Salatiga, Indonesia

Satya Wacana Christian University
Salatiga, Indonesia

Satya Wacana Christian University, or Universitas Kristen Satya Wacana , is a private university located in Salatiga, Central Java, Indonesia. Wikipedia.

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Dewantoro G.,Satya Wacana Christian University
International Journal of Power Electronics and Drive Systems | Year: 2016

DC Motor is the most basic electro-mechanical equipment and well-known for its merit and simplicity. The performance of DC motor is assessed based on several qualities that are most-likely contradictory each other, i.e. settling time and overshoot percentage. Most of controller’s optimization problems are multi-objective in nature since they normally have several conflicting objectives that must be met simultaneously. In this study, the grey relational analysis (GRA) was combined with Taguchi method to search the optimum PID parameter for multi-objective problem. First, a L9 (33) orthogonal array was used to plan out the processing parameters that would affect the DC motor’s speed. Then GRA was applied to overcome the drawback of single quality characteristics in the Taguchi method, and then the optimized PID parameter combination was obtained for multiple quality characteristics from the response table and the response graph from GRA. Signal-to-noise ratio (S/N ratio) calculation and analysis of variance (ANOVA) would be performed to find out the significant factors. Lastly, the reliability and reproducibility of the experiment was verified by confirming a confidence interval (CI) of 95%. © 2016 Institute of Advanced Engineering and Science. All rights reserved.

Sembiring I.,Satya Wacana Christian University
Proceedings - 2016 3rd International Conference on Information Technology, Computer, and Electrical Engineering, ICITACEE 2016 | Year: 2017

Securing communication is a comprehensive challenge due to the increasing of threats and attacks to network security. By knowing the various of threats and attacks, we can collect broad data from the network, by using honeypot. Implemented honeypot uses low-interaction type that is honeyd and other supporting software such as apache2 and bind9. Based on the research, honeypot is successfully giving responds to Distributed Denial of Service (DDoS) attacks and giving false information such as operation system and open ports which are usually sought by attackers. Log outcome given by honeypot is processed into chart and diagrams which are shown through the network interface by using honeyd-viz software so that the administrator will find it easy to analyze the form of the attacks from the attackers and it also can be used to increase the security of the server. © 2016 IEEE.

Nugroho D.B.,Satya Wacana Christian University | Susanto B.,Satya Wacana Christian University
AIP Conference Proceedings | Year: 2017

The aim of this study is to empirically investigate the performance of APARCH(1,1) volatility model with the Student-t error distribution on five foreign currency selling rates to Indonesian rupiah (IDR), including the Swiss franc (CHF), the Euro (EUR), the British pound (GBP), Japanese yen (JPY), and the US dollar (USD). Six years daily closing rates over the period of January 2010 to December 2016 for a total number of 1722 observations have analysed. The Bayesian inference using the efficient independence chain Metropolis-Hastings and adaptive random walk Metropolis methods in the Markov chain Monte Carlo (MCMC) scheme has been applied to estimate the parameters of model. According to the DIC criterion, this study has found that the APARCH(1,1) model under Student-t distribution is a better fit than the model under normal distribution for any observed rate return series. The 95% highest posterior density interval suggested the APARCH models to model the IDR/JPY and IDR/USD volatilities. In particular, the IDR/JPY and IDR/USD data, respectively, have significant negative and positive leverage effect in the rate returns. Meanwhile, the optimal power coefficient of volatility has been found to be statistically different from 2 in adopting all rate return series, save the IDR/EUR rate return series. © 2017 Author(s).

Handoko,Satya Wacana Christian University | Getta J.R.,University of Wollongong
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2017

Online data integration of large XML documents provides the most up-to-date results from the processing of user requests issued at a central site of heterogeneous multi-database system. The fragments of large XML documents received from the remote sites are continuously combined with the most current state of integrated documents. Online integration of fragmented XML documents has a positive impact on performance of entire online data integration system. This paper presents the online integration procedures for the fragments of large XML documents. We propose a new model of data for fragmented XML documents and we define a set of operations to manipulate the fragments. A new optimisation procedure presented in the paper finds the smallest core of each new fragment that can be integrated with the documents available at a central site. We show that processing of the smallest cores of XML fragments significantly reduces overall processing time. © Springer International Publishing AG 2017.

Setiawan A.,Satya Wacana Christian University
AIP Conference Proceedings | Year: 2016

In this paper it is described how to analyze SNPs data by using bootstrap method. The bootstrap method is used in case of the chi-square Q2 statistics and the likelihood ratio statistics G2. It is described how to use the method in case-control association studies. Simulation study is used to explore the properties of the method. Based on the original table, it can be construct a new table and related statistical value of statistics. Figure 1(a) and Figure 1(b) presents the number B = 1.000.000 statistical value of chi-square test and likelihood ratio test, respectively. The bootstrap p-values for two (original) statistical tests are 1.2 × 10-5 and 1.9 × 10-5, respectively. The described method can also be applied to the whole genome case-control association studies which uses thousands SNPs. © 2016 Author(s).

