• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.10
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• pp.55-60
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• 2007

This paper proposes a fast and scalable priority queue architecture for use in high-speed networks which supports quality of service (QoS) guarantees. This architecture is cost-effective since a single queue can generate outputs to multiple out-links. Also, compared with the previous multiple systolic array priority queues, the proposed queue provides fast output generation which is important to high-speed packet schedulers, using a special control block. In addition this architecture provides the feature of high scalability.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.295-297
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• 2003

실시간 운영체제는 여러 개의 독립적인 태스크가 동시에 실행될 수 있는 멀티태스킹 환경을 제공한다. 이러한 독립적인 태스크들 사이에 정보를 주고받기 위해서는 태스크들 사이의 통신이 필요하며 이러한 ITC(Inter-Task Communication)를 지원하는 방법에는 Global Variable과 Message 전송 두 가지 방법이 있다. Global Variable 은 Data Corruption 의 위험이 있기 때문에 보통의 실시간 운영체제에서는 Message 전송 방식을 주로 사용하는데 이러한 방식에는 메시지 큐, 메시지 메일박스, 메시지 포트 등이 있다. 본 논문에서는 태스크들 간에 또는 태스크와 ISR(Interrupt Service Routine)이 여러 개의 메시지를 서로 전달할 수 있는 메시지 큐에 대해서 설명하고 있다. 또한 태스크 또는 ISR 이 메시지 큐로부터 메시지를 주고받을 때 메모리의 동적 할당을 보다 효과적으로 처리함으로써 효율적인 메시지 큐 제어기법에 대해서 제시하고 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.615-618
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• 2011

본 논문은 IPTV, VoD와 같은 대용량의 비디오 스트리밍 트래픽을 처리함에 있어 큐 길이 변화를 최소화할 수 있는 SCQ(Smoothly Changing Queue) 스케줄링 방안을 제안한다. SCQ는 벌크하게 유입되는 스트리밍 트래픽에 대해 유입되는 패킷 양 및 속도를 고려하여 서비스율을 제어함으로써 큐 길이 변화율을 최소화할 수 있다. 벌크 특성을 갖는 스트리밍 서비스 전달에 있어 종단간 낮은 지연변이를 유지할 수 있으며 제안 방안을 이용할 경우 보다 안정적으로 서비스를 제공할 수 있다. 제안 방안의 유효성을 확인하기 위해 우리는 큐잉 모델을 이용하였으며, 그 결과 기존 평균 큐길이 기반 스케줄링 방안보다 낮은 큐길이 변화율을 보임을 확인하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.556-559
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• 2007

하나의 시스템을 다수의 사람들이 작업을 할 경우 한정된 자원을 각각의 작업에 효율적으로 배분하기 위하여 작업관리 시스템을 이용한다. IBM 시스템은 작업관리 시스템으로서 주로 LoadLeveler를 사용하고 있다. 작업관리 시스템은 작업을 처리할 수 있는 여러가지의 큐를 가지고 있으며, 큐는 시스템의 특성과 구성 그리고 사용자 작업의 패턴에 따라서 설계되어진다. 본 논문에서는 LoadLeveler에서 작업을 실행할 때 긴급한 작업을 우선적으로 처리할 수 있는 큐를 만들기 위하여 preemption 기능을 이용하여 구성하고, 해당 큐로 작업을 선점하여 실행하면서 각각 작업들의 메모리 사용 변화와 그에 따른 작업 처리 성능을 분석하고 방법을 연구하였다.

• Journal of Internet Computing and Services
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• v.2 no.2
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• pp.65-70
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• 2001

In this paper, a Modified RED algorithm for congestion avoidance in IP networks is presented. The RED detects incipient congestion by computing the average queue size. By notifying only a randomly selected fraction of connection, it causes to the global synchronization or fairness problem, And also, the network characteristics need to be known in order to find th optimum average queue length. When the average queue size exceeds a minimum threshold, a modified RED algorithm drops packets based on the state of each connection. Performance is improved because of keeping the average queue size low while allowing occasional bursts of packets in the queue, we compare performance of modified RED with RED and Drop Tail in terms of goodput, network utilization and fairness.

