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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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Penerapan Metode K-Means Untuk Clustering Mahasiswa Berdasarkan Nilai Akademik Dengan Weka Interface Studi Kasus Pada Jurusan Teknik Informatika UMM Magelang Asroni, Asroni; Adrian, Ronald
Semesta Teknika Vol 18, No 1 (2015): MEI 2015
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Abstract

The selection process among outstanding students in a department has a big problem. This process is not fair because only involve one criteria and ignore the other criteria. We need the best student to participate in a competition held by the Indonesia Security Incident Response Team on Internet Infrastructure (ID SIRTII) of the Ministry of Communication and Information. This process uses Weka software to calculate the best student. It provides the various method to explore the data. One of them is clustering method. There are many algorithms in clustering method. In this research, we will investigate widely about one of that algorithms. Its name is K-Means. This algorithm (K-Means) will give the recommendations about the best student based on the cluster. It will represent the many clusters of a student group. The best cluster can be calculated more to get the names of the best students group. They are eligible to enter the competition.  K-means involve the GPA (Grade Point Average) and related course to support the academic skill in order to get the best student. This research helps the teacher select the best student to enter the competition. Many similar cases can use this algorithm in order to get the best student.
Pengaruh Penggunaan Bambu Sebagai Pengganti Agregat Split terhadap Kuat Tekan Beton Ringan Pujianto, As’at; Tajuddin, M.
Jurnal Semesta Teknika Vol 15, No 2 (2012): NOVEMBER 2012
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The use of bamboo as an aggregate replacement is one of the efforts to reduce the density and static load of structural elements, sincethe structural strength of bamboo is high. This study focus on the issue of the using bamboo as aggregate concrete with flowing method on a review of specific gravity and compressive strength of the concrete. This study uses bamboo as a percentage of the aggregate at 0% (normal), 20%, 40%, 60%, 80% and 100% of the conventional split and using additional silicafume aggregates. Specimens used in this study is the concrete cylinder (diameter 15 cm and height 30 cm). The identification and testing of tap density after 14 days of treatment.Results show that using more bamboo aggregate will result lower slump value, higher water absorption, decreasing in both specific gravity and compressive strength.
Meningkatkan Efektivitas Arang Bakau Pada Proses Karburising Padat Baja Karbon Rendah Menggunakan Barium Karbonat Soemowidagdo, Arianto Leman; Mujiyono, Mujiyono
Jurnal Semesta Teknika Vol 12, No 2 (2009): NOVEMBER 2009
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The effect of BaCO3 on bakau charcoal effectiveness as a carburizer for pack carburizing process was investigated. Bakau charcoal being produced from bakau trees were sifted on 30 mesh sieve. BaCO3 was then added into the bakau charcoal sieves with composition of 0, 15, 20, 25, and 30 wt %. The pack carburizing was carried out at 850 0C for 2 hours. Low-carbon steel containing 0.156 %C was used as specimen. After being carburized, all specimens were reheated at 850 0C, hold it for 5 minutes, and subsequently quenched into water at 28 oC. The result shows that BaCO3 improves bakau charcoal effectiveness as a solid media in pack carburizing proces. By adding of 20, 25 dan 30 wt % of BaCO3, it produced the case depth of 190 mm, 250 mm dan 325 mm, respectively. Martensite structure that arises on steel surface after being quenched indicates the increase of the amount of carbon atoms. 
Mesin Pemisah Dan Pembersih Biji-Bijian / Butiran Sebagai Bahan Baku Pakan Burung Olahan Rofarsyam, Rofarsyam
Jurnal Semesta Teknika Vol 11, No 1 (2008): MEI 2008
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Abstract

