• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.4
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• pp.227-236
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• 1986

In this paper, an integrated voice/data packet network with window flow control is modeled by a colsed multichain queueing system, and its performance is analyzed by the mean value analysis method. Particularly, for the analysis of a packet network having various kinds of messages with different priority classes, we introduce an approach based on the mean value analysis and the concept of effective capacity. By the mathematical analysis and computer simulation, we obtain the following network statistics in the steady state: Mean buffer occupancy at each node, utilization of link throughput of a virtual channel, and mean delay time of each message. Our iterative analysis method can predict the link data status in most cases within about 10 percent of accurady, and the statistics of voice messages and external data within 5 percent as compared to simulation results.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.69-76
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• 2012

This paper proposes an efficient power consumption scheme using sleep mode in home gateway. The scheme by this paper classifies incoming real time packet and non-real time packet in home gateway and delay non-real time packet. Therefore, the home gateway can have longer sleep time because non-real time packet can get additional delay time by proposing mechanism using timer. We use non-preemptive two priority queueing model for performance analysis. As a results, we verify that power consumption of proposed scheme is reduced more than existing scheme by delay of non-real time traffic.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.139-147
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• 2004

To provide Internet QoS, the IETF Proposed two models of Integrated Services (IntServ) and Differentiated Services (DiffServ) Unlike IntServ where resource reservation and admission control is Per-flow based using RSVP. DiffServ supports aggregated traffic classes to provide various QoS to different classes of traffics. However a dynamic QoS management system is required to dynamically provide differentiated QoS for customers who require dynamic QoS change. This paper designed and implemented therefore a policy-based QoS management system to manage effectively and configure dynamically QoS of DiffServ networks. The validity of the system has been verified by the experimentation on the Linux-based DiffServ network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1208-1214
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• 2009

Sensor networks are vulnerable to data congestion and hot-spot compared with wireless networks. Mobile sink supporting route protocol has such problems as hot-spot and data congestion because agent of cluster node transmits all data packet. Therefore, mobile sink supporting route protocol needs to reduce the number of packets and keep the packets from concentrating on a single node. To solve these problems, we propose mobile sink supporting routing Protocol using agent of cluster node. Cutting down on the number of packets compared with the existing mobile sink supporting routing Protocol, our proposed protocol has reduced both communication overhead and energy consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1536-1547
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• 1994

This paper presented the implementation and design of narrowband wireless MODEM for packet transmission. The MODEM consists of transmitter, receiver, and the control unit. The BPSK modulation with narrowband filtering is used. The receiver consists of functional modules such as carrier recovery, bit synchronization, lock detector, etc. We evaluated the performance of packet transmission with three MODEM sets implemented in distributed packet radio network. We confirmed the transmission of packetized data through RS232C port of PC. Also, we presented results of experimental data by using measuring instruments. The implemented MODEM in this paper is expected to be useful for the design of wireless LAN system.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.59-75
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• 2006

In this paper, we propose a congestion control scheme to control the congestion due to the mobility of ubiquitous devices on ubiquitous computing environment. Especially, this congestion control scheme provides a reverse congestion avoidance state which can classify between packet error by features of wireless network and packet dropping by congestion. Also, it provides a slow stop state which can minimize bandwidth waste due to congestion control. The proposed congestion control scheme controls more adaptive than existing congestion control schemes. The proposed congestion control scheme is designed based on DCCP(Datagram Congestion Control Protocol) being proposed by IETF(Internet Engineering Task Force) and implemented on the Linux kernel. In simulation results, the proposed congestion control scheme provides good bandwidth throughput in wireless network as well as in wired network.

• Information and Communications Magazine
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• v.22 no.9
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• pp.51-62
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• 2005

3세대 이후의 이동통신시스템에서는 고속 및 대용량 전송을 통해 동영상, 영화, 방송 등 은 종류의 멀티미디어 서비스들이 제공될 것으로 전망된다. 본 논문에서는 이러한 서비스들의 제공이 가능한 3세대 이후 시스템으로 개발되고 있는 High-Speed Mobile Multimedia (HMm) 시스템을 매체접근제어 (MAC) 프로토콜을 중심으로 소개한다. HMm MAC 프로토콜은 광대역 무선 환경 하에서 고속의 그리고 효과적인 멀티미디어 전송을 목표로 설계되었다. 이러한 HMm MAC 프로토콜은 기지국 MAC과 단말 MAC의 두 서브시스템으로 나뉘며, 각 서브시스템은 상태관리, 전송제어, 버퍼관리, 임의 접근제어, 패킷 스케줄링 등의 기능을 수행한다.

• Information and Communications Magazine
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• v.27 no.6
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• pp.10-17
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• 2010

IMS는 IP 기반의 통합 서비스 관리 시스템으로 All-IP 기반의 차세대 통신망에서 모든 세션의 제어를 담당할 것으로 예상된다. 최근의 통신망은 회선망과 패킷망이 혼재되어 사용되는 이종망 환경이며, 이 때 패킷망 기반의 IMS가 어떻게 서비스 연속성을 제공하는지에 대한 문제가 대두되고 있다. 본 고에서는 3GPP의 표준화 문서를 바탕으로 이종망 환경에서 IMS 서비스 연속성 기술에 대해서 알아보고자 한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.17-21
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• 2000

TCP 프로토콜과 ATM 프로토콜과의 형태 및 제어방식의 차이로 인한 이질성 문제 때문에 ATM 층에서 한 개의 셀 손실은 상위 TCP층에서 하나의 패킷 손실을 초래하게 되어 망에 대한 충분한 QoS를 제공하지 못한다. 이러한 문제들을 해결하기 위해 처리율면에서 Early Packet Discard(EPD)와 공정성면에서 Selective Packet Discard(SPD), Fair Buffer Allocation (FBA) 등이 제안되었다. 본 논문에서는 ATM상에서 TCP 성능성향을 위해 기존의 알고리즘과 제안한 알고리즘에 대하여 비교분석하고 , VC의 수를 가변적으로 변화시켜도 제안한 알고리즘은 SPD나 FBA보다 나은 공정성을 보였고, 처리율면에서는 차이가 없음을 시뮬레이션결과를 통해 나타내었다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.30-34
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• 2001

본 논문에서는 근거리에 놓여있는 노트북, 휴대폰, PDA, 혜드셋 등 각종 이동 가능한 장치들을 하나의 무선네트워크로 연결할 수 있는 블루투스의 베이스밴드 시스템 프로토콜 기능을 분석하고 설계하였다. 즉, 전체적인 논리 기능구조를 설계한 후 하드웨어로 구현될 패킷생성 블록, HEC와 CRC 기능블륵, Whitening/Dewhitening 기능블록, FEC 기능블록, 입출력 블록(TX, RX 루틴), 클럭 생성 기능블록, 주파수 선별 기능블록, 오디오 기능블록 그리고, 패킷 제어 블록들의 처리절차를 Verilog HDL 코드로 설계 및 검증하였다.