• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1571-1574
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• 2002

최근 인터넷 환경에서는 고속의 패킷 처리 능력 및 새로운 프로토콜에 대한 요구들은 또한 인터넷 통신 시스템인 라우터의 개발에도 많은 요구를 가하고 있다. 전송 속도의 초고속화와 다양한 서비스를 지원하여야 하는 라우터의 개발에 있어서 효율성 및 프로토콜의 이식성을 높이는 방법을 요구한다. 이와 같은 요구사항에 발맞추어 네트워크 운영체제(Network Operating System) 개념이 등장하였다. 본 논문에서는 이런 특징을 갖는 네트워크 OS에 MPLS 관련 프로토콜을 이식하기 위한 요구사항을 분석하여 네트워크 응용 프로그램 인터페이스(API)를 설계하고자 한다.

• Electronics and Telecommunications Trends
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• v.21 no.3 s.99
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• pp.1-10
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• 2006

차세대 이동통신에 의한 새로운 정보통신 환경 실현은 21세기의 산업구조에도 막대한 영향을 주어서 대변혁을 가져올 것이다. 4세대 이동통신의 실현에 의한 정보통신환경의 Broadband화, Ubiquitous화, Mobile & Wireless화에 의해 주요한 산업으로 크게 확대되고, 융합.발전할 것으로 기대되고 있다. IMT-Advanced 이동통신 기술은 고속이동 환경에서 최대 100Mbps, 고정 또는 저속이동 환경에서 최대 1Gbps의 데이터전송속도로 비대칭/대칭적 패킷 서비스와 방송 서비스를 포함한 다양한 서비스를 IP기반으로 통합 제공하는 기술을 의미하며, IMT-Advanced 시스템뿐만 아니라 다양한 무선통신 시스템과 통합되는 형태로 실현될 것으로 예상된다. 본 고에서는 차세대 이동통신기술 동향과 국내외 개발 동향, 표준화 동향 등을 간략히 살펴보고자 한다. 특히, 차세대 이동통신 기술은 셀룰러 이동통신, 차세대 WLAN, 차세대 WPAN, SDR 등을 중심으로 살펴보고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1007-1010
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• 2005

In this paper, I propose the evolutional schemes of digital mobile communication systems based on 3GPP standards. The evolution process of those systems is going in for the purpose of support of high data rate service, radio link enhancement, If network support, and support of legacy service and realization of new enhanced service. It is essential for an efficient system configuration to analyze 3GPP network architecture based on standard and required technology for future IMS service.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1325-1328
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• 2002

최근 고속 데이터 전송과 멀티미디어 서비스에 대한 요구의 증가로 인한 문제점을 해결하고 서로 다른 서비스별 QoS를 보장 하고자 새로운 방안이 필요하게 되었다. MPLS는 이러한 요구사항에 부응하는 기술로 레이블이라는 짧고 고정된 길이의 식별자를 사용하여 패킷 포워딩을 하는 3계층 스위칭 방법이다. MPLS망에서 Differentiated Service를 지원함으로써 QoS를 보장하며 또한 동일한 서비스를 받는 PHB(Per-Hop Behavior)별로 VC merging을 함으로써 라우터가 관리하는 레이블의 수를 효율적으로 사용하여 망의 확장성을 높일 수 있다. 본 논문에서는 ATM기반 MPLS 망에서 Diffserv를 지원하며 트래픽의 QoS에 따른 VC merging과 Non VC merging 기술을 시뮬레이션을 통해 각각 비교 분석하고 VC merging 스케쥴러를 모델링하여 검증하였다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.237-245
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• 1997

In this paper, a flow control mechanism is proposed which is based on the priority control between communication path of a node. In this scheme, demanding length of a data queue for any pre-defined, then each node in that path is forced to maintains buffer size under the limit by controlling priority level of the path. The communication path which requires higher bandwidth sets its demanding queue length smaller. By providing relationship between the priority of a path and length of its queue, the high bandwidth requesting path has a better chance to get high bandwidth by defining the smaller demanding queue size. And also, by forcing a path which has high flow rate to maintain small queue size in the path of the communication, the scheme keep the transmission delay of the path small. The size of the demanding queue of a path is regularly adjusted to meet the applications requirement, and the load status of the network during the life time of the communication. The priority control based on the demanding queue size is also provided in the intermediate nodes as well as the end nodes. By that the flow control can provide a quicker result than end to-end flow control, it provides better performance advantage especially for the high speed network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2B
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• pp.138-143
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• 2003

