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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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Kompresi Citra Medis Menggunakan Alihragam Kosinus Diskret Dan Sistem Logika Fuzzy Adaptif Indah Soesanti
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.v11i1.772

Abstract

The required of bandwidth for communication of digital image data is increased. Limited channel capacity favors image compression techniques. These techniques attempt to minimize the number of bits needed to represent an image and to reconstruct it with little visible distortion. The image data compression techniques reduce memory of storage data and time needed to transmit data. One of the image data compression methods is using Discrete Cosine Transform and Adaptive Fuzzy Logic. The objective of this research is compressing medical image using Discrete Cosine Transform and Adaptive Fuzzy Logic System. Discrete Cosine Transform is applied to find the data will which be encoded and Adaptive Fuzzy Logic System is applied to classify sub image into certain class. The class classification of a sub image is according to their AC energy levels. The systems assign more bits to a sub image if the sub image contains much detail (large AC energy) and less bits if contains less detail (small AC energy). The result of the research shows that the accurate calculation of AC energy determines class classification of sub image and bitmaps used for image data compression must be matching with characteristic of image. Bitmaps used for image data compression determine compression ratio and reconstructed image quality. The medical image compression with ratio of 1:4.8028 result in a reconstruction image with SNR of 63.8197 dB, and visually shows that the image is similar to the original image without significant error.
Evaluasi Variabilitas Kinerja Struktur Perkerasan Jalan Berbasis Pengujian Seismik Sri Atmaja P. Rosyidi
Semesta Teknika Vol 24, No 2 (2021): NOVEMBER 2021
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v24i2.12868

Abstract

Evaluasi perkerasan jalan diperlukan untuk memeriksa kerusakan awal yang terjadi pada perkerasan. Penilaian perkerasan dilakukan untuk memprediksi kualitas material perkerasan secara fungsional dan struktural. Penelitian ini bertujuan untuk menilai dan mengevaluasi perkerasan jalan secara struktural menggunakan pengukuran seismik Spectral Analysis of Surface Waves (SASW). Metode SASW menguji sifat material perkerasan sebagai teknik evaluasi struktural. Metode SASW merupakan metode seismik non-destruktif yang menghasilkan, mengukur, dan memproses gelombang Rayleigh yang terdispersi. Selanjutnya, proses inversi dengan teknik optimasi digunakan untuk menganalisis data dispersi gelombang Rayleigh guna menghasilkan profil kekakuan setempat, dalam parameter kecepatan gelombang geser dan modulus elastisitas. Parameter kekakuan dari metode ini yang dihasilkan pada tingkat regangan mikroskopis yaitu kurang dari 0,001%, di mana pada tingkat ini, bahan tanah berperilaku elastis linier. Hasil dari uji SASW selanjutnya dibandingkan dengan uji Marshall dan nilai uji Dynamic Cone Penetrometer (DCP). Pengamatan visual juga dilakukan untuk menentukan penilaian fungsional untuk mengukur seberapa besar kerusakan permukaan jalan. Hasil penelitian menunjukkan bahwa metode SASW dapat secara efektif mengukur kecepatan gelombang geser dan variabilitas modulus elastisitas pada setiap lapisan perkerasan. Studi ini merekomendasikan pengujian seismik untuk memeriksa variabilitas kinerja struktural perkerasan jalan terpasang.
Analisis Drainasi di Saluran Cakung Lama Akibat Hujan Maksimum Tahun 2013 dan 2014 Puji Harsanto; Surya Budi Lesmana; Sherly Devianty
Semesta Teknika Vol 17, No 2 (2014): NOVEMBER 2014
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v17i2.416

Abstract

Flooding is an annual disaster for Indonesia. Jakarta is a city that each year nearly always experienced by flooding. The rapid development made the impervious area dropped drastically. Micro drainage is not capable of passing the volume of direct runoff. It makes many regions in Jakarta experienced by floodwaters. The aim of this research is to analyze the micro drainage capacity in Cakung Lama River. Simulations are performed with HEC-RAS 1D. The flood data is maximum rainfall on 2013 and 2014. Two scenarios normalization is done for reducing the inundated area around the river. Based on the simulation results, the existing conditions are not able to accommodate the discharge due to maximum rainfall 2013 dan 2014. Normalization of the river will give good results if the width of the river 5 m and the depth of the river is 3 m.
Penterjemah Report Signalling Message CCS #7 Aprilia Kurniati; Bledug Kusuma Prasaja
Semesta Teknika Vol 10, No 2 (2007): NOVEMBER 2007
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v10i2.846

