• Journal of the Korean Statistical Society
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• 제24권1호
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• pp.19-29
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• 1995

In this paper, we investigate the asymptotic distributions of maximum queue length for M/G/1 and GI/M/1 systems which are positive recurrent. It is well knwon that for any positive recurrent queueing systems, the distributions of their maxima linearly normalized do not have non-degenerate limits. We show, however, that by concerning an array of queueing processes limiting behaviors of these maximum queue lengths can be established under certain conditions.

• Journal of information and communication convergence engineering
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• 제6권1호
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• pp.19-23
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• 2008

The AQM (Active Queue Management) starts dropping packets earlier to notify traffic sources about the incipient stage of congestion. The AQM improves fairness between response flow (like TCP) and non-response flow (like UDP), and it can provide high throughput and link efficiency. In this paper, we suggest the QVARED (Queue Variation Adaptive RED) algorithm to respond to bursty traffic more actively. It is possible to provide more smoothness of average queue length and the maximum packet drop probability compared to RED and ARED (Adaptive RED). Therefore, it is highly adaptable to new congestion condition. Our simulation results show that the drop rate of QVARED is decreased by 80% and 40% compare to those of RED and ARED, respectively. This results in shorter end-to-end delay by decreasing the number of retransmitted packets. Also, the QVARED reduces a bias effect over 18% than that of drop-tail method; therefore packets are transmitted stably in the bursty traffic condition.

• Journal of the Korean Statistical Society
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• 제12권2호
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• pp.95-99
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• 1983

Limiting law for maximum queue length in G/M/1 queue system is derived. Furthermore, a simple approach using mixing sequence is also discussed.

• 한국경영과학회지
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• 제26권4호
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• pp.39-45
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• 2001

Maximum and minimum of rendom variables are frequently encountered in the stochastic modelling for various OR problems. We summarize and extend characteristics of maximum and minimum, emphasizing the case in which random variables are independent and all of them except one are distributed exponential. As an application, we derive a transform-free expression for the M/G/1 queue length distribution.

• 대한산업공학회지
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• 제28권1호
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• pp.36-43
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• 2002

We analyze bulk service $M/G^{b}/1$ queues using the arrival time approach of Chae et al. (2001). As a result, the decomposition property of the M/G/1 queue with generalized vacations is extended to the $M/G^{b}/1$ queue in which the batch size is exactly a constant b. We also demonstrate that the arrival time approach is useful for relating the time-average queue length PGF to that of the departure time, both for the $M/G^{b}/1$queue in which the batch size is as big as possible but up to the maximum of constant b. The case that the batch size is a random variable is also briefly mentioned.

• 한국통신학회논문지
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• 제22권1호
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• pp.162-172
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• 1997

In this paper, we investigated the performance of a binary feedback switch algorithm for the ABR(Available Bit Rate) service in ATM networks. A binary feedback switch is also called EFCI(Explicit Forward Congestion Indication) switch and can be classificed into input cell processing(IP) scheme according to processing methods for the EFCI bit in data-cell header. We proposed two implementation methods for the binary feedback switch according to EFCI-bit processing schemes, and analyzed the ACR(Allowed Cell Rate) of source and the queue length of switch for each scheme in steady state. In addition, we derived the upper and lower bounds for maximum and minimum queue lengths, respectively, and investigated the impact of ABR parameters on the queue length.

