• 소음진동
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• 제9권4호
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• pp.813-821
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• 1999

This paper presents the technique using wavelet analysis to solve the seismic response of a steam turbine-generator rotor system subjected to earthquake excitations. A brief review of the wavelet transform and its discretization, time-frequency representation of the earthquake wave and the seismic response for a rotor system is presented. The Daubechies wavelet has been used for describing the time-frequency characteristics of the input and the response in case of a recorded accelerogram during 1995 Hyogoken Nanbu earthquake. Also, the results in the wavelet domain has been illustrated through comparison with the time domain simulation results.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 춘계종합학술대회
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• pp.272-275
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• 1999

본 논문에서는 직접 대역 확산 통신 시스템에서 적응 알고리듬을 wavelet 변환 영역에 이용하여 협대역 간섭 성분을 효과적으로 억제할 수 있는 wavelet 변환 기저 적응 간섭 제거 시스템을 소개한다. 두 종류의 Daubechies wavelets(dbl, db8)를 이용한 간섭 제거 시스템의 성능 비교를 위하여 비트 오율을 Monte-Carlo 시뮬레이션을 이용하여 구하고 그 결과로부터 wavelet 특성에 따라 성능이 달라지며 효율적인 개선 효과를 기대할 수 있음을 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.864-867
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• 2005

In this paper we introduce a design of parallel architecture for wavelet transformation on FPGA. We implement wavelet transforms though lifting scheme and apply Daubechies4 transform equations. This technique has an advantage that we can obtain perfect reconstruction of the data. We divide our process to high pass filter and low pass filter. With this division, we can find coefficients from low and high pass filters simultaneously using parallel processing properties of FPGA to reduce processing time. From the equations, we have to design real number computation module, referred to IEEE754 standard. We choose 32 bit computation that is fine enough to reconstruct data. After that we arrange the real number module according to Daubechies4 transform though lifting scheme.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제1권1호
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• pp.24-28
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• 2001

Wavelet transforms are used for implementing digital watermarking methods in the frequency domain. In this paper, we construct the digital watermarking using various wavelet transforms such as the Daubechies transform, Coiflets transform, Symlets transform and the biorthogonal transform, and we compare each digital watermarking method with the others. We investigate the preservation of the watermark after the data compression attack based on the discrete on the discrete cosine transform. We show that the biorthogonal wavelet, denoted by bior3.5, has the best performance among the wavelet types we selected in an experiment.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.376-379
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• 1999

The wavelet transform chip is implemented with Daubechies' 4 tap filter. It works at 20MHz in Field Programmable Gate array (FPGA) implementation of Quadrature Mirror Filter(QMF) Lattice Structure. In this paper, the structure contains taro-channel quadrature mirror filter, data format converter(DFC), delay control unit(DCU), and three 20$\times$8 bits real multiplier. The structures for the DFC and DCU need to he regular and scalable, require minimum number of regular, and thereby lead to an efficient and scalable architecture for the Discrete Wavelet Transform(DWT). These results present the possibility that it can be used in Digital Signal Processing(DSP) application faster than Fourier transform at small area with lour cost.

• 한국자기공명학회논문지
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• 제5권2호
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• pp.66-72
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• 2001

The noise suppression of time domain NMR data by discrete wavelet transform with high order Daubechies wavelet coefficients exhibits severe peak distortion and incomplete noise suppression near real signal. However, the fact that even a shift averaged Harr wavelet transform with a set of Daubechies wavelet coefficients (1/2, -l/2) can be used as a new and excellent tool to distinguish real peaks from the noise contaminated NMR signal is introduced. New algorithms of shift averaged Harr wavelet were developed and quantitatively evaluated in terms of threshold and signal to noise ratio (SNR).

• 전기학회논문지P
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• 제57권4호
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• pp.377-382
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• 2008

For stator winding protection of AC generator, KCL(Kirchhoff's Current Law) is widely applied. Actually a CRDR(Current Ratio Differential Relay) based on DFT(Discrete Fourier Transform) has been used for protecting generator. It has been pointed out that defects can occur during the process of transforming a time domain signal into a frequency domain one which can lead to loss of time domain information. Wavelets techniques are proposed for the analysis of power system transients. This paper introduces an algorithm to choose a suitable Mother Wave1et for generator stator fault detection. For optimal selection, we analyzed db(Daubechies), sym(Symlets), and coif(Coiflects) of Mother Wavelet. And we compared with performance of the choice algorithm using detail coefficients energy and RMS(root mean square) error. It can be improved the reliability of the conventional DFT based CRDR. The feasibility and effectiveness of the proposed scheme is proved with simulation using collected data obtained from ATP (Alternative Transient Program) package.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4568-4575
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• 2010

홍채인식은 홍채의 무늬 패턴 정보를 이용하는 생체인식 기술로 안정성, 보안성과 같은 특징을 가지고 있기 때문에 높은 보안을 요구하는 환경에 특히 적합하다. 최근 들어 홍채정보를 이용하여 출입통제, 정보보안등의 분야에 많이 활용되고 있다. 홍채 특징 추출시 크기, 조명, 회전에 무관한 홍채 특징을 추출하는 것이 바람직하다. 홍채크기 및 조명 문제는 전처리를 통해 쉽게 해결할 수 있지만 회전에 무관한 홍채 특징 추출은 여전히 문제가 된다. 본 논문에서는 회전 보정으로 인한 인식률 및 속도 저하를 개선하기 위해 Zernike 모멘트와 Daubechies Wavelet을 이용한 홍채인식 방법을 제안한다. 제안한 방법은 회전에 불변한 Zernike 모멘트의 통계적 특성을 이용하여 회전된 홍채에 대해서 1단계로 유사홍채를 분류함으로서 홍채인식에 필요한 시간을 단축하였고, 인식성능 역시 기존 방법과 대등함을 보였다. 따라서 제안한 방법이 대용량의 홍채 인식 시스템에 효과적인 적용이 가능함을 확인할 수 있었다.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2003년도 제8차 학술대회 초록집
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• pp.75-75
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• 2003

목적： MR 영상에 나타나는 bias field, 즉 영상의 특정 부분이 주위보다 어둡거나 밝게 나타나는 현상을 보다 균일하게 보정시키는 방법으로 제시된 N3 방법에서 Gaussian kernel을 사용한 smoothing 방법 대신에 Wavelet(Daubechies, D4)함수를 smoothing기법으로 사용했을 때 어느 정도 균일함에 향상이 일어나는지를 알아보는 것이다.

• Journal of the Korean Data and Information Science Society
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• 제15권3호
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• pp.695-706
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• 2004

The use of wavelets in three-dimensional imaging is reviewed with an example. The insufficiencies of direct two-dimensional processing is showed as a major motivating factor behind using wavelets for three-dimensional imaging. Different wavelet algorithms are used, and these are compared with the direct two-dimensional approach as well as with each other.