• International Journal of CAD/CAM
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• 제2권1호
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• pp.39-44
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• 2002

This paper presents a structure and architecture of an integrated simulation method (ISM) to meet the requirements of virtual factory engineering (VFE). Combining CAD, VR and discrete event simulation techniques, the ISM provides static and dynamic simulation functions for implementation of VFE throughout the lifecycle. The static simulation can be used to evaluate the factory layout. The dynamic simulation enables us to evaluate ergonomics of factory, process performance of production system, feasibility of production plan and operation of factory, and to train operators safely, which cover the whole VFE lifecycle. The principles of the key techniques of VFE, including virtual factory data management system (VFDMS), static and dynamic simulation, are also discussed. To demonstrate and validate the ISM, a case study has been carried out in an assembly factory.

• 한국해양공학회지
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• 제13권3B호
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• pp.106-115
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• 1999

Modeling a discrete event system such as a sequential control system is difficult compared with a continuous system. Petri nets have been introduced as an analyzing and design tool for the discrete systems. One of the problems in its applications is that the model can not be analyzed easily in the case of large scale or complicated systems because of increase of the number of components of the system. To overcome this problem, some methods for dividing or reducing Petri nets have been suggested. In this paper, an approach for a hierarchical expression of Petri nets based on Sequential Function Chart(SFC) is proposed. A measuring tank system will be described as a typical kind of discrete systems. The system is modeled by sub Petri nets based on SFC in order to analyze and visualize efficiently about the dynamic behaviors of the system. Some numerical simulations using state equations are performed to prove the validity of the proposed method.

• 제어로봇시스템학회논문지
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• 제9권11호
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• pp.906-916
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• 2003

A multi-robot control algorithm using Petri-Net is proposed for 5vs5 robot soccer. The dynamic environment of robot soccer is modeled by defining the place and transition of each robot and converting it into Petri-Net diagram. Once all the places and transitions of robots are represented by the Petri-Net model, their actions can be chosen according to the roles of robots and position of the ball in soccer game, e.g., offensive, defensive and goalie robot. The proposed modeling method is implemented for soccer robot system. The efficiency and applicability of the proposed multiple-robot control algorithm using Petri-Net are demonstrated through 5vs5 Middle League SimuroSot soccer game.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.109-112
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• 1997

A Discrete Event Dynamic System is a system whose states change in response to the occurrence of events from a predefined event set. A major difficulty in developing analytical results for the systems is the lack of appropriate modeling techniques. This paper proposes the use of Real-time Temporal Logic as a modeling tool for the modeling and control of fixed-time traffic control problem which by way of a DEDS. The Real-time Temporal Logic Frameworks is extended with a suitable structure of modeling hard real-time constraints. Modeling rules are developed for several specific situations. It is shown how the graphical model can be translated to a system of linear equations and constraints.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.341-346
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• 1998

최신 제어이론의 한 분야인 이산사건 동적시스템 (DEDS ; Discrete Event Dynamic System) 제어이론을 원전의 제한 계통에 적용하였다. 이산사건 이론을 원전의 제한 계통 제어 절차에 적용하면 보다 체계적이고 조직적으로 제한 계통을 위한 제어기를 구축할 수 있는 장점이 있다. 본 논문에서는 제한 계통 상태 및 운전원의 조치사항을 이산사건 시스템으로 모델링하여 제약조건에 맞는 수퍼바이저를 구성하고 이를 바탕으로 제한 계통 제어기를 구축하는 방법을 제시하였다.

• 한국시뮬레이션학회논문지
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• 제21권1호
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• pp.27-34
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• 2012

본 논문의 목적은 복잡한 군수지원시스템의 모델링과 시뮬레이션을 위한 방법론을 제안하는 것이다. 제안하는 군수지원시스템 시뮬레이션 모델을 구성하는 요소들은 세 가지가 있다 : Logistics force agent(static model), Military supplies transport manager(function model), Military supplies state manager(dynamic model). Logistics force agent는 main function agent와function agent로 구성된다. Function agent가 다른 Logistics force agent에도 적용할 수 있도록 설계되었으며, 이는 에이전트의 높은 조합성과 재사용성을 가진다. Military supplies transport manager는 보급로에 대한 정보를 가지며 military supplies state manager로부터 받은 결정변수를 기반으로 보급로를 결정하고 군수품을 수송하는 역할을 하는 에이전트이다. Military supplies state manager는 군수품 보급을 요청받고 보급량, 우선순위 따위의 결정 변수를 military supplies transport manager에게 알려주는 역할을 한다. 본 논문에서는 군수 시뮬레이션 모델의 설계를 위해 Discrete Event Systems Specification(DEVS) formalism을 이용하였다.

