• 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.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.375-378
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• 1996

Robot control software is a hard real-time system that must output the planned trajectory points within an explicit short time period. In this paper, we present a design and implementation method for robot control software using commercial real-time operating systems, RTKemel 4.5. Therefore, various robot motions, efficient user interface, and system failure check are easily implemented by using multitasking function, intertask communication mechanism, and real-time runtime libraries of RTKernel. The performance analysis of commercial real-time operating system for robot control is presented based on Timed Petri net(TPN) and we can use these results to design an optimal system.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.6
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• pp.724-733
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• 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 KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.335-346
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• 2004

PtolemyII is an environment that supports heterogeneous modeling and design of concurrent systems such as embedded system. PtolemyII has several Domains which are physical rules to determine the way of communicating between components. PtolemyII has 11 domains such as PetriNet, Timed Multitasking, SR etc. Components of System can be specified using appropriate domains for their properties. Communicating Sequential Processes(CSP) is implemented as formally designed CSP domain, in PtolemyII. But CCS didn't be implemented as a domain. It is a kind of Process Algebra language which can be used for specifying and verifying concurrent systems formally. Thus, in this paper we implemented CCS domain. And that permitted developers using PtolemyII to use the same modeling pattern used in PtolemyII and to make system specifications in the base of the formal semantics of CCS. This caused the diversity of PtolemyII domains and the power of expression was improved. This paper will explain the structure of CCS domain implemented in PtolemyII and the way of implementing it.

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

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.189-192
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• 2005

In this paper, we present a Petri Net (PN) model for reliability analysis of a shared database system. The system consists of components; a database, two processors, two memory and a bus. The database should be operational and at least one of the component should be also operational. Otherwise system will be down. Each component can be failed and repaired individually. Stochastic Reward Net (SRN) Model for reliability analysis is developed. SRN is potential to define various reward function and can be easily used to obtain performance measures. The modeling techniques using variable cardinality, enabling function, timed transition priority in SRN are shown.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.315-319
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• 2005

In this paper, we present a Petri Net (PN) model for reliability analysis of fault-tolerant database system models that consists of components one shared memory, bus, processors and database (disk). Each component can be failed and repaired individually. The system is operational as long as database and one of component is operational. We develop Stochastic Reward Net (SRN) Model for reliability analysis of database system. SRN is potential to define various reward functions. and can be easily used to obtain performance measures. The modeling techniques using variable cardinality, enabling function, timed transition priority in SRN are shown.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.314-314
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• 1996

We investigate the scheduling problem for periodic job shops with blocking. We develop Petri net models for periodic job shops with finite buffers. A buffer control method would allow the jobs to enter the input buffer of the next machine in the order for which they are completed. We discuss difficulties in using such a random order buffer control method and random access buffers. We thus propose an alternative buffer control policy that restricts the jobs to enter the input buffer of the next machine in a predetermined order. The buffer control method simplifies job flows and control systems. Further, it requires only a cost-effective simple sequential buffer. We show that the periodic scheduling model with finite buffers using the buffer control policy can be transformed into an equivalent periodic scheduling model with no buffer, which is modeled as a timed marked graph. We characterize the structural properties for deadlock detection. Finally, we develop a mixed integer programming model for the no buffer problem that finds a deadlock-free optimal sequence that minimizes the cycle time.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.82-85
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• 2004

This paper proposes the development of delay compensator to minimize performance degradation caused by time delays in network-based real-time control systems. The delay compensator uses the time-stamp method as a direct delay measuring method to measure time delays generated between network nodes. The delay compensator predicts the network time delays of next period in the views point of time delays and minimizes performance degradation from network through considering predicted time delays. Control output considering network time delays is generated by the defuzzification of probable time delays of next period. The time delays considered in the delay compensator are modeled by using a timed Petri net model. The proposed delay prediction mechanism for the delay compensator is evaluated through some simulation tests by measuring deviation of the predicted delays from simulated delays.

• ETRI Journal
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• v.40 no.4
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• pp.483-498
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• 2018

Nowadays, with progresses in robotic science, the design and implementation of a mechanism for human-robot interaction with a low workload is inevitable. One notable challenge in this field is the interaction between a single human and a group of robots. Therefore, we propose a new comprehensive framework for single-human multiple-robot remote interaction that can form an efficient intelligent adaptive interaction (IAI). Our interaction system can thoroughly adapt itself to changes in interaction context and user states. Some advantages of our devised IAI framework are lower workload, higher level of situation awareness, and efficient interaction. In this paper, we introduce a new IAI architecture as our comprehensive mechanism. In order to practically examine the architecture, we implemented our proposed IAI to control a group of unmanned aerial vehicles (UAVs) under different scenarios. The results show that our devised IAI framework can effectively reduce human workload and the level of situation awareness, and concurrently foster the mission completion percentage of the UAVs.