• Journal of KIISE:Information Networking
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• v.31 no.4
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• pp.393-404
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• 2004

Recently, mSCTP (Mobile SCTP) has been proposed as a transport layer approach for supporting mobility. mSCTP is based on the ‘multi-homing’ feature of Stream Control Transmission Protocol(SCTP), and utilize the functions to dynamically add or delete IP addresses of end points to or from the existing connectionin order to support mobility. In this paper, we propose a mechanism to determine when to add or delete an W address, utilizing the link layer radio signal strength information in order to enhance the performance of mSCTP We also propose a mechanism for a mobile node to initiate the change of data delivery path based on link layer radio signal strength information. In addition, if it takes long time to acquire new data path, we propose an approach for reducing handover latency. The simulation results show that the performance of proposed transport layer mobility support mechanism is competitive compared to the traditional network layer mobility supporting approach. Especially, when the moving speed of mobile node is fast, it shows better performance than the traditional network layer approaches.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.883-886
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• 2001

DOS (Denial Of Service)에 대한 공격은 시스템의 정상적인 동작을 방해하여 시스템 사용자에 대한 서비스 제공을 거부하도록 만드는 공격으로 현재 이의 공격에 대한 탐지 알고리즘 및 연구들이 많이 제시되고 있다. 본 논문에서는 네트워크 또는 트랜스포트 계층에 해당하는 프로토콜(TCP/IP, ICMP, UDP) 공격을 분석하고 이들 프로토콜의 취약점을 공격하는 DOS 공격 이외의 다른 공격을 탐지하기 위하여 프로토콜의 기능별, 계층별에 따른 모듈화 작업을 통하여 네트워크 침입탐지 시스템을 구성하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1485-1488
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• 2005

현재 인터넷을 구성하고 있는 두가지 중요 이름공간(name space)인 IP(Internet Protocol) 주소와 DNS(Domain Name Service) 이름의 단점을 보완하기 위해 연구되고 있는 HIP(Host Identity Protocol)는 IP와 트랜스포트 계층 사이에 새로운 계층과 프로토콜을 제안함으로써 제한된 형태의 신뢰성을 제공하고 이동(mobility), 멀티홈(multihome), 동적 IP주소변경 등을 지원하며 DoS(Denial of Service) 공격 등을 방어한다. 본 논문에서는 현재까지 IETF에서 진행된 HIP관련 연구 동향을 분석한다.

• 대한공업교육학회지
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• v.33 no.2
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• pp.248-258
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• 2008

Current Internet uses HTTP (Hyper Text Transfer Protocol) as an application layer protocol and TCP (Transmission Control Protocol) as a transport layer protocol to provide web service. SCTP (Stream Control Transmission Protocol) is a recently proposed transport protocol with very similar congestion control mechanisms as TCP, except the initial congestion window during the slow start phase. In this paper, we present a mathematical model of object transfer latency during the slow start phase for HTTP over SCTP and compare with the latency of HTTP over TCP. Validation of the model using experimental result shows that the mean object transfer latency for HTTP over SCTP during the slow start phase is less than that for HTTP over TCP by 11%.

• Journal of KIISE:Information Networking
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• v.33 no.2
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• pp.156-164
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• 2006

The SCTP (Stream Control Transmission Protocol) implementation with the DAR (Dynamic Address Reconfiguration) extension is called the mSCTP (Mobile SCTP) that is proposed recently for mobility support in transport layer. The mSCTP does not satisfy short handover latency for real-time applications and it has no specific handover decision mechanisms. In this paper, we propose fast handover schemes for mobile nodes that are moving into different subnet using pre-acquisition RA (Router Advertisement) and L3 trigger for improving handover performance. Furthermore, we introduce three specific methods which are RA cache, FMIPv6 (Fast Handovers for Mobile IPv6) and dual interface and how proposed scheme can be interoperated with handover process respectively. Finally, we show two experimental results which are the mSCTP and the mSCTP using FMIPv6 on Linux platforms. Experimental results show that handover performance is improved with reducing the time of receiving RA which takes most of total handover latency.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.393-396
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• 2008

