• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.11
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• pp.1225-1230
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• 2015

MAC protocol for WBAN performs CSMA/CA(:Carrier Sense Multiple Access with Collision Avoidance)algorithm that handles traffic which occurs in emergency with top priority in order to deal with variable data of sensor node for medicine. Emergency message that node sends undergoes collision and delay of transmission by retransmission of emergency message and waste of energy by retransmission. This paper suggests algorithm that minimizes loss of frame caused by collision and applies different backoff parameters by setting order of priority between MAC instruction frame and data frame in CSMA/CA algorithm case which applies order of priority queuing to improve aforementioned problem. According to performance evaluation, it has been found that using suggested MAC protocol showed lower collision probability, higher packet transmission processing ratio and lower packet loss compared with using IEEE 802.15.6.

• Annual Conference of KIPS
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• 2015.10a
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• pp.387-389
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• 2015

IEEE 802.11e EDCA(Enhanced Distributed Channel Access)는 4개의 AC(Access Category)를 이용하여 트래픽에 따른 우선순위를 부여하고 QoS(Quality of Service)를 제공하기 위해 표준화되었다. EDCA는 이진 백오프 알고리즘을 갖는 CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) 방법을 이용한다. EDCA에서 패킷 전송에 실패할 경우 경쟁 윈도우 값은 두 배씩 증가 되고, 성공할 경우에는 최소 경쟁 윈도우 값으로 초기화된다. 따라서 경쟁 윈도우 값이 최적의 값을 유지하지 못해 많은 패킷 충돌을 야기하여 네트워크 성능을 감소시킨다. 이 문제를 해결하기 위해 기존에 제안된 논문에서는 패킷 전송 성공 후 경쟁 윈도우 값을 최소 경쟁 윈도우 값이 아닌 채널 혼잡 정도에 따라 계산된 값으로 설정한다. 그러나 이 방법은 트래픽 종류와 상관없이 같은 방법으로 동작하기 때문에 트래픽 종류에 따른 차별적 QoS를 보장하지 않는다. 또한 계산된 경쟁 윈도우 값은 현재 값에 비해 상대적으로 낮은 값을 갖기 때문에 여전히 높은 충돌율을 갖는다. 본 논문에서는 이 문제를 해결하기 위해 새로운 프로토콜을 제안한다. 제안된 방법에서는 네트워크의 혼잡 정도를 잘 반영하기 위한 새로운 경쟁 윈도우 계산 알고리즘을 제시한다. 또한 제안된 알고리즘은 트래픽 종류에 따른 QoS 보장을 위해 트래픽 종류에 따른 차별화 파라미터를 이용한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.12-19
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• 2015

In network-centric warfare, the communication network has played a significant role in defeating an enemy. Especially, the urgent and important data should be preferentially delivered in time. Thus, we proposed a priority MAC protocol based on CSMA/CA with Binary Exponential Back-off for tactical wireless networks. This MAC protocol suggested a PCW(Prioritized Contention Window) with differentiated back-off time by priority and a RBR(Repetitive Back-off Reset) to reset the remaining back-off time. The results showed that this proposed MAC has higher performance than those of DCF(Distributed Coordination Function) in the transmission success rate and the number of control packet transmission by reducing the packet collision. Thus, it produced more effective power consumption. In comparison with DCF, this proposed protocol is more suitable in high-traffic network.

• The Journal of the Acoustical Society of Korea
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• v.36 no.3
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• pp.211-217
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• 2017

In this paper, we propose a bidirectional full duplex MAC (Medium Access Control) protocol for underwater acoustic networks. An underwater sensor node can set a back-off timer according to the priority of transmission. When the back-off timer expires, the underwater sensor node acquires a transmission opportunity. If a source node wants to send data to a destination node, it broadcasts RTS (Request-To-Send) including ID of the destination node to neighbor nodes. The destination node receiving RTS sends CTS (Clear-To-Send) to the source node to inform the bidirectional full duplex communication. After the source node receives CTS, the source node and the destination node can send the data to each other. In the underwater environment, the existing MAC protocol may take a lot of time for successful transmission of data due to long underwater propagation delay. On the other hand, the proposed bidirectional full duplex MAC protocol improves the throughput by shortening the time for successful transmission of data. In this paper, we analyze the throughput of the proposed bidirectional full duplex MAC protocol. In addition, we show that the proposed bidirectional full duplex MAC protocol has better performance in the presence of the long underwater propagation delay compared with existing MAC protocols for underwater environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.97-105
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• 2010