• 한국정밀공학회지
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• 제11권4호
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• pp.126-137
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• 1994

Performance management of computer networks is intended to improve a given network performance in order for more efficient information exchange between subsystems of an integrated large-scale system. Importance of perfomance management is growing as many functions of the large- scale system depend on the quality of communication services provided by the network. The role of performance management is to manipulate the adjustable protocol parameters on line so that the network can adapt itself to a dynamic environment. This can be divided into two subtasks : performance evaluation to find how changes in protocol parameters affect the network performance and decision making to determine the magnitude and direction of parameter adjustment. This paper is the first part of the two papers focusing on conceptual design, development, and evaluation of performance management for token bus networks. This paper specifically deals with the task of performance evaluation which utilizes the principle of perturbation analysis of discrete event dynamic systems. The developed algorithm can estimate the network performance under a perturbed protocol parameter setting from observations of the network operations under a nominal parameter setting.

• 정보과학회 논문지
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• 제42권7호
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• pp.823-833
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• 2015

하이브리드 시스템은 연속 시스템과 이산 시스템으로 구성된 동적 시스템이다. 하이브리드 시스템은 자동차, 항공, 군사 방어 등 시스템을 명세 하는데 사용되고 있으며 이를 위해 다양한 모델링 언어와 지원 도구가 개발되고 사용되어 왔다. 제안되어 사용되고 있는 언어와 도구들은 목적에 따라 특정한 특징들을 갖고 있다. 한국전자 통신연구원에서 제안한 하이브리드 시스템 모델링 언어인 ECML (ETRI CPS Modeling Language)은 DEV&DESS (Differential Event and Differential Equation Specified System) 형식론을 CPS (Cyber-Physical System) 환경에 맞게 확장한 언어이며 모델링 및 시뮬레이션을 지원한다. 논문에서는 ECML을 소개하고 정형 정의를 제안한다. 또한 제안된 정의에 따라 간단한 차량 모델을 명세한 사례연구를 수행한다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.74-79
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• 1996

This paper describes a methodology for the development of models of discrete event system(DES). The methodology is based on transformation of continuous state space into discrete one to homomorphically represent dynamics of continuous processes in discrete events. This paper proposes a formal structure which can couple DES models within a framework. The structure employs the DEVS formalism for the DES models. The proposed formal structure has been applied to develop a DEVS model for the human cardiovascular system. For this, the cardiac cycle is partitioned into a set of phases based on events identified through VisSim simulation in the CS of the electrical analog model. VisSim is the simulation tool of visual environment for developing continuous, discrete, and hybrid system models and performing dynamic simulation. For each phase, a CS of the electrical analog model for the cardiovascular system has been simulated by VisSim 2.0. To validate this model, first develop the DEVS model, then simulate the model in the DEVSIM++ environment. It has same simulation results for the data obtained from the CS simulation using VisSim. The comparison shows that the DEVS model represents dynamics of the human heart system at each phase of cardiac cycle.

• 경영과학
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• 제9권1호
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• pp.3-15
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• 1992

In this paper, we study a manufacturing system of serial stages with general service times, in which the production of each stage and the coordination of stages are controlled by Kanban discipline. This Kanban discipline is modeled as a Discrete Event Dynamic System and a system of recursive equations is applied to study the dynamics of the system. The recursive relationship enables us to compare this Kanban discipline with the other blocking disciplines such as transfer blocking, service blocking, block-and-hold b, and block-and-hold K, and the Kanban is shown to be superior to the other disciplines in terms of makespan and throughput. As a special case, two stages Kanban system is modeled as $C_2/C_2/1/N$ queueing system, and a recursive algorithm is developed to calculate the system performance. In optimizing the system performance, the stochastic optimization approach of Robbins-Monro is employed via perturbation analysis, the way to estimate the stochastic partial derivative based on only one sample trajectory of the system, and the required commuting condition is verified. Then the stochastic convexity result is established to provide second-order optimality condition for this parametric optimization problem.