• 한국통신학회:학술대회논문집
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• 한국통신학회 1987년도 춘계학술발표회 논문집
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• pp.123-127
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• 1987

• 정보와 통신
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• 제10권12호
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• pp.91-102
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• 1993

• 한국통신학회:학술대회논문집
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• 한국통신학회 1995년도 하계종합학술발표회 논문집
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• pp.476-479
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• 1995

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.602-605
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• 2001

This paper focus on a method to use Ethernet Network for Industrial Communication Network. Ethernet use the CSMA/CD MAC(Medium Access Control) Protocol at the Data-Link Layer, Which isn't suit for Industrial Communication Network requiring Real-Time Communication, periodic data processing, critical data processing characteristics. In this paper we proposed the Virtual Polling Algorithm at the Application Layer will be solution of using the Ethernet Network for the Industrial Communication Network, Proposed Algorithm terminate the Collision in the network thus Delay Time is reduced and Real-Time Communication will be implemented.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
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• pp.152-156
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• 2000

Many industrial equipments use RS-232C interface. But Ethernet using CSMA/CD was widly spread recently. This interface is not compatible with RS-232C and requires PC based system. So In this Paper, We decribe a Internet control and monitoring system that control and watch plants without PC. We developed IP controller consisted of microprocessor and NIC and monitoring system using VC++ and SQL database. The protocol used this system is UDP/IP because it is applicable for real time system.

• 전자공학회논문지A
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• 제31A권1호
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• pp.1-8
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• 1994

In this paper, we have analyzed the performance of a BRAM (The Broadcasting Recognizing Access Method) protocol, as a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) scheme, which is widely used in wireles LAN systems. We have selected a Fair BRAM protocol among CSMA/CA schemes, considering the fairness of channel usage and the simplicity of the protocol. We have compared the performance of BRAM protocol to that of CSMA/CD. to research the characteristics of BRAM in wireless LAN system. In order to analyze the performance of this system, we have set up an imbedded Markov chain and calculated state transition probabilities. Then we have calculated steady state probabilities and finally derived the throughput of a Fair BRAM moder. To verify our analysis, we have simulated practical models. Then, we have found that analytic results are very close to simulation ones. Our analysis of the BRAM protocol will be expected to be very helpful to design and evaluate a MAC (Media Access Control) protocol in wireless LAN systems.

• 한국통신학회논문지
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• 제25권1A호
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• pp.74-80
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• 2000

본 논문에서는 초고속 통신망의 대안기술로 부각되고 있는 HFC 전속망을 기본 전송망으로 하는 CATV/LAN망에서 새로운 MAC프로토콜을 제안하고 성능해석을 수행하였다. CATV/LAN 전송망에서 주요 해석의 대상인 상향채널은 단방향 채널 특성과 단말의 위치에 따라서 우선적으로 접속되는 특성이 발생한다. 이런 전송망에서 공정성 문제를 해결하기 위하여 전송할 데이터가 발생하면 그 즉시 데이터를 전송하지 않고 Pi확률로 데이터를 전송하는 CSMA-CD/U/P(Unsoltted Pi-persistent CSMA-CD)프로토콜을 제안한다. 성능해석과 시뮬레이션 결과 전송망에서 공정성을 이루는 데이터 전송 확률값인 Pi의 분포를 구하였으며, 전송망의 공정성이 이루어 졌을 때 평균 지연 시간(mean delay time)을 구했다. 또한, 지연시간의 분산값을 구하였으며 단말의 버퍼큐에서 큐길이(queue length)분포도 구하였다. 평균 지연 시간과 큐길이 분포는 부하가 커질수록, 단말의 수가 많아 질수록 증가 하는 양상을 보인다.

• Journal of Communications and Networks
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• 제10권3호
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• pp.287-296
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• 2008

The IEEE 802.11 wireless standard uses the carrier sense multiple access with collision avoidance (CSMA/CA) as its MAC protocol (during the distributed coordination function period). This protocol is an adaptation of the CSMA/CD of the wired networks. CSMA/CA mechanism cannot guarantee quality of service (QoS) required by the application because orits random access method. In this study, we propose a new MAC protocol that considers different types of traffic (e.g., voice and data) and for each traffic type different priority levels are assigned. To improve the QoS of IEEE 802.11 MAC protocols over a multi-channel CSMA/CA, we have developed a new admission policy for both voice and data traffics. This protocol can be performed in direct sequence spread spectrum (DSSS) or frequency hopping spread spectrum (FHSS). For voice traffic we reserve a channel, while for data traffic the access is random using a CSMA/CA mechanism, and in this case a selective reject and push-out mechanism is added to meet the quality of service required by data traffic. To study the performance of the proposed protocol and to show the benefits of our design, a mathematical model is built based on Markov chains. The system could be represented by a Markov chain which is difficult to solve as the state-space is too large. This is due to the resource management and user mobility. Thus, we propose to build an aggregated Markov chain with a smaller state-space that allows performance measures to be computed easily. We have used stochastic comparisons of Markov chains to prove that the proposed access protocol (with selective reject and push-out mechanisms) gives less loss rates of high priority connections (data and voices) than the traditional one (without admission policy and selective reject and push-out mechanisms). We give numerical results to confirm mathematical proofs.

• 연구논문집
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• 통권25호
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• pp.137-146
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• 1995

This paper deals with multi protocol based data communication system, which allows to improve the performances. The hardware and software of the data cmmunication system was implemented by using the CSMA/CD and Token bus access methods. The performance evaluation was also carried out and the results were verified to validate

• 조명전기설비학회논문지
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• 제14권2호
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• pp.83-88
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• 2000

본 연구에서는 공장설비 방출폐수 감시를 위한 저가격의 데이터 수집 및 저장창치를 제안하였다. 제안된 시스템은 원칩 마이크로 콘트롤러를 이용하여 시스템의 회로를 간소화하였다. 구현된 시스템은 별도의 착탈 가능한 저장용 RAM 카드를 사용하여 데이터흘 손쉽게 수집할 수 있도록 하였다. 또한 수집 데이터의 분석를 위하여 ethernet에서 사용되고 있는 CSMA/CD방식에 적용하여 모니터링 컴퓨터와의 데0]터를 전송할 수 있도록 하였다. 본 연구에서는 이러한 데이터 수집 및 저장장치를 이용하여 하천으로 유입되는 폐수량에 대한 정보를 수집하였다. 수집된 수질정보는 오염 원인이다 경과를 분석하기 위하여 데이터베이스 구축에 사용되었다.