• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.362-367
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• 1996

In this paper, the eigenstructure of a class of linear time varying systems, termed as linear quasi-time invariant(LQTI) systems, is investigated. A system composed of dynamic devices such as linear time varying capacitors and resistors can be an example of the class. To effectively describe and analyze the LQTI systems, a generalized differential operator G is introduced. Then the dynamic systems described by the operator G are studied in terms of eigenvalue, frequency characteristics, stability and an extended convolution. Some basic attributes of the operator G are compared with those of the differential operator D. Also the corresponding generalized Laplace transform pair is defined and relevant properties are derived for frequency domain analysis of the systems under consideration. As an application example, a LQTI circuit is examined by using the concept of eigenstructure of LQTI system. The LQTI filter processes the sinusoidal signals modulated by some functions.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2179-2194
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• 2010

RAMS is becoming increasingly important in the decision making process for the rolling stock projects in order to improve competitiveness by reducing system life cycle cost while improving reliability, availability, maintainability and safety. In order to apply and manage RAMS of rolling stock systems effectively in the operator perspective, it is essential to integrate and control RAMS systematically from the early stage of rolling stock projects. RAMS management is to implement a RAMS system into rolling stock projects in terms of a rolling stock operator, which presents the strategic directions of RAMS policy, objectives, requirements, control, analysis, measurement and improvement throughout life cycle of rolling stock projects. This article presents a new framework of RAMS management that provides an effective and efficient way for managing RAMS in rolling stock systems in the railway industry.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.47
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• pp.57-68
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• 1998

Work environments have been changed with the advent of new technologies, such as computer technology. However, human cognitive limits can't pace up with the change of work environment. Designing human-computer system requires knowledge and evaluation of the human cognitive processes which control information flow workload. Futhermore, under limited reaction time and/or urgent situation, human operator may the work stress, work error and resultant deleterious work environment. This paper evaluate the visual factors of major information processing factors(information density, amount of information, operational speed of speed)on operator performance of supervisory control under urgent(limited reaction time)environments which require deleterious work condition. To describe the work performance int the urgent work situations with time stress and dynamic event occurrence, a new concept of information density was introduced. For a series of experiments performed for this study, three independent variables(information amount, system proceeding speed, information density) were evaluated using five dependent variables. The result of statistical analyses indicate that the amount of information affected on all of five dependent measure. Number of failure and number of secondary task score were influenced by both amount of information and operational speed of system. However reaction time of secondary task were affected by both amount of information and information density. As a result, the deleterious factors for the performances seemed to be a scanning time to supervise each control panel. Consequently, a new display panel was suggest to reduce operator work load for scanning task showing better operator performance.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.887-891
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• 1992

In this study, it is developed the interactive DNC(Direct Numerical Control) system, in using RS-232C cable and auxiliary computer, through the diagnosis of planning process and information evaluation. this DNC system recognize the Manufacturing planning and control it. This DNC system has a different notation. It can be done by an operator who hasn't knowledge about personnel computer. It is operated with automatic planning and measurement tec. by operator, using part program on the NC(Numerical Control).

• Nuclear Engineering and Technology
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• v.39 no.2
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• pp.123-128
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• 2007

In order to apply a static fault-tree (FT) method to a system or a plant whose configuration changes dynamically, condition gates and a post processing method are used to effectively accommodate these changes. An operator's performance change, which can be caused by these configuration changes, should also be considered to assess the risk to a plant in a more realistic manner. This study aims to develop an integrated framework to accommodate various configuration changes and their effect on an operator’s performance by using the FT model. We applied a condition-based human reliability assessment (CBHRA) method to consider various conditions endured by an operator. That is, we integrated the CBHRA method with the conventional post processing method for modeling the system configuration changes. The effect of the condition monitoring systems installed in a plant is also considered. In this study, we show an example application of the integrated framework to a probabilistic safety assessment for the shutdown phase of a nuclear power plant.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.6 s.237
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• pp.795-803
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• 2005

This paper studies the observability of calibration system with a measurement operator. The calibration system needs a simple digital indicator to measure the mobile table movements with respect to the MC coordinate. However, it yields the concern about the poor parameter observability due to measuring only a part of the movements. We uses the QR-decomposition to find the optimal calibration configurations maximizing the linear independence of rows of an observation matrix. The number of identifiable parameter is examined by the rank of the observation matrix, which represents the parameter observability. The method is applied to a 6-axis MC with parallel tilting table and the calibration results are presented. These results verify that all necessary kinematic parameters are observable and the calibration system has robustness to the noise using optimal calibration configurations.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.216-220
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• 1987

A graphic display and operator console system is developed for monitoring the operation of power plant. It has multiprocessor structure using VME bus and common memory. The graphic monitoring system is applied to fault tolerant control system for enhancing reliability of boiler analog controller. As a result, it displays all the operating date as color graphic images with 14 pages. Moreover, it can transfer the operator commands to the other micro-processors through common memory.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2498-2500
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• 2003

This paper describes on a teleoperation system with a simulator on operator's computer. When we control robots over the internet, communication propagation delays exist. These delays are potentially destabilizing the entire system, and degrade the operator's intuition and performance, so we designed teleoperation system with simulator. Instead of feedback image data of work space, remote operator can command by seeing simulator in the his computer. Consequently total working time can be decreased. In this paper, we show a propriety of the teleoperation system with a simulator by comparing with one without a simulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.8
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• pp.1161-1167
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• 2015

Distribution Management System(DMS) ienhancing distribution automation system-based operation efficiency is an optimized system by various operational applications in a distribution network. DMS employs various applications like topology reconfiguration, volt/var control, and restoration at events such as overload, voltage violation, and a fault in a distribution system. An operation efficiency to employ multi-applications as restoration with short-term load forecasting is higher than a performance by a single application; and the applications are accomplished by an operator’s control. Applications’ combination is determined by various alarm information which means critical issues in order to operate a distribution system. Thus, this paper proposes an application management system which can configure application combination, control applications depending on alarm information and check their performance condition. The proposed application management system can be customized by operator easily and have high operation efficiency and reliability because it is worked by reviewed alarm information from operator.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.4
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• pp.564-569
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• 1994

This paper presents an expert system for the fault section estimation and fault diagnosis in power transmission systems, which also has random event generation function for the purpose of operator training or educational experiment. The expert system is developed using an artificial intelligence language.