• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.1
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• pp.170-178
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• 2004

In this work a high speed 8-error correcting Reed-Solomon decoder is designed using the modified Euclid algorithm. Decoding algorithm of Reed-Solomon codes consists of four steps, those are, compute syndromes, find error-location polynomials, decide error-locations, and determine error values. The decoding speed is increased and the latency is reduced by using the parallel architecture in the syndrome generator and a faster clock speed in the modified Euclid algorithm block. In addition. the error locator polynomial in Chien search block is separated into even and odd terms to increase the overall speed of the decoder. All the functionalities of the decoder are verified first through C++ programs. Verilog is used for hardware description, and then the decoder is synthesized with a $.25{\mu}m$ CMOS TML library. The functionalities of the chip is also verified through test vectors. The clock speed of the chip is 250MHz, and the maximum data rate is 1Gbps.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1260-1266
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• 2007

Error propagation of source-relay (S-R) link limits the performance of decode-and-forward (DF) relay and prohibits DF relay from achieving full diversity gain. In order to solve this problem, the proposed deployment strategy focuses on two objectives. One is to achieve full diversity gain, and the other is to minimize the used power of the DF relay system. In order to achieve full diversity, the error probability of S-R link should be lower than that of maximal ratio combining (MRC) at destination without error propagation since the error probability of the weaker link dominates the total error probability. The proposed strategy of relay positioning points out the range of the relay position for achieving full diversity, and the used power of the relay is minimized by this range. Analysis of error probability and simulation results prove that the two objectives are achieved by the proposed strategy of the relay position.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.835-842
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• 2009

DVB-SSP is a new broadcasting system for hybrid satellite communications, which supports mobile handheld systems and fixed terrestrial systems. However, a critical factor must be considered in upper layer decoding which including erasure Reed-Solomon error correction combined with cyclic redundancy check. If there is only one bit error in an IP packet, the entire IP packet is considered as unreliable bytes, even if it contains correct bytes. IF, for example, there is one real byte error, in an If packet of 512 bytes, 511 correct bytes are erased from the frame. Therefore, this paper proposed two kinds of upper layer decoding methods; LLR-based decoding and hybrid decoding. By means of simulation we show that the performance of the proposed decoding algorithm is superior to that of the conventional one.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.6-14
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• 2007

In this paper, we propose and observe the Adaptive Modulation system with optimal Turbo Coded V-BLAST (Vertical-Bell-lab Layered Space-Time) technique that is applied the extrinsic information from MAP (Maximum A Posteriori) Decoder in decoding Algorithm of V-BLAST: ordering and slicing. The extrinsic information is used by a priori probability and the system decoding process is composed of the Main Iteration and the Sub Iteration. And comparing the proposed system with the Adaptive Modulation system using conventional Turbo Coded V-BLAST technique that is simply combined V-BLAST with Turbo Coding scheme, we observe how much throughput performance has been improved. In addition, we observe the proposed system using STD (Selection Transmit Diversity) scheme. As a result of simulation, Comparing with the conventional Turbo Coded V-BLAST technique with the Adaptive Modulation systems, the optimal Turbo Coded V-BLAST technique with the Adaptive Modulation systems has better throughput gain that is about 350 Kbps in 11 dB SNR range. Especially, comparing with the conventional Turbo Coded V-BLAST technique using 2 transmit and 2 receive antennas, the proposed system with STD (Selection Transmit Diversity) scheme show that the improvement of maximum throughput is about 1.77 Mbps in the same SNR range.

• Proceedings of the Korea Multimedia Society Conference
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• 1998.10a
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• pp.237-242
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• 1998

본 논문에서는 임의 형태 영상 영역에 대한 새로운 변환 부호화 방법을 제안한다. 제안된 방법에서는 영상 영역을 구성하는 각 열의 화소들을 변환 블록의 상단으로 이동시킨 후, 비어 있는 부분을 각 열의 화소 평균값으로 외삽한다. 그리고 수직 방향 1차원 변환을 실행한 후 외삽된 부분의 변환 계수들을 삭제한다. 수평 방향 1차원 변환은 각 행의 변환 계수들을 변환 블록의 좌측단으로 이동시킨 후, 수직 방향 1차원 변환에서와 동일한 과정을 실행함으로써 이루어진다. 복호화를 위해서는 먼저 삭제된 변환계수들을 복원한 후에 수평 방향 1차원 역변환 과정을 수행하며, 역변환 계수들 중 복원된 부분의 계수들을 삭제한다. 그리고 수평방향의 1차원 역변환 과정은 수직 방향 1차원 역변환 과정과 동일한 방식으로 수행한다. 역변환으로 만들어진 재생 영상은 변환 계수와 함께 전송된 형태 정보를 이용하여 원 위치로 이동된다. 모의 실험 결과는 제안된 방법의 압축 성능이 낮은 비트율에서 특히 우수함을 보여준다.

