• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.110-114
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• 1999

본 연구는 Zeigler가 제안한 이산 사건 시스템 형식론(DEVS: Discrete Event System Specification)을 이용한 거시적 및 미시적 교통류 시뮬레이션 방법론의 개발을 주 목적으로 한다. 도로 교통망의 모델링 방법은 미시적(microscopic)방법과 거시적(macroscopic)방법으로 분류된다. 이러한 모델링 방법들은 그 목적에 따라 각기 표현되어 제각기 사용되어 왔으나, 시스템 이론적으로 이들은 독립적 모델이 아니며 오히려 이들은 서로 동질적 추상화 관계에 있어서, 통합 모델링 환경의 구축시 미시적 모델들로부터 추상화에 의한 거시적 모델의 자동생성 등 설계상의 효율뿐 아니라 모델간의 일관성을 통한 모델 유효성을 보장할 수 있는 장점이 제공될 수 있다. 따라서, 본 논문에서는 서로 다른 표현 방법(즉, 이산시간 형식론과 이산사건 형식론)간의 통합 표현을 기반으로 양자간의 추상화 관계를 도출하고, 이를 이용한 모델 추상화를 통해 거시적 및 미시적 교통류 시뮬레이션 방법론을 제안한다. 시스템 이론적 접근을 토대로 접근한 통합 교통류 시뮬레이션 환경은 미국 Berkeley 대학 교통 연구소에서 개발한 SHIFT 등과 같은 최첨단 교통류 시뮬레이션 도구에 비하여 SES/MB를 기반을 시스템 이론적이며 소프트웨어공학적인 접근을 통하여, 1) 기존 제어 방식의 검증 및 신뢰도 분석, 2) 각종 사건, 사고의 시간별 파급효과 분석, 3) 도로건설 계획안에 대한 타당성 검토, 4) 운전자 및 관리자를 위한 예측된 교통정보 등을 제공할 수 있을 것으로 기대된다.

• Proceedings of the Safety Management and Science Conference
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• 2000.05a
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• pp.339-349
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• 2000

Inchon Port is the second largest import-export port of Korea, and has the point at issue such as the excessive logistics cost because of the limits of handling capacity and the chronic demurrage. There are few research activities on the analysis and improvement of the whole port operation, because Inchon Port not only has the dual dock system and various facilities but also handles a various kind of cargo. The purpose of this paper is to develop the simulation program as a long-term strategic support tool, considering the dual dock system and the TU(Terminal Operation Company) system executed since March, 1997 in Inchon Port. The basic input parameters such as arrival intervals, cargo tons, service rates are analyzed and the probability density functions for these parameters are estimated. The main mechanism of simulation model is the discrete event-driven simulation and the next-event time advancing. The program is executed based on the knowledge base and database. From the simulation model, it is possible to estimate the demurrage status through analyzing various scenarios and to establish the long-term port strategic plan.

• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.65-74
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• 2007

Virtual manufacturing (VM) is a powerful technology for developing a new product, new equipment and new manufacturing system, and three-dimensional (3D) simulation is a core technology in VM. 3D simulation involves both mechanical simulation and discrete event simulation. This paper introduces a case study of implementing 3D simulation for developing an automatic assembly line in a Korean optical factory. This factory produces a lens module that is the part of a phone-camera. 3D simulation technology is applied from the early stage of development. In the conceptual design and the initial design phases for individual equipment, 3D mechanical simulation using $CATIA^{(R)}$ and $IGRIP^{(R)}$ is conducted. 3D discrete event simulation with $QUEST^{(R)}$ is applied to the detailed design of the equipment and of the whole system. The focus of the simulation is to verify the technical and economical feasibility of the new automatic system. As a result, the takt time is reduced to the quarter of the manual system, and the number of workers in a line is reduced tremendously.

• Journal of the Korea Society for Simulation
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• v.27 no.1
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• pp.91-99
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• 2018

Discrete event simulation environments often need to be modified because additional questions to systems may become apparent while observing the simulation results repeatedly. It leads to increasing development budget and depreciating the effectiveness of the environment. To avoid the modifications and to generate the altered results, this paper applies an Event Control Model (ECM) with control functions that modulate, delete and generate the events at the simulation time. In addition, this paper suggests an easier approach for domain-users, who do not want to program at source code level, by using ECM templates. The simulators with the ECMs can have better extensibility because it becomes more adaptable to possibly unanticipated changes. It prevents increasing development costs due to modifications or development of new models by M&S experts, and it provides a new alternative step to domain users. To support the effectiveness of this approach, this paper describes a relevant example, which is composed of an initial simulation model based on our empirical studies. It will show that there exist the uncountable benefits because the existing simulator is reused by domain users without new projects.