This paper proposes an effective medium access mechanism which is based on IEEE 802.11 to transmit an urgent message, The main features of the proposed mechanism are as follows. First, when it comes to channel access to have high priority, it has a shorter interval between frames than that specified in standard document. Second, we use fixed window size instead of back-off window with an exponential increase. Performance evaluation of proposed mechanism is executed by simulation and compare with the node using the specified mechanism in standard document. Performance evaluation results show that according to increasing competition the nodes using proposed method have less accessing time than the conventional methods. Also, the proposed method can improve processing time because of the decreasing transmission delay.

• The Inventors News
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• no.50
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• pp.1-16
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• 2006

'제1회 여대생 발명캠프' 성황리에 마쳐/'발명으로 풍성한 가을을 맞이하시길'/IT기업, 국내 특허 30% 이상 넘었다/레이저 프린터 특허출원, 프린터 분야 중 최다/피부 보호하는 자외선 차단제, 특허출원 꾸준히 증가/액정표시장치 관련 특허 지속적 증가/진공청소기, 첨단 기술로 혁신 꾀해/소멸특허정보, 온.오프라인 제공/발명 지도자 양성 연수, 온라인에서 이루어진다/검색율증가로 활발한 지재권 활동 기대/'2006상표-디자인 전시회'/표준기술특허로 신제품 개발 쉬워져/김광림 전 차관, 세명대 총장에 취임/영양 살린 '기능성 국수' 눈길 끌어/특허청, 포스코와 혁신 파트너십 체결/한국특허정보원, 성과 관리제 도입으로 경영 성과 극대화/특허청, 상반기 미국 국제특허출원 심사 1백18건 유치/중소기업 48%, 고액 기술이전비 '지불 가능'/특허청, 고객눈높이 맞춘 민원서비스 제공/모범명세서 첨부제도로 특허 받기 쉬워져/'여성 발명인의 축제' 개최/'제5회 전국 대학발명 경진대회'/'미스터 차우' 둘러싼 상표권 분쟁 치열/외환은행, 외국인 근로자 해외송금서비스 특허 획득/재난 방지 시스템 구축 핵심기술, 특허출원 증가/비밀디자인 청구기간 확대/이젠, 여름용품 정리할 때/역사 속의 발명품/하루 10분 발명교실/특허Q&A/한경희 (주)한경희 생활과학 대표이사/특허청, 수해복구에 두 팔 걷고 나서/무선환경에서의 저작권보호 관련 외국인출원 급증/아이디어 착상 및 발명 기법/다림질 편하게 하는 요령 10가지/발명을 통한 사업화, 시대의 흐름과 인간의 마음을 담아야/스텐서의 전자레인지/3차원 구조물 만들수 있는 나노종이 개발/애플, 크리에이티브에 1억불 지급/흰 우유에 꽂으면 딸기맛 나는 '퍼니스토로우'/한올제약, 씹는 비만 치료제 특허 취득/음성군, 기술로 복숭아 털 알레르기 잡았다/향기로 소비자 마음을 사로잡는다/'독일 국제 아이디어.발명.신제품 전시회'/한국여성발명협회 회원사 발명품 가이드/코네쥬얼리, 우선심사 통해 특허등록/

• Journal of the Korean Geographical Society
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• v.38 no.2
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• pp.275-291
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• 2003

It was essential to develop the DB-type teaching and teaming material for geography instruction using a method of ICT. The DB-type teaching and learning material was considered as a alternative in solving the problems of web-based geography instruction. Accordingly, in this study, the geography image DB program as developed, and based on this program the CD-ROM called GEO-DB, having the function of electronic dictionary of geography image for geography teaching and teaming was made. The GEO-DB was composed of 3,060 geography images collected by teachers and learners. The GEO-DB was made to be used simply by teachers and learners. Especially, the portfolio function was Included in the GEO-DB, and that was focused to the instructional system design of teacher and the self-directed teaming ability development of learner. Teachers and learners using this GEO-DB assessed that because the GEO-DB had the easiness of use, the speed of reference and the unlimitedness of extension, it could enlarge the possibility of using a method of In, and it could contribute to the development of geography teaming ability and the change of geography teaming attitude.