• 한국자기공명학회논문지
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• 제10권1호
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• pp.59-73
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• 2006

Spin-lattice relaxation pathway of $CH_2$ spin system by two dimensional NOESY sequence has been discussed. Two-dimensional spectra governed by dipolar relaxation mechanism were simulated in term of transfer mode, the generalization of conventionally used magnetization mode in one dimension. The transfer matrix directly related to the Redfield relaxation matrix can be constructed by the multiplet of transfer mode. The observable relaxation transfer modes causes to variation of the off-diagonal signal intensity of phase sensitive NOESY spectra from which variable spectral density can be extracted with simple group theoretical calculation. The variation of the J-coupling peak intensity as a function of the mixing time in 2-D spectra for $n-Undecane-5-^{13}C$ and Bromoacetic $2-^{13}C$ acid has been theoretically traced.

• JSTS:Journal of Semiconductor Technology and Science
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• 제3권4호
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• pp.188-193
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• 2003

This paper describes a novel burst-mode clock and data recovery (CDR) circuit which can be used for 622Mbps burst mode applications. The CDR circuit is basically a phase locked loop (PLL) having two phase detectors (PDs), one for the reference clock and the other for the NRZ data, whose operations are controlled by an external control signal. This CDR was fabricated in a 1-poly 5-metal $0.25{\;}\mu\textrm{m}$ CMOS technology. Jitter generation, burst/continuous mode data receptions were tested. Operational frequency range is 320Mhz~720Mhz and BER is less than 1e-12 for PRBS31 at 622Mhz. For the same data sequence, the extracted clock jitter is less than 8ps rms. Power consumption of 100mW was measured without I/O circuits.

• 전기학회논문지
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• 제57권5호
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• pp.839-844
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• 2008

A novel state of health estimation method for hybrid electric vehicle lithium battery using sliding mode observer has been presented. A simple R-C circuit method has been used for the lithium battery modeling for the reduced calculation time and system resources due to the simple matrix operations. The modeling errors of simple model are compensated by the sliding mode observer. The design methodology for state of health estimation using dual sliding mode observer has been presented in step by step. The structure of the proposed system is simple and easy to implement, but it shows robust control property against modeling errors and temperature variations. The convergence of proposed observer system has been proved by the Lyapunov inequality equation and the performance of system has been verified by the sequence of urban dynamometer driving schedule test. The test results show the proposed observer system has superior tracking performance with reduced calculation time under the real driving environments.

• 한국통신학회논문지
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• 제35권4B호
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• pp.670-676
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• 2010

AT-DMB 수신에 적용하기 위한 PN 시퀀스 기반 시간 동기 방법을 제안한다. AT-DMB 변조 모드 정보를 전송하기 위해 PRS에 PN 시퀀스를 삽입하여 전송하는 방법을 적용할 수 있는데, 이 PN 시퀀스를 이용하여 효과적으로 AT-DMB의 시간동기를 획득할 수 있다. 제안한 PN 시퀀스 기반 시간동기 방법에 대해 이동 채널에서 BER 분석을 통해 성능 분석을 하였고 그 결과를 도시하였다.

• 전력전자학회논문지
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• 제12권6호
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• pp.433-440
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• 2007

에너지 절약과 환경 문제가 이슈화되면서 대표적인 전원공급장치인 SMPS의 대기모드 효율이 중요시되고 있다. 특히 많은 SMPS들이 다출력 구조로 설계됨에 따라 대기모드에서 전력손실을 줄이기가 쉽지 않다. 본 논문에서는 SSPR(Secondary Side Post Regulator)을 개발하여 단일 컨버터에서 Cross Regulation과 대기전력을 함께 해결하였다. 그리고, 다중 컨버터의 대기전력 감소를 위하여 전류모드 제어와 Power Sequence 제어기술을 제안한다. 제안된 기술은 이론적 해석과 더불어 120[W], 270[W]급 SMPS에 적용하여 그 타당성 및 우수성을 검증하였다.

