• Journal of Korea Society of Industrial Information Systems
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• v.12 no.2
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• pp.16-23
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• 2007

Tandem queueing systems well suit for modeling many telecommunication systems. Recently, very general $BMAP/G/1/N/1{\to}{\bullet}/PH/1/M-1$ type tandem queues were constructively studied. In this paper we illustrate application of the obtained results for optimization of a buffer pool design.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.403-406
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• 2006

This paper provides an M/G/1 queueing model for the operations management problem at the toll plaza. This queueing process is incorporated with two non-linear integer programming models - the user cost minimization model during the peak times and the operating cost minimization model during the off-peak hours.

• IE interfaces
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• v.2 no.2
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• pp.51-62
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• 1989

A computer-aided simulation modeling system has been developed to allow the automatic construction of complete discrete simulation models for queueing systems. Three types of knowledge are used in the specification and construction of a simulation modeling: Knowledge of queueing system, simulation modeling, and a target simulation language. This knowledge has been incorporated into the underlying rule base in the form of extraction and construction rule, and implemented via the expert system building tool, OPS5. This paper suggested a knowledge based approach for automatic programming to enable a user who lacks modeling knowledge and simulation language expertize to quickly build executable models.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.4
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• pp.288-291
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• 2002

We characterize multipath fading channel dynamics at the packet level and analyze the corresponding data queueing performance in various environments. We identify the similarity between wire-line queueing analysis and wireless network per-formance analysis. The second order channel statistics, i.e. channel power spectrum, is fecund to play an important role in the modeling of multipath fading channels. However, it is identified that the first order statistics, i.e. channel CDF also has significant impact on queueing performance. We use a special Markov chain, so-called CMPP, throughout this paper.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.4
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• pp.15-23
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• 1995

In this paper, we evaluate the performance of a transient queueing approximation when it is applied to modeling computer communication networks. An operational computer network that uses the ISO IS-IS(Intermediate System-Intermediate System) routing protocol is modeled as a Jackson network. The primary goal of the approximation pursued in the study was to provide transient queue statistics comparable in accuracy to the results from conventional Monte Carlo simulations. A closure approximation of the M/M/1 queueing system was extended to the general Jackson network in order to obtain transient queue statistics. The performance of the approximation was compared to a discrete event simulation under nonstationary conditions. The transient results from the two simulations are compared on the basis of queue size and computer execution time. Under nonstationary conditions, the approximations for the mean and variance of the number of packets in the queue erer fairly close to the simulation values. The approximation offered substantial speed improvements over the discrete event simulation. The closure approximation provided a good alternative Monte Carlo simulation of the computer networks.

• Journal of the military operations research society of Korea
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• v.5 no.1
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• pp.155-162
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• 1979

GERT modeling is in a dynamic stage of development. One of the most exciting and useful new developments in GERT modeling and Simulation is the modeling technology and computer package called Q-GERT. As the name implies, this provides the capability to analyze complex networks of queueing systems. The modeling approach is quite similar to GERT, but includes queue nodes called 'Select' nodes, which allow a considerable amount of logic to be included in the analysis of complex networks of multichannel, multiphase queueing systems should find the Q-OERT package of considerable interest.

• Journal of the Korea Society for Simulation
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• v.8 no.2
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• pp.29-43
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• 1999

As real-time processing of data with large storage space is required in the era of multimedia, disk arrays are generally used as storage subsystems which be able to provide improved I/O performance. To design the cost-effective disk array, it is important to develop performance models which evaluate the disk array performance. Both queueing theory and simulation are applicable as the method of performance evaluation through queueing modeling. But there is a limit to the analytical method using queueing theory due to the characteristics of disk array requests being serviced in the parallel and concurrent manner. So in this paper we evaluate the disk array performance using simulation method which abstract disk array systems in the low level. Performance results were evaluated through simulation, so that mean response time, mean queueing delay, mean service time, mean queue length for disk array requests and utilization, throughput for disk array systems, can be utilized for capacity planning in the phase of disk array design.

• Journal of Communications and Networks
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• v.11 no.4
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• pp.406-415
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• 2009

In this work, we consider performance modeling of a wireless sensor network with a time division multiple access (TDMA) media access protocol with slot reuse. It is assumed that all the nodes are peers of each other and they have two modes of operation, active and sleep modes. We model the sensor network as a Jackson network with unreliable nodes with on and off states. Active and sleep modes of sensor nodes are modeled with on and off states of unreliable nodes. We determine the joint distribution of the sensor node queue lengths in the network. From this result, we derive the probability distribution of the number of active nodes and blocking probability of node activation. Then, we present the mean packet delay, average sleep period of a node and the network throughput. We present numerical results as well as simulation results to verify the analysis. Finally, we discuss how the derived results may be used in the design of sensor networks.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.2
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• pp.153-165
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• 1995

Many closed queueing network models have been used as an effective tool to make a preliminary design of FMS. Although a loading/unloading function is an important factor to effect the utilization and throughput of FMS as well as a transfer function and a processing function, the Solberg's model did not clarify the loading/unloading function. In this paper, we propose a closed queueing network model for analyzing a flexible manufacturing system that consists of a load/unload station, a material handling system and a group of workstations for processing jobs, and define the expected utilization and the expected throughput of the FMS. As applications of the proposed model, the cases of a material handling system consisting of a conveyor and the FMS including an inspection station are also formulated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10B
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• pp.1971-1978
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• 1999

In this paper, we study the effects of long-range dependence (LRD) in VBR video traffic on queueing system. This paper consists of Part I and II. In Part I, we present a (LRD) video traffic model based on the shifting-level (SL) process. We observe that the ACF of an empirical video trace is accurately captured by the shifting-level process with compound correlation (SLCC): an exponential function in short range and a hyperbolic function in long range. We present an accurate parameter matching algorithm for video traffic. In the Part II, we offer the queueing analysis of SL/D/1/K called ‘quantization reduction method’. Comparing the queueing performances of the DAR(1) model and the SLCC with that of a real video trace, we identify the effects of SRD and LRD in VBR video traffic on queueing performance. Simulation results show that Markoivian models can estimate network performances fairly accurately under a moderate traffic load and buffer condition, whereas LRD may have a significant effect on queueing behavior under a heavy traffic load and large buffer condition.