Bird feed  ingredient process has been done traditionally which uses winnow that moved up and down by hands, just reach 6 kg/hour by a worker, that containt of 5.75 kg of solid grains, 0.25 kg empety grains and dust. For rising work efficiency needs separating process and cleaning process bird feed ingredient between solid grains and empety grains and dust by mechanical. Those are by build bird feed ingredient separating and cleaning machine. Construction and working principle designed, according to theory of subtance free fall, which forced by horizontal windy force by blower and motored by electrical motor  ½ Hp 1450 rpm completed by belt and pulley transmition. Capacity of bird feed ingredient separating and cleaning machine can reach 90 kg/hour consist 86.25 kg solid grains and 3.75 kg empety grains and dust. 
Pengaruh Ukuran dan Kedalaman Geotekstil Teranyam Tipe HRX 200 terhadap Daya Dukung Ultimit dan Penurunan Tanah Lempung Lunak Budi Kurniawan Thirayo, Anita Widianti , Azmania ,
Jurnal Semesta Teknika Vol 16, No 1 (2013): MEI 2013
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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 Anwari, Sabat
Jurnal Semesta Teknika Vol 9, No 2 (2006): NOVEMBER 2006
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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.
Pengaruh Grain Size Arang Aktif dari Bahan Limbah Industri Sagu Aren terhadap Penyerapan Polutan Limbah Batik Kuncoro Diharjo, Sudarja , Novi caroko ,
Jurnal Semesta Teknika Vol 14, No 1 (2011): MEI 2011
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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.
Pengujian Kinerja Pompa Sentrifugal Menggunakan Kontrol Inventer Putro, Wahyu Djalmono
Jurnal Semesta Teknika Vol 13, No 1 (2010): MEI 2010
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An alternative method for obtaining data on pump discharge and head in order enable to determine pump characteristics has been investigated and formulated. Three types of centrifugal pump, the snails house, diffuser and turbine, have been selected. According to their respective manufacturers, the heads of these pumps are 16 m, 11 m and 9 m, respectively; their respective debits are 105 m3/h, 105 m 3/h and 150 m3/h; and their respective efficiencies are 95 %, 70 % and 95 %. Two testing parameters, shaft rotation and ball valve opening portion have been considered. Five different rotations, 1500 rpm, 1750 rpm, 2000 rpm, 2500 rpm and 2800 rpm, and seven different ball valve opening portions, 0 %, 25 %, 30 % 45 %. 60 %, 75 % and 100 %, have been considered. The main units of the alternative methods for measuring pump discharge and head are an electric motor, an inventer, a U-tube manometer and an orifice. The result shows that the heads the pumps are 15,4 m,11,45 m and 9,7 m, respectively, the debits of the pumps are 103 m3/h, 108 m 3/h and 171 m3/h, and efficiency are 98 %, 69,5 % and 97,5 %, respectively. Controlled inventer method can be used as one of the alternative pump performance test.
Uji Triaksial Unconsolidated-Undrained pada Campuran Tanah Lanau - Kapur - Abu Sekam Padi dan Serat Karung Plastik Widianti, Anita; Hartono, Edi; Muntohar, Agus Setyo
Semesta Teknika Vol 11, No 2 (2008): NOVEMBER 2008
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Geotechnical and mechanical behaviour of soil stabilized with lime-rice husk ash and strengthened by randomly placed plastic fiber depends on the portions of the added materials and curing time. This research investigates the effect of the waste plastic sack fibers portion and the curing time to the stress – strain relationship and to the shear strength parameters of the mixture. In this study the portions of lime and rice husk ash were set as constant to the value of 12% and 24% respectively. The effect of four waste plastic sack fibers portion variation from 0.1% to 0.8% was measured by unconsolidated-undrained triaxial test. The samples were tested at 7, 14 and 21 days after mixing. In general, according to the test result, the inclusion of randomly waste plastic sack fiber and curing time have enhanced the shear strength parameters, the peak stress and the strain before failure.  With 0.2% fiber content, the cohesion and the internal friction angle values of the samples have increased 335% and 409% respectively compared with those of the samples having no added materials.
Perancangan Ulang Struktur Atas Jembatan Gajah Wong Yogyakarta dengan Menggunakan Box Girder Lukmanul Hakim, Sentot Hardwiyono , Bagus Soebandono ,
Jurnal Semesta Teknika Vol 16, No 1 (2013): MEI 2013
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The Gajah Wong bridge to be studied is located in road section of Selokan Mataram, connecting Gejayan Street and Seturan area, Sleman, Daerah Istimewa Yogyakarta Province. This bridge was built in order to increase economic and to support traffic activities in this area. Gajah Wong bridge has 40 m span. The designing of this bridge used I girder, and then would be done redesigning another form of prestressed-concrete bridge which is box girder. This redesign method being used is Bridge Management System (BMS) 1992. Excel is used to analyze the structure. AutoCAD 2010 software was utilized for scetching the design. Girder designed using prestressed concrete structures with cross-sectional profile of a trapezoid -shaped box girder type . In designing the structure beam is used full - prestress post-tensioning with trapezoidal cross section box with 2.5 m high with 0,3 m floor-slab thickness. Prestressed-steel using  7 strands which is based on ASTM A-416 specification and used angkur 28 pieces of VSL type E-55.

Page 12 of 72 | Total Record : 715

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