• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.48-57
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• 2005

Discrete Event Simulation은 기존에 생산 분야에서 적용되어지는 이론중의 하나로 생산에서 발생되는 작업을 Event 기반으로 분류하고 각각의 경우를 기초로 Simulation하여 평가하는 기법이다. 철도차량의 중정비는 핵심부품의 정비를 단계별로 세분화하여 이루어지는데 틸팅차량을 포함하는 신형 철도차량의 경우 주요 정비부품이 많은 제어장치와 전자장치로 구성되어 있다 대차의 경우 많은 주요부품이 중복되어 이것을 체계적이며 효율적으로 유지 보수하는 것이 절실한 것이다. 이러한 부품의 상태를 점검하고 평가하는 것은 유지보수에 관련된 인력이 아닌 이와 관련된 분석기계일 것이고 틸팅차량의 경우 다량의 주요 부품에 대한 유지보수기계의 성능의 평가가 요구될 것이다. 본 논문은 이러한 필요성에 기초하여 작성되었다. 우선 Discrete Event Simulation의 개념을 간략히 소개하였고 Discrete Event Simulation의 5단계 알고리즘을 철도차량 유지보수기계 기반으로 수정하였다 그리고 유지보수 요구 조건에 기초하여 Simulation 알고리즘을 적용하였다. 본 논문은 Discrete Event Simulation의 이론을 이전에 적용된 사례가 없는 철도차량유지보수 분야에 소개하여 유지보수 효율의 극대화를 위한 기법을 적용하였으며 향후 철도차량 유지보수관련 기계의 성능 평가 및 적용에 있어 도움이 될 수 있는 참고 자료로 활용 가능할 것이다.

• 대한교통학회지
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• 제14권1호
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• pp.101-116
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• 1996

Increased attention has been paid in recent years to the need of traffic management for alleviating urban traffic congestion. This paper presents a discrete event modeling and simulation framework for analyzing the traffic flow. Traffic simulation models can be classified as being either microscopic and macroscopic models. The discrete event modeling and simulation technique can be basically employed to describe the macroscopic traffic simulation model. To do this, we have employed the System Entity Structure/Model Base (SES/MB) framework which integrates the dynamic-based formalism of simulation with the symbolic formalism of AI. The SES/MB framework supports to hierarchical, modular discrete event modeling and simulation environment. We also adopt the Symbolic DEVS (Discrete Event System Specification) to developed the automated analysis methodology for generating optimal signal light policy. Several simulation tests will demonstrates the techniques.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.403-406
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• 1997

This paper presents a Petri net approach for the control and monitoring of discrete event system. The proposed model is fuzzy Petri nets based on the fuzzy logic with Petri nets and the hierarchy concept. Fuzzy Petri nets have been used to model the imprecise situations which can arise within automated manufacturing system, and also the hierarchy concept allow to handle the refinement of places and transition in Petri nets model. These will form the foundation of a simulator-tool with manipulation interface for application of fuzzy Petri nets.

• 한국멀티미디어학회논문지
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• 제20권7호
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• pp.1090-1101
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• 2017

This study analyzes spatial density and integration of Space Syntax and Discrete Event Simulation (DEVS) of complex system theory and analyzes spatial structure by property, type and depth. The aim of this study is to secure the validity of the theoretical application. The study evaluated the correlation between spatial density and integration by setting up eight types of analysis models. In addition, analyzed the correlation of structural characteristics and approached the application of discrete event simulation of spatial syntax theory. It is confirmed that the concept of integration of spatial syntax theory and analysis using discrete event simulation are valid as new spatial analysis methodology. Also expect that realistic and concrete predictions will be possible if discrete event simulation evolves into research for space allocation and space efficiency optimization.

• 한국시뮬레이션학회논문지
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• 제11권2호
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• pp.77-88
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• 2002

Petri nets is a widely used formalism for specification and analysis of concurrent systems which is a subclass of discrete event systems. The DEVS (Discrete Event System Specification) formalism provides a general framework for specification of discrete event systems in a hierarchical, modular form. Often, modeling a discrete event system may employ both Petri Nets and DEVS formalism. In such a case low-level operational logics are modeled by Petri Nets and high-level managements by the DEVS formalism. Analysis of the system requires simulation of the overall system. This paper presents an algorithm for transformation of Petri Nets to DEVS formalism. The transformation enables modelers to simulate an overall system, which consists of DEVS models and Petri Nets models, in a unified DEVS simulation environment such as DEVSim++. An example for such transformation will be given.