인터넷 주소자원과 관련된 연구 중 활발히 진행되고 있는 분야가 이동성과 멀티홈 제공에 관련된 분야들이다. 그들 중 대표적인 것인 HIP인데, 이것은 네트워크 계층과 트랜스포트계층 사이에 새로운 계층과 프로토콜을 제안하여 제한된 형태의 신뢰성과 이동성, 멀티홈 등을 지원하고 있다. 현재 멀티홈과 이동성을 제공하고자 하는 다양한 연구가 진행 중이며, 인터넷 망 망구조의 변화가 예상된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.323-326
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• 2013

최근 지능형 교통 시스템 (ITS) 에 대한 관심이 증가함에 따라 ITS 응용을 지원해 줄 수 있는 차량 에드혹 네트워크 (VANET, Vehicular Ad-Hoc Network) 기술이 주요 이슈로 대두되고 있다. 특히 트랜스포트 계층에서는 종단간 신뢰성이 요구되는 ITS 응용들을 지원하기 위해 TCP를 적용할 필요가 있다. 하지만 VANET 환경에서 TCP는 혼잡 제어 기능의 오동작, 이동성에 의한 경로 재설정 오버헤드, 경쟁(contention) 등으로 인해 throughput을 불필요하게 감소시킬 수 있다. 따라서 VANET 환경에서 TCP 성능을 향상시킬 수 있는 다양한 기법들에 대한 연구가 진행되고 있다. 본 논문에서는 이러한 기법들을 크게 혼잡 탐색 기법, cross-layer 기법으로 나누어 대표적인 두 가지 기법들을 각각 비교, 분석한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.916-919
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• 2003

Reliable multicast data transmission in a 1:N environment needs more sophisticated error control mechanism than that of in 1:1 environment due to ACK implosion and duplicated retransmission. Although there have been many related research on error control in reliable multicast, real implemented protocols are rare. As one of the reliable multicast transport protocols, ECTP is selected as an international standard reliable multicast protocol by ITU-T and ISO and implemented on RedHat 7.2 machine by us. In this paper, we evaluate the performance of the error control mechanism in the respect of throughput and generated control packet numbers with a real implementation code. From the results, it is concluded that the suitable values of error control parameters can be obtained from the local group size and network environments.

• The Journal of the Korea Contents Association
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• v.9 no.8
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• pp.73-83
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• 2009

TCP(Transmission Control Protocol) is currently used connection-oriented protocol as a typical transport layer protocol in the Internet. However, it has deficiency not be able to communicate with other TCP entities when any link included in the path is down because of single-homing on single path. SCTP(Stream Control Transmission Protocol) suggested as the new transport layer protocol supports multi-homing feature, which provides several paths between source and destination. It can communicate with other SCTP entities using alternate path even when any link on the primary path is down. This paper aims to measure and analyze the multi-homing effect of SCTP over TCP in case of link-down using NS-2 simulator. We classify SCTP into $SCTP_{single-homing}$ and $SCTP_{multi-homing}$ because SCTP with single-homing can also be used like TCP. We measured throughput and bandwidth utilization varying link-down duration, bandwidth, and RTT(round trip time), Simulation results show that throughput of $SCTP_{multi-homing}$ is more than that of TCP by 18 % on average. It is also shown that $SCTP_{multi-homing}$ on varying RTT and bandwidth increases the throughput of TCP by 'l7% and 9% on average, respectively in the link-down environment. In above cases, more or less difference between $SCTP_{single-homing}$ and TCP on throughput and bandwidth utilization was found To summarize, multi-homing effect of SCTP over TCP on throughput is about 18 % on average in the link-down environment This experimental result can be used as the benchmark in order to estimate the multi-homing effect of SCTP over TCP when the link-down happens in the real Internet.

• Journal of The Korean Association of Information Education
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• v.15 no.1
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• pp.129-136
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• 2011

The aim of this study is to present the handover procedures and the performance comparisons of layered mobility management schemes for wireless mobile Internet. To investigate efficient mobility management schemes providing seamless information services in a mobile environment, this paper provided the detailed discussions of existing network layered mobility management scheme, including Mobile IPv4, Mobile IPv6, and new transport layer mobility management scheme, stream control transmission protocol (SCTP) based mobility architecture (SMA). Network simulator-2 (ns-2) was used to compare the performance between Mobile IPv6 and SMA in the wireless mobile Internet environment. Simulation results show that for typical network configuration and parameters, SMA has a lower handover latency, lower packet loss rate, and higher throughput than Mobile IPv6.