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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Society for Simulation
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Journal DOI :
The Korea Society for Simulation
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Volume & Issues
Volume 9, Issue 4 - Dec 2000
Volume 9, Issue 3 - Sep 2000
Volume 9, Issue 2 - Jun 2000
Volume 9, Issue 1 - Mar 2000
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Improving Performance of Internet by Using Hierarchical Proxy Cache
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 1~14
Recently, as construction of information infra including high-speed communication networks remarkably expands, more various information services have been provided. Thus the number of internet users rapidly increases, and it results in heavy load on Web server and higher traffics on networks. The phenomena cause longer response time that means worse quality of service. To solve such problems, much effort has been attempted to loosen bottleneck on Web server, reduce traffic on networks and shorten response times by caching informations being accessed more frequently at the proxy server that is located near to clients. And it is also possible to improve internet performance further by allowing clients to share informations stored in proxy caches. In this paper, we perform simulations of hierarchical proxy caches with the 3-level 4-ary tree structure by using real web traces, and analyze cache hit ratio for various cache replacement policies and cache sizes when the delayed-store scheme is applied. According to simulation results, the delayed-store scheme increases the remote cache hit ratio, that improves quality of service by shortening the service response time.
Design and Analysis of the GOST Encryption Algorithm
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 15~25
Since data security problems are very important in the information age, cryptographic algorithms for encryption and decryption have been studied for a long time. The GOST(Gosudarstvennyi Standard or Government Standard) algorithm as a data encryption algorithm with a 256-bit key is a 64-bit block algorithm developed in the former Soviet Union. In this paper, we describe how to design an encryption chip based on the GOST algorithm. In addition, the GOST algorithm is compared with the DES(Data Encryption Standard) algorithm, which has been used as a conventional data encryption algorithm, in modeling techniques and their performance. The GOST algorithm whose key size is relatively longer than that of the DES algorithm has been expanded to get better performance, modeled in VHDL, and simulated for implementation with an CPLD chip.
A Simulation Model for Supporting System Design of Tire Manufacturing Cell
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 27~38
For developing a new Tire Manufacturing Cell, the cooperation between the designer of facilities and the designer of system is very important. The purpose of this paper is to develop a simulation model that can be applied to the system design of Tire Manufacturing Cell. The mechanic characteristics of new facilities are obtained from facility design team and the simulation model is developed with SIMPLE++ using those input data. A model for estimating the number of tire drum required is also suggested and it is verified with numerical examples. The results of simulations can be fed back to the facility design team and used for modifying the structure of the facilities.
A Study on the Development of Communication Control System for Pressure Automatic System
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 39~49
In this paper, we added that developed communication control system between the PLC of pressure machine and the control computer, and developed a new protocol in order to communicate between the PLC signal of pressure machine and the control computer. This communication control systems play an important role in transforming the PLC vendor self-interface type and between computer and PLC. This system has PLC access function to control computer on the backbone network, and then could be operated by PLC through this system. The benefits we can obtain by developing this communication control systems are as follows; First, we can improve the quality of goods and the management of materials using the communication network and then implement the centralization management. Second, we can decrease manpower for production. Finally, we can maximize the company's profit with the increasing productivity by supervising the equipment wrong workings in the central.
Dependability Analysis of Parallel Video Servers Using Fault Injection Simulation
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 51~61
In recent years, significant advances in computers and communication technologies have made multimedia services feasible. As a result, various queueing models and cost models on architecture and data placement for multimedia server have been proposed. However, most of these models do not evaluate dependability of systems. In the design phase of a system, simulation is an important experimental means for performance and dependability analysis. Fault injection simulation has been used in evaluation of dependability metric. In this paper, we develop fault injection simulation model to analyze dependability of parallel video servers. In addition, we evaluate reliability and MTTF(Mean Time To Failure) of systems by using the simulator.
A Study of Buffer Allocation in FMS based on Deadlock and Workload
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 63~73
Due to the complexity of part flow and limited resources, FMS(Flexible Manufacturing System) develops blocking, starvation and deadlock problems, which reduce its performance. In order to minimize such problems buffers are imposed between workstations of the manufacturing lines. In this paper, we are concerned with finding the optimal buffer allocation with regard to maximizing system throughput in limited total buffer capacity situation of FMS. A dynamic programming algorithm to solve the buffer allocation problem is proposed. Computer simulation using Arena is experimented to show the validation of the proposed algorithm.
A Study of Dependent Nonstationary Multiple Sampling Plans
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 75~87
In this paper, nonstationary multiple sampling plans are discussed which are difficult to solve by analytical method when there exists dependency between the sample data. The initial solution is found by the sequential sampling plan using the sequential probability ration test. The number of acceptance and rejection in each step of the multiple sampling plan are found by grouping the sequential sampling plan's solution initially. The optimal multiple sampling plans are found by simulation. Four search methods are developed U and the optimum sampling plans satisfying the Type I and Type ll error probabilities. The performance of the sampling plans is measured and their algorithms are also shown. To consider the nonstationary property of the dependent sampling plan, simulation method is used for finding the lot rejection and acceptance probability function. As a numerical example Markov chain model is inspected. Effects of the dependency factor and search methods are compared to analyze the sampling results by changing their parameters.
Optimization of Queueing Network by Perturbation Analysis
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 89~102
In this paper, we consider an optimal allocation of constant service efforts in queueing network to maximize the system throughput. For this purpose, using the perturbation analysis, we apply a stochastic optimization algorithm to two types of queueing systems. Our simulation results indicate that the estimates obtained from a stochastic optimization algorithm for a two-tandem queuing network are very accurate, and those for closed loop manufacturing system are a little apart from the known optimal allocation. We find that as simulation time increases for obtaining a new gradient (performance measure with respect to decision variables) by perturbation algorithm, the estimates tend to be more stable. Thus, we consider that it would be more desirable to have more accurate sensitivity of performance measure by enlarging simulation time rather than more searching steps with less accurate sensitivity. We realize that more experiments on various types of systems are needed to identify such a relationship with regards to stopping rule, the size of moving step, and updating period for sensitivity.
A Simulation Study on ITS/DSRC Communication Networks for Metropolitan Seoul area.
Journal of the Korea Society for Simulation, volume 9, issue 2, 2000, Pages 103~118
ITS(Intelligent Transportation System) is an advanced system which can effectively handle the current transportation problems. DSRC(Dedicated Short Range Communication) is considered as a promising technology since it has the capability of two-way communication and can serves to implement various ITS services. In this paper, we study DSRC based ITS telecommunication traffic analysis and suggest an architecture and network design of telecommunication network for DSRC services. We also perform a simulation study to validate the proposed network architecture and design for Metropolitan Seoul Area with various network alternatives. In this simulation, we use actual traffic data and road characteristics from Seoul area and use our DSRC service configuration.