• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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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.

• Journal of KIISE:Software and Applications
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• v.27 no.3
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• pp.210-216
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• 2000

Place/Transition(P/T) nets has been used in protocol verification and concurrent system verification since it is suitable for describing concurrency and provides several well-established verification techniques. And it has been used as a base formalism for such high-level Petri nets as colored Petri nets, object-oriented Petri nets and etc. However, when analyzing complex models using P/T nets and P/T nets-based high-level Petri nets, there may be state explosion in reachability analysis due to improper handling of concurrency. In this paper, we define a structural concurrency in P/T nets, propose a partitioning algorithm based on the detected structural concurrency, and provide analysis techniques for such properties as boundedness of places and liveness of transitions, which are performed on compositional reachability graphs. The analysis techniques based on Petri net slices can be used in efficiently analyzing P/T nets-based high-level Petri net models as well as P/T net models.

• Journal of the Korea Society for Simulation
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• v.11 no.2
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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.

• Journal of the Korean Operations Research and Management Science Society
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• v.19 no.3
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• pp.131-138
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• 1994

Petri Nets are a graphical and mathematical modeling and promising tool for describing and studying that are characterized as being concurrent, asychronous, dynamic, distributed and parrallel. The purpose of this paper is to analyze FMS Throughout-Rate by development of Petri Nets So, it applied to FMS composed of 7 machines and 4 different job types. The result of this paper shows the advantage of using Petri Nets.

• Journal of the Korea Society for Simulation
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• v.11 no.2
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• pp.67-75
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• 2002

This paper proposes a parallel simulation algorithm for bounded Petri nets in a single processor, which exploits the SIMD(Single Instruction Multiple Data)-type parallelism. The proposed algorithm is based on a data packing scheme which packs multiple bytes data in a single register, thereby being manipulated simultaneously. The parallelism can reduce simulation time of bounded Petri nets in a single processor environment. The effectiveness of the algorithm is demonstrated by presenting speed-up of simulation time for two bounded Petri nets.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.36-41
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• 2005

페트리 네트(Petri Nets)는 이산 사건 시스템을 모델링할 수 있는 그래픽하고, 수학적인 도구이다. 본 연구는 유연제조 시스템을 확률적인 페트리 네트(Stochastic Petri Nets)중의 하나인 임베디드 마코프 체인(Embeded Markov Chain)에 도입하고, 임베디드 마코프 체인의 방법 중에 하나인 일반화된 확률적 페트리 네트(Generalized Stochastic Perti Nets)에 적용시켰다. 그리고 결과치의 정확성을 알아내기 위하여, 페트리 네트 시뮬레이션과 아레나를 사용하여 실행하였다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1338-1341
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• 1993

We present here two Petri nets formalisms that can deal with uncertainty by the use of necessity-valued logic. The first and basic model, called necessity-valued Petri nets (NPN), can at the same time deal with uncertainty on markings are on transitions. The second model, called necessity-valued Petri nets (TNPN), is an extension of both NPN and timed Petri nets.

• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.108-114
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• 2001

Petri nets have been introduced as a powerful analyzing and design tool for the discrete systems such as sequential control systems. However, one of the important problems in its applications is that the model can be analyzed hardly when we deal with large scale systems because of increase of the number of Petri net components. To overcome this problem, some methods for dividing or reducing of Petri net have been suggested. In this paper, an approach for hierarchical expression of Petri net based on Sequential function Chart(SFC) and Bottom Up oriented Mehodology(BUM) is proposed. Especially, some definitions and rules are defined in order to divide and compose sub Petri nets. A measuring tank system will be described as a typical kind of discrete systems and modeled by some sub Petri nets based on the SFC and BUM by the proposed method in this paper.

• Journal of Korean Society for Quality Management
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• v.18 no.2
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• pp.54-68
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• 1990

Contingency response in a FMS system requires that the system be able to identify and evaluate a number of alternatives. This paper is outlined that DSS completes with a problem processor in corporating Timed Petri Nets model, and a data base system. DSS enables the FMS user to get the maximum benefit from a FMS. The structure of this DSS parallels the organizational activities involved in running the FMS. In designing a shop floor controller for FMS, interactions between the different real time, discrete event functions must be established. The specification of the machine tool and material handling system functions working as a concurrent and cooperative system is given in terms of Timed Petri Nets. In addition, the basic concepts and uses of Petri Nets are surveyed. The system to be studied is first modelled by a Timed Petri Nets and then procedure for evaluating the FMS system performance are presented. Numerical examples are studied to illustrate a session of the FMS used-DSS interaction.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.9
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• pp.1006-1016
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• 1990

A scheduler for a class of Factory Automation (FA) systems is suggested. The technique of Timed Petri Nets is used to model FA systems and, a new concept called Unit Timed Petri Nets is proposed to schedule the system. The scheduler consists of two parts, scheduling rules and input jobs. Since flexibility should be an indispensable ingredient of the scheduler for FA systems, the method using Timed Petri Nets is adopted to represent scheduling rules in a simple and systematic manner and the scheduler is implemented with the PROLOG language. The proposed scheduler is applied to the realistic problem of flow shop.