• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.78-80
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• 2006

A new low-cost asymmetric current-fed energy-recovery circuit (ERC) for a plasma display panel (PDP) is proposed. LC resonant circuit biased by $V_s/2$ and composed of single switch is used as ERC on both sides of the PDP, slow discharging and fast charging times can be employed, and inductor currents are built up before the PDP is charged and discharged. Therefore, it features a low cost, fully charged/discharged PDP, zero voltage switching (ZVS), low electromagnetic interference (EMI), low current stress, no severe voltage notch, and high energy-recovery capability.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.544-547
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• 2003

The purpose of this paper is to develop the straightforward design guidelines of PD/PID speed controller for Industry servo drives with plug and play concept. The controller gains are uniquely determined from the current control loop dynamics, speed loop delay, and mechanical parameters. In order to eliminate the mechanical friction uncertainties, an automatic PD/PI control mode switching algorithm Is introduced using online spectrum analysis of motor torque command. The dynamic performance of the proposed scheme assures a fast tracking response curve with minimal oscillation and settling time over the whole operating conditions. For comprehensive comparison of conventional PI control scheme, extensive test is carried out on actual servo system.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.635-638
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• 2003

In the paper, a three-phase-in three-phase-out Matrix Converter(MC) for the PMSM Is simulated by the PSIM simulator. A lighter L-C filters are installed at the input side of the Converter to remove the current harmonics around the switching frequency. In modelling the Matrix Converter, the PSIM is the powerful tool that the basic researches can be quickly performed within the given periods, because the simulation calculation by PSIM is very fast, compared to other simulators such as Matlab, Saber, and Pspice.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.447-454
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• 1998

This paper describes a modeling and current control techniques of Distribution static condenser (D-STATCON) for power factor compensation. The current control is based on the predictive and the space vector PWM scheme. The predictive current controlled PWM D-STATCON can maintain its performance with power factor compensation and fixed switching frequency. By using the space vector control low ripple and offset in the current and the voltage as well as fast dynamic responses are achieved with a small DC link capacitance employed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.820-825
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• 1996

This paper is concerned with effective operating method of pneumatic on-off valves for improving position control accuracy, valve life-time and position settling time using modified pulse width modulation with dead-zone. The pneumatic system using on-off valves studied in this paper has advantage of simple construction and low cost compared with a system with servo-valves. The performance of proposed control system is investigated experimentally for the position control of a pneumatic cylinder using on-off valves. Experimental results show that the proposed algorithm for valve operation can be used to obtain fast and accurate position control and to prevent on-off valves from unnecessary switching.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.199-204
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• 2007

This paper presents design of interleave configured dc-dc converter for high power distributed power system applications. The multi channel interleaving buck converter with small inductance has proved to be suitable for micro-grid, requiring medium output voltages, high output currents and fast transient response. Integrated magnetic components are used to reduce the size of the converter and improve efficiency. Unlike conventional methods, the distributed approach requires no centralized control, automatically accommodates varying numbers of converter cells, and is highly tolerant of subsystem failures. A general methodology for achieving distributed interleaving is proposed, along with a specific implementation approach. The design and simulation verification of switching frequency 10 kHz system is presented with interleaved clocking of the converter cells. The simulation (simulated by PSIM 6.1) results corroborate the analytical predictions and demonstrate the tremendous benefits of the distributed interleaving approach.

• Journal of Magnetics
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• v.13 no.4
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• pp.120-123
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• 2008

Magnetization ringing following domain wall collision on a ferromagnetic nanowire has been investigated by micromagnetic simulation. Suppressed magnetization ringing is observed with the introduction of a small ribbon to the nanowire. Magnetization ringing has been analyzed in a frequency space by a fast Fourier transform. With the introduction of a small ribbon and/or taping of the wire, the amplitude of ringing is reduced with a shifted frequency peak.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.393-395
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• 2005

Super In Plane Switching (S-IPS) technology is applied for large TFT-LCD panels used in TV applications. It has a lot of advantages in comparison to the alternative, VA technology. S-IPS shows excellent viewing angle properties and fast response time between intermediate gray levels. If the performance parameters which describe the actual visual performance are considered, S-IPS is much more $advantageous.^{1)}$ However, it shows relatively low contrast ratio in diagonal direction compared to viewing angle characteristic in upper/down direction in S-IPS. In order to compensate the relatively low diagonal contrast ratio, Super-IPS applying for optical film developed, but Super-IPS still has the problem of color shift in black $pattern.^{2)}$ So we improved this problem by developing Enhanced Super-IPS.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.567-570
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• 2005

Most researches on monostable LCD and bistable LCD have separately been carried out. We introduce a novel liquid crystal display mode which can be operated as both memory mode and dynamic mode. The novel LCD mode has not only a long term memory time of memory mode but also a fast response time of dynamic mode. We describe switching characteristics of dual mode. Electro-optical characteristics of memory mode and dynamic mode are unique and show the possibility of device application.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.537-540
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• 1988

This paper presents a new shadow testing acceleration scheme for ray tracing called hybrid shadow testing(HST), based on conditional switching between the conventional shadow testing method and Crow's shadow volume method, with the object polygons as well as the shadow polygons registered onto the corresponding cells under the 3-D space subdivision environment. Despite the preprocessing time for the generation and registration of the shadow polygons, the total shadow testing time of the new algorithm was approximately 50 % of that of the conventional shadow testing method for several examples while the total ray tracing time was typically reduced by 30% from the conventional approach.