• 대한전자공학회논문지SP
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• 제38권4호
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• pp.353-361
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• 2001

본 논문에서는 MPEG-2 multiview profile (MVP)를 이용한 스테레오 동영상 부호화기 구조를 제안한다. 제안한 부호화기에서 좌영상은 기저층에서 움직임 정보를 이용하여 부호화 되고, 우영상은 상위층에서 변이 정보를 이용하여 부호화를 수행한다. 그리고 변이 정보와 움직임 정보간의 관계를 이용하여 하위 계층의 움직임 정보와 변이 정보에서 상위 계층의 움직임 정보를 유도하여 영상 예측에 사용하였다. 이를 적용하기 위해서 상위 계층과 하위 계층의 부호화 순서와 예측 모드에 제약을 두었다. 제안한 스테레오 MPEG-2부호화기는 상위 계층의 부호화시 움직임 예측을 수행하지 않고 하위 계층에서의 예측 모드 제약으로 인해 부호화기의 구조가 간단하고 부호화 시간을 줄일 수 있었다. 실영상에 대한 실험 결과에서 상위 계층의 경우 움직임 예측과 변이 예측을 모두 수행했을 때와 거의 차이가 나지 않았으며 변이 예측만을 수행 경우보다 높은 SNR을 나타내었다.

• Journal of Power Electronics
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• 제18권1호
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• pp.70-80
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• 2018

A novel strategy based on a zero common mode voltage pulse-width modulation (ZCMV-PWM) technique and zero-sequence circulating current (ZSCC) feedback control is proposed in this study to eliminate ZSCCs between three-level neutral point clamped (NPC) voltage source inverters, with common AC and DC buses, that are operating in parallel. First, an equivalent model of ZSCC in a three-phase three-level NPC inverter paralleled system is developed. Second, on the basis of the analysis of the excitation source of ZSCCs, i.e., the difference in common mode voltages (CMVs) between paralleled inverters, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can be eliminated effectively under steady and dynamic states. Moreover, the proposed strategy exhibits the advantage of not requiring carrier synchronization. It can be utilized in inverters with different types of filter.

• 기술사
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• 제31권1호
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• pp.9-16
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• 1998

For the flow facing high1y informationized age, there is a flow from fixed communications connecting fixed places such as offices and homes to mobile communications connecting mobile objets such as automobiles, ships and aircraft. This flow has added to diversifying communications Including data and images. While the axed mode is diversifying information media by digitalization of communications network and computers, the mobile mode has brought higher sophistication of communication modes by a higher degree of electric wave utilization. The following descriptions outlines the mobile communication which is utilizing the electric wave phenomena. In sequence the following items are described: a brief history of mobile communications, the technical object and various kinds of services, propagation of electric wave signal.

• 기술사
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• 제31권2호
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• pp.65-72
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• 1998

For the flow facing highly informationized age, there Is a flow from fixed communications connecting fixed places such as offices and homes to mobile communications connecting mobile objets such as automobiles, ships and aircraft. This flow has added to diversifying communications including data and images. While the fixed mode Is diversifying information media by digitalization of communications network and computers, the mobile mode has brought higher sophistication of communication modes by a higher degree of electric wave utilization. The following descriptions outlines the mobile communication which Is utilizing the electric wave phenomena. In sequence the following items are described: a brief history of mobile communications, the technical object and various kinds of services, propagation of electric wave signal.

• 한국광학회지
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• 제1권2호
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• pp.185-190
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• 1990

4개의 프리즘으로 구성된 군속도분산 조절장치를 이용하여 CPM 링 색소 레이저에서 62fs의 펄스를 얻었다. Ar+ 레이저 출력, DODCI 농도 및 위치, 프리즘과 레이저 거울의 조정상태를 변화시켜 가며 레이저 펄스폭을 측정해서 가장 짧은 펄스폭을 얻을 수 있는 조건을 구했다.