• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.3
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• pp.199-207
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• 2010

In this paper considered is the provisioning quantity determination problem of consumable concurrent spare parts (CSP) of a new equipment system to minimize the procurement cost under the operational availability constraint. When a part fails, repair of the failed part is impossible and the part is replaced and cannibalization is allowed. The failure of a part is assumed to follow a Poisson process and the operational availability in CSP is defined. The solution procedure consists of two parts. Firstly, a heuristic algorithm is developed under the assumption that the failure rate is constant during the CSP period. Secondly, proposed is a simulation search procedure which improves the heuristic solution to the near optimal solution in a reasonable amount of time. An illustrative example is shown to explain the solution procedure.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.507-513
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• 2004

In this paper, we consider the methodology of efficient resource usage, specially web clustering system. We develope an algorithm that distributes the load on the web cluster system to use the system resources, such as system memory equally. The response time is chosen as a performance measure on the various clustering models. And based on the concurrent user to the web cluster system, the response time is also examined as the number of users increases. Simulation experience with this algorithm shows that the response time seems to have a good results compare to those with the other algorithm. And, also the effectiveness of clustered system becomes better as long as the number of concurrent user increases. The usage of developed algorithm is more useful when the system consists of many different sub-systems, a heterogeneous clustering system.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.3_4
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• pp.194-204
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• 2003

The performance of a shared memory multiprocessor system is dependent on the system software such as scheduling policy as well as hardware system. Most of existing simulators, however, do not support simulation for multi-programmed environment because they can execute only a single benchmark application at a time. We propose a multi-programmed simulation method on a program-driven simulator, which enables the concurrent executions of multiple parallel workloads contending for limited system resources. Using the proposed method, system developers can measure and analyze detailed effects of resource conflicts among the concurrent applications as well as the effects of scheduling policies on a program-driven simulator. As a result, the proposed multi-programmed simulation provides more accurate and realistic performance projection to design a multiprocessor system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.4
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• pp.382-395
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• 1991

A general purpose distributed processes communication control mechanism is a typical approach used for synchronizing concurrent processes involved in communication. The mechanism can provide a framework on which the layered communication architectures and protocols are efficiently implemented. The mechanism is realized under restricted environment where monitor facility is not available by means of simulation using semaphore.

• Journal of the Korea Society for Simulation
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• v.27 no.2
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• pp.61-69
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• 2018

As the technology of information and communication has developed over recent years, an embedded system is applied in multiple industries and becomes more complicated. For this reason, embedded system development cost and time are also increased. For decreasing the cost and time, this paper suggests requirement evaluation method for concurrent development of an embedded system based on Discrete Event System(DEVS) Formalism. This paper proposes a method of describing the requirements specification in the form of DEVS atomic model. Also, the paper proposes the evaluator model that compares evaluation target system and the requirements model that is an implementation of requirement specification and proposes the evaluation method using them. In addition, we propose a method to utilize the requirement model created for requirements evaluation in the concurrent development process of the embedded system. As the case study, this paper proceeds requirement evaluation of Kinect depth data processing system.

• Journal of Communications and Networks
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• v.12 no.3
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• pp.275-284
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• 2010

The current multihome-aware protocols (like stream control transmission protocol (SCTP) or parallel TCP for concurrent multipath data transfer (CMT) are not designed for high-capacity and large-latency networks; they often have performance problems transferring large data files over shared long-distance wide area networks. It has been shown that SCTP-CMT is more sensitive to receive buffer (rbuf) constraints, and this rbuf-blocking problem causes considerable throughput loss when multiple paths are used simultaneously. In this research paper, we demonstrate the weakness of SCTP-CMT rbuf constraints, and we then identify that rbuf-blocking problem in SCTP multihoming is mostly due to its loss-based nature for detecting network congestion. We present a simulation-based performance comparison of FAST TCP versus SCTP in high-speed networks for solving a number of throughput issues. This work proposes an end-to-end transport layer protocol (i.e., FAST TCP multihoming as a reliable, delaybased, multihome-aware, and selective ACK-based transport protocol), which can transfer data between a multihomed source and destination hosts through multiple paths simultaneously. Through extensive ns-2 simulations, we show that FAST TCP multihoming achieves the desired goals under a variety of network conditions. The experimental results and survey presented in this research also provide an insight on design decisions for the future high-speed multihomed transport layer protocols.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.519-522
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• 1998

The Constructive Battle simulation Model is very important to the recent military training for the substitution of the field training. However, real battlefield systems operate under rea-time conditions, they are inherently distributed, concurrent and dynamic. In order to reflect these properties by the computer-based simulation systems which represent real world processes, we have been developing constructive simulation model for several years. The constructive simulation system is one of the famous real-time system software, nd the one common feature of all real-time systems is defined as the correctness of the system depend not only on the logical result of computation, but also on the time at which the results are produced. Conventionally, scheduling and resource allocation activities which have timing constraints are major problem of real-time computing systems. To overcome these constraints, we elaborated on these issues and developed the simulation system on commercially available hardware and operating system with lock-free resource allocation scheme and rae monotonic scheduling.

• 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.

• Proceedings of the Korea Society for Simulation Conference
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• 1995.10a
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• pp.0-0
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• 1995

Simulation tools are widely used for performance evaluation of newly proposed systems. However, many industrial simulation projects fail to attain the original goals ,especially when very complicated decision logics of the experienced operatorsare needed to be modeled. We propose a technique to overcome the oabstacles. In the proposed technique, complicated decision logics are not directly modeled but an interface for interactive input is provided in the model. While running the simulation model in concurrent animation mode, whenever operator's decisions are needed an interfce screen is displayed for operator's decisions. The operator then makes decisions using the information which is provided by the animation proces itself. This technique was successfully applied to an industrial simulation projects in which alternatives were evaluated for increasingthe color lot size of car print shop.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.79-90
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• 2015

Multipath routing technique is recognized as one of the effective approaches to improve the reliability of data forwarding. However, the traditional multipath routing focuses only on how many paths are needed to ensure a desired reliability. For this purpose, the protocols construct additional paths and thus cause significant energy consumption. These problems have motivated the study for the energy-efficient and reliable data forwarding. Thus, this paper proposes an energy-efficient concurrent multipath routing protocol with a small number of paths based on interaction between paths. The interaction between paths helps to reinforce the multipath reliability by making efficient use of resources. The protocol selects several nodes located in the radio overlapped area between a pair of paths as bridge nodes for the path-interaction. In order to operate the bridge node efficiently, when the transmission failure has detected by overhearing at each path, it performs recovery transmission to recover the path failure. Simulation results show that proposed protocol is superior to the existing multipath protocols in terms of energy consumption and delivery reliability.