• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.88-95
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• 2002

Recent development in the field of RE-Ba-Cu-O (REBCO, RE: Y or rare earth elements) bulk high-Tc superconductors (HTS) is reviewed in the present paper. After the fatal weak link problem of sintered REBCO superconductors has been overcome by melt processing, this field has been greatly advanced during last ten years. The critical current density $J_c$ at 77 K has been enhanced by introducing effective flux pinning sites into the $REBa_2Cu_3O_y$ (RE123) superconducting matrix. Large melt-textured REBCO bulk crystals have been fabricated with the TSMG(top-seeded melt growth) technique. Mechanical properties of REBCO bulks have been improved by using the Ag additive or epoxy resin. Real bulk applications such as current lead, fault current limiter, flywheel energy storage system, magnetic field source, magnetic separation system, and etc., surely come true near future.

• Nuclear Engineering and Technology
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• v.36 no.3
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• pp.219-228
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• 2004

[1] and [2] present an approach to diagnosing possible defects in the mechanical systems of a nuclear power plant. In this paper, by using a fault library as a database and training data, we develop a diagnostic algorithm 1) to decide whether an Air Operated Valve system is sound or not and 2) to identify the defect from which an Air-Operated Valve system suffers, if any. This algorithm is composed of three stages: a neural net stage, a non-neural net stage, and an integration stage. The neural net stage is a simple perceptron, a pattern-recognition module, using a neural net. The non-neural net stage is a simple pattern-matching algorithm, which translates the degree of matching into a corresponding number. The integration stage collects each output and makes a decision. We present a simulation result and confirm that the developed algorithm works accurately, if the input matches one in the database.

• 연구논문집
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• s.30
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• pp.79-92
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• 2000

Chopper and sensors failures resulting from electric shock and mechanical vibration generated by rail irregularities are the serious problem deteriorating the performance in the electromagnetic suspension systems. Thus, this paper proposes a reliable output feedback control scheme for the electromagnetic suspension systems in the present of chopper, gap sensor and acceleration sensor failures. The designed controller is an extended version of a novel design technique which has the design method of the output feedback controller using dynamic compensator. The benefits of this scheme are demonstrated through the simulation and experimental results for proposed controller against chopper, gap sensor and acceleration sensor failures of electromagnetic suspension system.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.56-61
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• 2010

Simulator is a development equipment which enables the ECU to operate in normal mode by simulating the interface signal between ECU and mechanical system electrically. Embedded simulator means simulation function is embedded in ECU firmware, hence the electrical signal interface is replaced by the substitution of information at system program level. This paper explains the development of embedded transmission simulator for the verification of TCU firmware function which covers shifting control and on-board diagnosis. The embedded simulation program is executed in TCU processor along with the TCU firmware and it provides TCU firmware with not only the speed information those are appropriate both in driving and shifting conditions, but also the fault detection signals. Experimental results show that the validity of embedded simulator and its usefulness to the TCU firmware development and verification.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.1
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• pp.46-55
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• 2008

In this paper, we designed the bay control unit that is based on the microprocessors and integrates with the new technology of electrical, electronic, and mechanical fields. Nowadays the customers have required much more integrated multi-protection relay, monitoring, control devices and power management for better and easier maintenance, performance, electrical system analysis and communication according to new trend of switchboard This bay controller supplies those requirements of customers with easy handling and operation. This bay controller provides a graphic display with rear-lit liquid crystal LCD and push buttons as kinds of HMI(Human Machine Interface). This bay controller provides the parameter setting program, control setting program, various editors and fault recording and analysis program on Windows/95/98/NT/2000/XP for HMI. In addition, this bay controller can be set manually and this manual setting function helps user to interface easily.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.73-75
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• 1998

In this paper, a transient analysis method of Switched Reluctance Motors(SRM) is presented. The Finite Element Method(FEM) is used to model the nonlinear magnetic field and is coupled to the power circuits and mechanical system. The time derivative term in the differential equation is formulated by the time difference method. The proposed method is applied to a 4 phase 16/12 SRM to study starting characteristics and an fault due to the failure of a transistor in the converter.

• Journal of Aerospace System Engineering
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• v.8 no.4
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• pp.7-17
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• 2014

Objective of this paper is to introduce a new technology known as prognostics and health management (PHM) which enables a real-time life prediction for safety critical systems under extreme loading conditions. In the PHM, Bayesian framework is employed to account for uncertainties and probabilities arising in the overall process including condition monitoring, fault severity estimation and failure predictions. Three applications - aircraft fuselage crack, gearbox spall and battery capacity degradation are taken to illustrate the approach, in which the life is predicted and validated by end-of-life results. The PHM technology may allow new maintenance strategy that achieves higher degree of safety while reducing the cost in effective manner.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.144-150
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• 2013

The devolution of central government's affairs to local governments for several occupational safety and health(OHS) administration affairs was tried by Lee Myungbak's government in 2010. It seems that the trial was eventually failed since only trivial 3 items among 25 trials were made for the devolution. It was found that there was a procedural fault since stake-holders and experts were excluded during preparing the plan. Therefore validity and problems were not properly reviewed. It was also found that the devolution of the OHS administration affairs from the central government to local governments has several disadvantages such as high possibility of deregulation. The devolution of the OHS affairs to local governments is contradictory to uniform principle of safety standards and principle of coincidence of empowerment and responsibility. Therefore it is concluded that the devolution of the OHS affairs to local governments is inappropriate.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.1-8
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• 2013

Remanufacturing of automobile parts is important for increasing the recycling resources. ECU(Electronic Control Unit) systems are becoming an increasingly important part of an automobile. But production company are reported in the ECU remanufacturing industry of domestic automobile parts due to a lack of remanufacturing technology and marketability. This paper introduces the ECU of remanufacturing, also grasps the structure and the analyzes failure cause that is external factors and fault in the characteristic design and steps in the Independent ECU remanufacturing process. The ECU manufacturing industry of the US was examined. The results in this paper could be used as the system information for further remanufacturing industry of domestic automobile parts.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.923-927
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• 2012

This paper studies a busbar design of high power HVDC converter. In order to design a electrical busbar, we need to consider electrical, mechanical and environmental condition. In this papre, we focus on the electrical design in terms of temperaure and currnet. Busbar conductor can be damaged to burn due to the temperature and fault current of busbar. In this paper, Busbar design of Jindo-Jeju HVDC #2 System that will start operate in 2012 is considered.