• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.469-472
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• 1988

This paper deals with signal processing and pattern recognition for the pulsed doppler radar. In order to identify the class of moving targets detected by radar, linear predictive analysis is utilized to extract reflection coefficients of each radar signal as features, and Bayes decision theory is applied to classify them.

• 한국전자파학회논문지
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• 제16권1호
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• pp.33-39
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• 2005

동축선 프로브법을 사용하여 매질의 광대역 복소 유전율 값을 얻는다. 신뢰할 수 있는 복소 유전율 분포를 얻기 위해서는 먼저 측정된 반사계수의 정확성과 환산 모델의 안정성이 보장되어야 한다. 본 논문에서는 서로 다른 uncertainty를 갖는 계측기를 사용하여 환산 모델의 민감도를 해석하였다. 그리고 측정된 반사계수의 정확성에 영향을 주는 여러 요인에 대해 측정을 통해 조사하였다.

• 전자공학회논문지S
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• 제34S권10호
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• pp.141-150
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• 1997

In this paepr, we propose an intelligent double talk detector that can enhance the performance of the acoustic echo cancellation system. The conventional double talk detection methods often misunderstand the echo path changes as double talk. Although there exist several detection methods that can distinguish the echo path changes from the double-talks, they show poor tracking performance because of the excessive decision delay for the discrimination and can only be used after the adaptive digital filter converges. A new and more effective ditetion algorithm has been proposed, where the detection mechanism is performed by observing the change rate of the reflection coefficients of the two lattice predictors that re placed on the near-end and far-end terminals. The excellence of the proposed method is verified by extensive computer simulations using real speech signals.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.667-670
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• 1999

As the number of reference patterns increase in the text dependant speaker recognition, the recognition performance of the system degrades. So, if reference patterns were decreased the high recognition rate can be obtained. It’s because the speaker recognition can obtain the high discrimination. In this paper, to decrease the number of reference patterns, we choose candidate reference patterns to perform pattern matching with test pattern by high order component of the reflection coefficients of the uttered speech signal Consequently the total recognition rate of the proposed method is about 2% higher than that of the conventional method.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.143-150
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• 1999

Elastic wave propagation in a multilayered elastic half-plane is studied by using the Cagniard-de Hoop method. After the unknowns are expressed in terms of the reflection and transmission coefficients in the in terms of the reflection and transmission coefficients in the integral-transformed domains they are assmbled to form the global matrix equation. The inverse Laplace transform of each term is done by applying the Cagniard-de Hoop methods. As a numerical example a four-layered half-plane is considered where a point source is applied to the first layer. The method described in the present study can be used in checking other numerical methods such as FDM.

• 동력기계공학회지
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• 제20권4호
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• pp.26-31
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• 2016

The implementation of chirplet transform to locate axially aligned defects in pipes has been investigated. The results are obtained from experiments performed on a carbon steel pipe using magnetostrictive sensors. Chirplet transform is applied to the reflected signal to separate the individual modes from dispersive and multimodal waveform. The separated modes are used to calculate reflection coefficients which would be used to characterize defects. It is found that the reflection from a defect consists of the wave pulses with gradually decaying amplitudes. Also the results show that the reflection coefficient initially increases with the crack length but finally reaches an oscillating regime.

• 한국해양환경ㆍ에너지학회지
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• 제15권1호
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• pp.25-29
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• 2012

본 논문은 프로브의 반사계수를 이용하여 엔진오일의 열화정도를 측정하기 위해 반사 계수를 측정하는 회로를 설계한다. 프로브에 펄스를 인가하고 반사 신호를 측정할 수 있는 회로를 구현 하였다. 엔진오일의 상태가 열화 될 수록 반사 신호는 증가하는 것을 알 수 있었고, 엔진오일의 온도가 상승함에 따라 열화된 엔진오일의 유전율이 감소하는 현상을 측정하였다. 결론적으로, 프로브의 반사 계수를 이론치와 측정치를 비교 분석하였다.

• 한국음향학회지
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• 제26권6호
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• pp.243-249
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• 2007

본 논문은 Group Delay(GD)를 이용한 음성신호 기반의 효과적인 성별인식 시스템을 제안한다. 일반적인 음성 인식과 관련된 시스템에서 사용되는 특징들은 위상에 관한 정보를 제거한 크기만의 정보를 이용하여 구성한다. 본 연구에서는 위상에 관한 정보를 토대로 유도되어 지는 GD의 성별에 따른 특징을 알아보고, 보다 향상된 성별인식을 위해 MFCC(Mel-frequency cepstral coefficient), LPC(linear predictive coding) 계수, 반사계수(reflection coefficient) 그리고 포만트(formant)등과 같은 크기 정보와 GD를 이용한 결합 특징 벡터를 적용하였다. 실험을 통해 성별에 따른 GD의 특징을 확인할 수 있었고, 이를 이용한 제안된 특징 벡터를 사용했을 때 우수한 인식 성능을 얻을 수 있었다.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1997년도 정기학술강연회 발표논문 초록집 Annual Meeting of Korean Society of Coastal and Ocean Engineers
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• pp.39-44
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• 1997

As wind waves generated in deep water approach nearshore zone, they experience various physical phenomena caused by bathymetric variations, nonlinear interactions among different wave components and interferences with man-made coastal structures. Among these, the bathymetric variations may play a significant role in the change of wave climate. The accurate calculation of reflection and transmission coefficients of incident waves over a bottom topography is indispensible for the proper and economical design of coastal structures. (omitted)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.352.2-352
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• 2002

In this paper, Power Flow Analysis (PFA) method has been applied to the prediction of vibration energy density and intensity of coupled shell structures in the medium-to-high frequency ranges. To consider the wave transformation at joint between shell elements, power transmission and reflection coefficients are investigated for various joint angles, and here Donnell-Mushtari thin shell theory has been used. (omitted)