• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2004.11a
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• pp.50-58
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• 2004

Valy-Tyrosine (VY) derived from alkaline pretense hydrolyzate of sardine muscles showed the in vitro Angiotensin I converting enzyme (ACE) inhibitory activity and the in vivo antihypertensive effect in SHR. We investigated the antihypertensive effect of the VY on mild hypertensive subjects including subjects with high-normal blood pressure using a randomized double-blind placebo-controlled study. (1) Nineteen subjects (Age 48.9${\pm}$4.3, M/F;18/1) took a 100ml drink either containing 125${\mu}$g of VY or placebo twice daily for 4 weeks. The reductions of the systolic (SBP) and diastolic blood pressure (DBP) were observed in mild hypertensive subjects (n=5) with averages of 17.8${\pm}$2.5 mmHg (p<0.01 vs placebo) and 11.0${\pm}$2.0 mmHg(p<0.05 vs placebo), respectively. Neither SBP nor DBP changed in the subjects of both the placebo group and the high-normal blood pressure group. (2) A randomized double-blind cross-over placebo-controlled study was carried out in 10 mild essential hypertensive subjects (Age 50.6${\pm}$4.6, M/F;10/0). They took a 100ml drink either containing 62.5${\mu}$g of VY or placebo twice daily for 4 weeks alternatively with a 6-week interval. The percent changes in SBP and DBP were -6.9 % and -5.8 % (p<0.05) one week after the VY drink administration, respectively. No adverse effects such as coughing or allergic phenomena could be observed in any of the subjects of drinking VY during the experimental period. These results suggest that the drink containing at least 125${\mu}$g/day of VY may have a significant antihypertensive effect on mild hypertensive subjects without any adverse effects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.79-84
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• 2013

DC/DC switching power converters are commonly used to generate a regulated DC output voltage with high efficiency. The DC/DC converter is composed of a PWM-IC (pulse width modulation-integrated circuit) controller, a MOSFET (metal-oxide semiconductor field effect transistor), inductor, capacitor, etc. It is shown that the variation of threshold voltage and the offset voltage in the electrical characteristics of PWM-IC increase by radiation effects in TID (Total Ionizing Dose) testing at the low energy ${\gamma}$ rays using $^{60}Co$, and 4 heavy ions applied for SEL (Single Event Latch-up) make the PWM pulse unstable. Also, the output waveform for the given input in the DC/DC converter is observed by the simulation program with integrated circuit emphasis (SPICE). TID testing on PWM-IC is accomplished up to the total dose of 30 krad, and the cross section($cm^2$) versus LET($MeV/mg/cm^2$) in the PWM operation is studied at SEL testing after implementation of the controller board.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.42-48
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• 2005

A DC-DC converter is being widely used for various household appliances and for industry applications. The DC-CC converter is powered from single battery, and the voltage is varied according to the purpose. In the vehicle, various accessories whose electric power is different are being un4 Thus, plural number of DC-DC converter should be provided, so these situations bring complicated circuits, and accordingly, higher cost. Under such backgrounds, in this paper, we propose a novel buck-boost chopper circuit with simply configuration which can supply to two or more different output loads. The propose chewer circuit can control output voltages by controlling duty ratio by using typically two switching devices, which is composed by single boost-switch and single buck-switch. The output voltage can be controlled widely. A few modified circuits developed from the fundamental circuit are represented including the general multi-load circuit. And all this merits and appropriateness was proved by computer simulation and experience.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.154-162
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• 2000

A technique to suppress the low frequency ripple voltage of the DC output ${\gamma}$oltage in three-phase buck d diode rectifiers is presented in this paper. The proposed pulse frequency modulation method is employed to r regulate the output voltage of the buck diode rectifiers and guarantee zero-current switching of the switch over the Vvide load range. The pulse frequency control method used in tIns paper shows generally good p performance such as low THD of the input line current and unity power factor. In addition, the pulse f freιluency method can be effectively used to suppress the low frequency voltage ripple appeared in the dc output voltage. The proposed technique illustrates its validity and effectiveness through the respective s simulations and experiments.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.475-476
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• 2011

본 논문에서는 차량의 엔진-발전기를 이용한 교류 전원 시스템에 대한 연구를 수행한다. 엔진-발전기의 출력은 다이오드 정류기를 거쳐 직류로 변환되고, 이를 강압형 DC/DC 컨버터를 통해 안정적인 직류전압으로 제어한다. 다시 DC/AC 인버터를 통해 CVCF의 단상, 혹은 3상의 교류전압을 발생한다. PSIM을 이용한 시뮬레이션을 통해 시스템의 성능을 고찰한다.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.4
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• pp.101-109
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• 1999

본 논문에서는 절연형 DC-DC 컨버터의 설계자동화 도구를 제시한다. 절연형 DC-DC 컨버터는 입력과 출력 측의 분리에 의한 회로 보호, 다중출력으로의 확장, 승압 및 강압의 용이성 등의 장점을 가지고 있다. 설계자동화의 과정은 여러 단계로 나눌 수 있다. 토폴로지 선택, 전압 및 전류용량이 적절한 스위치 소자 선택, 인덕턴스와 캐패시턴스의 값 결정, 그리고 변압기 설계의 순서로 컨버터 회로의 자동합성이 진행된다. C언어를 이용하여 자동화 도구를 구현하였고 SMPS 데이터 북으로부터 얻은 실제 회로의 사양을 가지고 다양한 컨버터 회로를 합성함으로 검증하였다.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.277-278
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• 2013

본 논문은 인터리브드 기법을 적용한 양방향 DC-DC 컨버터의 구현 및 실험에 대해 서술하였으며 구현한 컨버터의 특성을 분석하였다. 구현한 컨버터는 변압기를 사용하여 절연효과를 가지고 있으며 벅/부스트 구조가 적용되어 비교적 낮은 권선비로도 높은 승압과 강압이 가능하다. 또한 인터리브드 기법을 적용하여 리플전류의 감소효과를 가지고 있다. 각 모드별로 컨버터의 특성을 분석하였으며 벅모드와 부스트모드에 대한 동작은 실험을 통하여 확인하였다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.100-101
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• 2017

This paper presents the dynamics of the current-mode controlled buck and boost converters, which are both connected to an ill-conditioned source. This paper investigates the origin of potential instability and demonstrates internal/external dynamics of the converters under adverse interactions with the source.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.64-71
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• 2006

A target of this paper is to study on the usefulness of the adaptive piezoelectric energy harvesting device as a wireless electrical power supply when it is driven by mechanical vibrations of low frequency. For this purpose, an adaptive control technique and a step-down converter are used. A THUNDER series a piezoelectric material (TH7-R), which has been developed by a NASA engineer is selected for this study. In order to provide a mechanical energy to the piezoelectric material, a mechanical motion vibrator is designed. The adaptive controller is implemented using a dSPACE DS1104 controller board. The do-dc converter with an adaptive control technique harvests energy at over five times the rate of direct charging without a converter.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.4
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• pp.100-108
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• 1997

A combined buck and boost push-pull quantum series resonant rectifier(PPQSRR) is newly proposed to achieve a power factor correction without start-up inrush current. Based on the developed dynamic modeling of the proposed rectifier, an inrush current elimination control technique is proposed and the usefullness of the proposed rectifier and control method are verified by computer simulation and experimental results. With the proposed control method, a high power factor and wide range of output voltage can be obtained.