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프레임 차등 신호 영역에서 변환 부호화 방식의 성능 비교
권상근 金烏工科大學校 1991 論文集 Vol.12 No.-
In the hybrid coding of a simple temporal prediction and transform coding., the DCT is adopted in many existing codecs because of it's good performance. The DCT is superior to other transform in the original domain, but in the FD domain, it may not have as good performance as in the original domain because the statistical properties of the FD are quite different from those of original image. In this paper, the statistical properties of FD are derived. Three transforms-DCT, WHT, HCT are compared in the FD domain by means of measures such as energy compaction ratio and rate-distortion function. As a result of simulation, it was found that in FD domain, the HCT have very similar performance to DCT.
권상근 한국통신학회 1992 韓國通信學會論文誌 Vol.17 No.6
본 논문에서는 인접 블록을 중복하며 변환하는 방식이 제안되었다. 제안된 방식은 웨이브렛 기저를 가지며 이러한 변환은 블록 효과를 감소시킨다. 모의실험 결과 중복 웨이브렛 변환은 이산 여현 변환과 거의 같은 성능을 보이며 블록 효과는 많이 감소함을 알 수 있었다. OWT is a tool for block transform coding with wavelet basis functions that overlap adjacent blocks. The OWT can reduce the block effect. Without increasing the transmission data in this paper transform matrix of OWT Is presented. Some simulation results show that performances are early same to BCT, but block effect is reduced to very low level.
직교 웨이브렛 기저를 이용한 일반화된 M-차원 중복 변환의 고속 구현 알고리즘
권상근 金烏工科大學校 1996 論文集 Vol.17 No.-
The design methods of orthogonal wavelet bases are closely related to its of QMF filter bank. In this paper, we proposed the fast implementation algorithm when signal is decomposed into generalized M-band by employing the orthogonal wavelet bases with its length L=2M. When direct filtering method is used, the number of multiplication and addition is 2M²and 2M²-M, respectively. But th number of Multiplication and addition is reduced to M²+M+l and M²+2M-1, respectively, by employing the proposed algorithm. Especially, the number of operation is reduced more when used unitary matrix can be implemented by fast algorithm.
M-대역 직교 웨이브렛 필터 뱅크를 이용한 경계영역 에지 검출을 위한 경계 필터의 설계
권상근 金烏工科大學校 2000 論文集 Vol.21 No.-
When infinite length signal is decomposed into M-band signals using M-band orthogonal wavelet filters, edge of image can be detected from the decomposed images. But in the case of image which has the finite length, it is difficult to detect the edges exactly in the boundary region by having the different dimension between the original image and the decomposed images. So to detect the edges in boundary region, new filters are applied to them. In this paper, the design method of boundary filters which can be detected the edge of boundary region perfectly was proposed, in case the dimension of M-band decomposed signal is the same as that of input signal. The boundary filters were designed using the perfect reconstruction condition of paraunitary matrix. In an application of edge detection of still image, the proposed boundary filters show better performance in edge detection of boundary region than the reflected method.
무손실 시스템을 이용한 일반화된 M-대역 웨이브렛 필터의 설계
권상근,김재균 대한전자공학회 1994 전자공학회논문지-B Vol.b31 No.12
Lossless system has been employed to design the perfect reconstruction filter banks and has particularly a close relation with the desing of orthogonal wavelet filter (OWF). With such a relation, we generalize 2-band OWF to the M-band OWF which has an improved performances. The improvement is achieved using the two techniques. One is that the wavelet low pass filter has (N-1)th order regularity with extra zeros while the existing filter has N-th order regularity. The other is that unitary matrix is designed by adding the zeros to the proper positions. As a result, M-band OWF designed by propose method has better performance than M-band OWF designed by exsiting method.
M-대역 직교 웨이브렛 필터를 이용한 부대역 부호화에서 경계 필터의 설계
권상근 한국정보통신학회 2000 한국정보통신학회논문지 Vol.4 No.5
유한길이 신호가 M-대역 직교 웨이브렛 필터로 구성된 QMF 뱅크의 입력인 경우, 이의 재생신호의 경계영역들은 완전히 재생되지 않는다. 따라서 경계영역신호를 완전히 재생하기 위해서는 경계영역에는 새로운 형태의 필터를 적용하여한다. 본 논문에서는 M-대역으로 분해된 신호가 입력신호와 같은 차원을 가지는 경우 경계영역 을 완전히 재생할 수 있는 경계필터의 설계방법을 제안하였다. 제안된 경계필터는 파라유니터리 행렬의 완전재생조건을 이용하여 설계되었다. 제안된 경계 필터를 부대역 부호화에 적용하여 모의실험한 결과 반사기법을 이용한 경우에 비하여 약 5%의 성능이 개선됨을 알 수 있었다. When finite length signal is the input of QMF banks which are composed of the M-band orthogonal wavelet filter, the boundaries of reconstructed signal are not reconstructed perfectly. For boundary signals to be reconstructed perfectly, different type filters or methods are applied to them. In this paper, the design method of boundary filters which can be reconstructed the boundary signal perfectly was proposed, in case the dimension of M-band decomposed signal is the same as that of input signal. The boundary filters were designed using the perfect reconstruction condition of paraunitary matrix. In an application of subband coding of still image, the proposed boundary filters achieve better PSNR about 5% in reconstructed image than reflected method at the same bit rate.
권상근,서성훈,Kwon, Sang-Keun,Seo, Seong-Hoon 한국약제학회 1995 Journal of Pharmaceutical Investigation Vol.25 No.2
Alginic acid is a hydrophilic , colloidal polysaccharide obtained from cell wall of seaweed or brown algae and has a broad range of applications. Alginlc acid becomes alginate gel bead due to its cation-induced gelation. Dried alginate beads can be reswollen according to environmental pH. The purpose of this paper is to explore the possible applicability of alginate beads as an oral controlled release system of ibuprofen. In this experiment ibuprofen was incorporated in alginate beads and alginate beads were treated with various methods. Ibuprofen release from alginate beads in phosphate buffer (pH 7.4) was laster than in distilled water and dilute HCl. The release of ibuprofen was more sustained in bead than simple mixture and coprecipitate of ibuprofen and sodium alginate. The dissolution rate of ibuprofen was decreased in using of bead that hardened with formaldehyde. The dissolution rate of the drug from the bead was the fastest in 12 hour dried beads, 1.5%-sodium alginate concentration and 1%-calcium chloride concentration. Sodium alginate bead can be used as a sustaind release drug delivery system of water-insoluble drugs.