• 한국통신학회논문지
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• 제21권5호
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• pp.1230-1239
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• 1996

This paper analyzes matched-filter acquistion performance of a direct-sequence spread-specturm multiple-access system in a Rayleigh fading channel. For an application of multiple access system, multiple access interference is considered in the performance analysis. A signal flow graph technique is used to derive mean acquisition time in terms of detection and false alarm probabilities. As aresult of performance analysis, it is shown that mean acquisition time increases as fading rate becomes faster andthe numbre of users increases, and it decreases as a matched-filter length becomes logner. The variation of parameter values hs much influence on acquisition performance as SNR/chip becomes smaller.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
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• pp.107-110
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• 2003

In this paper, we propose sharing 3D media between multisite using enhanced Access Grid (e-AG) which is a composition of 3D display and Access Grld (AG) Conventional AG and other collaborative systems have a limitation to share immersive 3D media Thus, proposed system supports sharing 3D media contents in a AG meeting section. Real object can be shared by acquiring stereo image with pre-calibrated stereo camera and by delivering, and virtual object can be shared by transmitting state information after downloading 3D model. And also, real video scene acquired by stereo camera and virtual object from 3D model can be displayed on the 3D display system of each node adaptively. The characteristics of proposed sharing method are sharing 3D media, displaying 3D media on a system adaptively, supporting real-time interaction. The proposed sharing method will be used remote lecture, remote collaboration with 3D media.

• 디지털산업정보학회논문지
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• 제7권1호
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• pp.41-49
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• 2011

We designed a security improved document DRM for protecting document based military information which is transmitted in the military information system environment. The user should be could not access document which not related to his/her role and duty, and must view the only document appropriate for his/her role and security level according to the security level of document. We improved the security of document DRM by adding to the access control module in DRM server. Our system allows operation mode authorizations for the document, considering the user's role & security level and the security level of document. And it prevents indiscriminate access to the document and damage the confidentiality and integrity of information.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.162-166
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• 1997

A message server have two basic functionalities, a server role for processing the processing the user environment as well as an entity role for transferring message to other entity in message system environment. The user who is going to send and receive his important information really wants to keep his own security requests. To satisfy this requirement, message server must be enforced by two seperated security policies- one for message processing security policy under department's computer working environment, the other for send/receive security policy under message system's communication path environment. Proposed access control model gurantees the user's security request by combining constrained server access control and message system access control with multi upper bound properties which come from inheritance attributes of originating user security contexts.

• 정보학연구
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• 제6권1호
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• pp.107-115
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• 2003

정보통신기술의 발달로 인터넷상의 공개키 인증서를 사용한 전자거래가 활성화되고 있다. 그러나 실제적으로 웹서버, 데이터베이서 서버에 접속하기 위한 접근통제를 위한 방안으로 속성인증서에 대한 연구도 활발히 진행되고 있다. 본 논문에서는 기존의 속성인증서에 대한 적용방식을 분석하고, 이를 이용하여 분산시스템에서 속성인증서를 이용한 다중 응용서버에 대한 접근통제방안을 제시한다.

• 한국멀티미디어학회논문지
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• 제11권6호
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• pp.828-834
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• 2008

This paper presents high-spread (HS) random interleavers based interleave-division multiple access (IDMA) scheme for the 4th generation mobile radio system. High-spread feature of a random interleaver offers high-spread characteristics to interleavers and thus produces extrinsic values with low correlation. As interleavers are key components for user separation in the IDMA, the HS interleavers with this feature are employed and analyzed in the IDMA for performance improvement. In addition, by replacing random interleavers with the HS interleavers in the IDMA, bandwidth efficiency is achieved by means of reducing the length of the repetition code. Performance evaluation shows that the proposed scheme of the IDMA with the HS interleavers provides superior BER performance and improved bandwidth efficiency.

