• 한국시뮬레이션학회논문지
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• 제21권2호
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• pp.19-30
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• 2012

최근 몇 십년간 이산사건시스템명세(DEVS) 형식론은 이산사건시스템을 모듈러하고 계층적으로 모델링할 수 있는 잘 정의된 의미론을 제공하여 왔다. 그럼에도 불구하고 실용 엔지니어들은 실세계의 시스템을 모델링에 적용하는데 어려움을 겪기도 하는데 이는 DEVS가 많은 상태와 사건들을 구조화되지 않은 형태로 명세해야 하는 것 때문이다. 본 논문은 집합 이론을 바탕으로 그러한 사건 및 상태집합들을 구조화된 형태로 표현하는 Structured DEVS 형식론과 이와 연관된 DEVS 다이어그램을 제안하고자 한다. 위상, 변수, 포트 등의 개념을 사용하여 집합들을 명세한 구조적 DEVS 형식론은 원래의 DEVS 형식론과 동등함을 증명하였다. DEVS 다이어그램을 이용하여 구조적 DEVS 형식론으로 표현된 예시 모델이 쉽게 객체지향 시뮬레이션 환경에서 구현될 수 있음을 보임으로써 제안된 형식론이 효과적임을 보였다.

• 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.

• 품질경영학회지
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• 제46권4호
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• pp.973-982
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• 2018

Purpose: The purpose of this study is to develop an effective simulation modeling formalism for autonomous control systems, such as unmanned aerial vehicles and unmanned surface vehicles. The proposed simulation modeling formalism can be used to evaluate the quality and effectiveness of autonomous control systems. Methods: The proposed simulation modeling formalism is developed by extending the classic DEVS (Discrete Event Systems Specifications) formalism. The main advantages of the classic DEVS formalism includes its rigorous formal definition as well as its support for the specification of discrete event models in a hierarchical and modular manner. Results: Although the classic DEVS formalism has been a popular modeling tool, it has limitations in describing an autonomous control system which needs to make decisions by its own. As a result, we proposed an extended DEVS formalism which enables the effective description of internal decisions according to its conditional variables. Conclusion: The extended DEVS formalism overcomes the limitations of the classic DEVS formalism, and it can be used for the effectiveness simulation of autonomous weapon systems.

• 한국항만학회지
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• 제14권1호
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• pp.47-55
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• 2000

In order to cope with the changes of container terminal situation in these days, many simulation studies for container terminal have been accomplished. But previous simulation studies using simulation language have limitations in model representation and difficulties in modeling of large scaled container terminal system. To make these problems better, this paper addresses an object-oriented simulation of container terminal system using a DEVS formalism. The DEVS(Discrete Event System Specification) formalism, developed by Zeigler, supports specification of discrete event system in a hierarchical and modular manner. The formalism provides a mathematical basis for studying discrete event systems with better understood and sounder semantics. In a step of system modeling, a DEVS formalism aims at the exact system modeling that has a basis of semantics and utilizing the object-oriented manner can flexibly cope with the changes of system environment. In this study a model is developed and verified through the simulation of some alternatives.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2002년도 추계학술대회 논문집
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• pp.85-89
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• 2002

Development of distributed simulation environment must be required in order to simulate the distributed models regionally and inter-operate with running simulations individually, Simulation based on DEVS formalism is difficult to simulate the distributed models. DEVS formalism is modeling methodology. To specify model, this formalism separates behavior and structure, therefore it is able to design complex model easily. HLA is standard framework of distribute simulation environment, It is defined to facilitate the interoperability and the reusability. RTI (Run Time Infrastructure) is software that provides common service to simulation systems and implementation of the HLA Interface Specification. Method of implementation is that modules cooperating with RTI are added to simulator on DEVS simulation environment. On the DEVS simulation environment (DEVS-Obj -C) that already developed, Highest class of abstract simulator uses service that RTI provide, then This environment is able to change DEVS model into Federate and run distribute simulation that inter-operates with the RTI. Because this distributed simulation environment includes convenience of modeling that obtains through the DEVS formalism and accompanies HLA standard, this environment make it possible to simulate with_ complex systems and heterogeneous simulations

• 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.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1999년도 추계학술대회논문집
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• pp.35-42
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• 1999

In order to cope with the changes of container terminal situation in these days, many simulation studies for container terminal have been accomplished. But established simulation studies using simulation language have restrictions in model representation and difficulties in modeling of large scaled container terminal system. To make these problems better, in this paper addresses object-oriented simulation of container terminal system using a DEVS formalism. In a step of system modeling, using a DEVS formalism aim at the exact system modeling that has a basis of semantics and utilizing the object-oriented manner can flexibly cope with the changes of system environment. In this study a model was developed and verified through the simulation of some alternatives.

• 한국시뮬레이션학회논문지
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• 제1권1호
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• pp.64-76
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• 1992

The DEVS(discrete event system specificaition) formalism specifies a discrete event system in a hierarchical, modular form. DEVSIM++ is a C++based general purpose DEVS abstract simulator which can simulate systems modeled by the DEVS formalism in a sequential environment. This paper describes P-DEVSIM++which is a parallel version of DEVSIM++ . In P-DEVSIM++, the external and internal event of DEVS models can by processed in parallel. For such processing, we propose a parallel, distributed optimistic simulation algorithm based on the Time Warp approach. However, the proposed algorithm localizes the rollback of a model within itself, not possible in the standard Time Warp approach. An advantage of such localization is that the simulation time may be reduced. To evaluate its performance, we simulate a single bus multiprocessor architecture system with an external common memory. Simulation result shows that significant speedup is made possible with our algorithm in a parallel environment.

• 한국시뮬레이션학회논문지
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• 제2권1호
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• pp.31-44
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• 1993

Zeigler's DEVS(Discrete Event Systems Specification) formalism supports formal specification of discrete event systems in a hierarchical , modular manner. Associated are hierarchical, distributed simulation algorithms, called abstract simulators, which interpret dynamics of DEVS models. This paper deals with performance evaluation of P-DEVSIM ++, a parallel simulation environment which implements the DEVS formalism and associated simulation algorithms in a parallel environment. Performance simulator has been developed and used to experiment models of parallel simulation executions in different conditions. The experimental result shows that simulation time depends on both the number of processors in the parallel system and the communication overheads among such processors.

• 한국시뮬레이션학회논문지
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• 제9권1호
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• pp.39-54
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• 2000

Presented in this paper is a modeling and simulation methodology for 3 dimensional man-made systems. Based on DEVS(discrete event system specification) formalism[13], we propose GK-DEVS (geometrical and kinematic DEVS) formalism to describe the geometrical and kinematic structure and continuous state dynamics. To represent geometry and kinematics, we add a hierarchical structure to the conventional atomic model. In addition, we employ the "empty event" and its external event function for continuous state changing. In terms of abstract simulation algorithm[13], the simulation method of GK-DEVS, named GK-Simulator, is proposed for combined discrete-continuous simulation. Using GK-DEVS, the simulation of an FMS(flexible manufacturing system) consisting of a luring machine, a 3-axis machine and a RGV-mounted robot has been peformed.en peformed.