• 전자공학회논문지S
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• 제35S권10호
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• pp.42-51
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• 1998

본 논문은 CL (ConnectionLess) 가입자와 CL 서버간, CL 서버간, 그리고 종단간 CL가입자간 궤한 루프와 CL서버의 헤더 변환 테이블을 이용하여CL 중첩망의 폭주 제어 방안을 제안한다. ITU-T(International Telecommunication Union-Telecommunication)에 의하여 정의된 CBDS(Connectionless Broadhand Data Service)을 위한 CL 중첩망은 프레임을 라우팅해 주는 CL 서버와 CL 가입자와 CL서버 또는 CL 서버를 연결해주는 링크들로 구성된다. 이와 같은 CL 중첩망에서, 두 종류의 폭주, 즉. CL 링크 폭주와 CL 서버폭주가 일어날 수 있다. 본 논문에서 두 종류의 폭주를 해결할 수 있는 방안을 제시한다. 링크-바이-링크 방법[18]은 CL가입자와 CL서버간 또는 CL 서버간 ATM 계층의 ABR(Available Bit Rate) 궤환 루프와 CL 서버의 헤더 변환 테이블을 이용한다. 그러나 이 방법은 출력 가상 채널의 폭주 발생시 링크를 통해 전송되는 모든 트래픽에 영향을 주게 되어 폭주에 관여하지 않은 트래픽에게도 영향을 주어 이 트래픽이 출력되는 출력 가상 채널의 링크 이용도가 떨어지게 된다. 이와 같은 단점을 보완하기 위하여 본 논문에서 제한한 하이브리드 방법은 링크-바이-링크 방법의 ABR 궤환 루프, CL 계층의 종단의 CL 가입자간 궤환 루프, 그리고 헤더 변환 테이블을 이용한 폭주 상태표를 이용한다. 이 방안은 링크-바이-링크 루프와 헤더 변환 테이블을 이용하여 폭주에 즉시 대처하고, 다음에 종단간 루프를 이용하여 실제 폭주에 관여한 CL 가입자의 전송속도를 조절하는 것이다.

• 한국통신학회논문지
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• 제40권7호
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• pp.1248-1256
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• 2015

강우에 취약한 특성을 갖는 Ku대역을 이용한 통신 링크 설계 시에는 반드시 정확한 데이터와 정밀한 예측모델을 이용하여 도출한 강우감쇠 값을 반영하여 링크 마진을 분석하여야 한다. 따라서 본 논문에서는 최근 TTA에서 제시한 국내 강우강도 분포를 분석하여 Rec. ITU-R PN.837-1 및 Crane 모델에서의 지역별 강우강도와 비교하고, 우리나라의 최근 강우강도 분포와 유사한 지역을 선택하여 Ku대역 주파수에 대한 해당 지역의 강우감쇠를 Rec. ITU-R P.618-8와 Crane 강우감쇠 예측 모델을 통해 무인항공기와 지상통신장비의 통신 링크 거리 및 연 시간율 (%)에 따라 분석한다.

• 한국통신학회논문지
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• 제11권4호
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• pp.227-236
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• 1986

본 논문에서는 window flow 제어기능을 가진 음성과 데이터가 집적된 패킷 통신망을 폐쇄 multichain queueing 시스템으로 modeling하고 평균치해석 방법으로 성능을 분석하였다. 서로 다른 priority 등급을 가진 여러가지 메시지를 전송하기 위한 패킷망 성능해석을 위해서 본 논문에서는 평균치해석과 effective capacity개념에 의한 성능해석 방법을 사용하였다. 구체적으로 각 노드에서의 평균 buffer 점유율, virtual channel의 link throughput의 이용도, 각 메세지의 평균지연시간등 망의 통계적 특성들을 이론으로 분석하고 simulation으로 검증하였다. 제안된 해석방법을 사용할 경우 link의 데이타의 상태를 10%이내의 정확도로 예측할 수 있고 음성 메시지와 외부 데이타의 상태는 5% 이내으 ㅣ정확도로 예측할 수 있다.