Abstract

Pensinyalan merupakan pertukaran informasi yang diperlukan bagi pembentukan, pemantauan dan pemutusan hubungan melalui jaringan dalam suatu aturan dan standar tertentu. Pada sentral telepon 5ESS produksi Lucent Technology (ATT), terdapat suatu program utility untuk menelusur (tracing) pensinyalan CCS#7 (Commond Channel Signalling # 7). Namun program tersebut tidak dapat langsung menterjemahkan data hasil telusuran tersebut khususnya data report signaling message, sehingga diperlukan sebuah program utility untuk melakukan proses penterjemahan tersebut dengan berpatokan pada standart penterjemahan yang ada. Pada sentral telepon yang tidak memiliki alat untuk menterjemahkan data report signalling CCS#7, program utility mutlak diperlukan.Pada perancangan menggunakan metode perancangan software untuk menterjemahkan report signalling message. Pesan yang diterima dalam bentuk format heksadesimal akan diterjemahkan ke dalam bit-bit dan mencupliknya menjadi informasi yang tepat dengan menggunakan software ini. Sebelum fungsi-fungsi software dibuat hal pertama yang dilakukan adalah melakukan membuat rancangan saoftware yang akan di buat. Data yang diperoleh berupa data print out dari report signalling message yang diperoleh dari PT. Indosat,tbk Jakarta. Data ini diperoleh dari pengamatan pada program procom yang digunakan di sentral Indosat. Adapun proses perancangan antar dibuat dua form yaitu form login yang digunakan sebagai form pengaman software penterjemah. Form kedua yang akan dibuat yaitu form penterjemah report signalling message yang akan digunakan untuk menterjemahkan report signalling message.Hasilnya adalah proses penterjemahan report signalling message dengan menggunakan software bisa lebih cepat dibandingkan dengan penterjemahan secara manual. Lamanya proses penterjemahan manual disebabkan karena petugas harus berulang kali membuka rekomendasi CCITT untuk menterjemahkan pesan tersebut dan mengartikan tiap oktet nya. Penterjemahan secara manual diperlukan w aktu + 15 menit untuk setiap 1 raw data saja, sedangkan penterjemahan dengan menggunakan software hanya dibutuhkan waktu + 1 menit untuk setiap raw data
Uji Beban dan Analisis Lendutan Model Pelat Fleksibel yang Didukung Tiang-Tiang pada Tanah Pasir Edi Hartono
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.v16i1.434

Abstract

Sand commonly has a good bearing capacity. Problems may occur when sand has low density and thick deposit. Flexible plate foundation may be used in this soil but plate deflection may be still high. To reduce deflection and improving soil density, piles were used to support the plate. Installing piles made foundation system stiffer. The objectives of this study are  to studies about behavior of plates and plate with a pile of sand on the ground, influence of plate thickness , pile length and spacing of the pole deflection, and the influence of the bond between the plate and the deflection of the pile .In this study is used test box of 1.2 m depth, 1.2 m width, 1.2 m length, and 1.0 m depth filled out with sand. Plate models were made from plexiglas of rectangular and square geometry. Piles were of steel pipesof 2.5cm diameter. Some parameters were as follows : plate thickness, plate geometry, pile length (L), pile spacing (s), bounding between plate and pile (fix or free), ’piled’ and freestanding foundation, and base pile enlargement. The behavior of the plateswere observed under loading (point load). The result shows that plate deflections were affected by the method of pile installation, plate thickness and pile length. For a ticker plate, contact surface between plate and soil was wider. For the 40cmx10cm plates with fix end pile, deflectionswere founf to reduced up to 70% compared with free end pile. The ’piled foundation’ on 40cmx10cm plates, L=20cm, s=4d, deflections were reduced 83,63% compared with free standing foundation.
Pengaruh Sudut Water Sprayer Dan Tekanan Air Dalam Sprayer Pump Terhadap Hasil Serbuk Alumunium Pada Proses Atomisasi Air Muhammad Budi Nur Rahman; Totok Suwanda
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.v9i2.869