• Proceedings of the Korea Society for Simulation Conference
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• 2004.05a
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• pp.13-19
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• 2004

본 논문은 SIMVA(Simulation Vulnerability Analyzer)를 이용한 시뮬레이션 기반의 네트워크 취약성 분석을 주목적으로 한다 SIMVA는 네트워크 상태를 감시하고, 이를 토대로 취약성을 분석하기 위하여 개발된 S/W로서, SES/MB (System Entity Structure / Model Base) 프레임워크 및 DEVS(Discrete Event System Specification) 이론을 적용하여 네트워크 보안 모델링을 수행할 수 있으며, 취약성 메트릭스를 통하여 정량적으로 취약성을 분석할 수 있다. 본 연구에서는 SIMVA를 이용하여 최근 네트워크 보안 문제에 심각한 영향을 미치는 슬래머 웜 공격 시나리오에 대한 취약성 분석을 수행함으로써 SIMVA의 검증 및 적용 가능성을 제시한다.

• Proceedings of the Korea Society for Simulation Conference
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• 1993.10a
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• pp.2-2
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• 1993

Inference for discrete event simulations usually relies on either independent replications or, if each simulation run is expensive, the method of batch means applied to a single replications. We present a new method, threshold bootstrap, which equals or exceeds the performance of independent replications or batch means. The method works by resampling runs of data created when a stationary time series crosses a threshold level, such as the sample mean of series. Computational results show that the threshold bootstrap matches or exceeds the performance of these alternative methods in estimating the standard deviation of the sample mean and producing valid confidence intervals.

• Journal of the Korea Society for Simulation
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• v.2 no.1
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• pp.46-54
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• 1993

Analytic and simulation models for prioritized token ring are presented in this paper. Its protocol is based on prioritized token ring with reservation (R-PTR). Since the protocol of the R-PTR is simple and the performance of the R-PTR is not inferior to that of the IEEE-PTR under almost all traffic load environments, we use the R-PTR as our token ring model. By using the properties of Markovian process, the expressions for average throughput and average packet transmission delay are derived. The results obtained from the analytic model are compared with that of the discrete event simulation model.

• Journal of the Korea Society for Simulation
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• v.1 no.1
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• pp.31-36
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• 1992

To estimate the probability of long delay in a queuing system using discrete-event simulation is studied. We contrast the coverage, half-width, and stability of confidence intervals constructed using two methods: batch means and new resampling technique; binary bootstrap. The binary bootstrap is an extension of the conventional bootstrap that resamples runs rather than data values. Empirical comparisons using known results for the M/M/1 and D/M/10 queues show the binary bootstrap superior to batch means for this problem.

• Proceedings of the Korea Society for Simulation Conference
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• 1992.10a
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• pp.13-13
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• 1992

To estimate the probability of long delay in a queuing system using discrete-event simulation studied. We contrast the coverage, half-width, and stability of confidence intervals constructed using two methods: batch means and new resampling technique; binary bootstrap. The binary bootstrap is an extension of the conventional bootstrap that resamples runs rather than data values. Empirical comparisons using known results for the M/M/1 and D/M/10 queues show the binary bootstrap superior to batch means for this problem.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.4
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• pp.446-459
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• 2017

Naval ships are assigned many and varied missions. Their performance is critical for mission success, and depends on the specifications of the components. This is why performance analyses of naval ships are required at the initial design stage. Since the design and construction of naval ships take a very long time and incurs a huge cost, Modeling and Simulation (M & S) is an effective method for performance analyses. Thus in this study, a simulation core is proposed to analyze the performance of naval ships considering their specifications. This simulation core can perform the engineering level of simulations, considering the mathematical models for naval ships, such as maneuvering equations and passive sonar equations. Also, the simulation models of the simulation core follow Discrete EVent system Specification (DEVS) and Discrete Time System Specification (DTSS) formalisms, so that simulations can progress over discrete events and discrete times. In addition, applying DEVS and DTSS formalisms makes the structure of simulation models flexible and reusable. To verify the applicability of this simulation core, such a simulation core was applied to simulations for the performance analyses of a submarine in an Anti-SUrface Warfare (ASUW) mission. These simulations were composed of two scenarios. The first scenario of submarine diving carried out maneuvering performance analysis by analyzing the pitch angle variation and depth variation of the submarine over time. The second scenario of submarine detection carried out detection performance analysis by analyzing how well the sonar of the submarine resolves adjacent targets. The results of these simulations ensure that the simulation core of this study could be applied to the performance analyses of naval ships considering their specifications.