• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.36C no.9
• /
• pp.76-84
• /
• 1999

EZW proposed by Shapiro is based on a zerotree constructed in a way that a parent coefficient in a subband is related to four child coefficients in the next finer subband of similar orientation. This fixed treeing based on 1-to-4 parent-child is suitable to exploti hierachical correlations among subbands but not to exploit spatial correlations within a subband. A new treeing by Joo, et al. is suggested to simulatneously exploit those two correlatins by extending parent-child relationship in a flexible way. The flexible treeing leads to increasing the number of symbols and lowering entorpy comparing to the fixed treeing, and therefore a better compression can be resulted. In this paper, we suggest two techniques to suppress the increasing of symbols. First, a probing bit is generated to avoid redundant scan for insignivicant coefficients. Second, since all subbands do not always require the same kind of symbol-set, produced symbols are re-symbolized into binary codes according to a pre-defined procedure. Owing to those techniques, all symbols are generated as binary codes. The binary symbols can be entropy-coded by an adaptive arithmetic coding. Moerover, the binary symbol stream can give comparatively good performances without help of additional entropy coding. Our proposed coding scheme is suggested in two modes: binary coding mode and arithmetic coding mode. We evaluate the effectivenessof our modifications by comparing with the original EZW.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.4
• /
• pp.1048-1056
• /
• 1998

In this paper, a fractal image coding based on discrete wavelet transform is proposed to improve PSNR at low bit rates and reduce computational complexity of encoding process. The proposed method takes the absolute value of discrete wavelet transform coefficients, and then constructs significant coefficients trees, which indicate the positions and signs of the significant coefficients. This method improves PSNR and reduces computational complexity of mapping contracted domain pool onto range block, by matching only the significant coefficients of range block to coefficients of contracted domain block. Also, this paper proposes a classification scheme which minimizes the number of contracted domain blocks compared with range block. This scheme significantly reduces the number of range and contracted domain block comparison.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 1996.06a
• /
• pp.373-376
• /
• 1996

• Proceedings of the IEEK Conference
• /
• 2000.06d
• /
• pp.23-26
• /
• 2000

본 논문에서는 정확한 비트 제어가 가능한 I-frame의 효율적인 부호화 방법을 제안한다. 기존 H.263＋의 DCT 계수들을 트리 구조로 재구성하여 각 계수에 대해 임베이드 제로트리 부호화 알고리즘을 적용시켜 부호화함으로써 코딩 효율을 향상시킴과 동시에 비트 율의 제어가 용이하도록 한다. 제안 방법의 유효성을 검증하기 위해 표준 동영상에 대한 컴퓨터 모의 실험 결과 제안 방법은 기존의 부호화 방법에 비해 비트 제어가 용이하고 부호화 성능이 개선됨을 확인했다.

• Journal of Biomedical Engineering Research
• /
• v.21 no.3 s.61
• /
• pp.247-254
• /
• 2000

We propose an efficient MR image compression technique using fractal coding in wavelet transform domain. In the Proposed method , we construct significant coefficient trees with the absolute values of discrete wavelet transform coefficients and then perform the fractal coding with the information of significant coefficients having high energy. For MR images, most Pixels including background have very low gray level values, the number of significant coefficients is small. so we can expect high compression rate. In addition. since this method uses the fractal coding in wavelet transform domain, blocking artifact is reduced prominently and edges sensitive to human visual system are well preserved. As a result of computer simulation, we obtained the reconstructed images with better quality than those by JPEG at the low bit rates below 0.33[bpp].

• Journal of Korea Multimedia Society
• /
• v.4 no.6
• /
• pp.500-509
• /
• 2001

Image compression based on Wavelet gives much better quality than JPEG based on DCT, but suffers from ringing or blurring effects around edges as the compression is increased. In this paper, we proposed enhanced image compression by pre-processing wavelet coefficients. This pre-processing is performed by making a low threshold and enhanced by zerotree scan method when subband's zerotrees are established. It might increase significants coefficient by means of modifying the threshold and reflect on the orientation of subbands. Some experimental results show our method is more efficient than the conventional methods, JPEG. And then the developed coding scheme improves the quality of images and visually shows more pleasing results for most practical images.

