• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2220-2227
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• 2000

In this paper, dynamic photoelastic hybrid method is developed and its validity is certified. The dynamic photoelastic hybrid method can be used on the obtaining of dynamic stress intensity factors and dynamic stress components. The effect of crack length on the dynamic stress intensity factors is less than those on the static stress intensity factors. When structures are under the dynamic mixed mode load, dynamic stress intensity factor of mode I is almost produced. Dynamic loading device manufactured in this research can be used on the research of dynamic behavior when mechanical resonance is produced and when crack is propagated with the constant velocity.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1613-1616
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• 2008

A Transcutaneous Energy Transmission System (TET) has been developed for the wireless energy transmission with two magnetically coupled coils. A resonance circuit is used to raise the induced voltage and current of the secondary coil. Its resonance frequency depends on the internal resistance of circuit and the transferred energy. Because the transferred energy usually changes in wide range, the output voltage is unstable and the energy transferring efficiency decrease. A push-pull class E amplifier is usedto generate high frequency AC voltage. To maintain proper resonance frequency, the voltage output of the amplifier was continuously monitored and adjusted to the optimized resonance frequency. Because of its high frequency (370 kHz), a phase lockedloop circuit and a comparator are used to monitor the output waveform. The results of experimentaldata show that the PLL circuit can increase the transmission efficiency and stabilize the output voltage of TET.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.129-133
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• 1998

This paper deals with a characteristic of output for high frequency resonant inverter type x-ray generator in short exposure time. In the same tube-voltage, the waveform is stable in long exposure time (200msec) but more decreasing exposure time (50msec), the waveform is distorted. The ripple factor of tube-voltage waveform distorted more and more increase tube-voltage and in this case output is also unstable. High-frequency resonant inverter type X-ray generator using PSU source which introduced in resent is stable tube-voltage waveform and low ripple factor.

• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.252-257
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• 1992

In this study, InGaAsP/InP MQW-DH wafer was grown by a vertical type LPE system and 10$\mu$m stripe MQW-LD was fabricated with the wafer. The threshold current was about 200 mA and when the cavity length of the LD was 470$\mu$m the central wavelenth of gain spectra was 1.32$\mu$m the lasing wavelength was 1.302$\mu$m which corresponded to the gain center of the quantum well thickness of 300 $\AA$.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.566-572
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• 2015

This study introduces an LCC resonant converter operating on a continuous conduction mode. The LCC resonant converter has the advantage of improving system efficiency, especially under the rated load condition, because it can reduce conduction loss by improving the resonance current shape and switching loss by increasing the lossless snubber capacitance. The proposed LCC resonant converter is applied to various applications, including a 60 kW EV fast charger, a 24 kJ/s high-voltage capacitor charger, and a 20 kV, 20 kW high-precision DC power supply. Experimental results prove that the proposed LCC resonant converter topology can be effectively used as a converter topology for these applications.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.139-140
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• 2013

본 논문에서는 철도차량용 25kW급 배터리 충전기 개발에 대해 설명한다. 열차 판넬 및 제어용 전원으로 사용되는 배터리 전원을 사용한다. 이를 상시 충전하기 위한 충전기는 기존에 보조전원장치의 3상 380V를 받아 강압 변압기를 사용하여 다이오드 정류 혹은 싸이리스터를 사용하였다. 하지만, 기존방식은 강압 변압기가 60Hz의 낮은 주파수로 인하여 사이즈 및 중량 증대를 유발 한다. 이에 본 논문에서는 가선의 높은 전압을 받아 공진형 컨버터를 사용하여 주파수를 높여 변압기의 사이즈 및 중량을 감소 하였으며, 안정적인 전원을 공급 하는 배터리 충전기를 개발 하였다. 이를 25kW급 시제품에 대한 시뮬레이션을 통해 입증 하였다.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.52-54
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• 2019

본 논문에서는 Anyplace Induction Cooktop 시스템의 설계 방안을 제시한다. 다수의 워킹코일이 적용된 Anyplace 시스템은 전력밀도 향상을 위해 고주파 동작이 필요하다. 따라서 시뮬레이션 및 수학적 계산을 통한 동작 주파수, 전력 반도체 소자 조건 별 시스템의 손실 및 부피 간 Trade-off 분석이 필요하다 따라서 분석 결과를 토대로 각 전력반도체 소자 기반 시스템의 적합한 동작 주파수 영역 및 공진 네트워크 설계 방안을 제시한다.

• 전기의세계
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• v.42 no.3
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• pp.12-18
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• 1993

유전체 공진기는 1970년대에 실용적인 소재 및 부품개발이 시작되었으나 본격적인 개발은 이동 및 위성통신에 대한 관심이 높아진 1980년대에 들어서 이루어지고 있다. 현재 일본, 미국등 기술 선진국에서의 Microwave 유전체에 대한 연구는 고도 정보화 사회를 여는 무선 통신장치에 없어서는 안될 중요한 부품의 하나로 인식되며 연구개발에 박차를 가하고 있으며, 이에 대한 응용 분야가 과거 군사 및 특수분야에서 자동차 전화, 위성통신등 민생분야로 확대되어 고부가가치성이 인식되면서 세계 각국의 연구소 및 기업체 등에서 실용화를 위한 많은 연구가 추진되고 있다. 현재 국내의 연구소, 기업 및 대학에서도 Microwave 유전체 재료에 대한 관심이 높아가고 있으며, 이에 대한 연구도 활발히 진행되고 있다. 그러나 우리가 직면한 제반 문제는 Microwave 유전체의 기초 연구를 통한 소재 및 부품개발을 서둘러야 하며, 고신뢰성 확보, 생산성 향상 및 원가 절감 등의 문제점을 해결해야 할 것으로 사료된다. 또한 특성 측정의 체계화 및 자동화를 위한 측정 system의 개발에 관한 연구도 병행되어야 할 것으로 사료된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.758-759
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• 2010

In this study, it was experimentally confirmed that the phenomenon of resonance effect of wave drag in two wavy walls. The channel had saw-tooth type of relief surfaces when supersonic gas flows into this channel. Experiment was carried out on the differential apparatus by conducting the comparative test of two nozzles (round sonic nozzle and two-dimensional nozzle with wavy walls). The two-dimensional nozzle was joined alternately with flat walls which had saw-tooth type of symmetrical and asymmetric reliefs. Two-dimensional nozzle was designed for the M=3 and profiled parabolic contour.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.4
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• pp.265-271
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• 2000

A non-contact battery charger for cellular phone is designed using half-bridge series resonant converter. This converter utilizes series resonance to reduce the undesirable effect of large leakage inductance of the detachable transformer and ZVS operation can reduce switching loss and switching noise. In this paper, analysis and design procedure of half-bridge series resonant converter with detachable transformer is presented. The input voltage is 85VAC∼270VAC, and the output voltage and current is 4.1V and 800mA, respectively. Furthermore, a method of calculating the secondary current of the transformer to control the battery charging current in the constant current charging mode is proposed. The performance of the charger is verified through experiments.