• 대한교통학회지
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• 제23권8호
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• pp.181-191
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• 2005

본 연구에서는 구간통행시간과 같은 링크의 속성정보를 수집 가능한 검지체계를 구간검지체계로 정의하여 이러한 검지체계를 기반으로 실시간 신호제어 알고리즘을 개발하였다. 신호제어를 위한 변수는 공간적 개념을 가지는 대기행렬길이를 제안하였다. 개별차량에 대해 검지기 통과 시 차량의 ID와 통과시각이 수집 가능한 DSRC와 같은 기술을 이용하여 링크 통행시간을 수집하며, 한 주기 동안 수집된 개별차량 통행시간은 지체를 경험한 차량과 그렇지 않은 차량으로 구분된다. 이를 이용하여 대기행렬 해소시간을 산출가능하며, 결정적 지체모형을 기반으로 주기별 최대대기행렬을 산출하였다. 실시간 신호제어의 목표는 접근로별 대기행렬의 균형화로서 각 접근로의 대기행렬이 사전에 정의된 임계대기행렬을 초과하지 않는 범위에서의 균등화될 수 있도록 대기행렬의 비율에 따라 신호시간을 배분하는 방법을 이용하였다.

• Journal of Communications and Networks
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• 제5권3호
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• pp.275-281
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• 2003

Random Early Detection (RED) [1] is an active queue management scheme which has been deployed extensively to reduce packet loss during congestion. Although RED can improve loss rates, its performance depends severely on the tuning of its operating parameters. The idea of adaptively varying RED parameters to suit the network conditions has been investigated in [2], where the maximum packet dropping probability $max_p$ has been varied. This paper focuses on adaptively varying the queue weight $\omega_q$ in conjunction with $max_p$ to improve the performance. We propose two algorithms viz., $\omega_q$-thresh and $\omega_q$-ewma to adaptively vary $\omega_q$. The performance is measured in terms of the packet loss percentage, link utilization and stability of the instantaneous queue length. We demonstrate that varying $\omega_q$ and $max_p$ together results in an overall improvement in loss percentage and queue stability, while maintaining the same link utilization. We also show that $max_p$ has a greater influence on loss percentage and queue stability as compared to $\omega_q$, and that varying $\omega_q$ has a positive influence on link utilization.

• 대한교통학회지
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• 제18권4호
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• pp.75-85
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• 2000

본 연구에서는 도시부도로 신호교차로의 대기행렬을 단기(one cycle ahead)예측함에 있어 단일검지체계에 기반을 둔 한 지점의 시계열적 패턴을 갖는 검지자료(detection data)를 학습자료로 구성할 경우와 통합차량검지체계하에 기반을 둔 시공간적 상관관계를 갖는 검지자료를 학습자료로 이용할 경우를 가정하여 이에 대한 인공신경망의 학습능력과 예측능력을 비교하였다. 연구결과는 도시부도로 신호교차로상에서 차량군(platoon)의 이동에 따라 발생되는 시공간적인 상관관계를 갖는 교통류변수 $\ulcorner$상류유입교통량(k-1)->통행시간(k-1)->대기행렬(k)->유출교통량(k)->대기행렬(k+1)$\lrcorner$를 인공신경망의 학습자료로 구성할 경우, 교통류 패턴의 학습능력이 뛰어난 것으로 밝혀졌다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1987년도 추계학술발표회 발표논문초록집; 중소기업협동조합중앙회, 서울; 31 Oct. 1987
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• pp.35-35
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• 1987

Consider a job shop that is modelled as an open queueing network of the Jackson(l957) type. All work stations in the shop have the same number of parallel servers. Two problems are studied : the loading of stations and the assignment of servers, which are represented by loading and assingment vectors, respectively. Ma jorization and arrangement orderings are established to order, respectively, the loading and the assignment vectors. It is shown that reducing the loading vector under ma jorizat ion or increasing the assignment vector under arrangement ordering will reduce the congestion in the shop in terms of reducing the total number of jobs(in the sense of likelihood ratio ordering), the maximum queue length(in the sense of stochastic ordering), and the queue-length vector( in the sense of stochastic majorization). The results can be used to supprot production planning in certain job shops, and to aid the desing of storage capacity. (OPEN QUEUEING NETWORK; WJORIZATION; ARRANGEMENT ORDERINC; LIKELIHOOD RATIO ORDERINC; STOCHASTIC ORDERING)