• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.317-320
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• 1996

Electrogastrography(EGG) has been an attractive method for physiological and pathophysiological studies of the stomach and now is on the verge of becoming a new clinical tool in gastroenterology. In this study 4 channel EGG measurement system was constructed and running spectrum analysis was developed for 2D and 3D display of power spectrum with time and frequency. A wavelet multiresolution method was utilized for elimination of baseline drift and for filtering out noises.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.214-216
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• 2004

Power quality has become concern both utilities and their customers with wide spread use of electronic and power electronic equipment. This paper deals with the use of a multiresolution analysis and a discrete wavelet transform to detect interruption, sag, swell, transients and etc. The simulation system is constructed by using PSCAD/EMTDC. To show the effectiveness of the proposed method, a various case studies are simulated.

• 대한전기학회논문지:전력기술부문A
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• 제49권9호
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• pp.425-432
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• 2000

Wavelet transform is a new method fro electric power quality analysis. Several types of mother wavelets are compared using voltage sag data. Investigations on the use of some mother wavelets, namely Daubechies, Symlets, Coiflets, Biorthogonal, are carried out. On the basis of extensive investigations, optimal mother wavelets for the detection of voltage sag are chosen. The recommended mother wavelet is 'Daubechies 4(db4)' wavelet. 'db4', the most commonly applied mother wavelet in the power quality analysis, can be used most properly in disturbance phenomena which occurs rapidly for a short time. This paper presents a discrete wavelet transform approach for determining the beginning time and end time of voltage sags. The technique is based on utilising the maximum value of d1(at scale 1) coefficients in multiresolution analysis(MRA) based on the discrete wavelet transform. The procedure is fully described, and the results are compared with other methods for determining voltage sag duration, such as the RMS voltage and STFT(Short-Time Fourier Transform) methods. As a result, the voltage sag detection using wavelet transform appears to be a reliable method for detecting and measuring voltage sags in power quality disturbance analysis.

• International Journal of Control, Automation, and Systems
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• 제1권3호
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• pp.385-389
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• 2003

In this paper, an improved technique for multiresolutive reconstruction of magnetoencephalography (MEG) source distribution is proposed. Using the proposed technique, focal solution with higher energy density can be reconstructed. Moreover, the proposed approach is very easy to implement compared to conventional ones. The usefulness of the proposed technique is verified by the application to a real brain model.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.907-910
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• 2001

In this paper, we address a new time delay estimation method using third-order statistics and subband adaptive filtering to improve the accuracy of target detection for acoustic backscattered signals in a noise interference environment. Each reference and primary signals are decorrelated using the multiresolution analysis framework through a M-band discrete wavelet transform(M-DWT). Then noise effect can be reduced. Here, time delays are estimated iteratively in each subband using two different adaptation mechanisms that minimize the mean squared error (MSE) between the references and primary signal. More specifically, third-order cumulants and projection cross-correlation(PCC) criterion are utilized to achieve an effective SNR improvement for the time delay estimation.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 추계학술발표회논문집(1)
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• pp.67-72
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• 1996

Wavelets are localized in space and in frequency. This localization properties result from the multiresolution analysis of wavelets. The wavelet transform can be used to detect singularity of dynamic systems after the signal is de-noised. We applied the wavelet transform decomposition and do-noising procedures to the Hanaro dynamics consisting of 39 nonlinear differential equation plus Gaussian noise. The numerical tests demonstrate that the wavelet transform de-noising is effective for detection of the abrupt reactivity change and computationally efficient. Thus this wavelet theory could be profitably utilized in a real-time system for automatic event recognition (e.g., reactor condition monitoring).

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.431-434
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• 2003

신호처리 분야의 새로운 기법으로 제시된 웨이브렛 변환은 시간 및 주파수 국부성을 가지므로, 다양한 신호를 해석하는데 용이할 뿐만 아니라, 다중 해상도 해석이 가능하므로 최근 여러 분야에 응용되고 있다. 그리고, 두 개의 웨이브렛 기저가 힐버트 변환쌍을 형성하도록 설계될 때, 웨이브렛 쌍은 펄스 형태의 데이터 검출에서 기존의 DWT보다 우수한 성능을 나타낸다. 따라서, 본 연구에서는 절단된 계수 벡터에 의해 설계된 두 개의 dyadic 웨이브렛 기저를 사용하여, 임펄스 노이즈의 위치를 검출하였다.

• 한국정보통신학회논문지
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• 제6권2호
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• pp.346-355
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• 2002

이 연구는 인식의 정확성을 향상시키기 위하여 단일생체 인식 대신에 얼굴, 입술, 음성을 이용하는 다중생체 인식방법을 제안한다. 각 생체 특징은 다음과 같은 방법으로 찾는다. 얼굴 특징은 웨이블렛 다중분해와 주성분 분석방법으로 계산하였고, 입술의 경우는 입술의 경계를 구한후 최소 자승법을 이용한 방정식의 계수를 구하였으며, 음성은 멜 주파수에 의한 MFCC를 사용하였으며, 역전파 학습 알고리즘으로 분류하여 실험하였다. 실험을 통해 본 방법의 유효성을 확인하였다.

• 전자공학회논문지A
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• 제32A권9호
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• pp.1244-1249
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• 1995

Wavelet transform technique is applied to two important electromagnetic problems:1) to analyze the frequency-domain radar echo from finite-size targets and 2) to the integral solution of two- dimensional electromagnetic scattering problems. Since the frequency- domain radar echo consists of both small-scale natural resonances and large-scale scattering center information, the multiresolution property of the wavelet transform is well suited for analyzing such ulti-scale signals. Wavelet analysis examples of backscattered data from an open- ended waveguide cavity are presented. The different scattering mechanisms are clearly resolved in the wavelet-domain representation. In the wavelet transform domain, the moment method impedance matrix becomes sparse and sparse matrix algorithms can be utilized to solve the resulting matrix equationl. Using the fast wavelet transform in conjunction with the conjugate gradient method, we present the time performance for the solution of a dihedral corner reflector. The total computational time is found to be reduced.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.448-451
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• 2002

본 연구는 인식의 정확성을 향상시키기 위하여 단일 특징을 이용한 인식 대신에 다중 특징을 이용하는 인식방법을 제안한다. 각각의 특징은 다음과 같은 방법으로 구하여진다. 얼굴 전체의 특징은 웨이블렛 다해상도 분해와 주성분 분석방법으로 계산하였고, 입술의 경우는 입술의 경계를 구한 후 최소 자승법을 이용한 방정식의 계수를 구하였으며, 또 하나의 특징은 얼굴요소의 거리 비율에 의해 구하였다. 위 값들을 입력으로 한 역전파 학습 알고리즘으로 분류하여 실험하여 제안된 방범의 유효성을 확인하였다.