• Proceedings of the IEEK Conference
• /
• 2000.09a
• /
• pp.291-294
• /
• 2000

본 논문에서는 웨이브릿 변환영역에서 개선된 모폴로지와 적응양자화를 이용한 영상부호화 방법을 제안한다 제안한 방법은 제로트리를 기반으로 한 기존의 방법들과 유사한 코딩성능을 가지면서 EZW, SFQ 등에서 나타나는 복잡성을 모폴로지를 사용하여 유효정보를 클러스터링 함으로써 복잡성을 줄일 수 있다. 그러나 클러스터의 개수가 많아지면 클러스터를 나타내는 부가정보의 양도 많아진다. 이러한 부가정보의 비율이 실제데이터에서 많은 비중을 차지하기 때문에 개선된 모폴로지를 적용하여 효율적으로 부호화 함으로써 영상의 화질을 개선하였다. 또한 고주파 대역에서의 유효계수를 효율적으로 코딩하기 위해 적응양자화를 적용하여 양자화 시 오차범위를 줄일 수 있다. 따라서 제안한 방법은 양자화 시 발생하는 많은 비교연산을 줄일 수 있으며, 기존의 방법에 비해 화질을 개선하였다.

• Korean Journal of Food Science and Technology
• /
• v.50 no.4
• /
• pp.420-429
• /
• 2018

Skin ageing is associated with compromised performance of its fundamental barrier functions, with undesirable changes in appearance. Since this may introduce a detrimental impact on the quality of life, significant effort to discover effective ingredients against ageing is being invested. Recently, collagen hydrolysates containing tripeptides such as GlyPro-Hyp (GPH) have been developed with anticipation of improved effects compared to that of existing collagen hydrolysate-products. To evaluate the cutaneous hydration effect of collagen tripeptides (CTP), meaningful biomarkers in human dermal fibroblasts (HDF) and NC/Nga Tnd mice were analyzed in this study. Increased levels of ceramide kinase, hyaluronic acid, collagen 1A, and hyaluronan synthase-2 (HAS2), and decreased levels of hyaluronidase-1 (HYAL1) and CD44 in HDF cells were demonstrated. Furthermore, significant reduction of transepidermal water loss (TEWL), scratching behavior, HYAL1, $TNF-{\alpha}$ and IL-6 and increased water content and HAS2 were verified by in vivo tests. These results strongly suggest the potential of CTP as a skin hydration agent.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.11
• /
• pp.62-71
• /
• 1996

In this paper we propose a method that improves PSNR at low bit rate and reduces computational complexity in fractal image coding based on discrete wavelet transform. The proposed method, which uses significant coefficient tree, improves PSNR of the reconstructed image and reduces computational comlexity of mapping domain block onto range block by matching only the significant coefficients of range block to coefficients of domain block. Also, the proposed method reduces error propagation form lower resolution subbands to higher resolution subbands by correcting error of lower resolution subbands. Some experimental results confirm that the proposed method reduces encoding and decoding time significantly and has fine reconstructed images having no blocking effect and clear edges at low bit rate.

• Food Science and Preservation
• /
• v.22 no.4
• /
• pp.559-566
• /
• 2015

The aim of this study was to develop an analytical method for determination of T-2 toxin and HT-2 toxin level in cereals and to survey their levels using LC-MS/MS. The T-2 and HT-2 toxins were simultaneously analyzed by electrospray ionization with a positive ion mode and multiple reaction monitoring (MRM) after filteration and immuno-affinity column clean-up. A matrix-matched standard calibration used for quantification and recoveries of T-2 and HT-3 toxins were in the range of $100.6{\pm}7.2%$ and $96.8{\pm}9.4%$, respectively. Limits of detection and quantification of T-2 and HT-2 toxins were estimated to be 0.5 and $1.5{\mu}g/kg$, respectively. Each repeatability (RSRr) of T-2 and HT-2 toxins was determined to be 0.9~6.0%, and 4.9~6.1%, respectively. Total 115 samples cereals were collected from 9 types of cereals for analysis. The positive percentages of T-2 and HT-2 toxins obtained from collected samples were found to be 72% and 80%, respectively. The contamination level of T-2 toxin and HT-2 toxin in cereals were $37.1{\mu}g/kg$, and $5.4{\mu}g/kg$, respectively. Therefore, this study suggests that the developed method could be an useful analytical method to determine the T-2 and HT-2 toxin level in cereals and the present data could be used as a reference to estimate the risk assessment.