Abstract

Metalurgi serbuk merupakan metode pembuatan benda-benda logam dengan menggunakan serbuk logam sebagai bahan dasar. Proses dalam teknologi metalurgi serbuk terdiri dari pembentukan serbuk, compacting, sintering dan finishing. Salah satu metode dalam pembuatan serbuk logam adalah dengan metode atomisasi air. Pembuatan serbuk dengan metode atomisasi air terdapat beberapa faktor yang mempengaruhi antara lain: sudut α (sudut tumbukan antara melting dengan butir air) dan tekanan air saat tumbukan. Penelitian ini bertujuan untuk mengetahui pengaruh sudut α, dan tekanan air terhadap optimalisasi hasil pembuatan serbuk dengan metode atomisasi air dan bentuk serbuk yang diamati dengan foto mikro. Proses pembuatan serbuk menggunakan metode atomisasi air dengan variabel bebasnya adalah sudut α yang ditentukan 30o, 40o, 50o dan 60o dan variasi tekanan air,  yaitu 25 kg/cm2, 30 kg/cm2, 35 kg/cm2 dan 40 kg/cm2. Bahan yang digunakan dalam proses atomisasi air adalah alumunium. Dalam penelitian ini diperoleh hasil bahwa sudut α dan tekanan tumbukan air pada melting mempengaruhi hasil produksi serbuk dengan metode atomisasi air. Hasil penelitian dengan variasi sudut α  diperoleh bahwa sudut  α = 30o menghasilkan produk 2,7%, sudut  α = 40o menghasilkan produk 4,05%, sudut α = 50o menghasilkan produk 3,23%, sudut α = 60o menghasilkan produk 1,8%. Penelitian dengan variasi tekanan air pada tekanan 20kg/cm2 tidak diperoleh serbuk, 25 kg/cm2diperoleh 2,9%, tekanan 30 kg/cm2 diperoleh 3,2%, tekanan 35kg/cm2 diperoleh 4,5% dan tekanan 40kg/cm2 diperoleh 2,9%. Hasil serbuk alumunium optimum secara teoritis dihasilkan pada sudut α 42,50 dan tekanan air 33,17 kg/cm2. Bentuk serbuk hasil proses atomisasi air sebagian besar adalah irregular, accicular dan flake.
Pemantauan Lapangan Sistem Penerangan Tenaga Surya 6 x 50 Wp di Sleman Muhammad Nadjib
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.v14i2.540

Abstract

Solar module and battery are important components in photovoltaic systems. These components have higher investment cost compared to controller device, lamp, cable, and the frame. Currently, there are six of 50 Wp of solar lighting systems (SLS) installed for cowshed lighting purpose in Sleman. The aim of this research is to investigate the pattern of electricity usage in SLS and to assess its performance, especially in the solar modules and their batteries after two months period of operation. The output voltage and current of solar module, the voltage of charging battery, the load consumption time, and the battery voltage at the end of charging and discharging were measured. The data were analyzed to determine the output power of solar module, average daily load, system performance ratio, and battery performance. It was revealed that the average daily load and performance ratio are 7.26 Ah/day and 49% respectively. Whilst at the end of charging of the battery is 100%, the maximum depth of discharge is 18.03% and its average efficiency is 59.85%. Overall, the SLSs have been well-operated; the solar module has produced electricity and all of the batteries were fully charged from the daily sunlight. However, it appears that the level of electric energy usage is still low. To increase the SLS’s efficiency it is recommended to optimize the usage of the produced electricity by intensifying livestock handling during night time. This solution also needs periodical monitoring of the SLSs which in turn will increase their lifetime.
Penghalusan Derau Pada Penerimaan Sinyal Video Televisi Berwarna Menggunakan Metode Wavelet Bledug Kusuma P; Fathul Qodir; Nurul Qhomariyah
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.v8i2.900

