• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.338-343
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• 2005

MIMO(Multiple Input Multiple Output) systems are considered as one of the most promising systems for next generation mobile communication systems which require efficient frequency resource utilization as well as high data rate transmissions. BLAST-STTC is the MIMO system which transmits information from many of STTC encoder groups with two transmit antennas and cancels the interference from other groups in receiver. In this paper we propose a reverse-ordered iterative decoding scheme for BLAST-STTC systems which achieve full diversity gain for all groups and improve the performance of interference cancellation, and compare the error performance of the proposed scheme with general schemes.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.2205-2208
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• 2003

대부분의 인터넷 서비스는 일대일 전송방식의 best-effort를 지향하는 유니캐스트(Unicast)가 보편화 되어있다. 하지만, 다자간 통신 서비스는 고려하지 않아 망 자원 이용측면에서 매우 비효율적이다. 최근, 인터넷방송이나 소프트웨어 분배, 원격 화상회의, 다중사용자 게임, 증권시세 정보서비스 등 다자간 멀티미디어 서비스가 주요 인터넷 사업으로 각광을 밭으면서, 멀티캐스트(Multicast) 전송기술의 사용범위가 점차 증가되고 있다. 멀티캐스트는 그룹참가자의 가입과 탈퇴가 빈번한 특징이 있어 키 전달 과정에서 네트워크의 과부하를 초래한다. 본 논문에서는 빈번하게 생성되는 그룹 키의 길이를 축소시켜 메시지의 생성과정을 단축하고, 독립된 그룹간 통신에 사용되는 유니캐스트에 IPSec(Internet Protocol Security Protocol)을 적용시켜 보다 안전하게 구간의 접근제어와 무결성 및 기밀성을 보장하는 SDKD(Secure Dynamic Key Distribution)를 제안한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1243-1248
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• 2016

This paper investigated the channel link budget for Wireless Avionics Intra-Communication (WAIC) in 4.4GHz. The band 4.2~4.2GHz was allocated for the communication service among aeronautical applications in world radiocommunication conference (WRC). Wireless channels in aircraft was modelled by the combination of path loss, shadowing effect caused by obstacles, and fading caused by multipath signals. In addition, wireless channels in aircraft are categorized into 6 groups according to various locations of transmitter and receiver. We analyzed the channel link budget for the 6 channel groups in terms of maximum transmission distance and outage probability. Our analysis and intensive computer simulation results show that the propagation characteristics of group A, B, and F is superior to group C, D, E, and the propagation of group E is the most vulnerable. Also, these results can be utilized as basic reference for the channel analysis of intra-aircraft or similar environment.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.635-642
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• 2003

The radical development of recent network technology provides the basic foundation which can establish a high speed and cheap cluster system. It is a general trend that conventional cluster systems are built as the system over a fixed level based on stabilized and high speed local networks. A multi-distributed web cluster group is a web cluster model which can obtain high performance, high efficiency and high availability through mutual cooperative works between effective job division and system nodes through parallel performance of a given work and shared memory of SC-Server with low price and low speed system nodes on networks. For this, multi-distributed web cluster group builds a sub-cluster group bound with single imaginary networks of multiple system nodes and uses the web distributed shared memory of system nodes for the effective data transmission within sub-cluster groups. Since the presented model uses a load balancing and parallel computing method of large-scale work required from users, it can maximize the processing efficiency.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.151-159
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• 2012

In this paper, we propose a new peer grouping scheme to consider locality among peers using TTL values in P2P-based IPTV systems. This scheme can select neighbor peers to minimize the number of intermediate routers between each pair of peers. Thus, it can save the network bandwidth as much as the amount of data that the reduced number of routers should transmit In addition, we have conducted various simulation experiments to show that our proposed TTL-based peer grouping scheme can outperform the conventional RTT-based grouping scheme. The experimental results show that our proposed scheme can reduce the jitter ratio as well as the number of data and control packets that all routers should transmit.

• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.119-124
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• 2008

The LEACH is a study method of a clustering base that was representative in many routing techniques that was suggested in sensor network environment. This is suggested technique to manage the sensor network group which consisted of many sensors in efficiency. However, it does not consider energy remaining quantity of the cluster header to manage cluster group, the problem where the cluster group is able to destroyed on the middle which transmits data. We are going to propose to solve such a problem by this paper for new clustering technique to accomplish management for a cluster group. It uses the technique which it proposes from the dissertation which it sees and are to the data transfer and the control also the connection directivity of the cluster group to improve also the lag time diminishes, test result it will lead and the possibility which it will know it was.

• Journal of Broadcast Engineering
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• v.13 no.2
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• pp.251-260
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• 2008

In this paper, we present two verifier-based multi-party PAKE (password-authenticated key exchange) protocols. The shared key can be used for secure content transmission. The suggested protocols are secure against server compromise attacks. Our first protocol is designed to provide forward secrecy and security against known-key attacks. The second protocol is designed to additionally provide key secrecy against the server which means that even the server can not know the session keys of the users of a group. The suggested protocols have a constant number of rounds are provably secure in the standard model. To the best of our knowledge, the proposed protocols are the first secure multi-party PAKE protocols against server compromise attacks in the literature.

• Journal of Software Assessment and Valuation
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• v.16 no.2
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• pp.77-85
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• 2020

In this paper, We studied the operation of distributed ledger technology used as a core technology for smart contracts and the components of distributed ledger technology. As a solution applying the entity of distributed ledger technology to NoE, we proposed the protocol of the distributed ledger technology using the thing user social group management function of NoE protocols being standardized in ISO/IEC JTC1 SC6. The management function of things user social group in NoE provides stable protocol functions and data transmission management, and provides group management functions such as member discovery function and data transmission channel management function. It is expected to be useful for member management functions of distributed ledger nodes by providing a service that apply the component of distributed ledger technology. We intend to actively reflect this technology in the future network functions of ISO/IEC JTC1 SC6, which is undergoing standardization.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.3
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• pp.69-76
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• 2000

In this paper we propose a new group key renewal scheme suitable for secure mobile communications in which all members of the group can re-share the new group common key excepted a revoked member using a key distribution center(a trusted center). A renewal group key in the proposed scheme can be shared many times using pre-distributed data by a smart card without a preparation stage. This scheme is also avaliable for a large group network because the transmitted data amount after identifying the revoked member does not depend on a size of group. The secuirty of this scheme is based on the difficulty of the discrete logarithm problem.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.102-104
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• 2011

최근 비디오 스트리밍과 대화형 비디오 서비스 등과 같은 광대역 멀티미디어 서비스를 지원하기 위하여 Wimax와 같은 4G 무선네트워크 시스템 기술이 발전해 왔다. 4G 무선네트워크의 OFDM(Orthogonal Frequency Division Multiplexing)과 MIMO(multi Input Multi Output)은 사용자들에게 매우 유연한 QoS(Quality of Service) 서비스를 제공해 줄 수 있다.[1] 이 논문에서는 다양한 네트워크 상황에서 멀티캐스트 그룹에게 효율적인 방법으로 통신 자원을 할당하기 위해 OFDM 방법을 사용 하였다. 이에 본 논문에서는 한 셀(cell) 내의 서로 다른 멀티캐스트의 그룹의 다른 SNR(Signal to noise Ratio)의 사용자 분포에 따른 적응적인 scalable 비디오 멀티캐스트 방식을 제안한다. 더 나은 수신율을 가진 사용자는 최적의 MCS(Modulation and Coding Scheme) 할당을 통해 서로 다른 화질의 scalable 비디오 계층 중 높은 해상도의 비디오를 받을 수 있다. 논문에서는 전체 전송률을 최적화 하는 대신 전송받은 전체 비디오의 평균 화질을 최적화하는 방법을 제안한다.