• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.196-204
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• 1996

The simplified dynamic models of the timer assembly in the diesel engine fuel injection system were developed. The first order system with time delay was assumed and the various parameters in this model were obtained by experimental data. These simplified dynamic models were used for the development of control algorithm of the injection timing control system. The PI control algorithm was modified to include the anti-windup property and disturbance compensation. This modified PI control algorithm was used for the control of the injection timing. Improved control accuracy and reduced control efforts were observed.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.336-338
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• 1991

Effects of $Nb_2O_5$ addition ranged from 0.0 to 0.75(wt%) on the microstructure and electrical porperties of PZT ceramics have been investigated. The Pb vacancy concentration increases with increasing NbO content. However, the experimental results show the resistivity increases with increasing $Nb^{5+}$ content. This behavior can be explained as a compensation effect and $Nb^{5+}$ can serve as a donar and contribute electrons to the conduction process. According to the law of mass action, this result may reduce the total charge carrier:thus the resistivity increase with NbO content in PZT.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.215-217
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• 2008

This paper describes development of hardware simulator for the PMSG wind power system, which was designed considering wind characteristic, blade characteristic and blade inertia compensation. The simulator generates torque and speed signals for a specific wind turbine with respect to given wind speed. This torque and speed signals are scaled down to fit the input of 2kW PMSG. The PMSG-side converter operates to track the maximum power point, and the grid-side inverter controls the active and reactive power supplied to the grid. The operational feasibility was verified by computer simulations with PSCAD/EMTDC, and the implementation feasibility was confirmed through experimental works with a hardware set-up.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.1
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• pp.33-39
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• 2005

In this paper, we propose a slider servo-mechanism driven by electro-magnetic actuator to improve straightness of linear motor stages. Based on axial-position dependent deterministic characteristics of the straightness error, a feedforward compensation control is appled to reduce the straightness error. In the consideration of uncertain properties of friction and its effects on positioning accuracy, a sliding mode control is applied. The effectiveness of the suggested mechanism and the control performances are illustrated along with some experimental results.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.143-146
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• 1998

A new stereoscopic codec. structure using MPEG-2 multiview profile is presented in this paper. In the suggested codec., the left image is coded with motion estimation in the base layerand the right image is coded with disparity estimation in the enhancement layer. Since it is possible to calculate rough motion of the right image sequence with disparity and motion of the left image sequence, motion compensation of the enhancement layer is performed without motion estimation. Since the proposed codec. does not perform motion estimation in the enhancement layer encoding, it is simple and reduces the encoding time. We compared the PSNR of encoded image with three different structured codec., and the experimental results show that suggested codec. has comparable with other codecs.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.5
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• pp.279-286
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• 2003

A new UPQC(unified power quality conditioner), which consists of series inverter, shunt inverter, dc/dc converter, and energy storage, is proposed. The proposing UPQC can compensate reactive power, harmonics, voltage sag and swell, voltage unbalance, and voltage interruption. The control strategy for the proposing UPWQC was derived using the instantaneous power method. The performance of proposing system was analyzed by means of the EMTDC/PSCAD simulation and the experimental work with the hardware prototype. The proposing UPQC has the ultimate capability of improving power quality at the point of installation on power distribution systems or industrial power systems and can be utilized for the custom power device in the future distribution system.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2023-2027
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• 1997

This paper presents the dynamic analysis and control-loop design of a zero-voltage-switched full bridge (ZVS-FB) PWM dc/dc converter. Based on the small-signal analysis results, the control-loop is designed using a simple two-pole one-zero compensation circuit. Design results are verified by both computer simulations and experimental data obtained from a 2kW prototype converter.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2028-2032
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• 1997

When a high performance current control is desired, a computation time delay of a digital control system may deteriorate the control performance of a current controller. Such a non-negligible effect can be considerable in transient state. This paper deals with the modified predictive current control that compensates the time delay effects of a conventional predictive current control. The method is closely related to a local average current control and a symmetrical PWM pattern generation. Also some theoretical approaches are presented to describe the voltage saturation boundary of the power converter. For validation, the proposed method is applied to an active power filter system. The experimental results show considerable improvement in current tracking capability.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.125-130
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• 1998

This paper describes a novel flux calculator for the estimation of real rotor flux angle which is indispensable to the field oriented control of induction motors. A pure integrator is used to estimate the real rotor flux precisely from voltage and current information. The proposed flux calculator adopts the new drift compensation method to overcome the drift problem of pure integrator. The motor speed is calculated using estimated flux angle and estimated slip frequency. The performance of this approach is verified through the experiment. The experimental results shows stable operation of proposed system even below 1/100 of rated speed.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.475-479
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• 2001

Compensation characteristics or active filters based on voltage detection are investigated. These active filters act equivalently as a passive circuit so that they may not cause practical problems such as stimulation of resonance in the distribution lines. Thus, these active filters can be used as the general-purpose active filters. On the other hand, these active filters may have a possibility of the anti-resonance associated with the line inductance of the distribution lines. In this paper, the relationship between the anti-resonance and the control parameters of the proposed active filters is clarified. Some methods to avoid the problems due to the anti-resonance are investigated. Experimental results are included to confirm the validity of the investigation presented in this paper.