• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.107-111
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• 2001

This study was carried out to investigate the effect of Meristotheca papulosa on lipid concentration of serum and liver in rats fed high fat diet for 4 weeks. Experimental groups ere divided into normal group (5% corn oil), high fat diet group (5% corn oil+20% lard), high fat diet and 5% or 10% Meristotheca papulosa treated group. The weights of kidney, heart and tests were not significantly different among the group, but weight of liver was significantly decreased by supplement of Meristotheca papulosa (10%). The contents of serum total lipid, trigly-ceride, total cholesterol, free cholesterol, cholesterol ester and atherogenic index were decreased, while HDL-cholesterol was increased by Meristotheca papulosa supplementation compared to high fat diet group. Meristotheca papulosa supplement has obvious effects on lowering hepatic total lipid, triglyceride and total cholesterol. Our findings suggest that Meristotheca papulosa supplement can improve lipid metabolism in high fat fed rats.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.143-146
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• 2000

This paper presents a study on design for the k-junction of a feeder waveguide with an inductive wall using FDTD method. The feed structure consists of a single waveguide plated on the same layer as radiating waveguide and is characterized by the unit divider, railed a $\pi$-Junction. This $\pi$-Junction with an inductive wall splits part of the power into two branch waveguide through one coupling window, and can excite densely arrayed waveguide at equal phase and amplitude. The power dividing characteristics of a $\pi$ -Junction obtained by FDTD method are compared with one of Galerkin's method of moments. The scattering matrices a $\pi$ -junction calculated by FDTD method are realized.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.147-151
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• 2000

This paper presents an analysis of a slot on the broad wall of a rectangular waveguide using the 3D FDTD method. In order to reduce the reflection loss, Mur's 2nd absorbing boundary condition is used. To realize the optimum design by FDTD, the effects of time step, excitation aperture size, analysis region and excitation position in model are derived. The analysis results are compared with the experimental results and they show a good agreement with each other.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.16-20
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• 2002

This paper describes the resistive FET mixer with low IF for the 4-Ch DBF(Digital Beam Forming) receiver with LNA(Low Noise Amplifier). This DBF receiver based on the direct conversion method is generally suitable for high-speed wireless mobile communications. A radio frequency(RF), a local oscillator(LO) and an intermediate frequency(IF) considered in this research are 2.09 ㎓, 2.08 ㎓ and 10㎒, respectively. The RF input power, LO input power and Vgs are used -10㏈m, 6㏈m and -0.4 V, respectively. In the 4-Ch resistive FET mixer with LNA, the measured IF and harmonic components of 10㎒, 20㎒, 2.09㎓ and 4.17㎓ are about -12.5 ㏈m, -57㏈m, -40㏈m and -54㏈m, respectively. The IF output power observed at each channel of 10㎒ is about -12.5㏈m and it is higher 27.5 ㏈m than the maximum harmonic component of 2.09㎓. Each IF output spectrum of the 4-Ch is observed almost same value and it shows a good agreement with the prediction.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.44-48
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• 2002

This paper describes an adaptive signal processing of digital receiver with DDC(Digital Down Convertor), DDC is implemented by using NCO(Numerically Controlled Oscillator), digital low pass filter. for the passband sampling, we present the results of digital receiver simulation with DDC. We confirm that the low IP signal is converted to zero IF by DDC. DOA(Direction Of Arrival) estimation technique using MUSIC(Multiple SIgnal Classification) algorithm with high resolution is presented. We Cow that an accurate resolution of DOA depends on the input sampling number.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1060-1070
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• 2003

The frequency selective surface for use in Ka/Ku band parabolic antenna of domestic satellite communications is proposed. The frequency selective surface structure consists of the infinite periodic arrays of the triple square loop slot element with narrow width on the honeycomb structure of multi-layered dielectric. The frequency selective surface is fabricated and measured. The good agreement is obtained between theory and experiment. It is demonstrated that the frequency selective surface passes 14/12 GHz band wave while reflecting 30/20 GHz band wave as required.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.299-300
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• 2006

현재 선박에서는 선상정보체계의 디지털화 추세가 가속화되어 고성능의 통합형 선방용 컴퓨터를 필요로 하며, 현재도 그 납품 실적이 꾸준히 증가하는 추세이다. 하지만 실제 선박 내의 운용환경을 충분히 고려한 선박용 컴퓨터의 개발은 그 실적이 부진한 실태로, 잦은 고장과 합리적이지 못한 인터페이스 장치들의 적재로 원활한 운용환경을 제공하지 못하고 있다. 그리하여 기초설계부터 특수한 해양환경에 적합하도록 고안되고, 선박의 통신체계(NMEA 0183)를 완벽히 지원하여 항해보조장치로서의 임무를 충실히 소화해 낼 수 있는 선박용 컴퓨터 개발을 필요로 하게 되었다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.301-302
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• 2006

초고주파 전력 증폭기의 바이어스 전압을 조절하여 온도 변화에 따른 드레인(Drain) 전류의 변화를 억제하기 위한 저가의 능동 바이어스 모듈을 개발한다. 능동 바이어스 모듈을 5 W급 초고주파 전력증폭기에 적용하였을 경우, $0{\sim}60^{\circ}C$까지의 온도변화에 대하여 소모전류 변화량은 0.1 A 이하로 되어야 한다. 본 기술 개발 대상인 능동 바이어스 모듈의 성능 시험을 위한 대상 전력증폭기는 $2.11{\sim}2.17GHz$ 주파수 대역에서 32 dB 이상의 이득과 ${\pm}0.1\;dB$ 이하의 이득 평탄도, -15 dB 이하의 입.출력 반사손실을 가진다.

• Journal of the Korean Solar Energy Society
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• v.34 no.2
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• pp.91-97
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• 2014

This paper presents the modeling and contingency analysis of Jeju power system. For the analysis of contingency with simulation, thermal power plants, current source type HVDC systems, wind farms, STATCOMs and Jeju power load are modeled by PSCAD/EMTDC program. And three kinds of simulation are carried out. Firstly, two STATCOMSs are in normal operation. Secondly, one STATCOM is in fault. Lastly, all of STATCOMs are in fault. These comparative studies will be useful for evaluating the effectiveness of STATCOM to stabilize for the Jeju power system.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.147-155
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• 2002

본 연구에서는 옥외에서 사용하는 소재의 신뢰성 평가(내후성)에 관한 연구를 수행하였는데 국내와 일본의 옥외환경시험장에 시험편을 동시에 폭로하여 기상인자 및 주변환경에 따른 시험편의 특성 변화를 상호 비교ㆍ평가하였고 인공 촉진내후성 시험을 실시하여 옥외내후성과의 상관관계를 관찰하였으며 그 결과는 다음과 같다. 국내 지역의 옥외환경시험장 중에서는 인천 옥외환경시험장에 폭로한 시험편에서 가장 많은 변화를 나타내고 있으며, 일본 지역은 가혹한 기상환경을 나타내는 미야고지마 옥외환경시험장에 폭로한 시험편에서 많은 변화가 나타남을 관찰할 수 있었는데 국내 지역보다는 온도와 습도 등 기상제조건이 더 가혹한 일본 지역의 옥외환경시험장에 폭로한 시험편의 노화가 더 빠르게 진행됨을 관찰하였다.