• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.244-252
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• 2013

In this paper, we show that supervisory control theory of discrete event systems can be applied to analyze the problem of power in political economy. For this purpose, we introduce the decision mechanism of control inputs based on power, and the consequent behavior of a supervised system. Specifically, this paper presents the notion of power-controllability as a necessary and sufficient condition to achieve a common control objective of competing groups (local controllers). If the power-controllability is met, a modular system controlled by local controllers with power functions is not deviated from a common control objective of them.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.2
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• pp.22-31
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• 2004

A problem of task rescheduling using a coordinator in a structural decentralized control of supervisory control theory is formulated. we consider that the overall system is divided into a number of local systems. Using an example of a chemical batch reaction process, it has shown that after local supervisors have been established for a given task, a coordinator can be used to solve some rescheduling problems among local plants for new or modified tasks. The coordination system models the interactions of local plants, and is consisting of only the shared events of local plants, so simpler to synthesize. A coordinator is designed based on the specifications given for the coordination system. Under the 'structural' conditions developed in this paper, the combined concurrent actions of the coordinator with the existing local supervisors will achieve the rescheduling requirements. Again since the conditions are structural (not specification-dependent), once the coordination architecture has been established, it can be used for a number of different tasks without further verifications.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.5
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• pp.375-383
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• 2001

As many industrial systems become more complex, it becomes extremely difficult to diagnose the cause of failures. This paper presents a failure diagnosis approach based on discrete event system theory. In particular, the approach is a hybrid of event-based and state-based ones leading to a simpler failure diagnoser with supervisory control capability. The design procedure is presented along with a pump-valve system as an example.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.10
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• pp.995-1001
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• 2014

In the aftermath of the financial crisis of 2008, while numerous members of the general public lost their homes and jobs, many of the largest banks held responsible for the crisis have been successfully rescued by bailouts. In this paper, through the analysis of income inequality, unemployment, tax cuts, and bailouts, we show that the interests of the general public are different from the interests of politicians and bankers. While the small elite group of politicians and bankers could set the deregulation policies with inordinate power based on full information, most people were ignorant and unconcerned about the policies, and hence did not oppose them. Specifically, we model the credit change in the financial markets of the United States by a finite state machine, and design three local supervisors representing three groups with different interests. It is then shown that the deregulation policies were adopted according to the difference of the supervisors' powers.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.6
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• pp.478-485
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• 2000

A discrete event systems (DES) is a physical system that is discrete in time and state space, asynchronous (event rather than clock-driven), and in some sense generative(or nondeterministic). This paper presents the design of fifteen modular supervisors to control an experimental CIM testbed. These supervisors are nonblocking, controllable and nonconflicting. After verification of the supervisors by simulation, the supervisors for AGV system have been implemented to demonstrate their efficacy.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.1
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• pp.34-42
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• 2015

Modeling and control of human-involved manufacturing systems poses a huge challenge on how to model all possible interactions among system components within the time and space dimensions. As the manufacturing environment are getting complicated, the importance of human in the manufacturing system is getting more and more spotlighted to incorporate the manufacturing flexibility. This paper presents a formal modeling methodology of affordance-based MPSG (Message-based Part State Graph) for a human-machine collaboration system incorporating supervisory control scheme for flexible manufacturing systems in automotive industry. Basically, we intend to extend the existing model of affordance-based MPSG to the real industrial application of humanmachine cooperative environments. The suggested extension with the real industrial example is illustrated in three steps; first, the manufacturing process and relevant data are analyzed in perspectives of MABA-MABA and the supervisory control; second, the manufacturing processes and task allocation between human and machine are mapped onto the concept of MABA-MABA; and the last, the affordance-based MPSG of humanmachine collaboration for the manufacturing process is presented with UMLs for verification.

• 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.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.101-106
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• 2011

In this paper, our goal is to design the controller which operates a manufacturing system, discrete event system, guaranteeing user specification. In specially, based on supervisory control theory W. M. Wonham, our work consists in performing the controller using Petri nets possible parallelism. In addition, we consider the problem of allocation for resources sharing of the issues to consider when designing using Petri net. The controller can be generated by synthesis of user specification model and plant model after giving the management for the resource sharing. This created controller can control the deadlock and starvation which can occur in the case with resource sharing. Previous studies proposed the Constrained Synchronous Reachability graph to synthesis of the two Petri nets models. Therefore, we provide the controlled system which forbids a deadlock and starvation using the result of previous studies.

• Industrial Engineering and Management Systems
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• v.4 no.2
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• pp.176-183
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• 2005

The theory of signal detection has been applied to a wide range of practical situation for a long time, including sonar detection, air traffic control and so on. In general, in this theory, sensitivity parametric index d' and bias parametric index $\beta$ are used to evaluated the performance of vigilance. These indices use observer's response "hit" and "false alarm" to explain and evaluate vigilance, but not considering reaction time. However, the reaction time of detecting should be considered in measuring vigilance in some supervisory tasks such as unlimited monitoring tasks (e.g., supervisors in nuclear plant). There are some researchers have used the segments of reaction time to generate a pair of probabilities of hit and false alarm probabilities and plot the receiver operating characteristic curve. The purpose of this study was to develop a quantitative vigilance-measuring model by fuzzy sets, which combined the concepts of hit, false alarm and reaction time. The model extends two-values logic to multi-values logic by membership functions of fuzzy sets. A simulated experiment of monitoring task in nuclear plant was carried out. Results indicated that the new vigilance-measuring model is more efficient than traditional indices; the characteristics of vigilance would be realized more clearly in unlimited monitoring task.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.3
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• pp.43-51
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• 2008

Recent advances in mobile computing technologies and platform-independent information systems have enabled to realize a ubiquitous environment. Community computing has been developed as a useful tool for realizing collaborative services in a ubiquitous environment. In this paper, we present a formal model of a ubiquitous space that takes community concept into consideration and propose two management frameworks that prevent conflicts among communities. To demonstrate the validity of the proposed frameworks, an example for coordinating two communities is provided.