• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.296-298
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• 2011

본 논문에서는 향상된 중간 시점 합성 영상을 위한 깊이 영상 부호화 방식을 제안한다. 깊이 영상은 실제 영상과 다르게 날카로운 경계를 기준으로 완만한 변화를 가지는 픽셀 값을 가지는 특성이 있다. 따라서 깊이 영상의 부호화에서는 경계 영역을 효율적으로 부호화하는 것이 중요하다. 기존의 다시점 비디오 부호화기 (Multiview Video Coding)가 하나의 프레임 내에서 고정된 양자화 파라미터 값을 사용하는 것에 반해, 제안된 방식에서는 경계 영역을 효율적으로 부호화하기 위해 블록의 특성에 따라 적응적으로 양자화 파라미터를 할당한다. 2 차 미분 영상의 분포에 기반해 각 블록을 경계 블록, 평탄 블록, 일반 블록으로 구분하고 이에 따라 양자화 파라미터를 할당한다. 실험결과로서, 제안하는 방법의 성능이 다시점 비디오 부호화기 참조 소프트웨어 JMVC 8.3 에 비하여 BD-PSNR 이 평균 0.18dB 향상되고, BD-BR 은 평균 4.03% 감소되어 부호화 효율이 우수함을 확인할 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.465-474
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• 2005

In this paper, a directional reconstruction of lost block in image over noisy channel is presented. DCT coefficients or pixel values in the lost blocks are recovered by using the linear interpolation with available neighboring blocks that are adaptively selected by the directional measure that are composed of the DDC (Difference of DC opposite blocks)and SAC(Similarity of AC opposite blocks) between opposite blocks around lost blocks. The proposed directional recovery method is effective for the strong edge and texture regions because we do not make use of the fixed 4-neighboring blocks but exploit the varying neighboring blocks adaptively by the directional information in the local image. In this paper, we describe the novel directional measure(CDS: Combination of DDC and SAC) composed of the DDC and the SAC and select the usable block to recover the lost block with the directional measure. The proposed method shows about 0.6dB PSNR improvement in average compared to the conventional methods.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.397-404
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• 2012

The purpose of this study is to investigate the change of hamstring muscle relaxation and craniosacral reciprocal movement by using S. O. T. (sacrooccipital technique) categoryⅠ block-intervention process. 26 subjects with heel tension were randomly divided into two groups (EXP=13 and CON=13). This study carried out the category I block-intervention process on the experimental group and the false block-intervention process on the control group. Then, this study measured the sit-and-reach and sacral reciprocal movement of subjects before and after the intervention. The result values before and after the intervention were analyzed through ANCOVA by using SPSS PC Program (Ver. 20.0). In both investigations, the degree of hamstring muscle relaxation and the change of sacral reciprocal movement, there were statistically significant differences between the experimental group and the control group as [F(1, 23)=7.73, p<0.5] and [F(1, 23)=7.07, p<.05] respectively. According to the results of this study, it is expected that S. O. T category I bllock-intervention technique will have positive effect on both hamstring muscle relaxation and craniosacral reciprocal movement.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.125-130
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• 2004

With development of information communications and network environments security importance to the informations deepen as time goes. In this viewpoint, cryptosystem is developing but proportionally cracking and hacking technology is developing Therefore, in this paper we proposed and designed block cryptosystem with byte variable operation. Designed cryptosystem based on byte operation is safe than existed cryptosystem because it is not generate the fixed DC and LC characteristics. Additionally, proposed cryptosystem have high processing rate and authenticated operation. Therefore proposed cryptosystem is considered to many aid in the network fields.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9B
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• pp.1299-1307
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• 2001

고정된 패턴을 사용하는 기존의 고속 블록기반 움직임 추정법에서는 국소 최소해로 고립될 가능성이 있을 뿐만 아니라, 여러 움직임이 공존하는 움직임 경계에서 정확한 움직임의 추정이 어렵다는 문제점을 가지고 있다. 이러한 문제점을 극복하기 위하여 본 논문에서는 탐색점의 수를 줄이는 동시에 국소 최소해로의 고립을 피하기 위하여 탐색 후보영역을 적용한 다중 국소 탐색법(multiple local search method : MLSM)을 제안한다. 또한, 블록 내의 움직임 영역별 정합오차의 최소편차를 고려하는 새로운 정합함수를 제안함으로써 움직임 경계에서 움직임 벡터추정의 부정확성과 움직임 보상영상에서의 화질저하문제를 개선하고자 한다. 실험결과, 제안한 방법은 기존의 방법에 비해 움직임 경계에서의 추정에서 우수한 결과를 보였으며, PSNR에 대해서도 전역탐색법과 유사한 결과를 얻을 수 있었고, 움직임 보상결과, 움직임 경계부근에서의 향상된 화질을 얻을 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.778-784
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• 2012

A symmetric block cryptosystem uses an identical cryptographic key at encryption and decryption processes. HIGHT cipher algorithm is 64-bit block cryptographic technology for mobile device that was authorized as international standard by ISO/IEC on 2010. In this paper, block cipher HIGHT algorithm is designed using Verilog-HDL. Four modes of operation for block cipher such as ECB, CBC, OFB and CTR are supported. When continuous message blocks of fixed size are encrypted or decrypted, the desigend HIGHT core can process a 64-bit message block in every 34-clock cycle. The cryptographic processor designed in this paper operates at 144MHz on vertex chip of Xilinx, Inc. and the maximum throughput is 271Mbps. The designed cryptographic processor is applicable to security module of the areas such as PDA, smart card, internet banking and satellite broadcasting.

