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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
 52   53   54   55   56 
Pengaruh Faktor Air Semen terhadap Kuat Tekan Beton dengan Agregat Batu Apung Agus Pujiono; Dwi Riyanto; As'at Pujianto; Bagus Soebandono
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.v16i2.4921

Abstract

Lightweight concrete is concrete that has a unit weight less than 1800 kg/m3. Pumice can be used to make lightweight concrete as the replacement of coarse aggregate in concrete mixtures. This research aimed to discover the compressive strength of lightweight concrete with water-cement ratio and the impact of the unit weight of the concrete. This research was divided into two types of method. Firstly, the concrete was produced with the water-cement ratio of 0.30, 0.32, 0.34, and 0.36 and additional superplasticiser 2% for each variation. Secondly, the concrete was created with water-cement ratio 0.36, 0.38, 0.40 and 0.42 without admixture. Samples were tested for compressive strength after 28 days and calculated the unit weight of the concrete with pumice as the replacement of coarse aggregate. The results of this study indicated that for the first method, the maximum compressive strength value of lightweight concrete with pumice and additional superplasticiser was 11.2880 MPa with water-cement factor 0.30 and unit weight 1691.59 kg/m3. While for the second experiment, results show that the maximum compressive strength of lightweight concrete with pumice without admixture reached at 10.4620 MPa with a water-cement ratio at 0.38 and unit weight 1692.74 kg/m3.
Deteksi Kecacatan Permukaan Buah Manggis Menggunakan Metode Deep Learning dengan Konvolusi Multilayer Laila Marifatul Azizah; Sitti Fadillah Umayah; Febriyana Fajar
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.212229

Abstract

Mangosteen is one of Indonesian potential export fruits. Nevertheless, mangosteens quality is compulsary. A good quality fruit surface is needed in export fruit. This is the reason of this research to detect the flaw in rind surface, particularly mangosteen. Some researcher has been done many type of image processing for fruit detection. However, there aren’t any research for mangosteen rind detection especially used Deep Learning. This research used CNN (Convolutional Neural Network) as deep learning method to detect mangosteen rind surface. Our research is to find configuration which was the best accurancy value. The rind detection calcuted between epoch and layer to obtain maximum accurancy value. This method achieved maximum value by parameter 4 layer and epoch value of 30. From our experiment, the test result for rind detection was 98% accurancy.
Prototipe Kotak Pengingat Minum Obat Sulis Irjayanto; Anna Nur Nazillah Chamim
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.v18i2.1820

Abstract

Patient adherence to long-term therapy of chronic diseases in developing countries less than 50%, including in Indonesia. Patient compliance is required to achieve therapeutic success, especially in the treatment of non-infectious diseases. Such as diabetes, hypertension, asthma, cancer, mental disorders, infectious diseases HIV / AIDS, and tuberculosis. One factor led patience to the non-compliance is their busyness, so they often forget to take medication. Prototype of medication reminder box is one of the solutions to remind patients to take medication on time. In previous researches, the medication reminder operated in android platform. But, gadgets equiped with android operating system are often in out of reach of many people in developing countries. So, in this study, the medication reminder box was built with alarm facility that can be regulated by the patient. This device is also used as a portable drugs storage, so that the patient can carry easily. This prototype of medication reminder box operates well as expected and supported with battery which its endurance is 24,7 hours.
Identifikasi Pola Aliran Dua Fasa Uap-Kondensat Berdasarkan Pengukuran Beda Tekanan pada Pipa Horisontal Sukamta Sukamta; Indarto Indarto; Purnomo Purnomo; Tri Agung Rohmat
Semesta Teknika Vol 13, No 1 (2010): MEI 2010
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v13i1.728

Abstract

An experiment of two-phase flow patterns of steam-condensate based on differential pressure measurement in horizontal tube was conducted by varying the flow rate of the steam. The experiment utilised annulus pipe with inner section test pipe was made from copper and outer section was made from Galvanized Iron Pipe (GIP) wrapped with a 10-mm-thick insulation. The pipe was 1.6 meter length, and 4 inch outer diameter and 17 mm inner diameter. The two-phase flow regime was investigated based on pressure gradien between its inlet and outlet. In order to support the result, visualition was conducted using a ¾ inch diameter and 1.3 m length of transparent pipe connected with the test pipe section. Five variations of steam flow rate ranging from 0.00211361 m3/s to 0.007078511 m3/s were selected. The results show that for lowest steam flow rate, stratified flow pattern was identified while for the ot her variations, stratified, wavy, plug and slug flow pattern were observed. Wavy flow pattern occured on transition of stratified to slug or plug. Annular flow pattern was not observed in this experiment. Generally speaking, an increase in steam flow rate resulted in a more significant pressure gradient signals.
Peran Sumber Energi Terbarukan dalam Penyediaan Energi Listrik dan Penurunan Emisi CO2 di Provinsi Daerah Istimewa Yogyakarta Rahmat Adiprasetya Al Hasibi
Semesta Teknika Vol 13, No 2 (2010): NOVEMBER 2010
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/jst.v13i2.716

