• 조명전기설비학회논문지
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• 제26권4호
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• pp.1-5
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• 2012

By using LED optical devices and improving the efficiency of optical devices as well as lighting apparatus for humans, LED lighting industry puts the purpose of manufacturing the main products related with information, electric, large-sized LCD BLU, automobile, shipbuilding, agriculture, medical treatment, environment, and telecommunications, etc. Moreover, the main products and the industrial lighting products are manufactured with fusion, as the result, LED lighting industry provides various effects as well as sources of technology based on practical use of LED technology in order to develop the industry from the perspective of the lower price, the higher efficiency, the higher function, the deeper reliance. In the future, not only the development of new LED technology but also the fusion and combination of digital IT technologies using wire-wireless communication, sensor, controller, and artificial intelligence will be expected to create new industrial fields.

• Journal of Power Electronics
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• 제3권3호
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• pp.167-174
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• 2003

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with the rotor position, because the position of rotor is an essential information. Although high resolution optical encoders or resolvers are used to provide a precise position information, these sensors are expensive. Moreover, in the high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low cost analog encoder suitable for practical applications is proposed. And the control algorithm to generate switching signals using a Simple digital logic is presented. The validity of the proposed analog encoder with a proper logic controller is verified from the experiments.

• 전력전자학회논문지
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• 제21권1호
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• pp.49-57
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• 2016

A modular multilevel converter is widely adapted for a high-voltage direct current power transmission system. This study proposes a design methodology for a novel digital control that mitigates the negative effects caused by time delay, including communication transport delay for a modular multilevel converter. The modeling and negative effect of time delay are analyzed theoretically in a frequency domain, and its compensation methodology based on an inverse model is described fully with practical considerations. The proposed methodology is verified through several simulation results using a modular 21-level converter system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.461-464
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• 1999

To improve traction effort performance and stability for the Korean High-Speed Railway Train, practical re-adhesion controller including a novel anti-slip control scheme is proposed. The presented method is verified by train running simulation results based on induction motor vector control with PWM inverter.

• 한국생산제조학회지
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• 제5권4호
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• pp.47-52
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• 1996

The interpolator is very important in CNC machines. This study proposed a parametric curve interpolator(PCI) which can be used for machining any sculptured surface represented in a parametric form and generates commands for tool motion between CAD data points according to given accuracy demands. The proposed interpolator is superior to the existing linear interpolator in accuracy, feed rate and acceleration continuity. Moreover in comparison to the recently developed cubic spline interpolator, the PCI has the capability of handling higher order parametric curves and also ensures precise tracking in the velocity domain. Results from real time simulations and experiments on open architecture CNC machines equipped with the proposed interpolator are presented to show its practical capagility. It is believed that the combination of the proposed interpolator and the open architecture machine controller further advances the area of command generation which is an important aspect of CAD/CAM.

• 대한전기학회논문지
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• 제41권7호
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• pp.773-783
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• 1992

There have been several control schemes for the single input systems with unmeasurable state variables using variable structure control(VSC) theory. However, each of them is a study on the systems which can be represented in the phase canonical form or non-phase canonical form dynamic equation separately. As these control algorithms have difficulties in practical application by its theoretical limitations, in this paper we propose a new VSC theory which overcomes those limitations, in this paper we propose a new VSC theory which overcomes those limitations of proposed schemes. This new control scheme can be realized for the general linear systems which have unmeasurable state variables. And the switching function of this VSS algorithm consists of measurable state variable function(reduced-order switching function) and its derivatives. Also in the construction of control imput only measurable state variables are used.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.511-513
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• 2004

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with the rotor position, because the position of rotor is an essential information. In the high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low cost analog encoder suitable for practical applications is proposed. The validity of the proposed analog encoder with a proper logic controller is verified from the experiments.

• Journal of Power Electronics
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• 제4권2호
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• pp.65-76
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• 2004

In this paper, the steady-state analysis of the three-phase self-excited induction generator (SEIG) driven by a variable-speed prime mover (VSPM) such as a wind turbine is presented. The steady-state torque-speed characteristics of the VSPM are considered with the three-phase SEIG equivalent circuit for evaluating the operating performances due to the inductive load variations. Furthermore, a PI closed-loop feedback voltage regulation scheme based on the static VAR compensator (SVC) for the three-phase SEIG driven by the VSPM is designed and considered for the wind power generation conditioner. The simulation and experimental results prove the practical effectiveness of the additional SVC with the PI controller-based feedback loop in terms of fast response and high performances.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.945-947
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• 2003

Various kinds of practical machines using single phase induction motor(SPIM) are necessary to control speed and torque. In particular, capacitor-run type SPIM has constitutional characteristics, the motor torque is changed by auxiliary capacitance variation. In this study, we manifest equivalent model having more simplicity, and study the relation between torque and capacitance value of SPIM. And analyze Magnetic vibration for FEM(Finite Element Method) simulation. Also, We design the experimental controller which is able to speed control accurately by phase angle control of AC input voltage. Through the simulation and experimental results, we confirmed validity of this study.

• 대한전기학회논문지:전력기술부문A
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• 제48권8호
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• pp.972-979
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• 1999

QFT(Quantitative Feedback Theory) is a very practical design technique that emphasizes the use of feedback for achieving the desired system performance tolerances in despite of plant uncertainty and disturbance. The fundamental concept of QFT is a loop shaping procedure that a suitable controller can be found by shaping a nominal loop transfer function. The loop shaping synthesis involves the identification of a structure and the specialization of parameter optimization of a desired system. This paper presents an improved loop shaping approach of QFT with model validation using GA(Genetic Algorithm). The method presented in this paper removes the problems of iterative operation, transformation error, and model validation in the conventional methods without consideration of frequency domain.