• Journal of the Institute of Electronics Engineers of Korea CI
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• v.39 no.1
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• pp.14-22
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• 2002

We propose the fuzzy BCMP queueing network model for the performance evaluation of distributed processing system with the ambiguous arrival rates of job, service requirements, and service rates of server by the network environments. This model is classified as the open and closed type whether or not the network accepts jobs from the system outside. We derived the measures for system performances such as the job average spending time, average job number in the system and server utilizations using fuzzy mean value analysis which can process the fuzzy factors for both types. Computer simulation was performed for verifying the effectiveness of derived equations of performance evaluation. The fuzzy BCMP queueing network model was evaluated according to the fuzzy arrival rates of job, the number of clients, and the fuzzy service requirements of job for each the open and closed type. The results were agreed with the predicted performance evaluations of the system.

• Communications for Statistical Applications and Methods
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• v.18 no.4
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• pp.433-443
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• 2011

We consider a compound Poisson risk model in which the premiums may depend on the state of the surplus process. By using the overflow probability of the workload process in the corresponding M/G/1 queueing model, we obtain the probability that the ruin occurs before the surplus reaches a given large value in the risk model. We also examplify the ruin probability in case of exponential claims.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.1
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• pp.67-73
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• 2011

Using the known result of the expected busy period for a controllable M/G/1 queueing model operating under the triadic Max (N, T, D) policy, its upper and lower bounds are derived to approximate its corresponding actual value. Both bounds are represented in terms of the expected busy periods for the dyadic Min (N, T), Min (N, D) and Min (T, D) and simple N, T and D operating policies. All three input variables N, T and D are equally contributed to construct such bounds for better estimation.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.4
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• pp.27-44
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• 2000

In this study we consider a spares provisioning problem for repairable items in which a parts inventory system is incorporated. If a machine fails, a replacement part must be obtained at the parts inventory system before the failed machine enters the repair center. The inventory policy adopted at the parts inventory system is the (S, Q) policy. Operating times of the machine before failure, ordering lead times and repair times are assumed to follow a two-stage Coxian distribution. For this system, we develop an approximation method to obtain the performance measures such as steady state probabilities of the number of machines at each station and the probability that a part will wait at the parts inventory system. For the analysis of the proposed system, we model the system as a closed queueing network and analyze it using a product-form approximation method. A recursive technique as well as an iterative procedure is used to analyze the sub-network. Numerical tests show that the approximation method provides fairly good estimation of the performance measures of interest.

• Journal of the Korea Computer Industry Society
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• v.6 no.2
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• pp.305-316
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• 2005

A heterogeneous webserver such as an HTTP server should be able to currently deal with numerous users. To the end, it is inevitable to formally analyze web traffics as well as a webserver itself. In particular, as most systems adopt HTTP 1.1 protocol instead of HTTP 1.0 protocol, it is more difficult to represent the system as a simple analytic mode. In addition, since most of previous models missed the detailed processes of the server, it is unsuitable for the current server based on HTTP 1.1 to tune itself with its own system parameters. On the basis of HTTP 1.1 Protocol supporting persistent connections, we thus present an analytical end-to-end tandem queueing model considering specific hardware configurations inside the webserver, which ultimately covers from accepting the customer requests to completing the services.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.1
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• pp.130-140
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• 1999

This paper deals with a priority queueing model in an ATM system. Two types of customers are considered. Type-1 customers have push-put priority over type-2 customers. Type-1 customers can enter the service only when the number of type-2 customers is less than a threshold T. We derive the joint probability of the number of customers in the buffer, the mean waiting time, and the loss probabilities of each type. We also propose an optimal control policy that satisfies a given quality of service.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.3
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• pp.71-77
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• 2009

Using the results of the expected busy periods for the dyadic Min(N, D) and Max(N, D) operating policies in a controllable M/G/1 queueing model, an important relation between them is derived. The derived relation represents the complementary property between two operating policies. This implies that it could be possible to obtained desired system characteristics for one of the two operating policies from the corresponding known system characteristics for the other policy. Then, upper and lower bounds of expected busy periods for both dyadic operating policies are also derived.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.3
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• pp.63-70
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• 2010

Based on the known results of the expected busy periods for the triadic Min (N, T, D) and Max (N, T, D) operating policies applied to a controllable M/G/1 queueing model, a relation between them is constructed. Such relation is represented in terms of the expected busy periods for the simple N, T and D, and the dyadic Min (N, T), Min (T, D) and Min (N, D) operating policies. Hence, if any system characteristics for one of the two triadic operating policies are known, unknown corresponding system characteristics for the other triadic operating policy could be obtained easily from the constructed relation.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.561-566
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• 2000

Computer-Communication System may be classified into two kinds of systems considering connection capability among terminal and computing facility : time sharing and distributed computer systems According to the different input characteristic, the buffer behavior of two systems is quite different. Here we restrict our study to the analysis of queueing behavior of a demultiplexing buffer of time sharing systems. The analysis shows that M/G/1 queueing model can be used model such behavior.

• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.395-408
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• 2003

Common Channel Signaling(CCS) networks need special controls to avoid overload of signaling networks and degradation of call process-ing rate, since they play an important role of controlling communication transfer networks. Congestion control and flow control mechanisms are well described in ITU-T recommendation on Signaling System No.7(SS7). For the practical provisions, however, we need an analysis on the relation among service objects, system requirements and implementation of congestion control algorithms. SS7 provides several options for controlling link congestion in CCS networks. In this paper we give a general queueing model of congestion control algorithm which covers both the international and national options. From the queuing model, we obtain the performance parameters such as throughput, message loss rate and mean delay for the international option. To show the performance of the algorithm, some numerical results are also given.