• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1032-1038
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• 2008

KTX train system is composed of TORNAD* network for transmitting information of train's internal equipments and OBCS which proceed information within train. OBCS of one trainset consisted of 28 equipments takes intelligent and dynamic composition according to equipment handling, train command and control flow. Each OBCS which is installed within trainset handle and supervise mutually action information about equipments, transmit it to driver to transmit information about train operation and preventive management. This mutual supervision and information transmission use KTX TORNAD* network system. TORNAD* network system is the one which is uniquely developped by GEC ALSTHOM, the KTX trainset manafacturing provider and this field is excluded from technical know-how transfer item. Through the research on analysis method of KTX TORNAD* system data structure which is operating on Seoul-Pusan Line, I hope that this thesis can contribute to train network system's standardization after applying it to improvement of train network system maintenance, enhancing quality of train service and applying it to future Korean rolling stock network system development.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.1
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• pp.6-12
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• 2004

Identification rate and time are very important in the identification of RFID tag, and the tag requires simple structure to use economically large quantity of tags. These factors make the MAC protocols of wired or wireless network environment result in different requirements. In the paper, we propose a method to apply spread spectrum scheme using orthogonal channel via Walsh function as the anti-collision communication system for the purpose of non-collision identification of multiple tags, and consider its property. The proposed system use two step identification. in the first step, collision is resolved via constructing to respond after specific delay time based on unique n, and conventional polling scheme follows in the second step.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.1
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• pp.55-68
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• 2010

IEEE WAVE is going through the final standardization process as the wireless access technology which provides drivers in high-speed vehicles with safety-related information and commercial services This paper presents an application-layer protocol for safe driving assistant service and a service system emulator based on this protocol. The safe driving assistant system includes a construction zone information service and a vehicle crash notification service, an emergency vehicle notification service, a probing service and a dilemma zone decision assistant service. Emulator System design for verifying functions of system, The emulator consists of an emulator server that models the movement of all vehicles and road states and a number of clients that models functional units for OBUs, RSUs, and a traffic control center).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.189-194
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• 2002

It is thesis that based on for Croup-Transferring a method of Transferring-Control during real-time. By the development of multimedia, spread of high-speed communication network and generalization of various multimedia services, various techniques an studied by requiring application services for multi-users (meeting-service, remote-service, broadcasting-service, education-service and so on). So we focused on the multimedia group transferring techniques except communication network techniques and multimedia processing techniques, and presented algorithms about a mettled of group-management, a method of delay-control-management that analyzed a effective method of Croup-Control and characters of each group network and used RTP(Real-Time Protocol) / RTCP(Real-Time Control Protocol).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7A
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• pp.548-553
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• 2009

The aim of 4G mobile communication systems is to connect arbitrary devices to high-speed network anytime, anywhere. Cellular system must solve the problem of inter-cell interference caused by frequency reuse for meeting needs of 4G. In this paper, to solve interference problem we propose the algorithm, the so-called Threshold-Based Region Decision (TBRD) and analyze characteristics and performance of the proposed algorithm through simulation. The proposed technique has high applicability and flexibility due to simple construction using only existing UE measurement, and achieves performance improvement through the threshold that can be easily controlled.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.251-257
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• 2014

The Viterbi algorithm(VA) is used to estimate the state transition of discrete-time finite state machine(FSM) that is in an uncorrelated noisy environment. This paper modified the Hamming Network to estimate the state transitions in the finite state machines, and proposed state-parallel and block-parallel Viterbi decoder. The modified Hamming Network(mHN) can perform the decoding of convolutional codes correctly as conventional Viterbi decoder. Furthermore, the complexities of the proposed Viterbi decoder are reduced approximately 10% less than conventional Viterbi decoder, and the processing times are improved approximately 40% more than conventional Viterbi decoder.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5A
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• pp.536-541
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• 2008

This paper proposes a mobility prediction algorithm for the effective handover among hybrid networks. The proposed algorithm is consisted of two mechanisms to predict a mobile terminal's path. First, the mobile terminal will be checking its received signal power level. Then the mobile terminal will judge its path in some network. Second, if the mobile terminal change its path suddenly, it will be dealing with this situation appropriately using the mobile terminal's speed. This paper introduces existing researches and the proposed algorithm. Finally, our algorithm is compared with existing approaches in terms of the handover delay by using the network simulator OPNet version 10.0.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.7
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• pp.519-525
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• 2013

The traffic classification is a preliminary and essential step for stable network service provision and efficient network resource management. However, the payload signature-based method has a significant drawback in high-speed network environment that the processing speed is much slower than other method such as header-based and statistical methods. In this paper, We propose the server IP, Port cache-based traffic classification method using application traffic locality to improve the processing speed of traffic classification. The suggested method achieved about 10 folds improvement in processing speed and 10% improvement in completeness over the payload-based classification system.

• Journal of Sensor Science and Technology
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• v.22 no.4
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• pp.302-307
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• 2013

The Sb-doped $SnO_2$ nanowire network sensors were prepared by thermal evaporation of the mixtures between tin and antimony powders. Pure $SnO_2$ nanowire networks showed high sensor resistance in air ($99M{\Omega}$), similar gas responses to 4 diffferent gases (5 ppm $C_2H_5OH$, CO, $H_2$, and trimethylamine), and very sluggish recovery speed (90% recovery time > 800 s). In contrast, 2 wt% Sb-doped $SnO_2$ showed the selective detection toward $C_2H_5OH$ and trimethylamine, relatively low resistance ($176k{\Omega}$) for facile measurement, and ultrafast recovery speed (90% recovery times: 6 - 18 s). The change of gas sensing charactersitics by Sb doping was discussed in relation to gas sensing mechanism.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.144-149
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• 1998

컴퓨터 하드웨어 기술의 발달과 무선 통신 기술의 발달로 이제는 이동성을 제공하는 Mobile Computing이 각광을 받고 있다. 그러나 이와 같은 이동 단말기의 하드웨어적인 제약점과 무선 통신의 근본적인 제약점으로 인하여 아직까지 유선통신에서 제공하는 신뢰성 있고 고속의 네트워크 환경을 지원하지 못하고 있다. 이동 단말기들은 이동성을 보장하기 위하여 작고 가볍게 만들어야 한다. 이렇게 만들기 위해서는 배터리를 사용하고 적은 양의 디스크를 사용하게 된다. 이는 컴퓨터가 사용 가능한 자원 즉, CPU, Memory, Disk등이 고정 컴퓨터에 비해 빈약해지고 배터리의 사용으로 인한 갑작스러운 전원 공급의 중단으로 인한 하드웨어적인 신뢰성과 무선의 특성으로 인한 데이타 전송의 신뢰성이 낮아진다. 이와 같은 하드웨어 제약성과 무선의 문제점을 극복하기 위하여 다양한 연구가 진행되고 있는 데 그 중에서 사용자들에게 무선 이동환경을 인식하지 않고 컴퓨터를 사용할 수 있는 환경을 제공하는 방향으로 연구가 진행 중이다. 이들 연구 중에서 무선의 제약점인 낮은 전송 속도와 잦은 끊어짐 등을 극복하고 사용자가 고정 호스트의 대용량의 디스크를 투명하게 사용할 수 있도록 하는 방법이 바로 "Disconnected Operation"을 지원하는 방법이다. 본 연구에서는 disconnected operation을 지원하는데 가장 중요한 부분인 hoarding에 대하여 최근까지 연구된 기법들을 조사하고 이들 기법들이 가지는 문제점을 파악하고 새로운 hoarding algorithm을 제시하고자 한다.