• 한국경영과학회지
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• 제17권3호
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• pp.79-99
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• 1992

The DEVS (Discrete Event system Specification) formal model for discrete event simulation is a hierarchical, modular model. Because the DEVS formal model has a mathematical structure, it provides a theoretic background of discrete event simulation model. However, the DEVS formal model is difficult to understand because of its mathematical structure. Also, since the DEVS formal model is often constructed by heuristic, subjective method of model designer from the model, a systematic model built-in methodology does not exist. In this paper, we propose the model formalization methodology from an informal model to the DEVS formal model. For this formalization methodology, we introduce formal tools for model construction based on the DEVS ( from an informal model : Event Dependency Graph (EDG) for the event analysis and State Representation Graph(SRG) for the system state analysis.

• 한국시뮬레이션학회논문지
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• 제21권4호
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• pp.35-46
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• 2012

실시간 시스템의 복잡도가 증가함에 따라 임시방편적 시스템 해석 방법은 시스템 동작 영역 전체를 완전하게 분석하는 데는 한계가 있다. 모델링을 기반으로 한 정형 기법은 그러한 한계점을 극복 할 수 있다. 본 논문은 모델 기반 정형 기법을 이용하여 실시간 시스템의 안전성 및 필연성 등과 같은 논리적 타당성을 이산 사건 모델 수준에서 분석하는 방법을 제안한다. 먼저, 분석 대상 실시간 시스템은 이산사건 수준에서 계층적으로 모듈화하여 모델을 명세하는 수학적 형식론인 DEVS (Discrete Event Systems Specification) 형식론으로 기술된다. 다음으로, 기술된 DEVS 모델은 시간 명세가 포함된 전역 상태 공간을 표현하는 C-DEVS (Communicating DEVS) 형식론으로 표현한 후 C-DEVS 형식론의 해석 알고리즘을 통해 시스템 동작을 분석된다. 제안된 C-DEVS 형식론 및 해석 알고리즘은 주어진 시스템의 동작 특성을 분석하는 과정에서 시스템의 상태 공간을 완전하게 빠짐없이 탐색하는 것을 보장한다. 간단한 건널목 제어 시스템의 안전성 분석 사례 연구를 통하여 제안된 모델 기반 해석 기법의 효율성을 예시 하였다.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
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• pp.453-458
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• 2001

A mobile agent is an autonomous software agent capable of moving from one computer to another while performing its tasks. We view the agent as a discrete event system in the view of its computation and communication. This paper presents a methodology far modeling and simulation of such a mobile agent system as a discrete event system. The methodology is based on the Mobile Discrete Event System Specification (MDEVS) formalism and the associated simulation environment AgentSim which are previously developed by the authors. Within the methodology an atomic model represents dynamics of a mobile agent; a coupled model is modeled as mobile agent servers for representation of structural changes between atomic agents. Being based on the object-oriented environment the modeling methodology exploits inheritance of basic classes AtomicModel and CoupledModel provided by AgentSim.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.411-413
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• 1997

This paper presents the problem of fault-tolerant robust supervisory control of timed discrete event systems (DESs). First the concept of faults is quantitatively defined in timed DESs and fault tolerable event sequences are presented as a desired legal language. Given a timed DES with model uncertainty, the conditions for the existence of a supervisor which always guarantees fault tolerable event sequences embedded in the system are derived.

• Industrial Engineering and Management Systems
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• 제8권3호
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• pp.155-161
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• 2009

We focus on discrete event systems with a structure of parallel processing, synchronization, and no-concurrency. We use max-plus algebra, which is an effective approach for controller design for this type of system, for modeling and formulation. Since a typical feature of this type of system is that the initial schedule is frequently changed due to unpredictable disturbances, we use a simple model and numerical examples to examine the possibility of applying the concepts of the feeding buffer and the project buffer of critical chain project management (CCPM) on max-plus linear discrete event systems in order to control the occurrence of an undesirable state change. The application of a CCPM-based framework on a max-plus linear discrete event system was proven to be effective.