Abstract

Electrical energy modelling involving renewable energy was produce using LEAP software. The model is based on electrical energy demand, renewable energy potential, and development planning in Yogyakarta Province. Renewable energy sources that have been simulated in this model are solar energy, wind energy, and micro hydro energy. The model describes the role of renewable energy in producing electrical energy to supply electrical energy demand in Yogyakarta Province. Furthermore, the role of renewable energy in CO2 emission reduction has also been simulated by the model. By optimal development, renewble energy gives 11,86 % share of electrictiy demand and reduce CO2 emission by 11,62%.
Kajian Penurunan Kadar BOD Limbah Cair Tahu Pada Berbagai Variasi Aliran Hendrasari, Ratna Septi
Semesta Teknika Vol 19, No 1 (2016): MEI 2016
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v19i1.1831

Abstract

Tofu is a food that derived from soybeans that have been fermented and taken juice. Tofu is a favored food of the community because of high nutritious and cheap. As a result, many emerging industries making tofu where this activity will produce liquid waste. Tofu liquid waste contains some substances including BOD. High BOD levels should not be directly disposed into the river. Therefore before the waste disposed, the levels of BOD should be reduced in accordance with the quality standards of waste. Decreased levels of BOD can be done in several ways such as by the waste stream in a stream. On the various streams will have different flow characteristics. The flow variation among others stepping on a sudden waterfall and stepping on the sudden expansion. Variations in flow was analyzed using the equations of continuity and momentum. The sample of liquid waste taken from the industrial society in Srandakan Bantul. From the results obtained in the laboratory testing, levels of BOD is 5571 mg/L. The study was conducted by assuming a square-shaped channel with a channel width of 0.2 m and a flow of 1 m3/s. The study was conducted by assuming a square-shaped channel with a channel width of 0.2 m and a flow of 1 m3/s. From the results of the study showed that the percentage reduction in BOD in liquid waste that declined most for the Froude number from 2 to 8 are on ΔZ/ h1 = 0.8 ie from 0.0134% to 0.0237%  and the b/B = 0.4 ie from 0.0589% to 0.0733%. BOD levels of liquid waste that has experienced a hydraulic stepping on a waterfall as well as the expansion of a sudden, for the Froude number from 2 to 18 in a row is 5569.916693 mg/L to 5569.779468 mg/L and 5566.916554 mg/L until 5570.999943 mg/L.
Klasifikasi Cacat Lintasan Dalam Bantalan Bola Berbasis Support Vector Machine (SVM) pada Fan Industri Berli Paripurna Kamiel; Arie Joko Wiranto; Bambang Riyanta; Sulis Yulianto
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.222246