Yang M.-S.,Chung Yuan Christian University | Nataliani Y.,Chung Yuan Christian University | Nataliani Y.,Satya Wacana Christian University
Pattern Recognition | Year: 2017

In fuzzy clustering, the fuzzy c-means (FCM) algorithm is the most commonly used clustering method. Various extensions of FCM had been proposed in the literature. However, the FCM algorithm and its extensions are usually affected by initializations and parameter selection with a number of clusters to be given a priori. Although there were some works to solve these problems in FCM, there is no work for FCM to be simultaneously robust to initializations and parameter selection under free of the fuzziness index without a given number of clusters. In this paper, we construct a robust learning-based FCM framework, called a robust-learning FCM (RL-FCM) algorithm, so that it becomes free of the fuzziness index m and initializations without parameter selection, and can also automatically find the best number of clusters. We first use entropy-type penalty terms for adjusting bias with free of the fuzziness index, and then create a robust learning-based schema for finding the best number of clusters. The computational complexity of the proposed RL-FCM algorithm is also analyzed. Comparisons between RL-FCM and other existing methods are made. Experimental results and comparisons actually demonstrate these good aspects of the proposed RL-FCM where it exhibits three robust characteristics: 1) robust to initializations with free of the fuzziness index, 2) robust to (without) parameter selection, and 3) robust to number of clusters (with unknown number of clusters). © 2017 Elsevier Ltd

Feriyonika,Bandung State Polytechnic | Dewantoro G.,Satya Wacana Christian University
International Journal of Artificial Intelligence | Year: 2013

In this study, injection velocity in injection molding process was analyzed. Since physical behavior of thermoplastic and environmental condition in injection machine such as high temperature and pressure make a complex dynamics in injection molding system, the injection velocity is consequently difficult to control by some classical control methods. Hence, robust and adaptive control (Fuzzy Sliding Mode Control) was proposed to control the injection velocity in finite time. In this control strategy, sliding mode control intended to overcome system dynamics, while Fuzzy controller would decrease both output error and chattering phenomena due to sliding mode process. The simulation results showed that proposed control could decrease chattering phenomena and followed velocity set point with small error. The two cycles of set point were also presented to examine controller's robustness. In future, this proposed control can be potentially applied in real system. © 2013 by IJAI (CESER Publications).

Purnomo H.D.,Chung Yuan Christian University | Purnomo H.D.,Satya Wacana Christian University | Wee H.-M.,Chung Yuan Christian University | Rau H.,Chung Yuan Christian University
Mathematical and Computer Modelling | Year: 2013

Two-sided assembly line is a set of sequential workstations where task operations can be performed in two sides of the line. The line is important for large-sized products, such as trucks, buses and cars. In this paper, we proposed a mathematical model for two-sided assembly line type II (TALBP-II) with assignment restrictions. The aim of the model is minimizing the cycle time for a given number of mated-workstations and balancing the workstation simultaneously. The model provides a more realistic situation of the two-sided assembly line problems. Genetic algorithm and iterative first-fit rule are used to solve the problem. The performances of both methods are compared using six numerical examples. Based on the experiments, the iterative first-fit rule can take the advantage of finding the best position over many workstations and the genetic algorithm provides more flexible task assignment and is significantly faster than the iterative first-fit rule. © 2011 Elsevier Ltd.

Dewantoro G.,Satya Wacana Christian University
Proceedings - 2015 7th International Conference on Information Technology and Electrical Engineering: Envisioning the Trend of Computer, Information and Engineering, ICITEE 2015 | Year: 2015

The finest design of the proportional-integral derivative (PID) controller plays an important role in achieving a satisfactory response of any rotational electro-mechanical system. This paper presents an optimal design of the PID controller in the DC motor by using the Taguchi method. The proportional gain, the integral gain, the derivative gain constitute the search space for the optimization problem. The objective of PID optimization is to minimize the integral squared error of the step response. The predicted optimum values of the control variables are determined by the Taguchi method using analysis of means. Analysis of variance (ANOVA) is used to select the most significant control parameters. Computer simulation shows that the performance of fine-tuned PID controller using Taguchi method is better than that of traditional open loop Ziegler-Nichols technique. © 2015 IEEE.

Mangimbulude J.C.,Satya Wacana Christian University | van Straalen N.M.,VU University Amsterdam | Roling W.F.M.,VU University Amsterdam
Waste Management | Year: 2012

Ammonium is one of the major toxic compounds and a critical long-term pollutant in landfill leachate. Leachate from the Jatibarang landfill in Semarang, Indonesia, contains ammonium in concentrations ranging from 376 to 929mgNL -1. The objective of this study was to determine seasonal variation in the potential for organic nitrogen ammonification, aerobic nitrification, anaerobic nitrate reduction and anaerobic ammonium oxidation (anammox) at this landfilling site. Seasonal samples from leachate collection treatment ponds were used as an inoculum to feed synthetic media to determine potential rates of nitrogen transformations. Aerobic ammonium oxidation potential (<0.06mgNL -1h -1) was more than a hundred times lower than the anaerobic nitrogen transformation processes and organic nitrogen ammonification, which were of the same order of magnitude. Anaerobic nitrate oxidation did not proceed beyond nitrite; isolates grown with nitrate as electron acceptor did not degrade nitrite further. Effects of season were only observed for aerobic nitrification and anammox, and were relatively minor: rates were up to three times higher in the dry season. To completely remove the excess ammonium from the leachate, we propose a two-stage treatment system to be implemented. Aeration in the first leachate pond would strongly contribute to aerobic ammonium oxidation to nitrate by providing the currently missing oxygen in the anaerobic leachate and allowing for the growth of ammonium oxidisers. In the second pond the remaining ammonium and produced nitrate can be converted by a combination of nitrate reduction to nitrite and anammox. Such optimization of microbial nitrogen transformations can contribute to alleviating the ammonium discharge to surface water draining the landfill. © 2011 Elsevier Ltd.

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