• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1108-1114
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• 2013

This paper presents a new winding topology for MW class offshore wind generator having modular and dual 3-phase. Based on proposed simplified relationship between magnetic flux and phase current in the air gap, several new windings for modular and dual 3-phase are made. In case of one inverter operation or faulty operation, the proposed model can have balanced 3-phase induced voltage whereas the conventional generator with modular winding has unbalanced induced voltage, which can be important issue in offshore generator. The model was applied into 6MW prototype machine with dual 3-phase. Using finite element analysis, induced voltage, inductance were investigated. The results show that the proposed modular winding can be applicable to dual inverter system with electrically balanced voltage.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.458-460
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• 2000

In this paper, we analyze the inductive coupling between overhead power transmission lines and neighbouring gas pipelines or other conductors, when they parallel to a line section in a phase-to-earth fault is assumed on the transmission line. A numerical procedure employing the finite-element method(FEM) is used in conjunction with Faraday's law, in order to predict the current in a faulted transmission line as well as the induced voltages across points on a pipeline running parallel to the faulted line and remote earth. The results lead to conclusion that may be useful to power system engineers.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.268-271
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• 2001

This paper presents observer-based on-line overload monitoring scheme for a PMSM(Permanent Magnet Synchronous Motor) drive system. Proposed scheme is to monitor overload status of motor drive system at remote place. The drive system is previously installed on main system and has no communication function. Proposed scheme consists of intelligent sensing head and monitoring part. Intelligent sensing head acquire motor 3-Phase currents and transmit data to monitoring part over serial communication interface. Monitoring part estimates motor speed using state observer. By comparing estimated speed with reference speed, we can detect motor fault. In this scheme observed information must coded and transmitted over a digital communication channel with finite capacity. We consider communication constraint as time delay and we design discrete-time observer. The proposed scheme is tested on the actual drive system.

• The Journal of Information Technology
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• v.10 no.2
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• pp.47-64
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• 2007

Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. Accurate predictions of software release times, and estimation of the reliability and availability of a software product require quantification of a critical element of the software testing process : test coverage. This model called enhanced non-homogeneous poission process(ENHPP). In this paper, exponential coverage and S-coverage model was reviewed, proposes the exponentiated exponential coverage reliability model, which maked out efficiency substituted for gamma and Weibull model(2 parameter shape illustrated by Gupta and Kundu(2001). In this analysis of software failure data, algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE statistics for the sake of efficient model, was employed.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.959-962
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• 2002

This paper presents a method of constructing the universal multiple processing element unit(UMPEU) based on De Bruijn Graph. The proposed method is as following. Firstly we propose transformation operators in order to construct the De Bruijn graph using properties of graph. Secondly we construct the transformation table of De Bruijn graph using above transformation operators. Finally we construct the De Bruijn graph using transformation table. The proposed UMPEU is capable of constructing the De Bruijn geraph for any prime number and integer value of finite fields. Also the UMPEU is applied to fault-tolerant computing system, pipeline class, parallel processing network, switching function and its circuits.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1553-1556
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• 2003

As the public use part of the railway and the road, the railway crossing is important to work properly by two transportation means. Also, It is important to provide the good face of friction on the railway crossing in aspect of protecting the railway crossing accident. Lately, the material of railway crossing panel is the wood. the asphalt, and the steel. As they have a various fault, it was studied to analyze the structural action of the new material. rubber panel. This paper analyzed eigenvalue, stress and displacement by truck passing weight and thermal stress using the FEM model.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.7
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• pp.815-823
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• 1999

This study considers an implementation of artificial neural networks to the receding horizon optimal control and is applications to power systems. The Generalized Backpropagation-Through-Time (GBTT) algorithm is presented to deal with a quadratic cost function defined in a finite-time horizon. A decentralized approach is used to control the complex global system with simpler local controllers that need only local information. A Neural network based Receding horizon Optimal Control (NROC) 1aw is derived for the local nonlinear systems. The proposed NROC scheme is implemented with two artificial neural networks, Identification Neural Network (IDNN) and Optimal Control Neural Network (OCNN). The proposed NROC is applied to a power system to improve the damping of the low-frequency oscillation. The simulation results show that the NROC based power system stabilizer performs well with good damping for different loading conditions and fault types.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.51-54
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• 2001

This Paper is described basic principles of arc quenching in Molded Case Circuit Breaker. We analyzed magnetic blowout forces acting on the arc in contact system when circuit breakers interrupt fault currents in different three models by 3-D FEM(Finite Element Method). The interrupting time simulated is compared with that of short circuit tests. The results of this study derive valid of the simulation method and present the techniques to improve arc quenching performance.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.779-780
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• 2006

This paper describes the effects of rotor-bar broken in induction machines. The analysis has been made on 7.5kW, 4P, 1,768[rpm], three-phase induction motors in a healthy and broken-rotor bars fault conditions at rated loading conditions. The effects of the rotor-bar broken, magnetic force are investigated by finite element method (FEM) and experiment. The results can be useful for real-time on-line monitoring of an induction motor.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.6
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• pp.259-263
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• 2001

The continuum model of transient point defect dynamics to predict the concentrations of interstitial and vacancy is established by estimating expressions for the thermophysical properties of intrinsic point defects. And the point defect distribution in a Czochralski-grown 200 mm silicon crystal and the location of oxidation-induced stacking fault ring(OiSF-ring) created during the cooling of crystals are calculated by using the numerical analysis. The purpose of this paper is to show that his approach lead to predictions that are consistent with experimental results. Predicted point defect distributions by transient point defect dynamic analysis are in good qualitative agreement with experimental data under widely and abruptly varying crystal pull rates when correlated with the position of the OiSF-ring .