Abstract

Fan adalah sebuah mesin industri yang berfungsi  mensirkulasikan udara di dalam sebuah ruangan. Salah satu komponen dari fan yang sering rusak adalah bantalan. Metode spektrum merupakan salah satu metode deteksi rusak/cacat bantalan berbasis getaran yang umum digunakan namun grafik spektrum sering sulit dipahami oleh operator di lapangan. Metode pengenalan pola (pattern recognition) adalah metode yang mudah digunakan karena tidak perlu menterjemahkan grafik spektrum. Metode pengenalan pola yang digunakan pada penelitian ini adalah Support Vector Machine (SVM). Tujuan penelitian ini adalah mendeteksi cacat lintasan dalam pada bantalan bola. Penelitian ini menggunakan dua kondisi bantalan yang berbeda yaitu bantalan normal, dan bantalan cacat. Cacat pada bantalan dibuat dengan metode Electrical Discharge Machine (EDM) pada lintasan dalam dengan kedalaman 1,4 mm dan lebar 0,4 mm. Sinyal getaran bantalan direkam dari rig uji fan industri menggunakan software MATLAB dengan merekam data sebanyak 700 file untuk setiap kondisi. Data tersebut diektraksi kedalam 17 parameter statistik yang kemudian diseleksi secara visual sebagai input SVM. Klasifikasi SVM dilakukan dengan variasi kernel Radial Basis Function (RBF), Polynomial dan Linear. Hasil penelitian menunjukkan parameter statistik entropy dengan standart error menggunakan variasi kernel Radial Basis Function (RBF), Polynomial dan Linear adalah rekomendasi untuk klasifikasi cacat pada bantalan lintasan dalam karena menghasilkan akurasi sebesar 100%. Industrial fan is one of -rotating machinery commonly used by industries to circulate air in a particular area. One of the most important component of a fan is the bearing which may fault during its operation Spectrum analysis  is one of vibration-based methods frequently used to detect faulty bearing  but this method has a disadvantage that is not easily understood by operators in the field. Pattern recognition method  is an easy method to be used because it does not need to interpret the spectrum. The pattern recognition method used in this study is Support Vector Machine (SVM). The purpose of this study is to detect inner race fault of a ball bearing using SVM. This study uses two different bearings, namely a normal bearing and a faulty bearing. Fault on the bearing were made by Electrical Discharge Machine (EDM) on the inner race with a width of 0.4 mm  and a depth of 1.4 mm. The test is carried out on an industrial fan test rig and recorded using MATLAB. The vibration signal is recorded to result of 700 files for each bearing condition. The vibration data is subsequently extracted into 17 statistical parameters which are then visually selected as input of SVM classifier. The SVM classifiear is trained using variations of the Radial Basis Function (RBF), Polynomial and Linear kernels. The results shows that the statistical parameters of entropy-standard error using variation of the RBF, Polynomial and Linear kernels gives the highest accuracy of 100%.
Pengaruh Perlakuan Sebelum Alkalisasi dan Waktu Alkalisasi terhadap Sifat Bending Komposit Serat Sisal/PMMA Rahman, Muhammad Budi Nur; Sosiati, Harini
Semesta Teknika Vol 23, No 1 (2020): MEI 2020
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v23i1.9349

Abstract

Penelitian komposit serat alam untuk meningkatkan kekuatan mekanis telah dilakukan, salah satunya memodifikasi permukaan serat. Tujuan penelitian ini adalah mengetahui pengaruh pencucian serat sebelum proses alkalisasi dan waktu alkalisasi terhadap sifat bending komposit serat sisal/PMMA. Serat sisal diberi perlakuan sebelum dicetak menjadi komposit dengan dicuci aquades, deterjen, dan direbus sampai mendidih dilanjutkan perlakuan alkali (6% NaOH) selama 12 jam. Variasi waktu alkalisasi adalah 4, 12, 24, dan 40 jam dengan pencucian aquades. Komposit dicetak menggunakan metode cold press dengan fraksi volume serat 20% dan tekanan 125 kg/cm2 ditahan selama 1 jam. Pengujian tarik dengan ASTM D3379-75, uji bending dengan ASTM D790-03 dan analisa morfologi serat menggunakan mikroskop optik dilakukan dalam penelitian ini. Pencucian serat sisal dengan aquades menghasilkan kekuatan tarik serat tunggal sebesar 4,87 MPa sedangkan pencucian serat menggunakan detergen sebesar 4,38 MPa dan serat yang direbus sebesar 4,00 MPa. Komposit dengan serat dicuci aquades memiliki kekuatan dan modulus bending tertinggi sebesar 136,602 MPa, dan 341,810 MPa sedangkan nilai regangannya terendah sebesar 0,117. Semakin lama perlakuan alkali akan menurunkan nilai kekuatan dan modulus elastisitas sedangkan reganganmya naik. Perlakuan 4 jam alkali, memiliki kekuatan sebesar 132,534 MPa, modulus bending 356,941 MPa, dan regangan 0,117. Struktur serat yang dicuci aquades tetap utuh sedangkan yang dicuci detergen dan direbus terjadi kerusakan. Semakin lama perlakuan alkali menyebabkan lignin terkikis sehingga ikatan serat menjadi lemah.Research on natural fiber composites to increase mechanical strength has been carried out, one of which is modifying the fiber surface. The purpose of this study was to determine the effect of washing the fibers before the alkalization process and the alkalization time on the bending properties of sisal fiber / PMMA composites. Sisal fibers were treated before being molded into a composite by washing with distilled water, detergent, and boiling until boiling followed by alkaline treatment (6% NaOH) for 12 hours. The variations in alkalization time were 4, 12, 24, and 40 hours with distilled water washing. The composites were molded using a cold press method with a fiber volume fraction of 20% and a pressure of 125 kg / cm2 held for 1 hour. Tensile testing with ASTM D3379-75, bending test with ASTM D790-03 and fiber morphological analysis using an optical microscope were carried out in this study. Washing sisal fibers with distilled water produces a single fiber tensile strength of 4.87 MPa, while washing the fibers using detergent is 4.38 MPa and boiled fiber is 4.00 MPa. Composites with distilled water washed fibers had the highest strength and bending modulus of 136.602 MPa and 341.810 MPa, while the lowest strain value was 0.117. The longer the alkaline treatment will decrease the strength and elastic modulus values while the strain increases. The 4 hours treatment is alkaline, has a strength of 132.534 MPa, bending modulus of 356.941 MPa, and strain of 0.117. The structure of the fibers washed with distilled water remains intact, while those washed with detergent and boiled are damaged. The longer the alkaline treatment causes the lignin to be eroded so that the fiber bonds become weak.
Pengaruh Perubahan Kecepatan Pemakanan Terhadap Kekasaran Permukaan Pada Proses Pembubutan Hadimi Hadimi
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.v11i1.773

