• Journal of Korean Institute of Industrial Engineers
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• 제22권1호
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• pp.95-104
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• 1996

We consider a two-phase queueing system with generalized vacation. Poisson arrivals receive a batch type service in the first phase and individual services in the second phase. The server takes generalized vacation when the system becomes empty. Generalized vacation includes single vacation, multiple vacation, and other types. We consider both gated batch service and exhaustive batch service. This is an extension of the model presented by Selvam and Sivasankaran [6].

• Journal of Korean Institute of Industrial Engineers
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• 제35권2호
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• pp.171-177
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• 2009

This study presents the switching strategy between admission control and pricing control policies and clarifies the properties of the switching strategy in an M/M/1/K queueing system. In addition, this study demonstrates that employing the switching strategy can significantly improve the maximum total expected profit.

• Journal of the Korean Operations Research and Management Science Society
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• 제21권2호
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• pp.203-213
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• 1996

A system is considered which is required to perform tasks that arrive randomly during a fixed mission duration. We develop queueing models to obtain the mission effectiveness and the blocking probabilities. Exact probabilities are computed by using the Finite Fourier Cosine Transform.

• Journal of the Korean Operations Research and Management Science Society
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• 제21권2호
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• pp.49-58
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• 1996

The generalized Erlang loss function, extensively studied in the literature, is revisited. We study the steady state loss probability in M/M/s/s + c queueing system and prove that it satisfies the first and second order properties in integral number of servers as well as integral queue capacities. Also we study the problem of allocating integral number of servers and queue capacities, and develop an algorithm to obtian an optimal allocation of them individually and jointly with the small number of computations.

• Journal of the Korean Operations Research and Management Science Society
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• 제31권1호
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• pp.83-90
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• 2006

By defining the partial busy period of the M/M/c/K queueing system as the time interval during which at least one server is in service, we derive the first two moments of both the partial busy period and the number of customers served during it. All expressions are given in explicit forms.

• Journal of the Korean Operations Research and Management Science Society
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• 제36권3호
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• pp.45-59
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• 2011

OFDMA systems have been expected to be widely used to provide multimedia services over wireless channels. To evaluate performance of the OFDMA system, power should be considered as system resource as well as subcarriers. This study propose a queueing traffic model incorporating two kinds of resources (power and subcarriers), and an extended model giving a priority to handoff calls over new calls. Some extensive experiments are conducted to illustrate the usefulness of the proposed traffic model.

• Journal of Korean Institute of Industrial Engineers
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• 제28권3호
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• pp.319-330
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• 2002

We consider BMAP/G/1 queueing system with N-policy and multiple vacations. We derive the vector generating functions of the queue length in a factorized form and interpret the factorization. We also derive the mean queue length.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.56-63
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• 1997

Under most system assumptions, closed form solutions of performance measures for ATM switches with input queueing are not available. In this paper, we present expressions and bounds for the derivatives of cell loss probabilities with respect to the arrival rate evaluated at a zero arrival rate. These bounds are used to give an approximation by Taylor expansion, thereby providing an economical way to estimate cell loss probabilities in light traffic.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제28권1호
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• pp.114-120
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• 2005

This paper studies procedures for bottleneck detection in closed queueing networks(CQN's) with multiple job classes. Bottlenecks refer to servers operating at $100\%$ utilization. For CQN's, this can occur as the population sizes approach infinity. Bottleneck detection reduces to a non-linear complementary problem which in important special cases may be interpreted as a Kuhn-Tucker set. Efficient computational procedures are provided.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제16권28호
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• pp.39-47
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• 1993

In this paper, We develop performance evaluation model for Twin fork Automated Storage/Retrieval systems. The system is modeled as a modified bulk service queueing system consisting of one exponential server with limited system capacity. The differance between this model and general bulk service queueing model is the inequality of transition service rate of each stage. The ejective of this model is to provide system characteristics for Twin fork AS/R system design problems, which are the number of customers in system, wait time in system and queue, the system queue size.