• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.79-81
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• 2002

최근에는 ATM, Fast Switched LAN, Fiber Channel과 같은 고속의 네트워크의 발달로 인해 분산 환경의 네트워크 파일 시스템에서 디스크를 접근하는 속도보다 원격지 클라이언트의 메모리를 접근하는 속도가 현저하게 증가되었다. 실제로 이와 같은 고속 네트워크 환경을 기반으로 하여 각 서버와 저장 장치를 분리하여 대용량 데이터를 관리하는 SAN(Storage Area Network)과 같은 새로운 네트워크 저장 시스템이 출연하고 있다. 본 논문에서는 이와 같은 새로운 분산 네트워크 파일 저장 시스템 환경에서 필수적으로 고려되어야 하는 광역 버퍼관리기를 설계 및 구현하였다. 본 논문에서 구현된 광역 버퍼 관리기는 크게 데이터 룩업과 버퍼리스트 관리 부분으로 나누어 구성되어 있으며, 이를 위한 적절한 자죠 구조와 시스템 내에 있는 각 호스트간의 버퍼블록정보 유지를 위한 방안 및 기존 운영체제의 커널내 버퍼 관리기와 통합하는 방안을 제시한다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.356-360
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• 2006

Recently, many power analysis attacks have been proposed. Since the attacks are powerful, it is very important to implement cryptosystems securely against the attacks. We propose countermeasures against power analysis attacks for elliptic curve cryptosystems based on Koblitz curves (KCs), which are a special class of elliptic curves. That is, we make our countermeasures be secure against SPA, DPA, and new DPA attacks, specially RPA, ZPA, using a random point at each execution of elliptic curve scalar multiplication. And since our countermeasures are designed to use the Frobenius map of KC, those are very fast.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.1
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• pp.105-111
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• 1997

This Paper Proposes a new efficient system design strategies for the acoustic-based underwater multiple modem and media access control protocol. The system aims to establish the acoustic-based communication network of an underwater vehicles for deep sea mining, which ensures a certain level of maximum throughput regardless of the propagation delay of acoustic and allows fast data transmission through the acoustic-based multiple channel. A media access control protocol for integrated communication network and it's acoustic-based communication modems that allows 'peer-to-peer' communication between a surface mining plant multiple underwater system is designed, and the proposed media access control protocol is implemented for its verification. Furthermore, a proposed design strategies which make it possible to control the multiple vehicle for an underwater mining is presented in this paper.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.3
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• pp.75-83
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• 2011

Cognitive radio (CR) technology is to maximize the spectrum utilization by allocating the unused spectrums to the unlicensed users. This technology enables the sharing of channels among secondary (unlicensed) and primary (licensed) users on a non-interference basis after sensing the vacant channel and as a result, it is possible to harness wireless frequency more efficiently. To enhance the accuracy of sensing, RDSS was suggested. It is a fusion mechanism based on the reputation of sensing nodes and WSPRT (weighted sequential probability ratio test). However, in RDSS, the execution number of WSPRT could increase according to the order of inputted sensing values, and the fast defense against the forged values is difficult. In this paper, we propose a transaction signing-based authentication scheme for secure distributed spectrum sensing to response the forged values. The validity of proposed scheme is provided by BAN logic.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.9-11
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• 2000

최근의 네트웍 환경에서는 멀티미디어 서비스와 대용량의 파일을 이용하는 어플리케이션의 증가로 인해 이를 충족시킬 수 있는 저장 장치가 요구되고 있는 실정이며 이러한 저장 장치를 이용한 분산 환경의 네트웍 파일 시스템이 필수적이 되었다. 실제로 ATM, Fast switched LAN, Fibre channel 같은 고속의 네트웍 발달로 인해 분산 환경의 네트웍 파일 시스템에서 디스크를 엑세스하는 속도보다 오히려 네트웍으로 연결된 원격지의 메모리를 액세스하는 것이 더 빨라졌다. 따라서 지역 디스크 캐싱 기법이 분산 환경의 네트웍 저장 시스템으로 적용되면서 전역적 메모리를 관리하는 것과 원격지간의 캐시 일관성 문제(cache consistency)를 고려하지 않을 수 없게 되었다. 본 논문에서는 분산 환경의 캐싱 기법을 살펴보고 전역적 메모리의 캐시 일관성 문제를 다루면서 이에 대한 설계방안 및 앞으로의 연구 방향을 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.139-141
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• 2004

무선 LAN은 기존의 유선 LAN 기능을 무선 주파수를 전송 매체로 이용하여 제공할 수 있도록 하고자 하는 것으로, 높은 전송 대역폭을 지원해 주는 기술 표준화와 단말 가격의 인하로 빠르게 대중화에 성공하고 있다. 무선 LAN에서의 빠른 이동성지원(fast handoff) 은 QoS가 요구되는 서비스를 지원하기 위한 필수적인 요소이다. 현재의 이동성 방안은 단말이 AP의 존재를 파악하고 이동할지를 결정하는 방법인데, 이와 같은 방법은 단말에 부하가 많고 시간이 오래걸리게 되며 이동을 결정하는 데 알수 있는 정보도 제약된다. 논문에서는 단말의 부하를 줄이고 더 빠르게 이동성을 지원할수 있는 방법으로 AP가 단말의 존재를 파악하고 단말에게 이동 정보를 알려주는 방법을 제시한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1041-1046
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• 2004

Orthogonal frequency division multiplexing(OFDM) is becoming the chosen modulation technique for wire and wireless communications with fast data rate because of good spectral efficiency and sufficient robustness of fading channel. Digital Video Broadcating is using OFDM to modulate. But Digital Video Broadcating has performance degradation in moving reception according to DOA(Direction of Arrival). The purpose of this paper is to improve reception performance using array antenna in environment with doppler effect.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.9
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• pp.2456-2469
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• 1996

A digital satellite communication channel has a nonlinearity with memory due to saturation characeristis of the high poer amplifier in the satellite and transmitter/receiver linear filter used in the overall system. In this paper, we propose a complex radial basis function network(CRBFN) based adaptive equalizer for compensation of nonlinearities in digital satellite communication channels. The proposed CRBFN untilizes a complex-valued hybrid learning algorithm of k-means clustering and LMS(least mean sequare) algorithm that is an extension of Moody Darken's algorithm for real-valued data. We evaluate performance of CRBFN in terms of symbol error rates and mean squared errors nder various noise conditions for 4-PSK(phase shift keying) digital modulation schemes and compare with those of comples pth order inverse adaptive Volterra filter. The computer simulation results show that the proposed CRBFN ehibits good equalization, low computational complexity and fast learning capabilities.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1486-1491
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• 2000

A Multicarrier system required a lower speed paralled-type of signal processing in contrast to a fast serial processing in a single carrier CDMA system. For the analysis we evaluate MC-CDMA system performance with that of a single-carrier CDMA system and a multi-carrier CDMA system based on the various jamming conditions. Also we studied to the capacity level against the threat environment through the performance comparison in commercial CDMA system and Limiting repeater system. as a result we found that M-CDMA system has a robustness to narrowband interference and multipath environments like as a Rayleigh fading.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.1
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• pp.109-116
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• 1998

In this paper, a back propagation neural network teaming algorithm based on the complex multilyer perceptron is represented for suppressing narrowband interference of the received signals in DS-SS mobile communication system. We proposed neural network adaptive correlator(NNAC) which has fast convergence rate and good performance with combining back propagation neural network and the receiver of DS-SS. We analyzed and proved that NNAC has lower bit error probability than that of traditional RAKE receiver through results of computer simulation in the presence of the tone and narrow-band interference and the co-channel interference.