• The KIPS Transactions:PartB
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• v.17B no.6
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• pp.405-412
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• 2010

Previous background generation techniques showed bad performance in complex environments since they used only temporal contexts. To overcome this problem, in this paper, we propose a new background generation method which incorporates spatial as well as temporal contexts of the image. This enabled us to obtain 'clean' background image with no moving objects. In our proposed method, first we divided the sampled frame into m*n blocks in the video sequence and classified each block as either static or non-static. For blocks which are classified as non-static, we used MRF framework to model them in temporal and spatial contexts. MRF framework provides a convenient and consistent way of modeling context-dependent entities such as image pixels and correlated features. Experimental results show that our proposed method is more efficient than the traditional one.

• Journal of Broadcast Engineering
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• v.4 no.2
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• pp.127-133
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• 1999

The conventional fractal image compression based on discrete wavelet transform uses the fixed block size in fractal coding and reduces PSNR at low bit rate. This paper proposes a fractal image coding based on discrete wavelet transform which improves PSNR by using variable block size in fractal coding. In the proposed method. the absolute values of discrete wavelet transform coefficients are computed. and the discrete wavelet transform coefficients of different highpass subbands corresponding to the same spatial block are assembled. and the fractal code for the range block of each range block level is assigned. and then a decision tree C. the set of choices among fractal coding. "0" encoding. and scalar quantization is generated and a set of scalar quantizers q is chosen. And then the wavelet coefficients. fractal codes. and the choice items in the decision tree are entropy coded by using an adaptive arithmetic coder. This proposed method improved PSNR at low bit rate and could achieve a blockless reconstructed image. As the results of experiment. the proposed method obtained better PSNR and higher compression ratio than the conventional fractal coding method and wavelet transform coding.rm coding.

• Journal of Broadcast Engineering
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• v.27 no.4
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• pp.477-486
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• 2022

In this paper, we propose a novel intra-prediction method using convolutional neural network (CNN) to improve a quality of a predicted block in VVC. The proposed algorithm goes through a two-step procedure. First, an input prediction block is generated using one of the VVC intra-prediction modes. Second, the prediction block is further refined through a CNN model, by inputting the prediction block itself and reconstructed reference samples in the boundary. The proposed algorithm outputs a refined block to reduce residual signals and enhance coding efficiency, which is enabled by a CU-level flag. Experimental results demonstrate that the proposed method achieves improved rate-distortion performance as compared a VVC reference software, I.e., VTM version 10.0.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.67-70
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• 2009

H.264/AVC 동영상 표준은 기존의 동영상 표준과 비교했을 때 뛰어난 압축률을 보인다. 특히 세밀한 움직임 예측을 통해 영상을 효율적으로 압축하지만 움직임 예측은 H.264/AVC 동영상 표준의 높은 복잡도의 원인 중 하나이다. 따라서 H.264/AVC의 부호화 시간을 단축하기 위해서는 고속 움직임 추정 기법이 필수적이다. 일반적으로 영상 신호는 인접한 화면과 매크로블록 사이에서 상관관계가 높고 부호화하고자 하는 매크로블록의 움직임벡터는 인접한 매크로블록에서 결정된 최적의 움직임 벡터와 유사한 방향성을 가진다. 그러므로 고정된 탐색 영역의 크기를 이용하면 불필요한 영역까지 움직임 예측 과정이 수행되어 계산량이 증가한다. 본 논문에서는 영상의 공간적, 시간적 상관도를 이용하여 탐색 영역의 크기를 결정하는 방법을 제안한다. 인접하는 블록들의 움직임 벡터의 표준편차를 이용하여 움직임이 작은 영역에서는 작은 탐색 영역을 이용하여 움직임 예측을 수행하고 반대로 움직임이 큰 영역에서는 큰 탐색 영역을 이용하여 움직임 예측을 수행한다. 또한 현재 화면과 참조 화면의 거리차가 클수록 참조 화면으로 선택되는 확률이 낮다는 사실을 이용하여 적응적으로 탐색 영역의 크기를 조절한다. 제안한 방법은 기존의 전 영역 탐색 방법과 유사한 부호화 성능을 보이면서 움직임 예측 시간이 평균 약 58.93% 감소하는 것을 확인할 수 있다.