• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.2
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• pp.149-159
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• 2001

The conventional block-based motion prediction suffers, especially in low bit-rate video application, from shortcomings such as blocking artifacts of motion field and unstable motion estimation. To overcome the deficiency, this paper proposes one method of adopting a new motion compensation scheme based on the irregular triangular mesh structure while keeping the current block-based DCT coding structure of H.263 as much as possible. To represent the reconstructed previous frame using minimal number of control points, the proposed method designs content-adaptive irregular triangular meshes, and then, estimate the motion vector of each control point using the affine transformation-based matching. The predicted current frame is obtained by applying the affine transformation to each triangular mesh. Experiment with the several real video sequences shows improvement both in objective and subjective picture quality over the conventional block-based H.263 method.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.11
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• pp.112-119
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• 1999

TMN5 has been used to evaluate the performance of H.263, the ITU-T/LBC standard of moving picture coding. As DCT is used as transform coding methods in TMN5, blocking effect exists seriously in reconstruction picture at low bit rate. In this pater, DWT is substituted for DCT and adaptive quantizer is designed while the structure of TMN5 is maintained to be excellent in the transplantation of conventional system. It has shown that average PSNR is reduced by 0.35dB in luminance but increased by 2dB in chrominance comparing with that of TMN5. As block effect is reduced in reconstruction picture, the subjective picture quality is better than that of TMN5. Picture drop is, also, reduced because much more frames are transmitted at same bit rate.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.503-504
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• 2008

최근 정보통신 기술들이 빠르게 발전하고 있다. 다양한 통신 기술들 중에서도 업무의 효율을 높이고자 회사 및 가정, 학교 등에서 자주 사용되고 있는 영상채팅시스템을 구현해보고자 한다. 쿼타임 코덱 중 가장 보편적인 코덱으로 인코딩이 쉽고 저사양의 CPU만으로도 실시간 스트리밍이 가능한 H.263 코덱을 사용하여 영상채팅시스템을 Visual C++로 구현을 하였다. 전송로의 지연을 줄이기 위하여 영상, 음성, 텍스트 등을 압축하고 복원하는 데 걸리는 시간을 최소화기 위하여 데이터의 전송대역폭을 적절히 조절하는 알고리듬을 제안하여 전송지연을 최소화하였다. 또한 P2P 방식을 사용하여 다양한 영상 환경에 대하여 영상 및 텍스트 데이터의 안정성과 화질이 우수함을 보였으며, 실시간 가스안전관리 상담에 이용하여 업무의 효율을 높이고자 한다.

• Journal of the Korea Computer Industry Society
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• v.5 no.1
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• pp.123-130
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• 2004

In this paper, an advanced error tracking algorithm by using feedback channel was proposed for error resilient transmission. Using this proposed algorithm, the propagation of errors were reduced within the decoded data over bit error prone network. The addresses of corrupted blocks are reported to encoder by decoder. With negative acknowledgments of feedback channel, the encoder can precisely calculate negative acknowledgments and track the propagated errors by examining the backward motion dependency for proper pixel in the current encoding frame. The error-propagation effects can be terminated completely by INTRA refreshing the affected macro-blocks by using proposed error tracking algorithm. By utilizing the selective four-corner error tracking approximation, the error tracking computations of the proposed algorithm is less than that of the algorithm using full pixel without substantial degradation in video quality. The proposed algorithm can track errors rapidly and accurately.

• The KIPS Transactions:PartB
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• v.8B no.1
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• pp.43-49
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• 2001

이동통신 채널과 같이 에러 발생율이 높은 환경에서 부호화된 비디오를 전송할 때 채널에어에 손상된 비트스트림은 복호되기 어려울 뿐만 아니라, 비트스트림의 다른 부분으로까지 에러를 전파시킨다. 한 프레임에 손실블록이 있을 때 기존방법에서는 주변블록들의 움직임벡터 평균을 구하거나 비슷한 예측을 통해 손실블록의 움직임벡터를 복원한다. 그러나 손실블록이 움직이는 객체의 경계부근에서 발생할 때 기존방법은 효율적이지 못한다. 따라서 제안 알고리즘은 기존방법보다 정확한 움직임벡터를 예측하기 위해 손실블록의 주변블록들 중세서 동일한 움직임을 갖는 블록들로 구성된 영역을 찾은 후, 동일움직임영역에 포함된 블록들의 움직임벡터를 이용하여 손실된 블록을 복원한다. 실험결과 제안방법이 기존방법에 비해 PSNR과 시각적인 화질면에서 우수한 성능을 보임을 알 수 있다.

• Bulletin of the Korean Mathematical Society
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• v.47 no.2
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• pp.263-274
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• 2010

In this paper, a new class of general nonlinear variational inclusions involving H-monotone is introduced and studied in Hilbert spaces. By applying the resolvent operator associated with H-monotone, we prove the existence and uniqueness theorems of solution for the general nonlinear variational inclusion, construct an iterative algorithm for computing approximation solution of the general nonlinear variational inclusion and discuss the convergence of the iterative sequence generated by the algorithm. The results presented in this paper improve and extend many known results in recent literatures.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.79-86
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• 2008

H.264/AVC is the newest international video coding standard developed by the joint ITU-T and ISO/IEC standards organizations. This newest video coding standard offers much higher coding efficiency than the H.261, H.263 and MPEG-4. But it has high computing complexity and high H/W resources wasting problem. This paper described the two unit parallel pipeline structure. This new structure comparing with standard model decreased the computing complexity of 67% and the H/W resources waste of 3%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.263-264
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• 2007

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1518-1531
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• 1999

The reconstructed images from highly compressed MPEG or H.263 data have noticeable image degradations, such as blocking artifacts near the block boundaries, corner outliers at cross points of blocks, and ringing noise near image edges, because the MPEG or H.263 quantizes the transformed coefficients of 8$\times$8 pixel blocks. A post-processing algorithm has been proposed by authors to reduce quantization effects, such as blocking artifacts, corner outliers, and ringing noise, in MPEG-decompressed images. Our signal-adaptive post-processing algorithm reduces the quantization effects adaptively by using both spatial frequency and temporal information extracted from the compressed data. The blocking artifacts are reduced by one-dimensional (1-D) horizontal and vertical low pass filtering (LPF), and the ringing noise is reduced by two-dimensional (2-D) signal-adaptive filtering (SAF). A comparison study of the subjective quality evaluation using modified single stimulus method (MSSM), the objective quality evaluation (PSNR) and the computation complexity analysis between the signal-adaptive post-processing algorithm and the MPEG-4 VM (Verification Model) post-processing algorithm is performed by computer simulation with several MPEG-4 image sequences. According to the comparison study, the subjective image qualities of both algorithms are similar, whereas the PSNR and the comparison complexity analysis of the signal-adaptive post-processing algorithm shows better performance than the VM post-processing algorithm.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.377-385
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• 2004

The quantity of radioactive waste generated from HANARO operation for the years of 1996 to 2003 has been analysed. It was found that the solid waste of $72, 999{\ell}$ and liquid waste of $263, 576{\ell}$ have been generated for the past 8 years. The amounts of Ar-41, I-131 and H-3 exhausted to the environment were 1, 225.6 Ci, 1.612E-2 Ci and 210 Ci, respectively.