Abstract

Persoalan pemrosesan sinyal-sinyal yang dialihragamkan, dengan tujuan dapat dikonstruksikan kembali dengan kerugian minimal, adalah bagaimana mendapatkan kembali sinyal asli telah terkontaminasi derau (nois). Penelitian dilakukan untuk melihat sejauhmana transformasi wavelet dapat merekonstruksi sinyal asli yang telah terkontaminasi derau. Transformasi wavelet merupakan suatu metode analisis sinyal beresolusi ragam. Melakukan transformasi wavelet maju berarti mendekomposisikan sinyal kedalam suatu fungsi basis wavelet yang mempunyai karakteristik penskalaan dan translasi. Karena sifat-sifat tersebut maka transformasi wavelet dapat digunakan untuk mengamati perubahan frekuensi sinyal terhadap waktu dan masing-masing komponen frekuensi dapat diamati berdasar skala yang sesuai. Hasil penelitian menunjukkan bahwa analisis foto digital menggunakan metode wavelet, dalam hal ini transformasi wavelet diskrit (DWT), dapat memisahkan (separate) sejumlah noise pada gambar digital. Sehingga gambar digital yang dihasilkan akan mendekati gambar originalnya.
Analisis Korosi pada Sambungan Double Nipple Pompa Submersible di Universitas Muhammadiyah Yogyakarta Bambang Riyanta , M. Al Aththar
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.v14i1.586

Abstract

Corrosion is the deterioration of metal or alloy due to electrochemical reactions with its surroundings. The current study was conducted to determine the types and causes of corrosion on the double nipple connection of submersible pump which is used to pump water flooding the generator room at Universitas Muhammadiyah Yogyakarta. Chemical composition test was conducted to determine the material characteristics. The type of corrosion was determined by visual observation and confirmed with microstructure test. Chemical composition test was also conducted to investigate the nipple surface whether it has already been corroded or not. The water flooding into the generator room was analyzed to dete4rmine its chemical composition. The result shows that the material of the nipple is dead mild steel consisting of 0.133% carbon. Selective corrosion occurs on the outersurface of the nipple destroying 96.6% of its galvanized coating, and further shifted into a bimetal corrosion which attack 0.14 mm or 5.1% of the nipple wall thickness. Differential aeration corrosion attacked the inner surface of the nipple wall, due to the presence of Cl which is observed in the flooding water.
Evaluasi Beton Bertulang terhadap Perlakuan Panas (Tinjauan pada Tegangan Tarik dan Modulus Elastis Tulangan Baja Lateral) Riswanto, Riswanto; Pujianto, As'at; Zulfiar, Muhammad Heri
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.v16i2.4908

Abstract

Fires phenomena have made demands to a building planner to protect, evaluate, and predict the performance of a building after a fires process. The main attention was given to the type of material, in this case, the reinforced concrete that used as a structural element, which due to heating and cooling cycles are alternating, and then the elements of reinforced concrete structures undergo a phase change both in the physical and chemical. This research related to the evaluation of reinforced concrete quality with a focus on heat treatment and reviews tensile stress and elastic modulus of the steel reinforcement. Specimens used in this study was a model of the reinforced concrete beam with a concrete cover types K250 and K300, 7.5 mm of rebar diameter and 2 cm of concrete cover thickness. Heat testing performed after 28 days of treatment with closed combustion in the furnace (heat chamber) without loading at a temperature of 1000ºC for 10 hours, holding time for 1 hour, and slows cooling for 10 hours. In normal specimens, the tensile test results show an equivalent stress value of 324.12 MPa. In specimens heat treatment with a concrete cover of K250, the tensile stress value was 259.52 MPa, while in the K300 was 263.76 MPa. Optimum tensile stress value in normal specimens was 568.62 MPa, and in specimens with heat treatment and with the K250 concrete cover was 473.74 MPa and amounted to 494.41 MPa for K300. The value of tensile fracture stress in normal specimens amounted to 552.52 MPa, and in specimens with heat treatment and with the K250 concrete cover amounted to 461.52 MPa and amounted to 465.24 MPa for K300. Elastic modulus values for normal specimen was 1,612,963.61 kg/cm2, while in specimen heat treatment with the K250 concrete cover was 1,287,888.05 kg/cm2 and was 1,311,545.42 kg/cm2 for K300.

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