• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 추계학술대회
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• pp.51-53
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• 2018

The Low Voltage DC-DC converters (LDCs) of the Electric Vehicles require high power density and high efficiency operation over the wide range of load and input voltage variations. This paper introduces a novel topology which combines three 1 MHz Half-Bridge (HB) LLC resonant converters and an Inverting Buck-Boost (IBB) converter to adjust the output voltage without frequency modulation. The switching frequency of the proposed converter is fixed at 1MHz to achieve a constant frequency operation for the resonant converter. In the proposed topology GaN FETs and planar transformers are employed to optimize the converter operation at high frequency. A 1 MHz/1.8 kW prototype converter is built to verify the feasibility and the validity of the proposed LDC topology.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권7호
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• pp.343-350
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• 2005

Conventionally, for transferring the primary power to the secondary one, the high frequency series resonant converter has been widely used for the contactless power supply system. However, the high frequency series resonant converter has the disadvantages such as the low efficiency, the high voltage gain characteristics and deviation of the phase angle in the overall load range. To improve this disadvantages, In this paper, the characteristics of the high efficiency and unit voltage gain as well as in-phase are revealed in the proposed three-level LCLC (Inductor-Capacitor- Inductor-Capacitor) resonant converter. The results are verified on the simulation based on the theoretical analysis and the 4kW experimental Prototype.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.102-105
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• 2005

For transferring the primary power to the secondary one, the high frequency series resonant converter has been widely used for the contactless power supply system. However, the high frequency series resonant converter has the disadvantages such as the low efficiency, the high voltage gain characteristics and deviation of the phase angle in the overall load range. To improve this disadvantage, In this paper, the characteristics of the high efficiency and unit voltage gain as well as in phase are revealed in the proposed three-level LCLC ( Inductor - Capacitor - Inductor -Capacitor)resonant converter. The results are verified on the simulation based on the theoretical analysis and the 4kW experimental prototype.

• 센서학회지
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• 제21권4호
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• pp.298-302
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• 2012

This paper describes the design and fabrication of a low frequency vibration driven high-efficiency electromagnetic energy harvester based on FR(Flame Resistance)-4 spring which converts mechanical energy into useful electrical power. The fabricated generator consists of a vertically polarized NdFeB permanent magnet attached to the center of spring and a planar type copper coil which has higher efficiency compare with cylindrical type coil. ANSYS finite analysis and Matlab were used to determine the resonance frequency and output power. The generator is capable of producing up to 1.36 $V_{pp}$ at 9 Hz, which has the maximum power of 639 ${\mu}W$ with a load resistance of $3.25k{\Omega}$.

• 대한의용생체공학회:의공학회지
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• 제29권1호
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• pp.82-87
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• 2008

In this paper, the study was carried out to design and implement the medical compound stimulator based on the preexisting individual medical stimulators with Low frequency, High frequency and cooling stimulation. The proposed equipment is designed to compound all the functions including a cooling stimulation with a range of $0{\sim}20^{\circ}C$ and the verified low and high frequencies of 250Hz, 500Hz, 1KHz and 1MHz respectively from the previous clinical experiment with a consideration of its credibility and efficiency. Also, it was constructed by using a new technique, thermoelectricity semiconductor with a consideration of miniaturization and stability. In accordance with patients' treatment purpose, the hand piece of low frequency/cooling stimulation and High frequency/cooling stimulation were separately designed for convenience. The frequency, accuracy and other factors of implemented medical compound stimulator was satisfied according to its measurement. It was also tested by Korean Testing Laboratory (KTL) for its stability and efficacy and it confirmed that the medical compound stimulator is suitable for use as it fits in with the medical equipment standards.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.491-492
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• 2008

According to high-speed large scale integration trend of Memory module product, many type of noises, such a reflection, cross-talk simultaneous switching noise, occur on the Package PCB and they make the deterioration of memory module's performance and reliability. As module products have more high efficiency, Hardware of test board and socket has to be considered In test of the high-speed Memory Module. we mainly focused on improvement of Signal integrity Using the High Frequency Test socket that we invented

• 조명전기설비학회논문지
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• 제22권3호
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• pp.40-51
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• 2008

This research presents a new active auxiliary resonant snubber with for induction heating PWM high frequency inverter solving the problem of induction heating PWM high frequency inverter circuit which is using widely in the practical application of an induction heating apparatus, the soft switching operation and power control are impossible when the lowest power supply in the active auxiliary resonant snubber with for induction heating PWM high frequency inverter. The inverter circuit which is attempted by the on-off operation of a switch has the effect of reducing the power loss due to soft switching and high frequency switching. This confirms that power regulation is possible on a continuous basis from 0.25[kW] to 2.84[kW] where the duty factor(D) changes from 0.08 to 0.3 under zero current switching which operates by an asymmetrical pulse width modulating control. The power conversion efficiency is 95[%]. Due to these results, the active auxiliary resonant snubber for an induction heating PWM high frequency inverter is considered effective as a source of induction heating.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권12호
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• pp.622-626
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• 2001

HID(high intensity discharge)lamps are high pressure mercury lamp, high pressure sodium lamp and metalhalide lamp. metalhalide lamp among these lamps has considered to be one of the most effective artificial light sources and this lamp has good efficiency, good color rendition and good focusing capability, But the shortcorning of metalhalide lamp is known as acoustic resonance phenomena in the discharge tube when lighted by electronic ballast and then acoustic resonance cause various problems such as the arc instability, light output fluctuations. In this paper, to reduce the acoustic resonence phenomena, the electronic ballast was designed by three methods for high frequency operation wish frequency-modulated sinusodial waves in acoustic resonance frequency band. These frequency-modulated methods are resonance frequency and resonance frequency, resonance frequency and non-resonance frequency non-resonance frequency and non-resonance frequency Experiment results could't show the Presence of acoustic resonance visually and it proved that the resonance-generating conditions can be avoided by continuously changing the two operating frequencies in acoustic resonance band (20.59kHz∼94.2kHz).

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.460-465
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• 1998

Due to high power ratings and low conduction loss, the IGBT has become more attractive in switching power supplies. However, its turn-on and turn-off characteristics cause severe switching loss and switching frequency limitation. This paper proposes 2.4kW, 48V, high efficiency half-bridge DC-DC converter using paralleled IGBT-MOSFET switch concept, where each of IGBT and MOSFET plays its part during on-periods and switching instants. The switching loss is analyzed by using the linearized model and the opteration of the converter are investigated by simulation results.

• 전기전자학회논문지
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• 제22권1호
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• pp.174-179
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• 2018

본 논문에서 저전력 PMIC를 위한 고효율 DC-DC 변환기를 설계하였다. IoT 및 웨어러블 기기의 발전에 따라 전력 공급을 위한 고효율 에너지 습득 기술이 중요해지고 있다. 에너지 습득을 통해서 얻을 수 있는 전압은 낮고 넓은 분포의 값을 가지므로 이를 사용하기 위해서 넓은 입력 전압 범위에서 고효율을 얻을 수 있는 설계 기법이 필수적이다. 넓은 입력 전압 범위에서 일정한 스위칭 주파수를 얻기 위해 전원 전압 변화 감지 회로를 이용한 주파수 보상 회로를 설계했으며, 낮은 전력에서 고효율을 얻기 위해 burst-mode 제어 회로를 구성하여 정밀한 스위칭 동작을 제어하였다. 설계한 DC-DC 벅 변환기는 0.95~3.3V의 입력 전압 조건에서 0.9V를 출력하며 부하 전류가 180uA일 때 최대 78%의 효율을 얻을 수 있다.