• Journal of the Korean Operations Research and Management Science Society
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• v.20 no.2
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• pp.159-178
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• 1995

Supervisory control is an approach based on formal language. it is used to model and control discrete event systems in which each discrete event process is represented as an automation. A supervisor is a generator that switches control patterns in such a way that a given discrete evenet process behaves in obedience to various constraints. A flexible manufacturing cell (FMC) is one of discrete evenet systems. Functions necessary for the operation of an FMC are characterized by operational components and informational compoments. The operational components can be modeled using the finite state machines and the informational components can be modeled using the abstract formalism which describes supporting operations of the cell controller. In this paper, we addressed function required for FMC control specification, software engineering aspects on FMC control based on supervisory control, a concept of event queue for resolving synchronization problem, and complexity reduction. Based on the mathematical model of an FMC. we synthesized the controller by integrating a supervisor for FMC with control specification that specifies event-driven operation of the cell controller. The proposed control scheme is stable mathematically so that the system always behaves on a controlled way even under the existence of uncontrollable events. Furthermore, using an event queue concept, we can solve a synchronization problem caused by the violation of instantaneity assumption of supervisory control theory in real life situation. And also, we can propotype a control software rapidly due to the modularity of the proposed control scheme.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.5
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• pp.329-339
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• 2019

Recently, the advancement of information and communication technology(ICT) is expanding the connectivity through Internet of Things(IoT), and the media of connection is also expanding from wire/cable transmission to broadband wireless communication, which has significantly improved mobility. This hyperconnectivity has become a key element of the fourth industrial revolution, whereas the supervisory control network of purification plants in korea is operated as a communication network separated from the outside, thereby lagging in terms of connectivity. This is considered the best way to ensure security, and thus there is hardly any consideration of establishing alternatives to operate an efficient and stable communication network. Moreover, security for management of a commercialized communication network and network management solution may be accompanied by immense costs, making it more difficult to make new attempts. Therefore, to improve the conditions for the current supervisory control network of purification plants, this study developed a industrial security L2 switch that supports modbus TCP(Transmission Control Protocol) communication and encryption function of the transmission section. As a result, the communication security performance improved significantly, and the cost for implementing the network management system using Historical Trend and information of HMI(Human Machine Interface) could be reduced by approximately KRW 200 million. The results of this study may be applied to systems for gas, electricity and social safety nets that are infrastructure communication networks that are similar to purification plants.

• 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.

• Analyses & Alternatives
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• v.2 no.1
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• pp.71-106
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• 2018

The 19th CPC National Congress has a key historical significance in the development of China's constitution. It will also play a decisive role in the history of the seventy years'constitutional change in New China. XiJinping's new socialist thought with Chinese characteristics established in the report of 19th CPC National Congress will be written in the preface of the March 2018 National People's Congress's constitutional amendment. The fifth revision of 1982 Constitution will touch on many issues such as the leadership of the CPC into the constitution, the abolition of the tenure of the president, the constitutional oath system, and the reform of the national supervisory system. In addition, the constitutionality review system, the establishment of the National Security Council, the constitutional status of socialist public property and private property and the adjustment of major economic system has become a hot topic in the theory field. In the history node towards a socialist country ruled by law, the theory and practice of the China indeed have the academic ideas, value position and path model differences, which will delay the Chinese constitutional development, but also is the necessary pain in the process of moving towards the rule of law in China. Indeed, how to the development and where to go in the future of Chinese constitutionalism itself has sample value, which deserves rational attention and in-depth inquiry from Chinese and Western academics.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.3
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• pp.398-403
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• 2009

The recent trend of logistics demands for improved monitoring system of the inside of containers including current temperature and other environmental conditions. This paper presents an information processing technique with fuzzy logic that recognizes the current situations inside the target container and can be implemented on intelligent container systems. The ZigBee modules are used to collect information such as temperature, humidity, and shock inside the container in ubiquitous environment. The information processing system using fuzzy logic and the InTouch, one of SCADA(Supervisory Control and Data Acquisition) systems, is implemented to monitor the inside of the container and predict the emergency state.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.975-980
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• 1993

In accordance with increase, if electronic power demanded, more efficient supervisory control of distribution system will be required. This study contains development of MMI(man-machine-interface) system with GUI(graphic-user-interface), for the automatic power distribution system. The main function of MMI system is to edit network of power distribution and to management of data base for network. The GUI function of MMI system enables more efficient management of power distribution system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.9
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• pp.485-490
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• 2006

According to the computerization of railway signaling systems, the interface link between the signaling systems has been replaced by the digital communication channel. At the same time, the importance of the communication link is more pronounced than before. In this paper, new Network-based protocol between railway signaling and SCADA (Supervisory Control and Data Acquisition system) has designed and the overview of designed protocol is briefly represented. And also this paper addresses analysis of newly designed train control systems. Fame error rates of the data transmissions are calculated and compared for the two cases that the CTC (Centralized Traffic Control)/SCADA has an extra data transmission error control (CRC16) besides the inherent error control of the Ethernet and that the CTC/SCADA has no extra data transmission error control. With simulation results it has been verified that the additional error control code contributes to lowering the frame error rate. It will be expected to increase the safety, reliability and efficiency of maintenance of the signaling systems by using the designed protocol for railway signaling system.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.129-134
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• 2001

Novel supervisory system for WDM transmission link using conventional optical time domain reflectometry was presented. By modifying the structure of erbuim doped fiber amplifier to support bi-directional transmission at arDR pulse wavelength and launching the optical pulse into transmission link in the opposite direction of data signal propagation to avoid the distortion by cross-gain modulation, it is possible to monitor the WDM link in service. To prove the validity of proposed scheme, the supervision result of 2.5 Gbps $\times$ 8 channel WDM 320 km transmission system in service by arDR was presented. And power penalty due to monitoring was measured as smaller than 0.3 dB. .3 dB.

• Journal of the Ergonomics Society of Korea
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• v.5 no.2
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• pp.3-9
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• 1986

The present paper deals with obtaining the proper application criteria for the control mode, by using computer graphic simulation, in order to recover the error effectively occurring in the practical supervisory contol work of hyman-robot system. In these experiments the opteations by human and by control program are performed as control modes for recovering the error. And then we compare and analyze tow control modes taking task error and task time as performance measures and task difficulty as a variable factor. Consequently as the task difficulty increases, the task error in the operation by hyman tends to be less than in the operation by control program and the task time is superior in the operation by control program. Therefore, we suggest that two control modes should be used jointly for recovering the error and the operation by control program should be applied in major fraction of control and the operation by human in minor fraction of control.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.9
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• pp.95-100
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• 2007

The importance of communication security is increased in the power industry. The representative communication network of power industry is the SCADA(Supervisory Control and Data Acquisition) systems. The SCADA system has been used for remote measurement and control in the power industry. Recently, many studies of SCADA network security have been carried out around the world. In this paper, we introduce recent security issues in the SCADA network and propose the application of a symmetric encryption method to the Korea SCADA network.