• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.811-814
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• 1998

REcent research about current testing($\textrm{I}_{DDQ}$ testing) has been emphasizing that $\textrm{I}_{DDQ}$ testing in addition to the logical voltage testing is necessary to increase the fault coverage. The $\textrm{I}_{DDQ}$. testing can detect physical faults other than the classical stuck-at type fault, which affect reliability. One of the most critical issues in the $\textrm{I}_{DDQ}$ testing is to insert a built-in current sensor (BICS) that can detect abnormal static currents from the power supply or to the ground. This paper presents a new BICS for internal current testing for large CMOS logic circuits. The proposed BICS uses a single phase clock to minimize the hardware overhead. It detects faulty current flowing and converts it into a corresponding logic voltage level to make converts it into a corresponding logic voltage level to make it possible to use the conventional voltage testing techniqeus. By using current mirroring technique, the proposed BICS can work at very high speed. Because the proposed BICS almost does not affects normal operation of CUT(circuit under test), it can be used to a very large circuit without circuit partitioning. By altenating the operational modes, a circuit can be $\textrm{I}_{DDQ}$-tested as a kind of self-testing fashion by using the proposed BICS.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.652-661
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• 2006

The cut slopes in Jinju area constitute the Cretaceous Sedimentary rock which is one of the most poor ground conditions. The geological rocks of the cut slopes are correlated with Jinju Formation. Most of the rocks consist of Black Shale layer, but the lower parts consist of Alkorsic White Sandstone. So, It is characteristic of the differential weathering due to the difference of rock species. Moreover, vertical joints which concentrate on the released rock and weak rock fragments are accompanied with minor faults. We make out face mapping about each slopes through the detailed field-study and deduce RMR and SMR from the field data. The strength properties of rocks were obtained from references, indoor tests, and Back Analysis method. And, choosing properties were used in the stability analysis as stereographic projection and limit equilibrium analysis and we establish the countermeasures for the cut slopes.

• KIEE International Transactions on Power Engineering
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• v.3A no.4
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• pp.181-190
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• 2003

This paper presents the design of a fuzzy power system stabilizer (FPSS) using an adaptive evolutionary algorithm (AEA). AEA consists of genetic algorithm (GA) for a global search capability and evolution strategy (ES) for a local search in an adaptive manner when the present generation evolves into the next generation. AEA is used to optimize the membership functions and scaling factors of the FPSS. To evaluate the usefulness of the FPSS, we applied it to a single-machine infinite bus system (SIBS) and a power system simulator at the Korea Electrotechnology Research Institute. The FPSS displays better control performance than the conventional power system stabilizer (CPSS) for a three-phase fault in heavy load, which is used when tuning FPSS. To show the robustness of the FPSS, it is applied with disturbances such as change of mechanical torque and three-phase fault in nominal and heavy load, etc. The FPSS also demonstrates better robustness than the CPSS. Experimental results indicate that the FPSS has good system damping under various disturbances such as one-line to ground faults, line parameter changes, transformer tap changes, etc.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.726-736
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• 2012

This paper deals with Spin/Stall Recovery Parachute System from design to ground taxiing stage which would be deployed on the high speed taxi of turbo-prop airplane. In detail design phase, design parameters- riser length, parachute type, size, porosity, parachute canopy filling time, and deployment method- were considered based on the analytical disciplines such as aerodynamics, structures, and stability & control. Before the installation of Spin/Stall Recovery System of turbo-prop airplane, all control functions of this system were validated by the SBTB(System Breakout Test Box) in the laboratory. SBTB was used to confirm if it can detect faults, and simulate the firing of pyrotechnic devices that control the deployment and jettison of it. Once confirmed normal operation, deployment of parachute on the high speed taxiing were performed.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.43.1-43.1
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• 2011

The detail simulation modeling of fully-fed induction generator is investigated through PC based MATLAB/Simulink environment. Generator's stator currents are controlled by indirect vector control method. In this method, generator side converter controls the maximum excitation (air gap flux) by stator d-axis current and controls generator torque by stator q-axis current. Induction generator speed is controlled by tip speed ratio (TSR) upon the wind speed variations in order to generate the maximum output power. The generator torque model is specified as a 3-blade wind turbine with rating, then, the model is simulated under normal operating condition and three different fault conditions. The matlab model designed for fully-fed induction generator based wind farm provides good performance under normal and grid fault conditions. It provides good results for different pwm techniques and fault conditions except the single-phase line to ground fault, which should be verified with real time data from wind farms.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.83-93
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• 1997

