• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.176-186
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• 1996

As the density of VLSI increases, the conventional logic testing is not sufficient to completely detect the new faults generated in design and fabrication processing. Recently, IDDQ testing becomes very attractive since it can overcome the limitations of logic testing. In this paper, G-ATPG (gyeongsang automatic test pattern genrator) is designed which is able to be adapted to IDDQ testing for combinational CMOS VLSI. In G-ATPG, stuck-at, transistor stuck-on, GOS (gate oxide short)or bridging faults which can occur within priitive gate or XOR is modelled to primitive fault patterns and the concept of a fault-sensitizing gate is used to simulate only gates that need to sensitize the faulty gate because IDDQ test does not require the process of fault propagation. Primitive fault patterns are graded to reduce CPU time for the gates in a circuit whenever a test pattern is generated. the simulation results in bench mark circuits show that CPU time and fault coverage are enhanced more than the conventional ATPG using IDDQ test.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.9
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• pp.1356-1365
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• 2008

As Korean retailers are expanding their return policies, customer abuse and fraud behaviors are increasing. This study attempts to understand customers' unethical return behaviors in the Korean retailing. As an exploratory approach, the study identifies behavioral patterns of unethical returns from retail employees' perspectives. A total of 168 cases collected from 112 individual interviews with retail employees are qualitatively analyzed. Unethical return behaviors are categorized into five groups: lenting/deshopping, product defects with customer faults, unreasonable compensation demands, selfish behaviors, and problem behaviors in the service encounter. The study indicates that a variety of unethical return behaviors are observed despite a short history of return policy in Korea, and renting/deshopping and product defects with customer faults are the most prevalent return abuse behaviors.

• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.666-670
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• 2011

In this paper, a method for detecting broken rotor bar and stator winding fault in a low voltage squirrel-case induction motor using an air-gap flux variation analysis is proposed to develop a simple and low cost diagnosis technique. To measure the leakage flux in radial direction, a radial flux sensor is designed as a search coil and installed between stator slots. The proposed method is able to identify two kinds of motor faults by calculating load condition of motors and monitoring abnormal signals those are related with motor faults. Experimental results obtained on 7.5kW three-phase squirrel-cage induction motors are discussed to verify the performance of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.4
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• pp.198-203
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• 2013

There are conditions that can be unbalanced three phase currents in a large generator by untransposed lines, unbalanced loads, unsymmetrical faults, and open phases. The unbalanced conditions can producing negative sequence components of current that induce two times frequence current in the surface of the rotor, the retaining rings, the slot wedges in the field windings. These rotor currents make the rotor rapidly overheat, so the rotor can cause substantial damage in a very short time. This paper presents the digital negative sequence relay algorithm for unbalanced protection in a generator. The proposed algorithm was tested by using collected current signals on PSCAD/EMTDC considering a hydro turbine based generator control system. It can be seen that the proposed relaying by negative sequence current is useful for detection of unbalanced state of large generator.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.5-6
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• 2014

According to 2013 fire statistical yearbook in the National Emergency Management Agency, the main cause of an electrical fire are classified to short circuit fault, overload fault, electric leakage, partial disconnection, and joint/contact badness. The occurrence factor of fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Devices(RCDs) of high sensitivity type used at single phase (220V) cut off earth leakage and overload but the RCDs can not cut off electric arc or spark to be a main cause of electrical fire. To be improved on such problem, this thesis is proposed to a auxiliary control device for RCD cut off electric arc or spark.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.317-324
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• 2019

A high energy arcing fault event occurred in the medium-voltage (13.8 kV and 4.16 kV) metalclad switchgears in a nuclear power plant not only affecting switchgear but also connected equipment due to the arc energy. The high energy arcing fault also causes a fire that influences the safety function of the unit. Therefore, from the safety point of view, it is necessary to evaluate the influences of high energy arcing fault events on the safety functions of nuclear power plants. The purpose of this paper is to elaborate the characteristics of high energy arcing faults and propose a high energy arcing fault mitigation scheme for medium voltage networks in nuclear power plants.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.56-59
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• 2003

As electric power systems grow to supply the increasing electric power demand short-circuit current tends to increase and impose a severe burden on circuit breakers and power system apparatuses. Thus, all electric equipment in a power system has to he designed to withstand the mechanical and thermal stresses of potential short-circuit currents. Among current limiting devices, Fault Current Limiter (FCL) is expected to reduce the short-circuit current. Especially, Superconducting Fault Current Limiters (SFCL) offer ideal performance: in normal operation the SFCL is in its superconducting state and has negligible impedance, in the event of a fault, the transition into the normal conducting state passively limits the current. The SFCL using high-temperature superconductors offers a positive resolution to controlling fault-current levels on utility distribution and transmission networks. This study contributes to the EMTDC based modeling and simulation method of DC Reactor type SFCL. Single and three phase faults in the utility system with DC reactor type SFCLs have been simulated using EMTDC in order to coordinate with other equipments, and the results are discussed in detail.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.11
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• pp.572-576
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• 2006

As the increasing of capacity and technology of power facilities, rotating machines such as turbine generators and water turbines are getting higher at capacity but smaller in size. Thus the monitoring and diagnosis of generators for fault detection and protection has attracted intensive interest. Most of electrical faults of rotating machines appear in their windings. In case of an after-fault in high capacity rotating machines, the recovering cost is usually very expensive and additional time is necessary for returning in a normal situation. In this paper, the magnetic flux patterns in air-gap of a generator under various fault states as well as a normal state are simulated by a conventional FEM tool. These results are successfully applied to detection and diagnosis of the short-circuit condition in rotor windings of a high capacity generator.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.23-30
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• 2013

This paper proposes a parametric model for inter-turn fault detection in a fault-tolerant permanent-magnet (FTPM) machine, which can predict the effect of the short-circuit fault to various physical quantity of the machine. For different faulty operations, a new effective stator inter-turn fault detection method is proposed. Finally, simulations of vector-controlled FTPM machine drives are given to verify the feasibility of the proposed method, showing that even single-coil short-circuit fault could be exactly detected.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.7
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• pp.70-79
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• 1996

To increase the functionality of the memories, previous studies have deifned faults models and proposed functional testing algorithms with low complexity. Although conventional testing depended strongly on functional (voltage) testing method, it couldn't detect short and open defects caused by gate oxide short and spot defect which can afect memory reliability. Therefore, IDDQ (quiescent power supply current) testing is required to detect defects and thus can obtain high reliability. In this paper, we consider resistive shorts on gate-source, gate-drain, and drain-source as well as opens in mOS FET and observe behavior of the memory by analyzing voltage at storge nodes of the memory and IDDQ resulting from PSPICE simulation. Finally, using this behavioral analysis, we propose a linear testing algorithm of complexity O(N) which can be applicable to both functional testing and IDDQ testing simultaneously to obtain high functionality and reliability.