• ETRI Journal
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• 제17권1호
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• pp.23-36
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• 1995

We present a performance evaluation model of cell reassembly mechanism in an ATM switching system. An ATM switching system may be designed so that communications between processors of its control part can be performed via its switching network rather than a separate inter-processor communications network. In such a system, there should be interface to convert inter-processor communication traffic from message format to cell format and vice versa, that is, mechanisms to perform the segmentation and reassembly sublayer. In this paper, we employ a continuous-time Markov chain for the performance evaluation model of cell reassembly mechanism with individual buffering, judicially defining the states of the mechanism. Performance measures such as message loss probability and average reassembly delay are obtained in closed forms. Some numerical illustrations are given for the performance analysis and dimensioning of the cell reassembly mechanism.

• 대한전자공학회논문지TC
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• 제40권12호
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• pp.145-154
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• 2003

본 논문에서는 NGN에서 차세대 멀티미디어 통신 서비스를 제공함에 있어서 다양한 유형의 서비스에 대한 연결제어를 담당하는 소프트스위치에 대하여 연결특성이 다른 두 가지 이상의 응용 서비스를 가정한 경우 연결형태별 호 처리를 위한 제어 메시지의 요구조건을 만족하는 서버를 설계하기 위한 호 처리 차별화 방안에 대한 몇 가지 대안들을 제안한다. 그리고 각 대안 별로 호 처리 모델의 성능분석을 통하여 제안된 호 처리 차별화 방안의 유효성을 입증하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.466-468
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• 2005

MMORPG enables thousands of players to play in an evolving virtual world at the same time over the internet. So, the load of this kind of games is heavier than that of any other precedents. One of load balancing methods is map-partition to divide the load of entire system which is vulnerable to delay message between clients and servers. In this paper, we propose a game architecture using MigAgent to help migration of player character between field servers and to reduce message traffic between clients and field servers.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.717-720
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• 2000

Event-driven communication protocols such as CAN(Controller Area Network) have inherent packet delays due to the contention process for the use of network medium. These delays are stochastic in nature because most packets arrive at random time instants. The stochastic property of the delay adversely influences the control system's performance in terms of stability, responsiveness and steady-state error. Another problem for safety-critical application such as brake-by-wire systems is the reliability of the communication modules that can fail abruptly. This paper deals with two methods to overcome the above problems : (i) scheduling method that can maintain packet delays under some acceptable level, and (ii) redundancy management of communication modules that prescribes dual-redundancy modules' behavior when one of them fails.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권4호
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• pp.1223-1236
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• 2014

With the extension of wireless technology, vehicular ad hoc networks provide important services for the dissemination of general data and emergency warnings. However, since, the vehicle topology frequently changes from a dense to a sparse network depending on the speed of the moving vehicles and the time of day, vehicular ad hoc networks require a protocol that can facilitate the efficient and reliable dissemination of emergency messages in a highly mobile environment under dense or intermittent vehicular connectivity. Therefore, this paper proposes a new vehicular broadcast protocol, called BL-CAST, that can operate effectively in both dense and sparse network scenarios. As a low overhead multi-hop broadcast protocol, BL-CAST does not rely on the periodic exchange of beacons for updating location information. Instead, the location information of a vehicle is included in a broadcast message to identify the last rebroadcasting vehicle in an intermittently connected network. Simulation results show that BL-CAST outperforms the DV-CAST protocol in terms of the end-to-end delay, message delivery ratio and network overhead.

• 전기학회논문지P
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• 제57권1호
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• pp.30-35
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• 2008

In this paper, the application of power Quality monitoring based on Sampled Value(SV) which is introduced in the IEC61850 International Standard for substation communication are discussed. Firstly, while Merging Unit(MU) is designed as a process level device transmitting sensor data, the practical problems such as time delay compensation and optical fiber communication are encountered. Secondly, the Sampled Value message which is proper to a power quality monitoring system is presented. Because the power quality monitoring system requests less time-critical service compared to protection and control applications, the Sampled Value service message structure is introduced to improve efficiency. Lastly, the power quality monitoring server having various power quality analysis functions is suggested to verify the performance of Merging Unit With the diverse experiments, it is proved that the process bus distributed solution is flexible and economic for the power quality monitoring.

• International Journal of Railway
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• 제3권3호
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• pp.106-112
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• 2010

Accidents at level crossing have large portion on train accidents, and causes economical loss by train delay and operational interruption. Various safety equipments are employed to reduce the accident at level crossing, but existing warning device, and crossing barrier are simple train-oriented protection equipments. In this paper, intelligent railway level crossing system is proposed to prevent and reduce accidents. For train driver's prompt action, image of level crossing and obstacle warning message are continuously provided to train driver through wireless communication in level crossing control zone. Obstacle warning messages, which are extracted by computer vision processing of captured image at level crossing, are recognized by train driver through message color, flickering and warning sound. It helps train driver to decide how to take an action. Meanwhile, for vehicle driver's attention, location and speed of approaching train are given to roadside equipments. We identified the effect of proposed system through test installation at Sea train and Airport level crossing of Yeong-dong line.

• 전기학회논문지P
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• 제56권1호
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• pp.13-18
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• 2007

In this paper, authors deal with an application of power quality monitoring using the Sampled Value which is described in the IEC61850 International Standard for substation communication. Firstly, while Merging Unit is designed as a process level device transmitting sensor data, the practical problems such as time delay compensation and optical fiber communication are issued. Secondly, the Sampled Value message which is proper to a power quality monitoring system is presented. Because the power quality monitoring system requests non time critical service comparing to protection and control applications, the Sampled Value service message structure is introduced to improve efficiency. At last, the power quality monitoring server having various power quality analysis functions is suggested to verify the performance of Merging Unit. With the diverse experiments, it is proved that the process bus distributed solution is flexible and economic for the power quality monitoring.

• 한국정보처리학회논문지
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• 제4권11호
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• pp.2732-2744
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• 1997

본 논문은 k-ary n-cubes에서 다중 전송에 기반을 두고 있으며, 결함허용과 채널 경쟁을 고려한 적응적 웜홀 라우팅 알고리즘을 제안한다. 제안된 알고리즘은 k-ary n-cube에서 차수 n에 대하여 (n-1)의 결함허용을 보장하기 위해 하나의 물리적 채널당 2n개의 가상채널을 사용한다. 이것은 결함허용을 고려한 기존의 적응적 라우팅 알고리즘보다 적은 수의 가상채널을 사용한다. 카오스 시뮬레이터를 이용하여 본 논문이 제안한 적응적 라우팅 알고리즘의 교통량과 결함허용을 고려한 메세지 지연도 함께 실험하였다．

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권2호
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• pp.440-456
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• 2011

In this paper, we introduce a novel Public Key Infrastructure (PKI) based message authentication scheme that takes advantage of temporal and spatial uniqueness in physical layer channel responses for each transmission pair in vehicular communication networks. The proposed scheme aims at achieving fast authentication and minimizing the packet transmission overhead without compromising the security requirements, in which most messages can be authenticated through an extreme fast physical-layer authentication mechanism. We will demonstrate that the proposed secure authentication scheme can achieve very short message delay and reduced communication overhead through extensive analysis and simulation.