• 한국광학회지
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• 제2권4호
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• pp.209-213
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• 1991

최근들어 극초단 광학펄스를 생성하고 증폭하는 기술의 발달로 인하여 시분해 레이저 분광학에 많은 영향을 끼치게 되었다. 그 중에서도 응용성이 넓은 순간흡수분광학장치를 본 연구실에서 개발하였다. 이 기술은 고출력 레이저 펄스를 이용하여 white light continuum pulse를 생성시켜 이를 조사빔으로 이용하고, pump pulse는 원래 상태의 레이저를 이용하는 것이다. 순간흡수율 변화를 여러 파장에서 측정가능하도록 photodiode array를 이용하였으며, pump와 probe pulse의 시간차이에 의한 순간흡수율 변화를 색소의 일종인 DDI를 이용하여 측정하였다.

• 융합신호처리학회논문지
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• 제25권1호
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• pp.1-6
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• 2024

방수배열소나의 주 기능은 적 수상함 및 잠수함, 어뢰 등에서 방사하는 펄스를 탐지하는 것이다. 펄스를 탐지한 경우에는 자함 입장에서 위험도가 높은 상황이므로 자함의 기동 및 생존을 위해 표적의 위치를 찾는 건 매우 중요하다. 표적의 위치는 각 센서에서 수신된 펄스의 시작점을 찾고 센서 간 시간지연 값을 계산하여 산출하게 된다. 펄스 시작점을 구하기 위해서는 신호의 포락선을 산출하고 미분 필터링 과정을 거치게 되는데 방수배열소나는 신호의 샘플링 주파수가 높아 처리하는 샘플 개수가 많으므로 이 과정은 연산량이 큰 문제가 있다. 이에 본 논문은 연산량을 줄일 수 있는 간축 적용 펄스 시작점 산출 방법을 제안하였다. 간축 계수를 변경하면서 시뮬레이션을 수행하였고 연산량이 감소함을 확인하였다. 제안한 방법은 실시간 처리 시스템에 효과적이며 자원 활용도에 장점을 가질 것으로 기대한다.

• Journal of Power Electronics
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• 제4권1호
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• pp.56-63
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• 2004

A new driving circuit for the SPSS (Single-Pulse Soft-Switching) PFC converter is proposed. The switching device of a SPSS converter switches once in every half cycle of an AC commercial power source. Therefore, it can be solved many problems caused by the high frequency operation. The proposed SPSS converter achieves the soft-switching operation and the EMI noise can be reduced. The resonant capacitor voltage supplies to the resonant inductor even if the input AC voltage is the vicinity of zero cross voltage. Then, the power factor and input current waveform can be improved without delay time. A new driving circuit achieves the operation of SPSS converter by one switching drive circuit. The proposed converter can be satisfied the IEC standard sufficiently

• Journal of Power Electronics
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• 제10권1호
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• pp.14-20
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• 2010

In this paper, a tightly regulated triple output asymmetrical half bridge flyback (ASHF) converter is proposed. In order to regulate all output voltages, pulse frequency modulation (PFM), pulse width modulation (PWM) and phase delay (PD) are used simultaneously. In comparison with the conventional PWM-PD method, the interactions among the control variables are minimized and the operating range is increased. By the utilization of a multi winding transformer, the auxiliary transformer and the blocking capacitor are eliminated and the size and cost of the proposed converter is reduced. The operation principle of the converter is explained and the modes of operation are investigated. Based on the results, the steady state characteristics of the converter are explored. A 24V/10A, 12V/5A, 5V/10A hardware prototype is built and tested to verify the analysis results and the voltage regulation of the triple outputs of the proposed converter.

