• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.3-5
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• 2002

The fourier transform yields good information on the frequency content of the transient, but the time at which a particular disturbance in the signal occurred is lost. Unlike the fourier transform, the wavelet transform provides a time information in addition to the frequency information. So the wavelet transform is more efficient in detecting power quality disturbances. In this paper, we use the wavelet transform for detecting the voltage sag.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.115-120
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• 2002

The rigid body properties of a structure may be estimated easily if the mass-line of the structure could be taken exactly. However, the exact mass-line may be hard to be obtained exactly in experiments. The mass line value can be read from the mass line in frequency response function. However, the mass lines in the frequency response function sometimes show the fluctuation with frequency, and it cannot be read correctly. In this paper, the wavelet transform is applied to obtain the good mass line value. The mass line calculated by using wavelet transform has unique value and showed in the range of fluctuated values of frequency response function. The rigid body properties obtained by wavelet transform also showed better results than those by fourier transform.

• Communications for Statistical Applications and Methods
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• v.22 no.2
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• pp.159-172
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• 2015

This paper considers the problem of reconstructing an underlying signal from noisy data. This paper presents a reconstruction method based on synchrosqueezed wavelet transform recently developed for multiscale representation. Synchrosqueezed wavelet transform based on continuous wavelet transform is efficient to estimate the instantaneous frequency of each component that consist of a signal and to reconstruct components. However, an objective selection method for the optimal number of intrinsic mode type functions is required. The proposed method is obtained by coupling the synchrosqueezed wavelet transform with cross-validation scheme. Simulation studies and musical instrument sounds are used to compare the empirical performance of the proposed method with existing methods.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.9
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• pp.725-730
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• 2002

The rigid body properties of a structure may be estimated easily if the mass-line of the structure could be taken exactly. However, the exact mass-line nay be hard to be obtained exactly in experiments. The mass line value can be read from the mass line in frequency response function. However, the mass lines in the frequency response function sometimes show the fluctuation with frequency, and it cannot be read correctly. In this paper, the wavelet transform is applied to obtain the good mass line value. The mass line calculated by using wavelet transform has unique value and showed in the range of fluctuated values of frequency response function. The rigid body properties obtained by wavelet transform also showed better results than those by fourier transform.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.14-16
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• 1988

With the development of VLSI technology, research on special processors for high-speed processing is on the increase and studies are focused on designing VLSI-oriented processors for signal processing. This paper processes a one-dimensional systolic array for Discrete Hartley Transform implementation and also processes processing element which is well described for algorithm. The discrete Hartley Transform(DHT) is a real-valued transform closely related to the DFT of a real-valued sequence can be exploited to reduce both the storage and the computation requried to produce the transform of real-valued sequence to a real-valued spectrum while preserving some of the useful properties of the DFT is something preferred. Finally, the architecture of one-dimensional 8-point systolic array, the detailed diagram of PE, total time units concept on implementation this arrays, and modularity are described.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7C
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• pp.601-607
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• 2007

In order to convert MPEG-2 into H.264 format in ubiquitous communication environments, the efficient conversion of the discrete cosine transform (DCT) coefficients to H.264 transform coefficients is essential. In this paper, two efficient conversion systems are proposed. The proposed systems are composed of two parts. In the first part, the DCT coefficients are denoised using the lapped transform (LT) to reduce the quantization noises and blocking effects. In the second part, the denoised DCT coefficients are converted into the integer transform (IT) coefficients of H.264. Simulation results show that the proposed methods provide visually fine images. Moreover, the computational complexity of the proposed method is reduced compared with the conventional method, since the number of the DCT coefficients, which should be converted, is reduced in the first part.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.6
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• pp.272-282
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• 2001

This paper developed improved fast Walsh transform based on dyadic-ordered fast Walsh transform, then regenerated signal flow graph of improved fast Walsh transform, and used it for digital filtering, and then measured fundamental frequency and harmonics for current and voltage signals of power system. Using the improved fast Walsh transform, we present a new algorithm which reduces the computational amount, and it can consequently calculate the real and imaginary components for current and voltage signals of power system in sampling intervals. The calculation amount is reduced to 2(N-1) at N samples to measure full harmonics using developed algorithm. When, in single harmonic measuring, it needs only 2(log2N-1) additions and subtractions.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.11
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• pp.610-616
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• 2000

This paper presents an active noise control algorithm via Walsh transform domain controller learned by genetic algorithm. Typical active noise control algorithms such as the filtered-x lms algorithm are based on the gradient algorithm. Gradient algorithm have two major problems; local minima and eigenvalue ratio. To solve these problems, we propose a combined algorithm which consist of genetic learning algorithm and discrete Walsh transform called Walsh Transform Domain Genetic Algorithm(WTDGA). Analyses and computer simulations on the effect of Walsh transform to the genetic algorithm are performed. The results show that WTDGA increase convergence speed and reduce steady state errors.

• Journal of Biomedical Engineering Research
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• v.17 no.3
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• pp.347-354
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• 1996

This paper presents digital hearing aids signal processing system in WT(wavelet transform) domain. For implementation of hearing aids in WT domain, the gain in frequency domain is approximated in WT domain. We also present the gain selection algorithm to deal with the change of input signal power. Most transform methods produce blocking effect, and this effect degrades the convergence rate of feedback canceller. As a solution, we proposed wavelet transform bascd feedback canceller. To evaluate the performance, we compared it with LOT (lapped orthogonal transform) method in the frequency domain. This system has not shown the blocking effect, and improves convergence rate as compared with the LOT based feedback canceller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.827-832
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• 2003

There has been a number methods for the presentation of time-frequency analysis of non-stationary signal. In this paper, STFT(short time Fourier transform), wavelet transform, Wigner distribution, and higher order Wigner distribution are discussed in details with simulation signals. They are also applied to the analysis of the wave propagation of a semi finite beam. Wigner distribution and higher order Wigner distribution have good time-frewuency resolutions. Wavelet transform is required for impact analysis but should be applied carefully. STFT suffers from time-frequency resolutions. Each method is has its advantage and disadvantage depending on each application signals.