Abstract

 This research done to know existence of transformation influence of feeding speed at turning process to surface roughness of work substance. Specimen material is ST 37 with Ø 30, 40, 50 and 70 mm, with transformation of feeding speed 0,05, 0,069, 0,088, 0,125 and 0,17(mm/rev), depth of feed 0,2 mm, and speed of revolution of engine 950 rpm. Then the several assaying of surface roughness level of the specimen and calculation statistic by using one way variant analytical method based on data result of assaying. Result of research indicates that existence of influence significant to surface roughness value caused by transformation of feeding speed at specimen turning process Ø 30, 40, 50 and 70 mm, ST 37 material with depth of feed 0,25 mm and revolution of engine 950 rpm. Average of smallest roughness value is at Ø 30 mm yielding best surface roughness. This thing indicates that feeding speed and substance diameter lathed influential to surface roughness value.
Analisis Pola Sebaran Kualitas Air Sumur di Kawasan TPST Piyungan Senoaji, Farhan; Lesmana, Surya Budi
Semesta Teknika Vol 24, No 1 (2021): MEI 2021
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v24i1.13001

Abstract

Pada daerah yang dekat dengan timbunan sampah, seringkali problematika yang muncul adalah bau akibat sampah dan juga kualitas air permukaan yang menjadi sumber air dari masyarakat yang ada di sekitarnya. Dampak akibat adanya timbunan sampah terhadap kualitas air dapat diukur dengan beberapa parameter yaitu: kadar keasaman (pH), kadar besi (Fe), biological oxygen demand (BOD), dan dissolved oxygen (DO). Penelitian ini bertujuan untuk mengetahui pola sebaran kualitas air sumur akibat dari pengaruh air lindi di sekitar kawasan TPST Piyungan. Penelitian ini dilakukan dengan mengambil sampel air sumur yang berada di sekitar TPST Piyungan, dan selanjutnya sampel diuji di laboratorium dan dianalisis terhadap baku mutu kemudian dilanjutkan dengan analisis spasial berbasis SIG menggunakan software Arc-GIS dengan metode Multiple Ring Buffer. Pada hasil analisis SIG dilakukan pemberian perbedaan warna, untuk zona kualitas air yang baik warnanya terang, dan zona kualitas tidak baik warnanya cenderung gelap. Standar baku mutu yang digunakan mengacu pada  Peraturan Menteri Kesehatan No. 32 Tahun 2017 Tentang Standar Baku Mutu Kesehatan Lingkungan dan Persyaratan Kesehatan Air Untuk Keperluan Higiene Sanitasi, Kolam Renang, Solus Per Aqua, dan Pemandian Umum serta Peraturan Daerah Daerah Istimewa Yogyakarta No. 7 Tahun 2016 Tentang Baku Mutu Air Limbah. Hasil dari analisis menunjukkan bahwa kadar pH pada semua sampel masih berada pada standar baku yang telah ditetapkan, parameter Fe masih berada pada standar baku mutu yang telah ditetapkan yaitu dengan maksimal kadar 1 mg/l, parameter BOD masih berada pada standar baku mutu yang telah ditetapkan yaitu dengan kadar maksimal 100 mg/l, parameter DO belum memenuhi standar baku mutu dengan kadar minimal 4 mg/l.

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