• Journal of Internet Computing and Services
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• v.3 no.5
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• pp.87-94
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• 2002

This paper proposes a group key management protocol for a secure of all the multcast user in PIM-SM multicast group communication. Each subgroup manager gives a secure key to it's own transmitter and the transmitter compress the data with it's own secure key from the subgroup manager, Before the transmitter send the data to receiver, the transmitter prepares to encrypt a user's service by sending a encryption key to the receiver though the secure channel. after checking the user's validity through the secure channel, As the transmitter sending a data after then, the architecture is designed that the receiver will decode the received data with the transmitter's group key, Therefore, transmission time is shortened because there is no need to data translation by the group key on data sending and the data transmition is possible without new key distribution at path change to shortest path of the router characteristic.

• Convergence Security Journal
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• v.2 no.2
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• pp.19-27
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• 2002

This paper proposes a group key management protocol for a secure of all the multicast user in PIM-SM multicast group communication. Each subgroup manager gives a secure key to it's own transmitter and the transmitter compress the data with it's own secure key from the subgroup manager. Before the transmitter send the data to receiver, the transmitter prepares to encrypt a user's service by sending a encryption key to the receiver though the secure channel, after checking the user's validity through the secure channel. As the transmitter sending a data after then, the architecture is designed that the receiver will decode the received data with the transmitter's group key. Therefore, transmission time is shortened because there is no need to data translation by the group key on data sending and the data transmition is possible without new key distribution at path change to shortest path of the router characteristic.

• Convergence Security Journal
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• v.2 no.1
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• pp.99-107
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• 2002

This paper proposes a group key management protocol for a secure of all the multicast user in PIM-SM multicast group communication under electronic commerce. Each subgroup manager gives a secure key to it's own transmitter and the transmitter compress the data with it's own secure key from the subgroup manager. Before the transmitter send the data to receiver, the transmitter prepares to encrypt a user's service by sending a encryption key to the receiver though the secure channel, after checking the user's validity through the secure channel. As the transmitter sending a data after then, the architecture is designed that the receiver will decode the received data with the transmitter's group key. Therefore, transmission time is shortened because there is no need to data translation by the group key on data sending and the data transmition is possible without new key distribution at path change to shortest path of the router characteristic.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.541-548
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• 2003

A fair exchange protocol enable two parties to exchange secrets with fairness, so that neither can gain any information advantage by quitting prematurely or otherwise misbehaving. Therefore a fair exchange is the most important for electronic transactions between untrusted parties. To design new fair exchange, after describing basic concepts, definitions and existing protocols and designing a non-interactive OT protocol using ELGamal's public key system, I will design new protocol to support fair exchange. In my designed new protocol, untrusted parties exchange secrets obliviously and verify that their received secrets are true by using transformed Zero Knowledge Interactive Proof extended to duplex. At this time, concerned two parties can't decrypt the other's ciphertext. .After all of the steps, two parties can do it. It is the most important to provide perfect fairness and anonymity to untrusted parties in this protocol.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.843-850
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• 2006

This is devoted to first, to propose a hash chain algorithm that generates more secure key than conventional encryption method. Secondly, we proposes encryption method that is more secure than conventional system using a encryption method that encrypts each block with each key generated by a hash chain algorithm. Thirdly, After identifying the user via wired and wireless network using a user authentication method. We propose a divided session key method so that Although a client key is disclosed, Attackers cannot catch a complete key and method to safely transfer the key using a divided key method. We make an experiment using various size of digital contents files for performance analysis after performing the design and implementation of system. Proposed system can distribute key securely than conventional system and encrypt data to prevent attacker from decrypting complete data although key may be disclosed. The encryption and decryption time that client system takes to replay video data fie is analogous to the conventional method.