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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Soetjipto H.,Satya Wacana Christian University | Martono Y.,Satya Wacana Christian University
IOP Conference Series: Materials Science and Engineering | Year: 2017

The main purposes of this study are to compile antibacterial activity data of essential oils from Indonesian's plants in order which can be used as a natural antibiotic in "jamu" to increase potential Indonesian medicinal herb. By using Agar Diffusing method, Bioautography and Gas Chromatography Mass Spectrum, respectively, antibacterial activity and chemical compounds of 12 plants essential oils were studied in the Natural Product Chemistry Laboratory, Department of Chemistry, Faculty of Science and Mathematics, Satya Wacana Christian University, Salatiga since 2007 until 2015. The results of this studies showed that all of the essential oils have a medium to a strong antibacterial activity which are in the range of 30 - 2,500 μg and 80-5,000 μg. Further on, the essential oils analyzed by GCMS showed that each essential oils have different dominant compounds. These data can be used as basic doses in the usage of essential oils as natural antibiotics. © Published under licence by IOP Publishing Ltd.

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.

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).

Papilaya V.N.,Satya Wacana Christian University | Vinck A.J.H.,University of Duisburg - Essen
IEEE Transactions on Power Delivery | Year: 2015

We call the Häring-iterative scheme with the clipping-nulling scheme as the preprocessing impulsive noise (IN) mitigation scheme: Mengi-Häring (MH)-iterative scheme. In this paper, we report two ideas that can significantly improve its performance. The first idea is to use the replacement-nulling scheme as the preprocessing IN mitigation scheme. The second idea is to use the output vector of the preprocessing IN mitigation scheme in all iterations. To show the performance comparison between the MH-iterative scheme and our proposed scheme, we conduct some simulations in the simplified model of the Middelton's additive white class A noise model and present performance in terms of the bit-error rate as a function of the signal-to-noise ratio. © 2014 IEEE.

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.

Hendry,Chaoyang University of Technology | Pramadharma H.,Satya Wacana Christian University | Chen R.-C.,Chaoyang University of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

Website is a media that can be used to find information. Every website visitors have different characteristics that makes them interested in the different parts of information. The information is often displayed in the form of a picture or a link, by allowing user to manipulate images or links based on their needs, it will make the website more personalized. This technology is then applied to a browser extension called W-Changer extension. W-Changer extension works by injecting its functions into a website page and allows the user to manipulate images and links in the website page according to their needs. Then, the results of the manipulation can be saved in web storage by applying HTML5 web storage technology. It can be implemented for website which is not use DOMContentLoaded event. © Springer International Publishing Switzerland 2015.

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.

Timotius I.K.,Satya Wacana Christian University | Setyawan I.,Satya Wacana Christian University
2014 International Conference on Information Technology Systems and Innovation, ICITSI 2014 - Proceedings | Year: 2014

In this paper we present our evaluation of the Edge Orientation Histograms (EOH) as feature descriptors in an automatic face-based gender classification application. The feature descriptors extracted from an input image are evaluated using estimated arithmetic means of accuracies to select the feature descriptors that play the most important role in classification success. Our experiments show that features corresponding to the jawline of the subject play the most important role, yielding an average classification accuracy of up to 86%. © 2014 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.

Andadari R.K.,Satya Wacana Christian University | Mulder P.,VU University Amsterdam | Rietveld P.,VU University Amsterdam
Energy Policy | Year: 2014

In low- and middle-income countries, Liquefied Petroleum Gas (LPG) can be an attractive alternative to the widespread use of traditional kerosene. Not only is LPG a relatively clean, safe and cost-effective fuel for households, its large-scale adoption also reduces the heavy burden of kerosene consumption subsidies on government budgets. Against this background, we evaluate the impact of a large government program to substitute LPG for kerosene in Indonesia. Using a household survey across urban, suburban and rural regions we find that this program was very effective in causing a large scale shift from kerosene to LPG. This shift was positively influenced by level of education, household size and household income. Contradicting the energy-ladder model, the LPG program, reinforced by an increase in the price of kerosene, led to increased stacking of fuels, including increasing consumption of both electricity and traditional biomass. In addition, our analysis shows that the LPG program failed to substantially reduce the overall number of energy-poor people, but it has been effective in alleviating extreme energy-poverty. Finally, we find that medium and higher income households in suburban areas benefitted most from the LPG program. © 2013 Elsevier Ltd.

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