One of the important design issues for IP routers responsible for packet forwarding in computer networks is the route-lookup mechanism. For each incoming packet, IP routing requires that a router performs a longest-prefix-match address lookup in order to determine the next hop that the incoming packet should be forwarded to. In this paper, we present a new scheme which applies the hashing function for IP address lookup. In the proposed scheme, the forwarding table is composed of multiple SRAMs, and each SRAM represents an address lookup table in each prefix. Hashing function is applied in order to find out the matching entries from the address lookup tables in parallel, and the entry with the longest prefix match among them is selected. Simulation using the MAE-WEST router example shows that a large routing table with 37000 entries can be compacted to a forwarding table of 300 Kbytes in the proposed scheme. It is also shown that the proposed scheme achieves one route lookup every 1.93 memory accesses in average.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.3
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• pp.96-102
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• 2013

In recent years, a variety of ITS services are available such as driving information, road conditions, V2X messages as well as navigation and traffic jams notification. The development of ITS services is accelerating by V2X communication technologies for high-speed vehicles. In this paper, WAVE communication devices based on the IEEE802.11p standard is introduced as a solution of V2X communication technologies. The H/W and S/W structures of the WAVE communication device and the characteristics of RF/antenna are described. The performance is evaluated in the test road by measuring throughput, PER and latency. The implemented WAVE communication device has 6~7 Mbps throughput with 10% PER at 1km coverage. The packet latency is less than 3ms for the whole test road. It is shown that the implemented WAVE technology is satisfactory to provide ITS services and Internet video-streaming services.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1425-1431
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• 2005

In this paper, we consider the ISR(Intelligence, Surveillance, and Reconnaissance) system which collects the imagery intelligence from an airplane and CDL(common data link) communication system which transports the information obtained by the ISR system. The IMINT(imagery intelligence) consists of MPEG-2 transport stream packets and they transmit through CDL. We have some simulations for communication performances of CDL and show performance improvements using convolutional coding. We have compared BER performances under AWGN channel and fading channel which is caused by the velocity of an airplane.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2839-2846
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• 2014

New VHF band for use in VDE is determined by WRC-12 due to the overload of AIS VDL, and the system characteristics of the VDE is recommended as ITU-R M. 1842-1. CS-TDMA, a multiple access method of AIS class B, is recommended as that of the VDE. It is inefficient for CS-TDMA just applying the report interval used in AIS class B to transmit high speed data with higher payload in the aspect of efficiency. In this paper, a simulation is executed in order to determine adequate report interval according to the number of active ships that affects directly network traffic. To this end, the performance of CS-TDMA, which includes the number of received packets, reception success rate, channel utilization, and collision rate, is investigated via a simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1194-1201
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• 2003

Measurements of network traffic have shown that self-similarity is a ubiquitous phenomenon spanning across diverse network environments. We have advance the framework of multiple time scale congestion control and show its effectiveness at enhancing performance for fast TCP prototype control. In this paper, we extend the fast TCP prototype control framework to window-based congestion control, in particular, TCP. This is performed by interfacing TCP with a large time scale control module which adjusts the aggressiveness of bandwidth consumption behavior exhibited by TCP as a function of "large time scale" network state. i.e., conformation that exceeds the horizon of the feedback loop as determined by RTT. Performance evaluation of fast TCP prototype is facilitated by a simulation bench-mark environment which is based on physical modeling of self-similar traffic. We explicate out methodology for discerning and evaluating the impact of changes in transport protocols in the protocol stack under self-similar traffic conditions. We discuss issues arising in comparative performance evaluation under heavy-tailed workload. workload.