• Title, Summary, Keyword: queue theory

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Evaluation of Patients' Queue Environment on Medical Service Using Queueing Theory (대기행렬이론을 활용한 의료서비스 환자 대기환경 평가)

  • Yeo, Hyun-Jin;Bak, Won-Sook;Yoo, Myung-Chul;Park, Sang-Chan;Lee, Sang-Chul
    • Journal of the Korean Society for Quality Management
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    • v.42 no.1
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    • pp.71-79
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    • 2014
  • Purpose: The purpose of this study is to develop the methods for evaluating patients' queue environment using decision tree and queueing theory. Methods: This study uses CHAID decision tree and M/G/1 queueing theory to estimate pain point and patients waiting time for medical service. This study translates hospital physical data process to logical process to adapt queueing theory. Results: This study indicates that three nodes of the system has predictable problem with patients waiting time and can be improved by relocating patients to other nodes. Conclusion: This study finds out three seek points of the hospital through decision tree analysis and substitution nodes through the queueing theory. Revealing the hospital patients' queue environment, this study has several limitations such as lack of various case and factors.

The Unfinished Work Transition Probability Distribution of Modulated $n^*$D/D/1 Queue (확률적 $n^*$D/D/1 대기모형의 부하량 전이 확률 분포)

  • Lee, Sang-Cheon;Hong, Jung-Wan
    • IE interfaces
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    • v.13 no.4
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    • pp.738-744
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    • 2000
  • This Paper presents a method for unfinished work transition probability distribution of modulated $n^*D/D/l$ queue with overload period. The Modulated $n^*D/D/l$ queue is well known as a performance analysis model of ATM multiplexer with superposition of homogeneous periodic on-off traffic sources. Theory of probability by conditioning and results of $N^*D/D/l$ queue are used for analytic methodology. The results from this paper are expected to be applied to general modulated $n^*D/D/l$ queue.

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Modiied Fuzzy-based WRR Algorithm for QoS Guarantee in DiffServ Networks (DiffServ 망에서 QoS를 보장하기 위한 개선된 퍼지 기반 WRR 알고리즘 개발)

  • Chung Kyung-Taek;Park Joon;Kim Byun-Gon;Chon Byoung-Sil
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.3
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    • pp.135-143
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    • 2006
  • PQ(Priority Queue) and WRR(Weighted Round Robin) are the most famous schedulers, however, these schedulers have both points of advantages and disadvantages. In this paper, we propose an algorithm that can be adopted in my kind of scheduling type with making up for weak points of PQ and WRR. The proposed algorithm includes a fuzzy theory in the scheduler to assign priorities dynamically in the DiffServ network. This algorithm produces the control discipline by the fuzzy theory to assign priorities of the Queue effectively with checking the Queue status of each class dynamically under the discipline.

A Study of Traffic Flow Characteristics for Estimating Queue-Length in Freeway (고속도로 대기행렬길이 산정모형 개발을 위한 연속류 특성 분석)

  • 노재현;손봉수;도철웅;신치현
    • Journal of Korean Society of Transportation
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    • v.17 no.2
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    • pp.179-191
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    • 1999
  • To device effective freeway traffic flow control strategies and freeway traffic information dissemination strategies, it is very important to estimate real physical queue length on the freeway. Shock wave theory and queueing theory have limitation to be used to estimate the queue length. The primary objective of this study is to develop a reliable method for estimating the physical queue length and level of congestion. Queueing propagation processes were analysed by using such traffic data as main line traffic volume, ramp volume, density. speed, and physical queue length collected by video photographing on Olympic Freeway. As a result of analysis, it has been confirmed that the real queue length can be estimated by using the traffic counts arriving the congested region and passing a bottleneck location. Further more, a reliable method for estimating the level of congestion could be developed on the basis of real-time traffic counts.

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Improvement and Comparative Study of Control Theory-based AQM Methods for Networks with Realistic Traffic

  • Bigdeli, N.;Haeri, M.;Pakravan, M.R.
    • 제어로봇시스템학회:학술대회논문집
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    • pp.767-771
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    • 2004
  • In this paper the performance of some control theory-based Active Queue Management (AQM) methods are improved and investigated through simulation. The simulation scenario is considered to be closely realistic, in which the traffic is mainly due to http sessions. The results show the best performance of PID controller with respect to the others in good queue regulation as well as high link utilization and low delay metrics.

