sites. The method consists of generation, measurement, and processing of dispersive elastic waves in layered systems. The test is performed on the pavement surface at strain level below 0.001%, where the elastic properties are considered independent of strain amplitude. During an SASW test, the surface of the medium under investigation is subject to an impact to generate energy at various frequencies. Two vertical acceleration transducers are set up near the impact source to detect the energy transmitted through the testing media. By recording signals in digitised form using a data acquisition system and processing them, surface wave velocities can be determined by constructing a dispersion curve. Through forward modeling, the shear wave velocities can be obtained, which can be related to the variation of stiffness with depth. This paper presents the results of two case studies for near-surface profiling of two different asphalt pavement sites. 
Pengaruh Grain Size Arang Aktif dari Bahan Limbah Industri Sagu Aren terhadap Penyerapan Polutan Limbah Batik Sudarja , Novi caroko , Kuncoro Diharjo
Semesta Teknika Vol 14, No 1 (2011): MEI 2011
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v14i1.589

Abstract

Sago palm industries leave large amount of wood waste that is about 30% of the volume of tree trunks, 20% in large size which can be used for the handcraft and about 10% in small-size which only wasted. On the other hand, batik industries produce hazardous and toxic waste (B3), that should be neutralized since this liquid waste are bad smell and  hard color, and even toxity  (contain various kinds of chemical elements and heavy metals such as Mercury (Hg), Lead (Pb), Chromium (Cr), Cadmium (Cd), and Copper (Cu)) and if the elements are absorbed by human body exceeds the threshold point, it would be dangerous. Therefore, experiment on activated carbon engineering and its use in adsorbing the B3 batik liquid waste is urgently required.  The main objective of the experiment is to know the adsorbsion effectivity of activated carbon in adsorbing the batik liquid waste. The main material used in producing activated carbon is waste palm tree trunks. The main material is heated to be charcoal in retort for about 5 hours, temperature around 500 º C. Furthermore, charcoal is crushed finely and screened in sizes of mesh 25, 35 and 50. Carbon powder then chemically activated using H2SO4 solution by heating in 500 ˚C for about 30 menutes. Finally this activated carbon used for adsorbing the hard colour and heavy metal (Pb, Cr, Cd) in the batik waste water. This research concluded that the sago aren industrial waste may be an alternative material for activated carbon which is effective in adsorbing the hard colour and hazardous heavy metal. Higher mesh size (grain size) of activated carbon give higher adsorbsion in colour and heavy metal. Activated carbon in mesh 25 adsorbed  68.59% Cd, 16.65% Cr, and 100% Pb, mesh 35 adsorb  76.25% Cd, 37.55% Cr and Pb at 100%, while mesh 50 adsorb 81.61% Cd, 58,33% Cr, and 100%  Pb.
Peningkatan Efisiensi Kompor LPG Dengan Menggunakan Reflektor Radiasi Panas Bersirip Sudarno Sudarno; Fadelan Fadelan
Semesta Teknika Vol 18, No 1 (2015): MEI 2015
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v18i1.710

Abstract

Heat wasted due to radiation from the flame around the LPG stovecan lower stove efficiency. The wasted heat would be exploited by using a finned heat reflector . The working principle of this tool is to capture the wasted heat  and reflect to the load so that it becomes useful energy . Preliminary data indicate that areflector without fins can increase stove efficiency., The objective of this research isto determine the performace finned heat reflectorin increasing LPG stove  efficiency. A piece of stainless steel plate as a truncated cone-shaped finned experimental model was used as a reflector. The efficiency test is done through  boiling water test. The number of fin of the the same dimensions were varied, starting from one-line to three-line fins. The performance of the stoves using reflectorwith fins were compared with that of stove using reflector without finsand with that of stove without reflectot. Based on test results, it is found that the use of finned reflectors is able to increase the efficiency of LPG stoves. The highest efficiency is obtained on the use of reflectors with three rows of fins, which amounted to 44.09%. The magnitude of the increase is compared to without using a reflector at 5.22%, while compared with the reflector without fins for 5.01%. Based on the test of temperature distribution is obtained also that the use of reflector finned heat radiation can increase the area of complete combustion.
Perbandingan Analisis Two Way Slab With Beam dengan Flat Slab (Studi Kasus: Coal Yard PLTU Kalimantan Barat) Muhammad Ibnu Syamsi
Semesta Teknika Vol 18, No 2 (2015): NOVEMBER 2015
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v18i2.1818

Abstract

Floor slab of coal yard as a storehouse was designed as two way slab with beam and flat slab in order to compare those two systems based on needs of materials and ease of implementation. The design process is based on the provision of SNI 03-2847-2002. Through the design results and analysis of material requirements can be concluded that the need for concrete material on a flat slab system is 2.1% greater than on the two way slab with beam. Meanwhile the steel material requirements for flat slab system is 9.7% greater than two way slab with beam. However, in term of ease of implementation, relatively flat plate systems are superior to the briquette plate system because the number of items of work a little more

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