• Journal of Korea Multimedia Society
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• v.15 no.8
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• pp.1038-1047
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• 2012

The SIP(Session Initation Protocol) is an application layer protocol that is used to establish, release, and change the call session of the IP telephony. In the SIP signalling networks, when the number of the UA(User Agent) requested the call session increase, the number of messages to be processed by SIP proxy server increase. It often will be caused the overload of the SIP proxy server. In this paper, we proposed the overload control method with a normal queue and a delay queue in the SIP proxy server. When it is estimated the overload of the server by the excess of the high threshold in the normal queue, new INVITE messages will be put into the delay queue to reduce the load of the server. It results in some delay of the call session from the INVITE message. Subsequently when the number of messages in the normal queue is reduced below the low threshold, the INVITE messages in the delay queue is processed. The simulation results showed that the number of the retransmission messages by our proposed method was 45% less than the one by the method with single queue. The results also showed that the average call success rate by the proposed method was 2% higher than the one by the method with single queue.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.847-854
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• 2005

Since the propagation speed of the Internet worms is quite fast, worm detection in early propagation stage is very important for reducing the damage. Virus throttling technique, one of many early worm detection techniques, detects the Internet worm propagation by limiting the connection requests within a certain ratio.[6, 7] The typical throttling technique increases the possibility of false detection by treating destination IP addresses independently in their delay queue managements. In addition, it uses a simple decision strategy that determines a worn intrusion if the delay queue is overflown. This paper proposes a two dimensional delay queue management technique in which the sessions with the same destination IP are linked and thus a IP is not stored more than once. The virus throttling technique with the proposed delay queue management can reduce the possibility of false worm detection, compared with the typical throttling since the proposed technique never counts the number of a IP more than once when it chicks the length of delay queue. Moreover, this paper proposes a worm detection algorithm based on weighted average queue length for reducing worm detection time and the number of worm packets, without increasing the length of delay queue. Through deep experiments, it is verified that the proposed technique taking account of the length of past delay queue as well as current delay queue forecasts the worn propagation earlier than the typical iuぉ throttling techniques do.

• Korean Journal of Optics and Photonics
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• v.28 no.6
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• pp.351-355
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• 2017

In this paper, we conduct a simulation of manipulating various pulsed laser operations through tuning the modulation depth of the saturable absorber in a laser cavity. The research, showing that various pulsed operations could be manipulated from Q-switching through Q-switched mode locking to mode locking by tuning the modulation depth of the saturable absorber in a cavity, has been studied by experimental means. We conduct a simulation with the Haus master equation to verify that these experimental results are consistent with expectations from theory. The time dependence of the gain was considered to express Q-switching fluctuation through applying a rate equation with the Haus master equation. Laser operation was manipulated from mode locking through Q-switched mode locking to Q-switching as modulation depth was increased, and this result agreed well with the theoretical expectation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.987-995
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• 1999

The handoff is a distinctive characteristic of the mobile networks. In the CDMA systems, if base stations support multiple Frequency Assignment (FA), they provide both soft handoff and hard handoff. Under the CDMA environments, the soft handoff guarantees the favorable service quality and the continuity of call connection without interruption, and increases the service capacity of the base stations. This paper proposes call connection control schemes with handoff queue for supporting efficient handoff processing. The proposed schemes are divided into two categories: single handoff queue scheme and multiple handoff queue scheme. We analyze the performance of the proposed call connection control schemes using numerical analysis. From the analysis results, we can say that it is more desirable to avoid hard handoff as long as handoff queues are used. When a single handoff queue used, adaptive scheme that properly mixes avoidable and avoidable hard handoff method under the given traffic condition is more desirable. In case that multiple handoff queues are used, the suitable trade-off needs to be developed between handoff blocking probability and hard handoff probability to guarantee a given blocking probability threshold.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.613-618
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• 2012

ICT education guidelines revised in 2005 reinforce computer science elements such as algorithm, data structure, and programming covering all schools. And Ministry of Education emphasizes STEAM education. Most important is that "How instruct them". This means necessity of contents. So this paper suggests learning method of Stack and Queue using LEGO MINDSTORMS NXT. The main purpose is that how stack and queue are used, when robot explore realistic maze. Teaching and learning strategies are algorithm, flowchart, and NXT-G programming. Simple maze has path in left or right, but complex maze has three-way intersection. These are developed by authors. Master robot explores maze and push stack, and then return to entrance using stack. Master robot explores maze and transmits path to slave's queue. And then slave robot drives without exploration. Students can naturally learn principles and applications of them. Through these studies, it can improves ability of logical and creative thinking. Furthermore it can apply to ICT and STEAM education.