• Title/Summary/Keyword: 카운터플로우

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The Counterflow Speed and Density of a Fire fighter in Corridor (복도에서 소방관에 의한 카운터플로우 발생 시 밀도와 속도 측정)

  • Kim, Woon-Hyung;Kim, Heung-Youl;Joung, Woo-In;Kim, Jong-Hoon
    • Journal of the Society of Disaster Information
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    • v.15 no.1
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    • pp.76-83
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    • 2019
  • Purpose: The purpose of this study is to present data of density and speed through the experiment of the counterflow by firefighter in corridor. Method: Experimental setup including a corridor in building was prepared for measuring data with 1.5m and 2m width. Normal flow and counterflow were created for each. Data were measured using camera and acquired by video image analysis. Results: The counterflow in corridor resulted in increasing average density of about $0.55P/m^2$ and decreasing average movement speed of about 0.61 m/s. These data measured during the time when the counterflow occurred. Conclusion: It was found that counterflow by firefighter in corridor momentary increasing the density and decreasing walking speed of evacuee. Further experiments of the counterflow effect in the total evacuation time are needed.

MBAC Mechanism for blocking probability fairness guarantee (Blocking Probability Fairness 보장을 위한 MBAC 메커니즘)

  • Jin, Min-Sook;Kim, Ki-Il;Kim, Sang-Ha
    • Proceedings of the Korea Information Processing Society Conference
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    • 2001.04a
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    • pp.491-494
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    • 2001
  • IP 망에서 Qos(Quality of Service)를 보장하기 위하여 요구되는 것이 수락 제어이다. 기존의 수락 제어 메커니즘은 크게 RSVP(Resource Reservation Protocol) 시그널링 방법과 MBAC(Measurement Based Admission Control)로 분류된다. 첫번째 방법의 경우 코어 망에서 각 플로우마다 상태를 유지해야 하는 확장성 문제때문에 적용이 쉽지 않고, 두 번째 방법의 경우 긴 경로를 가진 플로우의 경우 짧은 경로를 가진 플로우에 비해 블록킹 확률이 높아지는 문제점이 있다. 본 논문에서는 IP 코어 망에서 사용자의 QoS 요구사항과 서로 다른 경로상의 플로우간 블록킹 확률의 공평성을 위한 TPED MBAC(Two-Phase Edge-to-Edge Distributed Measurement Based Admission Control) 메커니즘을 제안한다. 이 MBAC 메커니즘은 수락 제어를 Quantitative Provisioning 단계와 Qualitative Provisioning 단계로 나누어 수행하며 프로빙 패킷 전송을 위해 홉 카운터에 기반 한 WRR(Weighted Round-Robin) 스케쥴링을 적용함으로써 각 플로우간의 블록킹 확률의 공평성을 제어할 수 있는 메커니즘이다.

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Flow Labeling Method for Realtime Detection of Heavy Traffic Sources (대량 트래픽 전송자의 실시간 탐지를 위한 플로우 라벨링 방법)

  • Lee, KyungHee;Nyang, DaeHun
    • KIPS Transactions on Computer and Communication Systems
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    • v.2 no.10
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    • pp.421-426
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    • 2013
  • As a greater amount of traffic have been generated on the Internet, it becomes more important to know the size of each flow. Many research studies have been conducted on the traffic measurement, and mostly they have focused on how to increase the measurement accuracy with a limited amount of memory. In this paper, we propose an explicit flow labeling technique that can be used to find out the names of the top flows and to increase the counting upper bound of the existing scheme. The labeling technique is applied to CSM (Counter Sharing Method), the most recent traffic measurement algorithm, and the performance is evaluated using the CAIDA dataset.

Router Algorithms for Improving Fairness in Differentiated Services (인터넷 차별화 서비스를 위한 라우터의 공평성 향상 알고리즘)

  • Nam, Dong-Ho;Choi, Young-Soo;Kim, Byung-Chul;Cho, You-Ze
    • Journal of KIISE:Information Networking
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    • v.29 no.4
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    • pp.358-367
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    • 2002
  • The IETF Differentiated Services (Diffserv) WG focused on Providing service differentiation on the Internet. One problem of the Diffserv Assured Services (AS) architecture is that it cannot guarantee fairness and throughput assurance. In this paper, we propose two schemes for guaranteeing fairness among the various target rates in the AS architecture. One is a variant of RED with IN and OUT (RIO), called the improved RIO (IRIO). The other is a variant of Time Sliding Window (TSW), called the improved TSW (ITSW). To validate the Proposed schemes, their behaviors are then examined under various simulation environments. The simulation results showed that IRIO and ITSW improved fairness and the throughput assurance in the AS architecture.

Ternary Bloom Filter Improving Counting Bloom Filter (카운팅 블룸필터를 개선하는 터너리 블룸필터)

  • Byun, Hayoung;Lee, Jungwon;Lim, Hyesook
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.1
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    • pp.3-10
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    • 2017
  • Counting Bloom filters (CBFs) have been popularly used in many network algorithms and applications for the membership queries of dynamic sets, since CBFs can provide delete operations, which are not provided in a standard 1-bit vector Bloom filter. However, because of the counting functions, a CBF can have overflows and accordingly false negatives. CBFs composed of 4-bit counters are generally used, but the 4-bit CBF wastes memory spaces by allocating 4 bits for every counter. In this paper, we propose a simple alternative of a 4-bit CBF named ternary Bloom filter (TBF). In the proposed TBF structure, if two or more elements are mapped to a counter in programming, the counters are not used for insertion or deletion operations any more. When the TBF consumes the same amount of memory space as a 4-bit CBF, it is shown through simulation that the TBF provides a better false positive rate than the CBF as well as the TBF does not generate false negatives.

The IEEE 802.11 MAC Protocol to solve Unfairness Problem in Multihop Wireless Ad Hoc Networks (다중 무선 에드혹 네트워크에서 불공정 문제를 해결하기 위한 802.11 MAC 프로토콜)

  • Nam, Jae-Hyun
    • Journal of the Korea Society of Computer and Information
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    • v.12 no.6
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    • pp.229-234
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    • 2007
  • In the IEEE 802.11 Wireless Local Area Networks (WLANs), network nodes experiencing collisions on the shared channel need to backoff for a random period of time. which is uniformly selected from the Contention Window (CW) This contention window is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. The BEB scheme suffers from a unfairness problem and low throughput under high traffic load. In this paper, I propose a new backoff algorithm for use with the IEEE 802.11 Distributed Coordination Function.

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