This paper deals with measurements and evaluation of the time-changing electric and magnetic fields at a high-voltage laboratory. The electromagnetic disturbances originate mainly from ground faults and on/off operations of electric power equipments. The electronic circuits and control devices are very sensitive to electromagnetic interferences. It is necessory to evaluate the levels of interferences for a given electromagnetic environment. The electric field was observed by the electric field sensor having the bandwidth of the range from 40 Hz to 200 MHz, and the time-changing magnetic field was measured by the loop sensor of which the output is directly proportional to the incident signal. Also, the frequency components of the time-changing electric and magnetic fields induced by an oscillatory transient current and a chopped impulse voltage were analyzed by terms of the fast Fourier transformation, and those give the information about the levels of the electromagnetic interferences and the design of the electromagnetic shielding enclosures.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1054-1056
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• 2017

The Preparation for a flight test of the launch vehicle to verify the performance of the liquid rocket engine(LRE) is proceeding. Flight test of liquid rocket engine costs an enormous amount of money, has a restriction on measurement channels, so it requires the optimal measurement plan to check the prelaunch operation and determine the cause of abnormal situation. This paper surveys the foreign sources for LRE flight test. In recent years, as the tendency to eliminate all faults of LRE at the ground test the number of flight test is decreasing and in contrast, the number of measurements and measurement accuracy is increasing. This paper may be used as a reference for the preparation of an LRE flight test.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.883-886
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• 1996

Instead of point-to-point hard wiring between substation yard equipments and SCADA RTU(Remote Terminal Unit), fibre optic cable will be used in the portion between Local Units and Central Unit in the future KEPCO 765kV substation. The connections between substation yard equipments and nearby Local Unit remain the same hard wiring. The new fibre optic system will provide security especially during ground faults and is immune to electrical noise. A prototype system will be manufactured and installed in the existing 154kV Yeosan Substation by the end of July this year and operated for one year. By incorporating the operation experiences acquired in the system, an improved system will be commercially applied to 765kV Shin-An-Seong Substation where 345kV GIS will be installed initially and act as the switching station in the year 1998. The system is composed of one Central Unit and several Local Units. The Central Unit is composed of two workstation level computers, one is in operation and the other backup, and a Communication Control Unit. The Local Unit uses the existing SCADA RTU technology and takes the form of a distributed one. Between the Communication Control Unit and Local Units, the fibre optic system with star-coupler is used.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.10
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• pp.1354-1363
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• 2014

In this paper, an improved method of fault indicator generation algorithm in FRTUs is proposed for the present Distribution Automation System. In order to find fault area, correct FI information should be generated. But when a single line-to-ground fault occurs, FI information is generated in downside of the fault in some circumstance because existing FI algorithm considers only magnitude. It is found that the upside fault current direction if different from the downside fault current direction. Therefore, in order to prevent to generate the wrong fault indication information for FRTU at the downside of the fault, an improved fault indication generation method is developed. Not only the basic conditions are taken into account, but also the directions from the angle difference between zero and positive sequence currents are considered to generated the fault indication information. In case study, the proposed method has been testified and shown the reasonability in generating correct the fault indication information, for many kinds of faults according to conditions.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.41-45
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• 2011

The fire event occurred in fire proof zone often causes serious electrical problems such as shorts, ground faults, or open circuits in nuclear power plants. These would be directed to the loss of safe shutdown capabilities performed by safety related systems and equipments The fire event can treat the basic design principle that safety systems should keep their functions with redundancy and independency. In case of a cable fire, operators can not perform their mission properly and can misjudge the situation because of spurious operation, wrong indication or instrument. These would deteriorate the plant capabilities of safety shutdown and make disastrous conditions. In this paper, the cables of the representative nuclear power plant in korea is selected and the cable functional failure temperature by exposed fire using Cable Response to Live Fire(CAROLFIRE) is studied. It is expected that the results are very useful to know the cable failure temperature by exposed fire. We confirmed the safety and integrity of the cable by exposed fire and those results will use the based data of cable exposed fire characteristics.