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Dynamic Optimization of Active Queue Management Routers to Improve Queue Stability

  • Radwan, Amr
    • Journal of Korea Multimedia Society
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    • v.18 no.11
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    • pp.1375-1382
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    • 2015
  • This paper aims to introduce the numerical methods for solving the optimal control theory to model bufferbloat problem. Mathematical tools are useful to provide insight for system engineers and users to understand better about what we are facing right now while experiment in a large-scale testbed can encourage us to implement in realistic scenario. In this paper, we introduce a survey of the numerical methods for solving the optimal control problem. We propose the dynamic optimization sweeping algorithm for optimal control of the active queue management. Simulation results in network simulator ns2 demonstrate that our proposed algorithm can obtain the stability faster than the others while still maintain a short queue length (≈10 packets) and low delay experience for arriving packets (0.4 seconds).

A Dynamic Queue Management for Network Coding in Mobile Ad-hoc Network

  • Kim, Byun-Gon;Kim, Kwan-Woong;Huang, Wei;Yu, C.;Kim, Yong K.
    • International journal of advanced smart convergence
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    • v.2 no.1
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    • pp.6-11
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    • 2013
  • Network Coding (NC) is a new paradigm for network communication. In network coding, intermediate nodes create new packets by algebraically combining ingress packets and send it to its neighbor node by broadcast manner. NC has rapidly emerged as a major research area in information theory due to its wide applicability to communication through real networks. Network coding is expected to improve throughput and channel efficiency in the wireless multi-hop network. Many researches have been carried out to employ network coding to wireless ad-hoc network. In this paper, we proposed a dynamic queue management to improve coding opportunistic to enhance efficiency of NC. In our design, intermediate nodes are buffering incoming packets to encode queue. We expect that the proposed algorithm shall improve encoding rate of network coded packet and also reduce end to end latency. From the simulation, the proposed algorithm achieved better performance in terms of coding gain and packet delivery rate than static queue management scheme.

An M/G/1 queue under the $P_{\lambda,\tau}^M$ service policy

  • Kim, Jong-Woo;Lee, Ji-Yeon
    • 한국데이터정보과학회:학술대회논문집
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    • pp.25-29
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    • 2005
  • We analyze an M/G/1 queueing system under $P_{\lambda,\tau}^M$ service policy. By using the level crossing theory and solving the corresponding integral equations, we obtain the stationary distribution of the workload in the system explicitly.

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Determination of Deceleration Lane Length in Interchange with Shock-Wave Theory (충격파를 고려한 입체교차로의 감속차로 길이 산정방안)

  • Kim, Jeong-Hyun
    • International Journal of Highway Engineering
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    • v.11 no.1
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    • pp.145-151
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    • 2009
  • Current highway design standards is based on the safety under the free flow condition. The length of deceleration lane is also determined in terms of the deceleration distance which is necessary for the driers to adjust the vehicle speed from the speed limit on the main road to that on the exit ramp of the interchange. However, the queues are frequently developed on the deceleration, and the following vehicles to exit must decelerate on the main road. It may cause delay on the main road and traffic accidents. This study is to suggest a methodology to minimize such problems with the shock-wave theory. The queue length of exiting vehicles can be estimated by the design speeds, traffic volumes of main road and the exiting ramp, and the countermeasures to the operational problems. According to the results, the queue length can be shortened to 80% by upgrading the design speed of exit ramp as the amount of 10km/h. Fifty percent of queue length can be shortened by adding an additional lane on the ramp to two lanes.

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A MIrcroscopic Application of the Little's Formula (Little's 법칙의 미시적 활용 사례)

  • Yoon, Bong-K.;Kim, Nam-K.;Chae, Kyung-C.
    • Journal of Korean Institute of Industrial Engineers
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    • v.25 no.1
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    • pp.125-129
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    • 1999
  • The Little's formula, $L={\lambda}W$, expresses a fundamental principle of queueing theory: Under very general conditions, the average queue length is equal to the product of the arrival rate and the average waiting time. This useful formula is now well known and frequently applied. In this paper, we demonstrate that the Little's formula has much more power than was previously realized when it is properly decomposed into what we call the microscopic Little's formula. We use the M/G/1 queue with server vacations as an example model to which we apply the microscopic Little's formula. As a result, we obtain a transform-free expression for the queue length distribution. Also, we briefly summarize some previous efforts in the literature to increase the power of the Little's formula.

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