• ETRI Journal
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• 제46권3호
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• pp.432-445
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• 2024

This paper demonstrates improved throughput and energy efficiency of wireless communications by exploiting nonorthogonal multiple access (NOMA), multiple input-multiple output (MIMO), and radio frequency energy harvesting (EH) technologies. To assess the performance of NOMA MIMO communications with EH (MMe), we consider the nonlinear characteristics of EH devices and propose explicit expressions for throughput and outage probability. Based on our results, the system performance is significantly mitigated by EH nonlinearity and is considerably improved by increasing the number of antennas. Additionally, by appropriately adjusting the system parameters, our NOMA MMe innovation can avert complete outages while optimizing system performance. Moreover, the results demonstrate the superiority of the NOMA MMe over its orthogonal multiple access MMe counterparts.

• 한국통신학회논문지
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• 제38A권1호
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• pp.68-78
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• 2013

본 논문에서는 다양한 무선 접속 기술(Radio Access Technology : RAT)들이 공존하는 클라우드 기지국 시스템에서의 효율적인 무선 접속 방법으로 무선인지기술(Cognitive radio)을 활용한 이른 스펙트럼 감지(Early Spectrum Sensing : ESS) 기법을 제안한다. 다중 모드 단말은 무선 접속 시도에 앞서 다중 무선 접속 시스템의 전체 주파수 대역을 대상으로 스펙트럼 감지를 수행하여 그 결과 스펙트럼 활용도가 가장 낮은, 즉 가용 스펙트럼이 가장 많을 것으로 예상되는 시스템을 선택하여 무선 접속을 시도함으로써 시스템 접속 성공 확률을 높일 수 있다. 제안 기법의 성능 분석을 위해 컴퓨터 시뮬레이션을 수행 했으며 그 과정에서 최대한 다양한 무선 접속 시스템이 혼재하는 상황을 고려하고자 했다. 우선, 서킷과 패킷 시스템으로 구별한 후, 다시 패킷 시스템을 반송파 결합(Carrier Aggregation : CA) 가능 여부에 따라 다시 구별했으며, 단말기의 경우, 서킷 전용, 패킷 전용, 다중 모드로 구별함과 동시에 CA 능력에 따라서 역시 구별하였다. 또한, 패킷 트래픽의 경우, 실시간 트래픽과 3단계의 패킷 지연 허용 정도를 갖는 비실시간 트래픽으로 구분하였다. 이러한 다양한 무선 접속 환경이 고려된 클라우드 기지국 시스템에서 호 발생에서 호의 서비스 품질(Quality of Service : QoS)이 고려된 자원 할당까지의 일련의 과정을 시뮬레이션에 반영하여 시스템 접속 실패 확률, 평균 시스템 접속 시간, 시스템 균형 인수, 패킷 손실 확률 측면에서 제안 방식의 성능을 분석하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1459-1462
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• 2002

Emergence of the fourth generation mobile communication system (4G system) is now in its dawn. This paper pro- poses a perspective framework on the 4G system, and discusses system aspects of radio access technologies. The focus of the paper is to define the scope and features of the 4G system in an overall system/network viewpoint. From the foreseeable development trends, it is highly expected that whatever emerges in the 4G system will be some kind of constantly evolving and grand recursive concatenation of all the existing system/network developments.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.689-689
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• 2010

Since the apartment was built by Korea National Housing Cooperation in 1961, the amount of its supply has been increased greatly, especially from the late 70's. Recently there are many ongoing studies regarding sustainable construction apartment in Korea, one of the research is developing sustainable apartment that has longer life cycle. Also according as life's quality of residents is upgrading, complain for impact noise and plumbing system noise from upstair or downstair are increasing more and more. To solve this complains, government established impact noise standard as lightweight impact noise of 58dB, heavyweight impact noise of 50dB and presented standard floor system or recognition floor system to satisfy this impact noise standard. So in this study, the aim is to develop dry ondol access floor system for sustainable apartment which have pleasant and quiet life environment.