• Journal of the Korea Society for Simulation
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• v.9 no.1
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• pp.67-81
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• 2000

In this paper, a new software package for modeling and simulating discrete-event dynamic systems is developed. The new software is a general-purpose, graphical tool based on timed Petri-nets and is developed using Visual Basic and Visual C++ for the window environment. It allows the user to graphically build a Petri-net model and enter input data for executing the Petri-net simulation model. It is equipped with a deadlock detection and recovery function as well as an automatic error check function. In addition, the software supports various enabling functions and distribution functions and provides various statistics for the performance measures of interests pertaining to the system. We expect the new software will be used in a wide number of applications including computer, communication and manufacturing systems.

• Journal of Information Processing Systems
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• v.5 no.1
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• pp.19-24
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• 2009

Many researchers have developed frameworks that are capable of handling context information and can be adapted and used by any Web service. However, no research involving the systematic analysis of existing frameworks has yet been conducted. This paper examines the Context Framework, an example of existing frameworks, using a Petri net, and analyzes its advantages and disadvantages. Then, a Petri net model - with its disadvantages removed - is introduced, and a new framework is presented on the basis of that model. The proposed PAWS (Privacy Aware Web Services) framework has a expendability for context management and communicates flexible context information for every session. The proposed framework can solve overhead problems of context in SOAP messages. It also protects user privacy according to user preferences.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.677-682
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• 2007

Concurrent competition for finite resources by multiple parts in flexible manufacturing systems(FMS's) and inappropriate initial marking or net structure of Petri net with share resources results in deadlock. This is an important issue to be addressed in the operation of the systems. Deadlock is a system state so that some working processes can never be finished. Deadlock situation is due to a wrong resource allocation policy. In fact, behind a deadlock problem there is a circular wait situation for a set of resources. Deadlock can disable an entire system and make automated operation impossible. Particularly, an unmanned system cannot recover from such a status and a set of jobs waits indefinitely for never-to-be-released resources. In this paper, we proposed a deadlock prevention method using siphon and trap of Petri net. It is based on potential deadlock which are siphon that eventually became empty. This method prevents the deadlock by the control of transition fire and initial marking in the Petri net. An given example of FMS is shown to illustrate our results with deadlock-free.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.3
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• pp.197-206
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• 1989

In this paper, we represent an improved algorithm of performance evaluation for communication protocol. It is an algorithm that analyzes Extended Timed Perti Net models including time which have been successfully used to model and evaluate the performance of distributed system. While Timed Petri Nets generally limted to free-choice and safe nets, our algorithm permits the construnction of elegant models of restricted concurrent processing. Furthermore, to reduce the state space size of Timed Reachability Graph, we improve the algorithm by using Maximum Firing Rule and sets of simultaneously firing transitions. Procedures for constructing of Timed Reachability Graphs and analyzing are presented, and we demonstrate the usefulness of this algorithm by applying it to the analysis of the communication protocol.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.619-622
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• 1996

This paper presents the formal integration of process planning and shop floor control with Petri net formalism. Formal integration means that both planning and control problems can be modeled, interfaced, and transformed with the Petri net formalism. This integrated framework provides a systematic approach for rapidly developing a formal shop floor controller from process planning with respect to shop floor configuration.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1099-1104
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• 1993

The real time control system for FMS(Flexible Manufacturing System) is implemented at this paper. To achieve this goal, the Colored and Timed Petri-Net model is constructed and used to simulate the real time operation of FMS. Using the Colored and Timed Petri-Net model, evaluating any kind of FMS plant is possible. On-line shceduler, intelligent dispatcher, real time monitor and the simulation model of shop floor are contructed using LAN communication, relational database system in this paper. Finally, this real time control system is applied to the FMS/CIM center at Seoul National University.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1998.12a
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• pp.443-453
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• 1998

본 논문에서는 Petri-net 형태로 침입탐지 규칙을 구성한다. 이것은 실시간 침입탐지가 가능하고 지연공격과 다중공격을 방어할 수 있다. 그리고, Petri-net의 플레이스에 퍼지값을 적용한다. 이 값은 침입의 진행에 따라 변경되며 침입을 판정하는 기준이 된다. 또한, 변형공격에 대응할 수 있도록 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.97-98
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• 2007

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.106.3-106
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• 2002

1. Introduction 2. Petri-Net 3. Dynamic environment recognition 4. Simulation 5. Conclusion. References

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.213-220
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• 2008

The object of this paper is to propose a method to deal with the problem of modeling user specifications in approaches based on supervisory control and Petri nets. However, most of Petri Net approaches are based on forbidden states specifications, and these specifications are suitable the use of tool such as the reachability graph. But these methods were not able to show the user specification easily and these formalisms are generally limited by the combinatorial explosion that occurs when attempting to model complex systems. Herein, we propose a new efficient method using FSSTP (Forbidden Sequences of State-Transitions Problem) and theory of region. Also, to detect and avoid the deadlock problem in control process, we use DAPN method (Deadlock Avoidance Petri nets) for solving this problem in control model.