• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.16-23
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• 2006

This paper presents a novel single-stage high frequency resonant inverter link type DC-DC converter using zero voltage switching with high power-factor. The proposed topology is integrated half-bridge boost rectifier as power factor corrector(PFC) and half-bridge high frequency resonant converter into a single-stage. The input stage of the half-bridge boost rectifier works in discontinuous conduction mode(DCM) with constant duty cycle and variable switching frequency. So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. Simulation results have demonstrated the feasibility of the proposed high frequency resonant converter. Characteristics values based on characteristics analysis through circuit analysis is given as basis data in design procedure. Also, experimental results are presented to verify theoretical discussion. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, fluorescent lamp and DC-DC converter etc.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.1
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• pp.32-34
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• 2015

AlN Single Crystal were grown by PVT (Physical vapor transport) method on bulk seed. It was performed by high-frequency induction-heating coil. AlN source powder was loaded at bottom side of the carbon crucible and the crystal seed was loaded at the upper side of the crucible. The temperature conditions of the growth was varied $2000{\sim}2100^{\circ}C$ and the surrounding pressure was $1{\times}10^{-1}{\sim}200$ Torr. And the hot-zone of the heating position was controlled elaborately according to growth. The 17 mm-diameter, 7 mm-thickness AlN single crystal is obtained for about 600 hours growing. It was recognized that the growth direction of as grown crystal was R[011] by the Laue X-Ray camera measurement.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.141-149
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• 2009

In this paper, quasi-static FDTD method is implemented by FORTRAN programming, and it is used for analysis of body induced current in middle frequencies. The quasi-static FDTD program is validated by comparing the calculation result with analytic solution of the test model, to which it is difficult to apply conventional FDTD. It is confirmed that the time-step is reduced by $5.68{\times}10^6$ times. Using validated numerical technique, body induced current distribution in high resolution 3-D human model is calculated for 20[kHz] magnetic field exposure and 1[MHz] electric field exposure. Also, the effect of grounding condition of both feet on the distribution and amplitude of the induced current is analyzed. It is expected that this research can be applied to various fields including safety assessment of body induced current and development of diagnosis devices using bio-electricity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.18-19
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• 2005

EDDC(Evaporation using Drum in Dual Chamber) deposition system was manufactured for 100m long superconducting coated conductor. It is composed of reaction chamber, evaporation chamber and differential chamber. The drum is located across the differential and exposed to both of the evaporation chamber and the reaction chamber, and the tape is wound on the drum. The elements of superconducting material are co-evaporated from respective element boats in the evaporation chamber and deposited on the drum and reacted with oxygen in the reaction chamber. This process repeats by rotating the drum. When the total pressure of the reaction chamber was 5 mTorr, that of the evaporation chamber was $5{\sim}10^{-5}$Torr. This atmosphere can be achieved by means of differential pumping. There are four evaporator in the evaporation chamber. One is the radiation heating evaporator and the others are the high frequency induction evaporator. EDDC is one of promising methods for commercialization of superconducting coated conductor.