• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.148-151
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• 2009

In these days it is important to secure the life and stability of the structure such as aircrafts, automobiles and building. So the structural health monitoring is needed. In conventional lamb wave techniques, damage is identified by comparing the measured data (baseline signals) and the current data. But this method can lead to high false signal in the intact condition of the structure due to environmental conditions of the structure. As a solution to resolve it, the structural health monitoring method which doesn't use baseline signals is necessary. Damaged structure has unusual elastic wave. This paper proposed a PC(pitch-catch) method which doesn't use baseline signal. New baseline signals can get from detection signal. Damage signals based on new baseline signals. This paper made an image includes damage information by applying damage-signals to beamformming.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.121-125
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• 1993

This paper proposes two kinds of novel switching method for a single phase current-controlled voltage-type ac-to-dc converter. Proposed are modifications of the conventional hysteresis current control, and are named by the half suppressing method and unipolar method, respectively. The first one suppresses an inactive half of the four switching signals and uses active another half for current control. The second method uses only one, a quarter of switching signals suppresed the others. Both the simulation and experimental results show that proposed methods are more efficient in switch utilization and have comparable or better performance when compared with conventional method.

• 한국소음진동공학회논문집
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• 제14권11호
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• pp.1091-1100
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• 2004

This paper presents an approach for the monitoring and detection of faults in induction machine by using data fusion technique and Dempster-Shafer theory Features are extracted from motor stator current and vibration signals. Neural network is trained and Hosted by the selected features of the measured data. The fusion of classification results from vibration and current classifiers increases the diagnostic accuracy. The efficiency of the proposed system is demonstrated by detecting motor electric and mechanical faults originated from the induction motors. The results of the test confirm that the proposed system has potential for real time application.

• 전기학회논문지
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• 제57권8호
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• pp.1470-1477
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• 2008

In this paper, a new detection method of series arc-fault signals occurring at the wiring of home appliances is proposed. The discrete wavelet transform was used for the numerical analysis of the variation rate in peak, RMS, noise energy, shoulder of the arc-fault current wave. As a results, the arc distinction threshold value of these variation rates was about 0.1 in most cases. The arc-fault current of the loads with the active PFC circuit showed a high rate of variation in noise energy and shoulder, but arc-fault current of the loads without the active PFC circuit showed a high rate of variation in peak and RMS. The arc fault current in resistive loads showed a high rate of variation in shoulder.

• 비파괴검사학회지
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• 제30권4호
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• pp.330-337
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• 2010

본 논문은 원전 증기발생기(SG, steam generator) 세관의 정밀 진단을 위한 차세대 탐촉자인 배열형 와전류 탐촉자의 특성 해석에 대한 3차원 전자기 수치해석을 수행하였다. 다양한 결함 해석을 위해 ASME(American Society of Mechanical Engineers) 표준시험편과 X-probe combo 표준보정시험편(inline EXP/spiral groove combo standard)을 선정하여 탐상신호를 획득하고, 실제 실험 신호와 비교하여 결과의 타당성을 검증하였다. 표준 보정 시험편의 해석 결과를 바탕으로 원전 SG 세관에서 주로 발생하고 있는 pitting, SCC(stress corrosion cracking), multiple SCC, wear 결함에 대하여 탐상신호를 획득하였다. 해석 대상으로는 원자력발전소 SG 세관으로 사용하고 있는 Inconel 600 도체관을 사용하였고, 이때의 시험주파수는 300 kHz이다. 본 논문을 통하여 각각의 결함에 대한 신호 특성을 파악하여 배열형 와전류 탐촉자의 결함의 종류에 따른 신호 특성을 확인할 수 있었다. 본 논문의 결과는 배열형 와전류 탐촉자의 와전류 탐상 신호 평가시 도움이 될 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.59-62
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• 1992

Power system fault transient signals are highly distorted due to the presence of high frequency components in the voltage and current signals and an exponentially decaying dc-offset component in the current signals. Modern protective relays have to make reliable fast decisions about the nature of a fault in the presence of such transients. To use a dc-offset removing filter makes relay algorithms much fast and reliable for detecting a fault. In this paper, several dc-offset removing filters are described, and characteristics of them are compared.

• 한국정보통신학회논문지
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• 제2권1호
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• pp.147-156
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• 1998

본 논문에서는 다치 논리를 이용한 연산기를 설계하였다. 다치 논리를 구현하기 위해서 전류모드 CMOS 회로를 이용하였으며 이진 전압모드 신호를 다치 전류모드 신호로 바꾸어 주는 인코더와 연산 결과인 다치 전류모드 신호를 이진 전압모드 신호로 바꾸어 주는 디코오더를 사용하여 기존의 이진 시스템에 적용할 수 있도록 하였으며, 승산기 설계시 부분곱 수를 줄이기 위하여 기존의 Booth 알고리즘을 확장한 4진 SD수 부분곱 발생 알고리즘을 사용하였다. 제안된 회로는 SPICE 시뮬레이션 및 FPGA Chip을 이용한 하드웨어 에뮬레이션으로 그 유효함을 확인하였다

• Journal of information and communication convergence engineering
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• 제7권4호
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• pp.556-560
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• 2009

We have investigated the spectral characteristics of semiconductor lasers locked to the external light injected from a modulated laser. study on FM sideband injection locking has shown that when SLs are locked to the target sidebands of the directly modulated ML, the presence of the unselected sidebands influences the resulting microwave signals. The unselected signals can produce the unwanted beat signals around the desired beat signal, which degrade the overall system performance. This analysis way to generate Giga HZ signal generation.

• 천문학회보
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• 제39권1호
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• pp.79.2-79.2
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• 2014

A few years from now, gravitational wave (GW) detectors of LIGO and VIRGO consortiums are expected to reach the sensitivity necessary to detect GW signals from astronomical sources. Identification of the counterparts to the GW sources in electromagnetic wave is very important, since the localization of the GW signals is going to be very poor (~1000 $deg^2$) for the first detections and the nature of the GW-emitting sources will be uncertain with the GW detection only. In this talk, we will discuss possible astronomical sources that could be responsible for the first GW signals, and outline our current efforts to do follow-up observation of GW sources in collaboration with LIGO/VIRGO groups.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2002년도 High Temperature Superconductivity Vol.XII
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• pp.44-44
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• 2002