• JSTS:Journal of Semiconductor Technology and Science
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• 제3권2호
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• pp.102-106
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• 2003

This paper describes novel low-power high-speed flip-flop called dual edge-triggered NAND keeper flip-flop (DETNKFF). The flip-flop achieves substantial power reduction by incorporating dual edge-triggered operation and by eliminating redundant transitions. It also minimizes the data-to-output latency by reducing the height of transistor stack on the critical path. Moreover, DETNKFF allows negative setup time to provide useful attribute of soft clock edge by incorporating the pulse-triggered operation. The proposed flip-flop was designed using a $0.35{\;}\mutextrm{m}$ CMOS technology. The simulation results indicate that, for the typical input switching activity of 0.3, DETNKFF reduces power consumption by as much as 21 %. Latency is also improved by about 6 % as compared to the conventional flip-flop. The improvement of power-delay product is also as much as 25 %.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.1002-1007
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• 2003

A new driving circuit for the SPSS (Single-Pulse Soft-Switching) PFC converter is proposed. The switching device of a SPSS converter switches once In every half cycle of an AC commercial power source. Therefore, it can be solved many problems caused by the high frequency operation. The proposed SPSS converter achieves the soft-switching operation and the EMI noise can be reduced. The resonant capacitor voltage supplies to the resonant inductor even if the input AC voltage is the vicinity of zero cross voltage. Then, the power factor and input current waveform can be improved without delay time. A new driving circuit achieves the operation of SPSS converter by one switching drive circuit. The proposed converter can be satisfied the IEC standard sufficiently.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.276-280
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• 1998

This paper proposes a harmonic a harmonic reduction technique of the parallel-connected twelve-pulse thyristor rectifiers. The proposed system is an improvement over the diode rectifier system with an active interphase reactor [2]. In this scheme, a low KVA (0.15 Po (PU) ) active current source injects a triangular current into an interphase reactor of a twelve-pulse thyristor rectifier along the phase delay angle. The current injection results in near sinusoidal input current with less than 1% THD. Detailed analysis of the proposed scheme along scheme along with design equations is illustrated. Simulation results verify the concept.

• 전기학회논문지
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• 제61권12호
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• pp.1903-1910
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• 2012

This paper presents a data based low-order controller design algorithm for a linear time-invariant process with a time delay. The algorithm is composed by combining an identification step based on open loop pulse test with a low-order controller design step to obtain the entire set of controllers achieving multiple performance specifications. The initial information necessary for this algorithm are merely the width and amplitude of a rectangular pulse, a controller of four types (PI, PD, PID, first-order), and design objectives. Various parametric approaches that have been developed are merged in the controller design algorithm. The resulting controller set satisfying the design objectives are displayed on the 2D and 3D graphics and thus it is very easy for us to pick a controller inside the admissible set because we can check the corresponding closed-loop performances visually.

• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1829-1832
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• 2004

We have developed a new femtosecond probe technique by using stimulated Raman spectroscopy. The cross phase modulation in femtosecond time scale associated with off-resonant interaction was shown to be eliminated by integrating the transient gain/loss signal over the time delay between the Raman pump pulse and the continuum pulse. The stimulated Raman gain of neat cyclohexane was obtained to demonstrate the feasibility of the technique. Spectral and temporal widths of stimulated Raman spectra were controlled by using a narrow band pass filter. Femtosecond stimulated Raman spectroscopy was proposed as a highly useful probe in time-resolved vibrational spectroscopy.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.99-102
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• 1999

In recent years, attempts have been made to greatly improve the display quality of active-matrix liquid crystal display devices, and many techniques have been proposed to solve such problems as gate signal delay, feed-through voltage and image sticking. To improve these problems which are caused by the fried-through voltage, we have evaluated new driving methods to reduce the fled-through voltage. Two level gate-pulse was used for the gate driving of the cst-on-common structure pixels. And two-gate line driving methods with the optimized gate signals were applied for the cst-on-gate structure pixels. These gate driving methods were better feed-through characteristics than conventional simple gate pulse. The evaluation of the suggested driving methods were performed by using a TFT-LCD array simulator PDAST which can simulate the gate, data and pixel voltages of a certain pixel at any time and at any location on a TFT array. The effect of the new driving method was effectively analyzed.