• Proceedings of the IEEK Conference
• /
• 2000.07b
• /
• pp.649-652
• /
• 2000

Beyond free choice net system this paper presents some liveness knowledge in asymmetric net system including necessary and sufficient condition for an asymmetric net system being live and having liveness monotonicity, and an algorithm, polynomial time complexity, for such deciding. Also two conjectures about system livenss are in the contribution.

• Journal of Information Technology Application
• /
• v.2 no.1
• /
• pp.113-137
• /
• 2000

Even though there is no doubt that ERP(Enterprise Resource Planing) system is a prevailing solution for integrating corporate information, many companies still hesitate adopting ERP system because of a great deal of cost including maintenance cost. In special, unless consulting knowledge that is infused into process reengineering phase or adequately embedded in customized ERP system is upgraded on time, then we cannot guarantee the optimality of system performance. Hence, this paper aims to construct an ERP system that adapts itself to environmental changes that are issued by database and users. To do so, we adopt intelligent agent technology and Petri net theory. The agents autonomously cooperate each other to investigate databases and to find any exceptional changes and analyze how the changes will affect ERP performance. The dynamics of the agents are represented as Petri nets. The newly proposed ERP system is to make corresponding BPR processes maintain optimality. To show the feasibility of the proposed ERP maintenance system, logistics component is described as an illustrative example.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.6
• /
• pp.724-733
• /
• 1999

An effective method of system modeling and dynamic scheduling for the back-end line of semiconductor manufacturing is proposed. The virtual factory, describing semiconductor manufacturing line, is designed in detail, and then a Petri net model simulator is developed for operation and control of the modular cells of the virtual factory. The petri net model is a colored timed Petri nets (CTPNs). The simulator will be utilized to analyze and evaluate various dynamic status and operatons of manufacturing environments. The dynamic schedulaer has a hierarchical structure with the higher for planning level and the lower for dynamic scheduling level. The genetic algorithm is applied to extract optimal conditions of the scheduling algorithm. The proposed dynamic scheduling is able to realize the semiconductor manufacturing environments for the diversity of products, the variety of orders by many customers, the flexibility of order change by changing market conditions, the complexity of manufacturing processes, and the uncertainty of manufacturing resources. The proposed method of dynamic scheduling is more effective and useful in dealing with such recent pressing requirements including on-time delivery, quick response, and flexibility.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.9
• /
• pp.133-141
• /
• 2002

In this paper, we propose a hierarchical motion controller with stand-alone vision system to enhance the flexibility of the robot soccer system. In addition, we simplified the model of dynamic environments of the robot using petri-net and simple state diagram. Based on the proposed model, we designed the robot soccer system with velocity and position controller that includes 4-level hierarchically structured controller. Some experimental results using the stand-alone vision system from host system show improvement of the controller performance by reducing processing time of vision algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.14 no.3
• /
• pp.207-215
• /
• 1989

In this Paper prestnting an extended timed Petri net model which Can be used for the performance analysis of Distributed System. An analysis methodology based on a reachiabilitylike approach is prestented efficiency to find out the behaviour of these nets in terms of performance. And the proposed extended timed prtri net models are simulated to show practicability of the accuracy of the extended model in representing system specification.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.3
• /
• pp.745-755
• /
• 2000

In designing distributed databases, DAP(Data Allocation Problem) is one of the key design issues. Because, however, most of previous researches on DAP have considered only cost aspect, they cannot increase the performance and availability and they are not proper to the system requiring high-availability or real-time processing. Therefore, we need a more formal data allocation model considering multiple aspects. In this paper, we propose the MAPN (Multiple Aspects Petri Net) modeling method for the distributed transaction modeling. The MAPN model, an extended classical petri net, is proposed for the formal modeling considering multiple aspects (cost, performance and availability) concurrently. We demonstrate that we can compose the valid DAP evaluation model considering not only cost but also performance and availability concurrently by using the MAPN structure and MAPN graph.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.41 no.3
• /
• pp.1-10
• /
• 2004

Quite many papers about moving objects database (MOD) have been Published. Most of them are concerning of improving efficiency of updating policy, but none of them talks about verification of system's requirements. No matter how efficient updating policy is employed, a system designer still has to verify if the MOD satisfies user's requirement at the beginning of system lifestyle. For example, if a MOD serves n moving objects, then the designer must verity if it can update information for n moving objects and provide new information to moving objects within specified time limit. For the purpose of requirement analysis of MODs, we build a Petri net model for MOD using Design/CPN, and then we show how to verify whether the MOD satisfies user's requirements by simulation. The contribution of this paper is providing a simulation model for requirement analysis of MOD for the first time. The model is expansion of our previous fuzzy-timing Petri net model. The distance-based updating policy, and distributed database management system are reflected in this model and system analysis for moving objects is considered. It is built in Design/CPN so that the simulation can be automatically performed. The application of our model is not limited to requirement analysis, it is useful to study other MOD design issues, such as the trade-offs between update cost and information accuracy, and between the tim interval needed for updating database and MOD system resources, etc.

• Journal of Computing Science and Engineering
• /
• v.9 no.1
• /
• pp.9-19
• /
• 2015

The most important challenge in the region-based abstraction method as an approach to compute the state space of time Petri Nets (TPNs) for model checking is that the method results in a huge number of regions, causing a state explosion problem. Thus, region-based abstraction methods are not appropriate for use in developing practical tools. To address this limitation, this paper applies a modification to the basic region abstraction method to be used specially for computing the state space of TPN models, so that the number of regions becomes smaller than that of the situations in which the current methods are applied. The proposed approach is based on the special features of TPN that helps us to construct suitable and small region graphs that preserve the time properties of TPN. To achieve this, we use TPN-TCTL as a timed extension of CTL for specifying a subset of properties in TPN models. Then, for model checking TPN-TCTL properties on TPN models, CTL model checking is used on TPN models by translating TPN-TCTL to the equivalent CTL. Finally, we compare our proposed method with the current region-based abstraction methods proposed for TPN models in terms of the size of the resulting region graph.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.66-66
• /
• 2000

In this parer, we introduce an algorithm to control flows of the traffic in multi-intersections. It is pointed out that the main problem in traffic control is how to resolve the congested situations for the particular time-durations and directions. The heavy load to a certain direction usually leads the intersection to congested situations, and the adjacent intersections are affected. We control and analyze the traffic flow of multi-intersections consisting of five intersections, in which four intersections are linked to the four directions of the central one. The entrance of vehicles of each direction is described using the concept of probability. We compare the performance of the pretimed signal controls to the traffic adaptive signal controller using a Petri Net simulation tool, Exspect.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.16 no.2
• /
• pp.128-147
• /
• 1991

We propose a dynamic incidence matrix (DIM) for reflecting states and time conditions of a timed Petri net (TPN) explicitly. Since a DIM consists of a conventional incidence matrix, two time-related vectors and two state-related vectors, we can get the advantages inherent in the conventional incidence matrix of describing a static structure of a system as well as another advantage of expressing time dependent state transitions. We introduce an algorithm providing the DIM with a state transition mechanism. Because the algorithm is, in fact, an algorithmic model for discrete event simulation of TPN models, we provide a theoretical basis of model transformation of a TPN model into a DEVS(Discrete Event system Specification) model. By executing the algorithm we can carry out performance analysis of computer communication protocols which are represented TPN models.