• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.181-183
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• 2006

This paper proposes an intelligent decision framework for update of the environment model using GSPN(generalized stochastic petri nets). The GSPN has several advantages over direct use of the Markov Process. The modeling, analysis, and performance evaluation are conducted on the mathematical basis. By adopting the probabilistic approach, our decision framework helps the robot to decide the time to update the map. The robot navigates autonomously for a long time in dynamic environments. Experimental results show that the proposed scheme is useful for service robots which work semi-permanently and improves dependability of navigation in dynamic environments.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.971-974
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• 2002

Petri net is an effective modeling tool for concurrent systems. Liveness problem is one of analysis problems in Petri net theory verifying whether the system is free from any local deadlocks. It is well known that computational complexity of liveness problem of general Petri net is deterministic exponential space. Some subclasses, such as marked graph and free choice net, are suggested where liveness problem is verified in less complexity. This paper studies liveness of siphon containing circuit (SCC) net. Liveness condition based on algebraic inequalities is shown. Then polynomial time decidability of liveness of SCC net is derived, if the given net is known to be an SCC net a priori.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.2
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• pp.121-129
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• 2000

In this paper, an optimal group control for elevator systems is proposed with timed Petri net based approach. Elevator system is modeled by time Petri nets and hall call response times are estimated with moment generating functions (MGFs) methos, which is applicable to real traffic patterns. Two assignment policies are proposed to satisfy the demands of passengers(i.e. hall/car calls) and to handle exceptional situations. In addition, optimal algorithms are implementated to minimize cost functions. THe performances of the elevator system employing the proposed algorithms are compared with each others in ways of several performance measures by a computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.59-59
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• 2000

In this paper, we present a framework for modeling and control of multiple mobile robots which cowork within a bounded workspace and limited resources. To achieve this goal, we adopt a formalism of discrete event system and supervisory control theory based on Petri nets. We can divide our whole story into two parts: first, we search the shortest path using the distance vector algorithm, and then we construct the control scheme from which a number of mobile robots can work within a bounded workspace without any collision. The use of Petri net modeling allows us In synthesize a controller which achieves a control specification for the desired closed-loop behavior efficiently. Finally, the usefulness of the proposed Petri net formalism is illustrated by a simulation study.

• Nuclear Engineering and Technology
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• v.28 no.6
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• pp.522-531
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• 1996

The adoption of expert systems mainly as operator supporting systems is becoming increasingly popular as the control algorithms of system become more and more sophisticated and complicated. The verification phase of knowledge base is an important part for developing reliable expert systems, especially in nuclear industry. Although several strategies or tools have been developed to perform potential error checking, they often neglect the reliability of verification methods. Because a Petri net provides a uniform mathematical formalization of knowledge base, it has been employed for knowledge base verification. In this work, we devise and suggest an automated tool, called COKEP(Checker Of Knowledge base using Extended Petri net), for detecting incorrectness, inconsistency, and incompletensess in a knowledge base. The scope of the verification problem is expanded to chained errors, unlike previous studies that assume error incidence to be limited to rule pairs only. In addition, we consider certainty factor in checking, because most of knowledge bases have certainty factors.

• Journal of the Korea Society for Simulation
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• v.12 no.2
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• pp.13-24
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• 2003

In this study, we propose a scheduling analysis method of the Flexible management system using the transitive matrix. The Scheduling problem is a combination-optimization problem basically, and a complexity is increased exponentially for a size of the problem. To reduce an increase of a complexity, we define that the basic unit of concurrency (short BUC) is a set of control flows based on behavioral properties in the net. And we propose an algorithm to divide original system into some BUC. To sum up, we divide a petri net model of the Flexible management system Into the basic unit of concurrency through the division algorithm using the transitive matrix. Then we apply it to the division-scheduling algorithm to find an efficient scheduling. Finally, we verify its efficiency with an example.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.439-443
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• 1987

This paper presents a method for constructing model of manufacturing processes for simulation and design of the discrete control logic. The models represent the discrete vent evolution of the system as well as features of the underlying continues processes, for applications such as discrete parts manufacture and assembly, the process is decomposed into operations and for each operation the required resources and associated discrete resource slates are Identified. The structure of the discrete-level control is modeled by modified Perti nets which are synthesized from single resource activity cycles. Construction of nets provides discrete control logic with guaranteed properties based on extended Petri nets theory, for illustration, the proposed method is applied to the high-level discrete control of a two-robotic assembly cell.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.3
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• pp.76-81
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• 2011

Intrusion prevention systems (IPS) are important solution about solved problems for inside system security or outsider attacks. When introduce this system, first consideration item is secured rather than multiple function. Colored Petri Nets (CPNs) used that in order to secured verification for user authentication function of intrusion prevention system security model. CPNs is a graphical modeling language suitable for modeling distributed, concurrent, deterministic or non-deterministic systems with synchronous. Like these CPNs was expressed every possible state and occurrence graph. Secured of IPS security model was verified because expression every state using CPN tool and as a result of analyzing the occurrence graph was without a loop or interruption.

• The Journal of the Korea Contents Association
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• v.9 no.7
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• pp.95-101
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• 2009

Cognitive Radios are encouraging solutions to improve the utilization of the radio spectrum In this paper, we propose channel allocation model for cognitive radio and analyse the performance of the model with Petri Nets. We design the model with an assumption that only partial information about current channel allocation information is known to CR users. The model is designed to communicate efficiently avoiding interference with primary and CR users and contains channel reobtaining process of CR users. The dropping rate and throughput of CR users under the various channel utilization of primary users are given as performance index.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1303-1310
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• 1999

In this paper, the Timed Petri-Nets(TPN) modeling of Modular Cell Manufacturing Systems(MCMS) was investigated to overcome the limit of batch mode operation, which has been one of the most popular manufacturing types to produce an extensive industrial output and to be able to adopt to suitable and quickly changing manufacturing environments. A model of the MCMS was developed in reference to the actual TFT-LCD manufacturing system. TFT-LCD manufacturing system is not mass-productive in batch mode, but it operates in the form of MCMS which consists of a sequence of several cells with four processes of operation, including those of color filter(C/F), TFT, cell, and module. The cell process is further regrouped in those of Front-End and Back-End. For the Back-End cell process, it is reconstructed into a virtual model, consisting of three cells. The TPN modeling encompasses those properties, such as states and operations of machines, the number of buffers, and the processing time. The performance of the modeling was further examined in terms of scheduling system. The productivity in each cells was examined with respect to the change of failure rate of the cell machines and Automatic Guided Vehicles(AGV) using simulation by TPN.