• Broadcasting and Media Magazine
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• v.15 no.4
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• pp.45-54
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• 2010

최근 ISO/IEC와 ITU는 공동협력팀(Joint Collaborative Team on Video Coding-JCT-VC)을 구성하여 HEVC(High Efficiency Video Coding)라 불리는 새로운 비디오 압축 표준 기술을 개발하고 있다. JCT-VC의 목표 중 하나는 H.264/AVC 압축률의 2배를 향상하는 것으로 최근 HEVC 테스트 모델(HEVC Test Model - HM)을 확정했다. HM의 여러 기술 중에서 확장 블록 구조 (large block structure) 기술은 CTB(Coded Tree Block)와 TU(Transform Unit), PU(Partition Unit)로 구성된다. CTB와 TU는 압축 단위와 변환 기술을 확장한 반복적인 문법구조(recursive syntax structure)이며, PU는 H.264/AVC과 동일한형태를 띈다. 확장 블록 구조는CTB, PU, TU의 여러 조합에 의해 다양한 모드를 지원하여 압축 성능은 높아졌지만 HM 부호화기의 복잡도는 증가한다. 본 논문에서는 HM에 채택된 확장블록구조 및 변환 기술에 대해 설명한 후, TMuC 및 HM의 테스트 영상을 이용하여 다양한 최대 CTB 및 TU 크기의 압축성능 및 선택비율을 분석한다.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.113-116
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• 2002

We demonstrate 16 ch.$\times$2.5 Gb/s WDM transmission over 10,880 km using a re-circulating loop and forward error correction (FEC) code. The performances of all 16 channels were measured to be lower than 10$^{-10}$ .

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.487-497
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• 1999

In this paper, the performances of MC-CDMA systems for wireless ATM(WATM) is analyzed through computer simulations. The proposed MC-CDMA systems can support the 25 Mbps data rate with about 18.2 MHz bandwidth at 5 GHz carrier frequency, satisfying the specifications of wireless physical layer proposed by Wireless ATM Working Group(WATM WG). For the channel coding strategies, convolutional code, TCM and Turbo TCM(T-TCM) are explored and their performances are compared. From the simulation results, T-TCM becomes superior to the other coding schemes as interative decoding is performed.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.83-86
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• 1999

In this paper, a serially concatenated space-time code (SCSTC) with bandwidth efficiency and high data rate is studied. The suggested SCSTC is composed of space-time code, the convolutional code and Interleaver. The SCSTC has a very high BER performance than the conventional space-time code. The BER performance of the suggested SCSTC can be proven by using computer simulation through the iterative decoding method. The first decoder uses Symbol-MAP algorithm and the second decoder uses Bit-MAP algorithm for decoding tile information bits. The simulation results show the performance of the suggested SCSTC is better than the conventional Space-Time Code.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.42-45
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• 2011

최근ISO/IEC와 ITU는 공동 협력팀(Joint Collaborative Team on Video Coding-JCT-VC)을 구성하여 HEVC(High Efficiency Video Coding)라 불리는 새로운 비디오 압축 표준 기술을 개발하고 있다. JCT-VC의 목표 중 하나는 H.264/AVC 압축률의 2배를 향상하는 것으로 최근 HEVC 테스트 모델(HEVC Test Model - HM)을 확정했다. HM의 여러 기술 중에서 확장 블록 구조 (large block structure) 기술은 CU(Coding Unit)와 TU(Transform Unit), PU(Partition Unit)로 구성된다. CU와 TU는 압축 단위와 변환 기술을 확장한 반복적인 문법구조(recursive syntax structure)이며, PU는 H.264/AVC과 동일한 형태를 띈다. 확장 블록 구조는 CU, PU, TU의 여러 조합에 의해 다양한 모드를 지원하여 압축 성능은 높아졌지만 HM 부호화기의 복잡도는 증가한다. 본 논문에서는 HM에 채택된 확장 블록 구조 기술에 대해 설명한 후, 계층적 B프레임 구조로 부호화 되는 경우 이전 레벨의 CU Depth 정보를 이용하여 현재 레벨의 CU Depth를 효과적으로 제한하여 기존의 방법보다 빠르게 부호화하는 방법을 제안한다.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.179-180
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• 2007

In this paper, it proposes an efficient iterative stopping rules using absolute mean values for the LLR difference values between the first and second decoder in the present decoding process. It is verifying that the proposal algorithm can be reduced the average number of iterations compared to conventional scheme with a negligible degradation of the error performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.21-28
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• 2004

In this paper we apply block turbo coding at the transmitter and iterative decoding algorithm at the receiver for different operating modes, based on the 5 ㎓ IEEE 802.1 la WLAN system, instead of convolutional coding and soft decision viterbi algorithm to improve forward error correcting performance. Experimental results showed that each coding scheme outperforms coding gains of up to 3.5 ㏈ at the BER of 10$\^$-3/.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.321-324
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• 2000

채널만을 고려한 부호화 방법보다 소스의 특성을 이용해 채널 부호화를 수행하는 것이 더 효율적이라는 사실은 일반적으로 잘 알려져 있다. 따라서 소스의 특성을 이용한 채널 부호화 방법은 중요한 연구과제이며 이에 대한 많은 연구가 진행되었다. 이러한 연구 결과로써 IP-SCCC(Interleaved puncturing serially concatenated convolutional codes)는 터보코드와 마찬가지로 반복복호가 가능하고 가변 부호율의 채널부호화를 수행할 수 있는 특징을 갖는다. 본 논문에서는 영상에 대한 웨이블렛 변환의 다른 스케일간의 자기 유사성을 이용한 SPIHT(set partitioning in hierarchical tree) 알고리즘으로 부호화된 정지영상에 대해 IP-SCCC를 사용한 UEP(unequal error protection) 채널부호화 방법을 제시한다. 또한 레일리 페이딩과 부가 백색 가우시안 잡음이 동시에 존재하는 채널을 모델링해서 실험을 수행하고 제안 방법의 성능을 검증한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.6 s.360
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• pp.42-49
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• 2007

CABAC(Context-based Adaptive Binary Arithmetic Coding) among various entropy coding schemes which are used to improve compression efficiency in H.264/AVC has a high hardware complexity and the fast calculation is difficult because data dependancy exists in the bit-serial process. In this paper, the proposed architecture efficiently compose the renormalization process of binary arithmetic encoder which is an important part of CABAC used in H.264/AVC. At every clock cycle, the input symbol is encoded regardless of the iteration of the renormalization process for every input symbol. Also, the proposed architecture can deal with the bitsOutstanding up to 127 which is adopted to handle the carry generation problem and encode input symbol without stall. The proposed architecture with three-stage pipeline has been synthesized using the 0.18um Dongbu-Anam standard cell library and can be operated at 290MHz.

• Journal of Broadcast Engineering
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• v.4 no.1
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• pp.76-85
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• 1999

The degradation of image quality by block loss is more serious in fractal coded images with the error propagation due to mapping from the lost blocks than in DCT coded images. Therefore. a new algorithm is presented for recovering the blocks lost in the transmission through the lossy network as A TM network of the images coded by Jacquins fractal coding. Jacquins fractal code is divided into two layers of header code and main code according to its importance. The key technique of the proposed BLRA (block loss recovery algorithm) is a fractal extrapolation that estimates the lost pixels by using the contractive mapping parameters of the neighboring range blocks whose characteristics are similar to a lost block. The proposed BLRA is applied to the lost blocks in the iteration of decoding. Some experimental results show the proposed BLRA yields excellent performance in PSNR as well as subjective quality.