• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.451-458
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• 2010

To detect and recover packet losses over wireless links is very important in terms of reliability in packet transmission. Most wireless communication systems adopt an automatic repeat request (ARQ) protocol operating at link layer. However, it has been constantly addressed that the interaction not harmonized sufficiently between ARQ and TCP rather degrades TCP performance. In this paper, therefore, we propose an improved scheme from the aspect of the interaction with TCP loss recovery mechanism that can be applied to selective repeat ARQ (SR-ARQ) protocol and prove that the proposed scheme improves TCP performance significantly by OPNET simulations.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.406-408
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• 2002

TFRC 혼잡제어는 멀티미디어, 인터넷 전화등 실시간성이 강조된 서비스에 적합한 프로토콜이다. 그러나 이러한 TCP-friendly 혼잡제어 알고리즘은 네트워크 혼잡이 심해져 손실률이 커짐에 따라 TCP와의 공정성(fairness)이 떨어지는 문제점을 가지고 있다. 이러한 문제를 해결하기 위해서는 전송률을 결정하는 제어식을 높은 손실률일 때 보정을 해주어야 한다. 본 논문에서는 TFRC 혼잡제어 알고리즘의 전송률 결정에 있어서 중요한 변수인 재전송 타임아웃 값(RTO)의 재 정의를 통하여 전송률을 보정함으로서 공정성 하락을 방지함을 보이고, 시뮬레이션을 통하여 이를 입증한다.

• The Korean Journal of Rehabilitation Nursing
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• v.18 no.1
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• pp.29-37
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• 2015

Purpose: This study was conducted to develop effective timeout protocol in coordination with current practice and test its clinical effectiveness in pursuit of safety management for patients undergoing cataract surgery. Methods: A total of subjects were 60 women, 50~65 years old, who visit C ophthalmology clinic in D city. They were assigned to 30 experimental group and 30 control group, respectively. Based on the comprehensive literature review, timeout protocol that was suitable for patients undergoing cataract surgery was developed, and then test its effectiveness by measuring blood pressure, pulse, anxiety and sense of well-being among surgical patients. Results: The timeout protocol was found to reduce blood pressure, pulse, and anxiety and increase well-being among surgical patients. Conclusion: As a results, it is necessary to introduce an effective timeout protocol giving positive responses to surgical patients, hence it should be develop a timeout protocol and explore the effectiveness of the protocol.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.142-144
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• 2001

멀티미디어 에플리케이션과 모바일 컴퓨팅지원은 현재 컴퓨터 시스템에서 가장 부각되는 두 가지 분야이다. 이 두 분야가 부각될수록 인터넷상에서 이동 호스트에게 QoS를 지원해야 할 펄요성은 더욱 커진다. RSVP는 송신 호스트와 수신 호스트간에 일정한 수준의 QoS를 보장하기 위한 자원 예약 프로토콜이다. 그러나 RSVP는 유선 네트워크의 고정 호스트들을 위해서 설계되었기 때문에 이를 이동 네트워크에 그대로 접목하는 것은 적합하지 않다. 본 논문에서는 무선 네트워크에서 이동 호스트에게 QoS를 효율적으로 지원하기 위해서 '지역성'을 노려하는 새로운 프로토콜을 제안한다. 제안된 프로토콜을 주요 요소로서 LRP(지역 예약 관리자)와 그 예약 서비스 범위를 나타내는 타임아웃 값을 사용하고 모바일 IP의 루트 옵티마이제이션을 프로토콜 환경으로 사용한다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.262-264
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• 2001

컴퓨터 네트웍 시스템에서 부각되고 있는 두 가지 중요한 추세는 아마도 ‘멀티미디어’와 ‘이동 컴퓨팅’일 것이다. 멀티캐스트는 멀티미디어 데이터가 차지하는 많은 네트웍 트래픽을 수신 컴퓨터들에게 효율적으로 분배함으로써 네트웍 트래픽을 줄일 수 있다. 그러나 이동 호스트를 지원하는 이동 네트웍에서의 멀티캐스팅은 빈번한 그룹 멤버쉽의 변화와 함께 그룹 멤버의 위치변화로 인해서 기존의 고정 호스트를 기본으로 설계된 멀티캐스트 프로토콜을 적용하는 것은 적합하지 못한다. 이런 점에서 Mobile IP를 기본 유니캐스팅 환경에서 채택하여 이동 호스트에게 멀티캐스트를 지원하기 위한 몇 가지 방법이 제시되었으나, 비최적 경로로의 데이터 전송, 비효율적인 데이터 중복 전송, 또는 빈번한 멀티캐스트 트리의 재구성으로 인한 오버헤드 등의 문제점을 내포하고 있다. 제안된 프로토콜에서는 이동 호스트에게 멀티캐스트 서비스를 제공하는 FMA(Foreign Multicast Agent)를 유동적으로 선정하고 이동 호스트가 가지는 타임아웃 값을 이용하여 이동성으로 인해 발생하는 문제점들을 완화시킴으로써, Mobile IP를 이용하는 이동 호스트에게 IP멀티캐스팅을 효과적으로 제공한다.

