• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.5 s.45
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• pp.41-52
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• 2005

Using the variable control gain scheme on the basis of fuzzy-based decision-making process, Fuzzy supervisory control (FSC) technique exhibits better control performance than linear control technique with one static control gain. This paper demonstrates the effectiveness of the FSC technique by evaluating the robust performance of the FSC technique under the presence of uncertainties in the models and the excitations. Robust performance of the FSC system is compared with that of optimally designed LQG control system for the benchmark cable-stayed bridge presented by Dyke et al. Parameter studies on the robust performance evaluation are carried out by varying the stiffness of the bridge model as well as the magnitudes of several earthquakes with different frequency contents. From the comparative study of two control systems, FSC system shows the enhanced control performance against various magnitudes of several earthquakes while maintaining lower level of power required for controlling the bridge response. Especially, FSC system clearly guarantees the improved robust performance of the control system with stable reduction effects on the seismic responses and slight increases in total power and stroke for the control system, while LQG control system exhibits poor robust performance.

• 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 Mechanical Science and Technology
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• v.14 no.4
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• pp.418-425
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• 2000

Recently, many passenger cars have adopted automatic transmissions for shifting gears, and thus the smooth and precise control of gear shifts of passenger car automatic transmissions has become more and more essential for the riding comfort of vehicles equipped with automatic transmissions. In this article, a neural network-based supervisor for an automotive shift controller considering the throttle opening, variations in throttle opening, and the driving load is presented. For using the driving load information, an observer-based driving load estimation algorithm is proposed. A proportional-integral-derivative controller along with an open loop controller is used as a low level controller for controlling the gear shifts, and a supervisory controller for properly adapting the shift control parameters of the low level shift controller is designed using ANFIS. To evaluate the control performance of the proposed supervisor-based shift controller, both simulation studies and experimental studies are performed for various shifting situations.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.888-894
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• 2015

This paper presents a unified model based assessment framework to quantify threats and vulnerabilities associated with control systems, especially in the SCADA (Supervisory Control and Data Acquisition) system. In the past, this system was primarily utilized as an isolated facility on a local basis, and then it started to be integrated with wide-area networks as the communication technology would make rapid progress. The introduction of smart grid, which is an innovative application of digital processing and communications to the power grid, might lead to more and more cyber threats originated from IT systems. However, an up-to-date power system often requires the real-time operations, which clearly implies that the cyber security would turn out to be a complicated but also crucial issue for the power system. In short, the purpose of this paper is to streamline a comprehensive approach to prioritizing cyber security risks which are expressed by the combination of threats, vulnerabilities, and values in the SCADA components.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.318-323
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• 1993

The paper discusses the problem of computing coarser observation functions in supervisory control of discrete event systems. It is shown that when a supervisor that realizes a given language L has certain properties, L-realizability of a coarser observation function is equivalent to control-compatibility of the states in some subsets of the state space of the supervisor. This characterization is then used to devise an iterative procedure of computing coarser L-realizable observation functions, where supervisor reduction and L-realizability verification of an observation function are performed at each iteration.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1996.10a
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• pp.172-175
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• 1996

In the paper is proposed a hierarchical self-learning fuzzy controller for balancing and position control of an circular inverted pendulum system. To stabilize the pendulum at a specified position, the hierarchical fuzzy controller consists of a supervisory controller, a self-learning fuzzy controller, and a forced disturbance generator. Simulation example shows the effectiveness of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.476-481
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• 1991

This paper investigates the relationship between the two problems, supervisor reduction and observation function (projection) design, which arise in supervisory control of DEDS. It is shown through an example that a reduced supervisor of minimal size does not necessarily result in a maximal projection when a projection design method which uses the transition structure of a supervisor is applied. Also, if an L-realizable projection P is available and if a supervisor has a special structural feature, a cover C for supervisor reduction can be easily obtained. By investigating the control-compatibility of states of the reduced supervisor based on C, we can also check maximality of P in a simple manner.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.674-677
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• 1988

SCADA (Supervisory Control And Data Acquisition) system for control and supervision of power system is now being operated in KEPCO with high performance. But the performance of RGS(Report Generating System) is comparatively insufficient because the SCADA system was produced for special purpose performing in real time. Therefore, we have performed this study applied for the purpose of processing the statistic data of power network and improving facilities and availabilities of the system.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.111-115
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• 2012

In this paper, a solar energy powered bicycle linked to a wireless sensor network (WSN) which monitors the transfer of solar energy to an electrical energy storage unit and an analysis of its effectiveness is proposed. In order to achieve this goal, a solar-powered bicycle with an attached ZigBee and a far-end wireless network supervisory system is setup. Experimental results prove that our prototype, solar energy powered bicycle, can achieve enough solar energy for charging a two lead-acid battery pack. As a result, the user, through use of a wireless network in the parking period can be kept aware of the data on the amount of immediate solar radiation, the degree of illumination, the ambient temperature, and electrical energy storage capacity information of the bicycle through an internet interface.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.5
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• pp.505-518
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• 1987

In this paper, the 2-level and 3-level types of PWM technique have been analyzed, and a multiprocessor has been designed as controller for these two types of PWM inverters. Designed multiprocessor employing a hierarchical structure of a SUPERVISORY PROCESSOR which interconnects three LOCAL PROCESSOR through a common memory technique has showed as elaborate digital control characteristic. Using this multiprocessor configuration the system could gain a great degree of freedom in change of software. Also software was simpler than a single processor configuration.