• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
• /
• pp.2351-2354
• /
• 2003

A new transform coder for arbitrarily shaped image segments is proposed. In the encoder, a block-based DCT is applied to the resulting image block after shifting pixels within the image segment to block border and padding the mean value of the pixels to empty region. For reducing the transmission bit rate, the transform coefficients located in padded region are truncated and only the remaining transform coefficients are transmitted to the decoder. In the decoder, the transform coefficients truncated in the encoder are recovered using received transform coefficients and a block-based inverse DCT is performed.

• 한국통신학회논문지
• /
• 제32권7C호
• /
• pp.601-607
• /
• 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.

• Kyungpook Mathematical Journal
• /
• 제62권3호
• /
• pp.557-581
• /
• 2022

The anisotropic-diffusion convection equation with exponentially variable coefficients is discussed in this paper. Numerical solutions are found using a combined Laplace transform and boundary element method. The variable coefficients equation is usually used to model problems of functionally graded media. First the variable coefficients equation is transformed to a constant coefficients equation. The constant coefficients equation is then Laplace-transformed so that the time variable vanishes. The Laplace-transformed equation is consequently written as a boundary integral equation which involves a time-free fundamental solution. The boundary integral equation is therefore employed to find numerical solutions using a standard boundary element method. Finally the results obtained are inversely transformed numerically using the Stehfest formula to get solutions in the time variable. The combined Laplace transform and boundary element method are easy to implement and accurate for solving unsteady problems of anisotropic exponentially graded media governed by the diffusion convection equation.

• 한국항행학회논문지
• /
• 제12권4호
• /
• pp.378-383
• /
• 2008

본 논문에서는 DCT 변환과 퍼지추론을 이용하여 영상을 분석하는 방법을 제안 한 바, 병해충 과실 등의 특성을 분석 할 수 있는 퍼지추론 알고리즘과 변환계수에 시각특성파라미터를 접목하는 방법에 중점을 두었다. 전처리 과정에서 이산코사인 변환계수로부터 엔트로피와 텍스처 등의 시각특징 파라미터들을 구하였고, 이 변수들을 이용하여 퍼지 추론의 입력 변수를 생성 하였다. 맘다니 연산자와 ${\alpha}$-cut 함수를 적용하여 영상 분석을 실험한 결과, 제안한 방법의 응용가능성을 입증하였다.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 2000년도 추계학술대회 학술발표 논문집
• /
• pp.149-152
• /
• 2000

This paper addresses the wavelet fuzzy modeling using Virus-Evolutionary Genetic Algorithm (VEGA). We build a fuzzy system model which is equivalent to the wavelet transform after identifying the coefficients of wavelet transform. We can obtain an accurate system model with a small number of coefficients due to the energy compaction property of the wavelet transform. It thus means that we can construct a fuzzy system model with a small number of rules. In order to identify the wide-ranged coefficients of the wavelet transform, VEGA is adopted, which has prominent ability to avoid premature local convergence that is suitable to complex optimization problems. We demonstrate the superiority of our proposed fuzzy system modeling method over the previous results by modeling nonlinear function.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 하계종합학술대회 논문집
• /
• pp.745-748
• /
• 1999

This paper propose the method to derive RM(Reed-Muller) expansion coefficients for Multiple-Valued function. The general method to obtain RM expansion coefficient for p valued n variable is derivation of single variable transform matrix and expand it n times using Kronecker product. The transform matrix used is p$^{n}$ $\times$ p$^{n}$ matrix. In this case the size of matrix increases depending on the augmentation of variables and the operation is complicated. Thus, to solving the problem, we propose derivation of RM expansion coefficients using p$\times$p transform matrix and Karnaugh-map.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 2006년도 가을 학술발표논문집 Vol.33 No.2 (D)
• /
• pp.302-305
• /
• 2006

In this paper, we have proposed a novel method using quantization of wavelet coefficients for secret data communication. First, speech signal is partitioned into small time frames and the frames are transformed into frequency domain using a WT(Wavelet Transform). We quantize the wavelet coefficients and embedded secret data into the quantized wavelet coefficients. The destination regard quantization errors of received speech as seceret dat. As most speech watermark techniques have a trade off between noise robustness and speech quality, our method also have. However we solve the problem with a partial quantization and a noise level dependent threshold. In additional, we improve the speech quality with de-noising method using wavelet transform. Since the signal is processed in the wavelet domain, we can easily adapt the de-noising method based on wavelet transform. Simulation results in the various noisy environments show that the proposed method is reliable for secret communication.

• 한국통신학회논문지
• /
• 제32권8C호
• /
• pp.729-737
• /
• 2007

가장 최근에 표준화된 H.264/AVC 동영상 압축 부호화 방식은 기존의 방법인 MPEG-2에 비해 우수한 압축 효율을 보이지만, 아직 많은 응용분야에서 MPEG-2가 적용되고 있기 때문에 MPEG-2에서 H.264/AVC로의 변환 기법 개발이 필요하다. 본 논문에서는 이러한 변환을 위해 가장 첫 번째 단계로 볼 수 있는 DCT 계수에서 H.264 변환 계수로의 변환을 위한 효율적인 방법을 제안한다. 이러한 변환은 영상의 압축을 위한 변환기술로 MPEG-2에서는 $8{\times}8$ discrete cosine transform(DCT)를 사용하고 있고, H.264/AVC 표준안에서는 $4{\times}4$ integer transform을 사용하고 있기 때문에 필수적이다. 제안하는 알고리듬에서는 부호화 성능을 유지하면서 효율적으로 계산량을 감소시킬 수 있는 방법을 제시하고 계산량 분석과 모의실험을 통해서 이를 입증한다.

• ETRI Journal
• /
• 제4권3호
• /
• pp.18-29
• /
• 1982

In a block adaptive filtering procedure, the filter coefficients are adjusted once per each output block while maintaining performance comparable to that of widely used LMS adaptive filtering in which the filter coefficients are adjusted once per each output data sample. An efficient implementation of block adaptive filter is possible by means of discrete transform technique which has cyclic convolution property and fast algorithms. In this paper, the block adaptive filtering using Fermat Number Transform (FNT) is investigated to exploit the computational efficiency and less quantization effect on the performance compared with finite precision FFT realization. And this has been verified by computer simulation for several applications including adaptive channel equalizer and system identification.

• 한국통신학회논문지
• /
• 제30권9C호
• /
• pp.860-870
• /
• 2005

본 논문에서는 karnaugh map(k-map)상의 셀을 이용하여 $2^{n}$개의 서로 다른 극수(polarity)를 갖는 GRM(Generalized Reed-Muller)상수를 생성하는 새로운 기법을 제안하였다. n개의 입력변수에 대한 일반적인 GRM 함수의 생성 방법은 단일 변수에 대한 변환 행렬을 구하고 이를 n번의 Kronecker 곱을 행한 변환 행렬을 이용하여 GRM 상수를 구하는 것이다. 이런 방법을 사용하는 경우, 변수의 숫자가 증가함에 따라 변환 행렬의 차수가 $2^{n}\times2^{n}$로 커지는 단점을 갖는다. 이에 반하여 본 논문에서는 k-map상에서 변수를 축약시킨 셀 [$f_{i}$]을 구하고 이를 단일 변수 변환 행렬과 연산하여 GBM 상수를 구하는 새로운 기법을 제안한다. 본 논문에서 제안한 새로운 방법과 타 논문과의 비교를 한 결과, 기존 방법은 가산기, 승산기, KP(Kronecker 곱 승산기)회로가 필요한데 반하여 본 논문에서는 가산기만이 필요하므로 효율적인 VLSI 설계에 유리하다