• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1960-1962
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• 1998

Reference/modulating waveform continuity is not a necessary condition for the implementation of switching patterns for three-phase pulse-width modulated(PWM) converters. This is based on the fact that the converter phase-voltages do not need to be sinusoidal and switching pattern discontinuities do not degrade the quality of output/input voltage/current waveforms by introducing low-order harmonics if certain parameters are optimized. This paper introduces the selected harmonic elimination to reduce the switching frequency and low-order harmonics compared with continuous PWM techniques and some discontinues switching patterns for PWM converter.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2118-2120
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• 1998

Recently the automatization and the robotization of the arc welding industry is promoted and also the improvement of the welding quality and the work efficiency is required strongly. In this paper, special welding current waveform control algorithm is developed for less spatter and improvement of welding performance in the high speed and low arc voltage range. And the output control and the short circuit waveform control to the varition of the welding is studied by appling the algorithm to the power source for pulse arc welding.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1153-1154
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• 2006

This paper proposes the optimal design method based on NDZ analysis to secure the islanding defection ability and to maintain the stability and power quality when the grid is connected. A PSiM-based model and analysis of the system is presented, specialty aimed at improving the effectiveness of phase shift anti-islanding method with frequency feedback, which causes the inverter current to be generated slightly lower or higher in frequency than the frequency of the terminal voltage. The proposed method can cause frequency jump with leading and lagging phase of output current in two line cycles. As a result, the proposed algorithm is more sensitive and reliable than the conventional phase shift method. Experimental results, on a 3 kW inverter connected to 220 V, 60 Hz utility, are discussed.

• Proceedings of the Safety Management and Science Conference
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• 2003.11a
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• pp.185-198
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• 2003

This study is to develop and operate the R-FCE(Real-time Fuzzy Control Expert System) model on the SBR(Sequency Batch Reactors) type sewage disposal facility which is for the environmental problem of future and the effective treatment. It is the system that regularly handles the input, output information in real time by the Fuzzy control IF-THEN rule. Nowadays the water pollution caused by the increase of population and the industrialization already exceeds the purifying ability of nature and is getting worse. The sewage disposal facility needs an expert having wide experience and know-how because the quality or quantity of inflow water is so irregular that the process of sewage disposal is difficult. In the nation, however, the accumulation of technology is so weak because field-operators avoid the long-term duty. So the accurate and speedy decision or control of field are difficult in the case of emergency situation.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1347-1350
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• 2009

Rail human factors research has grown rapidly in both quantity and quality of output over the past few years. The continual influences of safety concerns, new technical system opportunities, reorganisation of the business, needs to increase effective, reliable and safe use of capacity, and increased society, media and government interest have now accelerated rail human factors research programmes in several countries. In this paper we review international standards and guidelines on rail human factors, covering driving, signalling and control, maintenance, reporting systems, passenger interests, management, planning and technical systems change. The purpose of this study is to define the criteria regarding human factors for managing railway system safety. Therefore, some rail human factors suggested in this study may be used as basic data for supporting the Korean railway system safety.

• Journal of Computational Design and Engineering
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• v.2 no.3
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• pp.137-147
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• 2015

In this study, a new methodology in predicting a system output has been investigated by applying a data mining technique and a hybrid type II fuzzy system in CNC turning operations. The purpose was to generate a supplemental control function under the dynamic machining environment, where unforeseeable changes may occur frequently. Two different types of membership functions were developed for the fuzzy logic systems and also by combining the two types, a hybrid system was generated. Genetic algorithm was used for fuzzy adaptation in the control system. Fuzzy rules are automatically modified in the process of genetic algorithm training. The computational results showed that the hybrid system with a genetic adaptation generated a far better accuracy. The hybrid fuzzy system with genetic algorithm training demonstrated more effective prediction capability and a strong potential for the implementation into existing control functions.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.3
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• pp.11-23
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• 2011

Recently, Open APIs are getting attention with the advent of Web 2.0. Open APIs are used to combine services and generate new services by Mashup. However, the growing number of available Open APIs raises a challenging issue how to locate the desired APIs. We automatically build ontologies from WSDL, WADL, HTML, and their underlying semantics. The key ingredient of our method is a technique that clusters input/output parameters in the collection of API methods into semantically meaningful concepts, and captures the hierarchical relationships between the terms contained in a parameter. These semantic ontologies allow search engines to support a similarity search for Open APIs based on various protocols such as SOAP, REST, JavaScript, and XML-RPC, and significantly improve the quality of APIs matching by the clustering and hierarchical relationships mechanism.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2284-2293
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• 2016

With the rapid development of clean energy, photovoltaic (PV) generation has been utilized in the harmonic compensation of power systems. This paper presents a novel multi-function PV micro-inverter with three stages (pseudo-two-stage). It can inject active power and compensate harmonic currents in the power grid at the same time. In order to keep the micro-inverter working under the maximum allowable output power, an optimized capacity limitation strategy is presented. Moreover, the harmonic compensation can be adjusted according to the customized requirements of power quality. Additionally, a phase shedding strategy in the DC/DC stage is introduced to improve the efficiency of parallel Boost converters in a wide range. Compared with existing capacity limitation methods, the proposed strategy shows better performance and energy efficiency. Simulations and experiments verify the feasibility of the micro-inverter and the effectiveness of the strategy.

• Journal of the Korean Graphic Arts Communication Society
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• v.24 no.2
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• pp.69-78
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• 2006

Proofing is one of the inspection operations of printing and can be considered a process control step. The three main kinds of proofs are press proofs, photomechanical proofs, and digital proofs. Photomechanical and digital proofs are also generally refered to as "off-press" proofs. Off-press color proofs are more economical than press proofs. Digital proofs offer fast production time along with a much lower cost per page. Hard-copy digital proofs can be output using thermal transfer printers, ink jet printers, and color laser copiers, as well as dye sublimation and electrophotographic technology. Ink jet method is commonly using because of the reasonal price. But ink jet system is difficult to reproduce an exact color proof. This research was carried out for the purpose of optimization of ink jet color proofing, using two kinds of ink jet printers with 6 colors (C, M, Y, K, mC, mM) and 4 colors (C, M, Y, K) system.

• Journal of the Korea Society for Simulation
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• v.13 no.2
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• pp.23-34
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• 2004

Regenerative simulation (RS) is a method of stochastic steady-state simulation in which output data are collected and analysed within regenerative cycles (RCs). Since data collected during consecutive RCs are independent and identically distributed, there is no problem with the initial transient period in simulated processes, which is a perennial issue of concern in all other types of steady-state simulation. In this paper, we address the issue of experimental analysis of the quality of sequential regenerative simulation in the sense of the coverage of the final confidence intervals of mean values. The ultimate purpose of this study is to determine the best version of RS to be implemented in Akaroa2 [1], a fully automated controller of distributed stochastic simulation in LAN environments.