• 전기학회논문지
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• 제57권6호
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• pp.1063-1068
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• 2008

BACnet(Building Automation and Control Networks) is a standard data communication protocol specifically designed for building automation and control systems, BACnet provides six options for data link layer protocols and these six data link layer options can be applied with various wired transmission media. Recently wireless technology prevails in automation area. ZigBee is an IEEE 802.15.4 based standard communication protocol for low-rate wireless personal area networks. In this study, we propose a BACnet over ZigBee model that adopts ZigBee communication channel as a wireless data link layer protocol in a BACnet-based communication network system. The technology proposed in this paper can expand the BACnet application using the advantages of wired and wireless integrated network solution.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.96-96
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• 2000

Today, Internet is an everyone's tool for information searching and communication. Furthermore, with the wireless Internet, we can get connected while moving. The Internet, especially wireless Internet could be an excellent data Link for DGPS because of its interactive two-way communication capability and well-constructed network infra. The user with his own mobile communication device doesn't necessarily get equipped with the other specific data link for DGPS This paper will show that how the Internet based DGPS system could be constructed on the computer network in real time, Its performance is demonstrated by the field experiments. Comparing to the DGPS system with the conventional data Links, Like beacon and FM DARC, the Internet based DGPS could provide us a convenient and cost effect DGPS system.

• Journal of information and communication convergence engineering
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• 제10권3호
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• pp.248-252
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• 2012

The sensor network standard DASH7 was proposed to improve transmission quality and low power communication. Specifications for the standard are currently being developed, so the security specification has not been firmly implemented. However, without a security specification, a network cannot work due to threats from malicious users. Thus we must ensure confidentiality and authentication of data packets by using a cryptography method. To contribute to the DASH7 security specification, this paper shows the implementation results of network and data link layer security by using advanced encryption standard (AES) counter with CBC-MAC (CCM) over CC430 sensor nodes.

• 대한산업공학회지
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• 제18권2호
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• pp.11-22
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• 1992

Up to now, most researches on production automation have concentrated on local automation, e. g. CAD, CAM, robotics, etc. However, to achieve total automation it is required to link each local modules such as CAD, CAM into a unified and integrated system. One such missing link is between CAD and computer vision system. This thesis is an attempt to link the gap between CAD and computer vision system. In this paper, we propose algorithms that carry out edge detection, thinning and pruning from the image data of manufactured parts, which are obtained from video camera and then transmitted to computer. We also propose a feature extraction and surface determination algorithm which extract informations from the image data. The informations are compatible to IGES CAD data. In addition, we suggest a methodology to reduce search efforts for CAD data bases. The methodology is based on graph submatching algorithm in GEFG(Generalized Edge Face Graph) representation for each part.

• 시스템엔지니어링학술지
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• 제1권1호
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• pp.46-52
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• 2005

The Tactical Data Link System(TDLS) is a standardized communication link to exchange and interface positional, situational information, command and control in real time. It has been evalua ted that the link would play an important role for tactical interoperability, situation awareness, and execution of joint operations in the future war. But considering the rapidly changing war situations, even though being admitted the necessity of the TDLS of Army helicopter, one of superpowers in the Army, it is not yet built the detailed operational concept. Therefore, this work presents how to embody the TDLS through the systems engineering approach based on the TDLS operating concept analysis of helicopters-ground units.

• 대한산업공학회지
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• 제26권4호
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• pp.306-314
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• 2000

In this paper we present a new approach to estimate link travel speed based on the hybrid neuro-fuzzy network. It combines the fuzzy ART algorithm for structure learning and the backpropagation algorithm for parameter adaptation. At first, the fuzzy ART algorithm partitions the input/output space using the training data set in order to construct initial neuro-fuzzy inference network. After the initial network topology is completed, a backpropagation learning scheme is applied to optimize parameters of fuzzy membership functions. An initial neuro-fuzzy network can be applicable to any other link where the probe car data are available. This can be realized by the network adaptation and add/modify module. In the network adaptation module, a CBR(Case-Based Reasoning) approach is used. Various experiments show that proposed methodology has better performance for estimating link travel speed comparing to the existing method.

• 한국철도학회논문집
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• 제6권2호
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• pp.135-141
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• 2003

According to the computerization of railway signaling systems, the interface link between these signaling equipment is also replaced by digital communication channel, expecially communication link for interface between EIS and LDTS, but there are some problems in the present state of railway signaling. First of all, different communication protocol is applied to interface between above two signaling equipment although they have same functions. The other is that the communication protocol currently used in railway field has some unreasonable points such as structure, formation of byte, error correction scheme and etc. To solve these problems, the standard communication protocol for railway signaling is designed. The structure of designed communication protocol and the results of performance analyses are represented in this paper. It will be expected the increase of safety, reliability and efficiency of maintenance of signaling system by using of the designed communication protocol for railway signaling.