• Korean Journal of Adult Nursing
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• v.20 no.2
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• pp.353-363
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• 2008

Purpose: This study was conducted to develop a timeout protocol as the process of patients verification in the operating room, and to evaluate its effects. Methods: The timeout protocol was developed based on the experience of practices and the universal protocol of JCAHO 2004. The subjects of this study were 192 surgical members working in the operating room at an university hospital in Daegu, Korea. Results: The timeout protocol was developed in six steps; participants verification, encouragement of compliance, verification of right 3 PSP, agreement of surgical team members, verification of the parties to a patient, patient agreement. The data which have been resulted from the experimental group show significantly higher than those of control group as follows; cognition(t = -6.580, p = .000), contents of performance; progress of anesthesiologist as leader(${\chi}^2$ = 29.029, p = .000), verification of right patient, right site and right procedure(${\chi}^2$ = 40.663, p = .000), participation of surgical team(${\chi}^2$ = 68.412, p = .000), and the number of cases of performance(${\chi}^2$ = 242.900, p = .000). Conclusion: It suggests that medical accidents caused by failures in a preoperative verification process can be prevented if a timeout is conducted active involvement and effective communication among surgical team members for a final verification of the correct patient, procedure, and site.

• Journal of KIISE:Information Networking
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• v.36 no.5
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• pp.383-388
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• 2009

In this paper, we focus on the retransmission following transmission failure in impulse radio ultra wideband (IR-UWB). The reasons of transmission failure are classified and a new 'selfish' retransmission protocol is proposed because time hopping can support multiple transmissions at the same time. Selfish retransmission protocol retransmits packets immediately without any kind of timeout or channel observation. Simulation results show that the proposed protocol improves throughput up to 50% and decreases retransmission delay also up to 70%, compared to a conventional retransmission system in IR-UWB.

• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.443-451
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• 2005

Stateful inspection devices must maintain flow information. These devices create the flow information also for network attack packets, and it can fatally inflate the dynamic memory allocation on stateful inspection devices under network attacks. The memory inflation leads to memory overflow and subsequent performance degradation. In this paper, we present a guideline to set the flow entry timeout for a stateful inspection device to remove harmful embryonic entries created by network attacks. Considering Transmission Control Protocol (TCP) if utilized by most of these attacks as well as legitimate traffic, we propose a parsimonious memory management guideline based on the design of the TCP and the analysis of real-life Internet traces. In particular, we demonstrate that for all practical purposes one should not reserve memory for an embryonic TCP connection with more than (R+T) seconds of inactivity where R=0, 3, 9 and $1\leqq{T}\leqq{2}$ depending on the load level.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.741-746
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• 2012

Transmission control protocol(TCP) widely used as a transport protocol in the Internet includes a loss recovery function that detects and recovers packet losses by retransmissions. The loss recovery function consists of the two algorithms; fast retransmit and fast recovery. There have been researches to avoid nonnecessary retransmission timeouts (RTOs), which leads to selective acknowledgement (SACK) option and limited transmit scheme that are standardized by IETF (Internet Engineering Task Force). Recently, a method that covers the case in which a retransmitted packet is lost again has been propsed. The method, however, is not proved in terms of the additive increase multiplicative decrease (AIMD) principle of TCP congestion control. In this paper, therefore, we analyzed the method in terms of the principle by ns-simulations.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.382-390
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• 2005

As today's networks evolve towards an If-based integrated network, the role of transmission control protocol(TCP) has been increasing as well. As a well-known issue, the performance of TCP is affected by its loss recovery mechanism that is comprised of two algorithms; fast retransmit and fast recovery. Although retransmission timeout(RTO) caused by multiple packet losses can be avoided by using selective acknowledgement(SACK) option, RTO cannot be avoided if a retransmitted packet is lost. Therefore, we propose a simple modification to make it possible for a TCP sender using SACK option to detect a lost retransmission. In order to evaluate the proposed algorithm, simulations have been performed for two scenarios where packet losses are random and correlated. Simulation results show that the proposed algorithm can improve TCP performance significantly.