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김정일(Kim Jeong Il),이광배(Lee Kwang Bae),김현욱(Kim Hyen Ug) 한국정보처리학회 1998 정보처리학회논문지 Vol.5 No.4
This paper describes a new fractal image coding algorithm to shorten time to take on fractal image encoding by using limited search area method and scaling method. First, the original image is contracted respectively by half and by quarter with the scaling method. And then, the corresponding domain block of the quarter sized image which is most similar with one range block of the half-sized image is searched within the limited area in order to reduce the encoding time extremely. This searched block is used in encoding. Also, we propose a algorithm to enhance compression ratio by using bit-plane image. As the result of the evaluation, the proposed algorithm provided much shorter encoding time and better compression ratio with a little degradation of the decoded image quality than Jacquin's method.
김정일(Kim Jeong Il),안광태(An Kwang Tae),김재철(Kim Jae Cheol),유충열(Yoo Choong Yeol),이광배(Lee Kwang Bae),김현욱(Kim Hyen Ug) 한국정보처리학회 1997 정보처리학회논문지 Vol.4 No.10
In this paper we propose new image coding using wavelet transform. The new method constructs hierarchical bit plane and progressively transports each bit plane. The proposed algorithms not only supports multi-resolution, dividing original image into special band and various resolution but also reduces blocking effects that come int JPEG. In encoding time this algorithm considers each band characters and priority of transport order, and applies to fast search of image.
이광배(Lee Kwang Bae),김현욱(Kim Hyen Ug),송광석(Song Kwang Suk),김정일(Kim Jeong Il),강경인(Kang Kyeong In),박경배(Park Gyong Bae) 한국정보처리학회 1996 정보처리학회논문지 Vol.3 No.5
In this paper, we propose a fast fractal image coding algorithm to shorten long to take on fractal image encoding. For its performance evaluation, the algorithm compares with other traditional fractal coding methods. In the traditional fractal image coding methods, an original image is contracted by a factor in order to make the corresponding image to be compared with. Then, the whole area of the contracted image is searched in order to find the fixed point of contractive transformation of the original image corresponding to the contracted image. It needs a lot of searching time on encoding. However, the proposed algorithm considerably reduces encoding time by using scaling method and limited search area method. On comparison of the proposed algorithm with Jacquin''s method, the proposed algorithm is at least 180 times as fast as that of Jacquin''s method on encoding time with a little degradation of the decoded image quality and a little increase of the compression rate. Therefore, it is found that the proposed algorithm largely improves the performance in the aspect of encoding time when compared with other fractal image coding methods.
강경인(Kang Kyeong In),김정일(Kim Jeong Il),정근원(Jeong Keun Won),이광배(Lee Kwang Bae),김현욱(Kim Hyen Ug) 한국정보처리학회 1997 정보처리학회논문지 Vol.4 No.3
In this paper, we propose a new algorithm to perform DCT(Discrete Cosine Transform) within the area reduced by predicting position of quantization coefficients to be zero. This proposed algorithm not only decreases the encoding time and the decoding time by reducing computation amount of FDCT(Forward DCT) and IDCT(Inverse DCT) but also increases compression ratio by performing each different horizontal-vertical zig-zag scan according to the classified block size for each block on the huffman coding. Traditional image coding method performs the same DCT computation and zig-zag scan over all blocks, however this proposed algorithm reduces FDCT computation time by setting to zero instead of computing DCT for quantization coefficients outside classified block size on the encoding. Also, the algorithm reduces IDCT computation time by performing IDCT for only dequantization coefficients within classified block size on the decoding. In addition, the algorithm reduces Run-Length by carrying out horizontal-vertical zig-zag scan appropriate to the classified block characteristics, thus providing the improvement of the compression ratio. On the other hand, this proposed algorithm can be applied to 16*16 block processing in which the compression ratio and the image resolution are optimal but encoding time and the decoding time take long. Also, the algorithm can be extended to motion image coding requiring real time processing.
윤성만(Sung man Yoon),박석천(Seok cheon Park),김현욱(Hyen ug Kim),이광배(Kwang bae Lee),안영훈(Young hun Ahn),임선배(Sun bae Lim),이택희(Teag hee Lee) 한국정보과학회 1994 한국정보과학회 학술발표논문집 Vol.21 No.2B
네트워크 관리 시스템으로서 네트워크 구성요소의 intelligent화에 따라 좀 더 경제적이고 효율적인 운용보전을 위해 운용보전 시스템(Operation And Maintenance system)을 이용한 운용보건 체제가 구축되고 있다. 본 연구에서는 이동통신망 상에서 정보의 전송을 정확하고 효율적으로 전송하기 위한 HLR용 No.7 접속모듈의 유지보수 및 운용관리 시스템으로서 공통선 신호망 운용방식과 네트워크 관리 시스템의 요구사항 분석을 통해 CMP를 효과적으로 운용, 유지, 관리 하는 OAM 시스템을 개발 하였으며, 성능 테스트를 통해서 CMPOAM 시스템의 올바른 기능 수행 결과를 확인하였다.
박경배(Park Kyung Bae),정우석(Jung Woo Suk),김정일(Kim Jung Il),정근원(Jeong Keun Won),이광배(Lee Kwang Bae),김현욱(Kim Hyen Ug) 한국정보처리학회 1995 정보처리학회논문지 Vol.2 No.5
프랙탈을 이용한 대부분의 영상 부호화는 최적의 유사 변환점을 얻기 위해서 방대한 비교 연산이 필요하여 장시간의 부호화 시간이 요구되는 문제점이 있다. 이러한 문제는 블럭특성에 적합한 블럭 분류기를 설계함으로써 해결할 수 있다. 일반적으로 공간 영역에서 보다는 주파수 영역에서 좀더 정확하고 다양한 블럭의 형태를 예측할 수 있다. 본 논문에서는 DCT특성을 이용하여 블럭의 형태를 예측할 수 있는 블럭 분류기를 제안하였다. 이 분류기는 프랙탈 특징과 부합하여 부호화 시간을 줄임과 동시에 복원된 영상의 화질을 높이는 장점이 있다. 주파수 영역에서의 AC 계수의 크기는 다양한 블럭 형태를 예측 가능하게 함으로써 최적의 축소 변환점을 얻기 위한 도메인 블럭과 레인지 블럭간에 비교 연산을 줄일 수 있다. 특히 DCT 각 계수의 부호값은 프랙탈 적용을 위한 8가지 변환에 대해 불필요한 변환을 생략함으로써 2가지 변환만으로도 축소 변환점을 찾는 장점을 나타낸다. Most fractal image codings using fractal concept require long encoding time because a large amount of computation is needed to find an optimal affine transformation point. Such a problem can be solved by designing a block classifier fitted to characteristics of image blocks. In general, it is possible to predict more precise and various types of blocks in frequency domain than in spatial domain. In this paper, we propose a block classifier to predict the block type using characteristics of DCT(Discrete Cosine Transform). This classifier has merits to enhance the quality of decoded images as well as to reduce the encoding time by meeting fractal features. AC coefficient values in frequency domain make it possible to predict various types of blocks. As the results, the number of comparisons between a range block and the corresponding domain blocks to reach an optimal affine transformation point can be reduced. Specially, signs of DCT coefficients help to find the optimal affine transformation point with only two isometric transformations by eliminating unnecessary isometric transformations among eight isometric transformations used in traditional fractal codings.