• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.2
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• pp.169-172
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• 2002

The voltage holding ratio(VHR) and the residual DC property in the in-plane switching (IPS) cells on a polyimide surface was studied. Several IPS cells which have different concentrations of cyano liquid crystals (LCs) were fabricated. We found that the VHR of the IPS cell was decreased with increasing concentration of cyano LCs. Also, the VHR of the IPS cell was increased with increasing specific resistivity of fluorine LCs. The residual DC voltage of the IPS cell by capacitance-voltage (C-V) hysteresis method was decreased with increasing concentration of cyano LCs. The residual DC property of the IPS cell on the rubbed PI surface can be improved by high polarity of cyano LC.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.4
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• pp.263-269
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• 2008

In this paper, an interleaved boost converter (IBC) with ZVT cell using a single resonant inductor in continuous conduction mode (CCM) is proposed. The IBC with the proposed ZVT cell has advantages such as a simple circuit, reduced size and low cost by using a single resonant inductor. It is more suitable for high power applications. The proposed ZVT cell circuit and principles for the IBC are explained in detail. The validity of the IBC with proposed ZVT cell is verified through experimental results.

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.255-262
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• 2011

This paper proposes a grid-tied power conditioning system for fuel cell, which consists of three-phase current-fed DC-DC converter and three-phase PWM inverter. The three-phase current-fed DC-DC converter boosts fuel cell voltage of 26-48 V up to 400 V with zero-voltage switching (ZVS) scheme, while the three-phase PWM(Pulse Width Modulation) inverter controls the active and reactive power supplied to the grid. The operation of the proposed power conditioning system with fuel cell model is verified through simulations with PSCAD/EMTDC software. The feasibility of hardware implementation is verified through experimental works with a laboratory prototype with 1.2 kW proton exchange membrane (PEM) fuel cell stack. The proposed power conditioning system can be commercialized to interconnect the fuel cell with the power grid.

• Journal of Information Display
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• v.6 no.2
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• pp.7-11
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• 2005

This paper investgates the transflective liquid crystal displays (LCDs) associated with fringe-field switching (FFS) mode to achieve high image quality. In the past, several cell structures were used to fabricate transflective FFS LCDs. Their structures and characteristics are carefully examined to find their merits and demerits. In addition, we attempt to optimize cell parameters to achieve a single driving circuit.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.132-134
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• 2006

This paper presents the design and implementation of 1 kW prototype DC-DC power converter with bridge voltage-doubler suitable for small scale PEM fuel cell system and its associated control scheme. The operation principle of this converter is described using some operating waveforms and the switching mode equivalent circuits based on simulation results and a detailed circuit operation analysis and soft-switching conditions.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.175-177
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• 2006

Here we report an enhanced flexoelectric switching in a self-assembled system of smectic liquid crystal and some specific dopant. The assembled unit block seemed to have electric dipole and as a result induces large flexoelectric polarization due to its asymmetric shape and shows fast switching to the electric field. The unit blocks are oriented in a helical fashion in the cell with large gap (${\sim}5{\mu}m$) and shows selective reflection property. In the thin cell (${\sim}2{\mu}m$), the unit blocks are aligned homeotropically on the bare ITO substrate with no surface treatment and shows fast decaying time.

• Journal of Information Display
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• v.10 no.1
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• pp.16-18
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• 2009

A three-terminal hybrid-aligned nematic liquid crystal (3T-HAN LC) cell capable of fast turn-off switching is proposed in this paper. By employing the relaxation process initiated by an electric-field pulse, a fast turn-off time of less than 1 ms can be obtained through optically hidden relaxation. A low operating voltage and high transmittance were confirmed through simulations and experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.171-171
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• 2010

Electro-optic characteristics of liquid crystal display using fringe field switching(FFS) device depend on many parameters such as cell retardation, electrode structure, rubbing angle, cell gap and dielectric anisotropy. In this paper, the light efficiency of FFS mode will be analyzed to confirm the electro-optic characteristics according to positive dielectric anisotropy such as transmittance, operating voltage and response time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.3
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• pp.260-266
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• 2006

In this paper, We coupled fluid balance and director balance equation from Ericksen-Leslie's continuum theory and observed the motion of Liquid Crystal molecular. We simulated flow velocity and director distribution in which flow effect is considered in switching on and switching off state. We interpreted the dynamic response characteristic caused by the flow. As the result of the simulation, We could see the flow effect. In the case of Twisted Nematic(TN) cell, this flow caused abnormal twist temporarily in switching off state. We could prove that this abnormal twist is a direct cause of optical bounce phenomenon known well until now with the result of simulation. In addition, We analyzed the mechanism of the fast response due to flow in the case of Optically Compensated Bend(OCB) cell.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.249-250
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• 2008

In this paper, we propose the single polycrystalline silicon flash EEPROM IC with a new structure which does not need the high voltage switching circuit. The design of high voltage switching circuits which are needed for the data program and erase, has been an obstacle to develop the single-poly EEPROM. Therefore, we has proposed the new cell structure which uses the low voltage switching circuits and has designed the full chip. A new single-poly EEPROM cell is designed and the full chip including the control block, the analog block, row decoder block, and the datapath block is designed. And the each block is verified by using the computer simulation. In addition, the full chip layout is performed.