• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.279-282
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• 1996

The authors have already proposed a method for grouping of inputs of a logical circuit under test (LCUT) by use of M-sequence correlation. We call this method as input grouping (IG) method. In this paper, the authors propose a new method to estimate the faulty part in the circuit by use of IG when some information on the candidate of faulty part can be obtained beforehand. The relationship between IG and fault probabilities of a LCUT, and undetected fault ratios are investigated for various cases. Especially the investigation was made in case where the IG was calculated by use of n correlation functions (I $G_{inp}$). From the theoretical study and simulation results it is shown that the estimation error ratio of fault probabilities and undetected fault ratio of LCUT are sufficiently small even when only a part of correlation functions are used. It is shown that the number of correlation functions which are to be memorized to calculate IG can be considerably reducible from 2$^{n}$ - 1 to n by use of I $G_{inp}$. So this method would be very useful for a fault diagnosis of actual logic circuit.uit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.26-30
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• 2008

The simulation and experiment for the fault current limiting characteristics of the superconducting fault current limiter (SFCL) using the magnetic coupling of series connected two coils were performed. The magnetic fluxes generated from two coils were canceled out during a normal time. However, the resistance generation of high-Tc superconducting (HTSC) element after a fault occurrence allows the magnetic fluxes of two coils and contributes to the fault current limiting operation. Through the computer simulation and the current limiting experiment for this SFCL, the operational current and the limiting impedance of the SFCL could be confirmed to be improved by adjusting the inductance ratio of two coils.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.414-417
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• 2014

At present, the demand for electric power increases, the electric power system is complicated. The size of the line-to-ground fault and the line-to-line fault occurred with complication of electric power system continue to increase, therefore several issues are raised. To address these issues effectively, the superconducting fault current limiter (SFCL) has been proposed, this study is ongoing. In this paper, we applied the SFCL in three-phase transformer and comparative analysis of the electric power burden to the SFCL. The superconductor is combined to the third winding of transformers in connection structure. In case of a third line-to-line fault, we did comparative analysis of the electric power burden to the SFCL based on the turn ratio of transformer third winding. In this case, we could confirm as the third turn ratio increased, electric power impressed to the superconducting element increased.

• Earthquakes and Structures
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• v.12 no.1
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• pp.135-144
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• 2017

Near-fault ground motions are characterized by high values of the ratio between the peak of vertical and horizontal ground accelerations, which can significantly affect the nonlinear response of a base-isolated structure. To check the effectiveness of different base-isolation systems for retrofitting a r.c. framed structure located in a near-fault area, a numerical investigation is carried out analyzing the nonlinear dynamic response of the fixed-base and isolated structures. For this purpose, a six-storey r.c. framed building is supposed to be retrofitted by insertion of an isolation system at the base for attaining performance levels imposed by current Italian code in a high-risk seismic zone. In particular, elastomeric (e.g., high-damping-laminated-rubber bearings, HDLRBs) and friction (e.g., steel-PTFE sliding bearings, SBs, or friction pendulum bearings, FPBs) isolators are considered, with reference to three cases of base isolation: HDLRBs acting alone (i.e., EBI structures); in-parallel combination of HDLRBs and SBs (i.e., EFBI structures); FPBs acting alone (i.e., FPBI structures). Different values of the stiffness ratio, defined as the ratio between the vertical and horizontal stiffnesses of the HDLRBs, sliding ratio, defined as the global sliding force divided by the maximum sliding force of the SBs, and in-plan distribution of friction coefficient for the FPs are investigated. The EBI, EFBI and FPBI base-isolation systems are designed assuming the same values of the fundamental vibration period and equivalent viscous damping ratio. The nonlinear dynamic analysis is carried out with reference to near-fault earthquakes, selected and scaled on the design hypotheses adopted for the test structures.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.349-352
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• 1999

In this paper, we present simplified fault set which is made by analyzing fault relation to design specification in CMOS operational amplifier. The hard fault is easily modeled because an effect of hard fault is out of all design specification. However, the soft fault is not easily modeled because an effect of soft fault on design specification is varied according to position and depth of fault. We simulated hard and soft fault by HSPICE, varying threshold voltage and W/L ratio from 90% increase to 90% decrease. The decrease of test time and the production of high reliability mixed-mode IC are possible by the proposed fault set.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.403-411
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• 2016

A three-dimensional finite element analysis was conducted to analyze the predictable distances of a fault zone by using longitudinal displacement on tunnel face, trend line, L/C ratio, and C/C₀ ratio at tunnel crown. The analysis used 28 numerical models with various fault attitudes. As a result, those faults that have drives with dip could be predicted earliest in L/C and C/C₀ ratio analysis. And those faults that have drives against dip could be predicted earliest in L/C ratio and longitudinal displacement analysis. In addition, the fault zone ahead of tunnel was predicted in most models by using longitudinal displacement, trend line, L/C ratio, and C/C₀ ratio. However, the longitudinal displacement among these methods may be most usefully predict a fault zone since it is displacements can be measured immediately after tunnel excavation.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2058-2064
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• 2014

In transformer fault diagnosis, dissolved gas analysis (DGA) is been widely employed for a long period and numerous methods have been innovated to interpret its results. Still in some cases it fails to identify the corresponding faults. Due to the limitation of training data and non-linearity, the estimation of key-gas ratio in the transformer oil becomes more complicated. This paper presents Intuitionistic Fuzzy expert System (IFS) to diagnose several faults in a transformer. This revised approach is well suitable to diagnosis the transformer faults and the corresponding action to be taken. The proposed method is applied to an independent data of different power transformers and various case studies of historic trends of transformer units. It has been proved to be a very advantageous tool for transformer diagnosis and upkeep planning. This method has been successfully used to identify the type of fault developing within a transformer even if there is conflict in the results of AI technique applied to DGA data.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.160-169
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• 2007

In this study, Analyzed stress history, state of stress, ratio of stress/strength to use FEM. Fault Zone depth is 3m, 6m, 9m, 12m and 15m for study, and also Distance is 3m, 6m, 9m, 12m and 15m at center of tunnel with thickness 3m fault zone. It is not appeared that Arching in stress state and stress history by FEM. On the other hand, excessive shear stress and high compressive stress happened. Therefore, Tunnel design is desirable that do it so that state of stress that is the imbalance may be uplemented. it is important that examine each state of stress and stress history in detail tunnel design.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.500-502
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• 2002

Receltly, Underground transmission system is getting increased. Therefore the design of grounding system becomes very important to discharge overcurrent of lightning and fault through earth and reduce sheath induced voltage and sheath circulation current. This paper describes fault current distribution ratio for grounding line with grounding types of normal joint box and sheath grounding resistor at line-to-ground fault of cable.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.463-468
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• 1987

In this paper, a high impedance fault detection on 22.9kV multigrounded distribution system that has been very difficult by any existing conventional protective relaying systems is studied. Because the fault current is very low, it cannot be distinguished from neutral current caused by load unvalanced on multigrounded distribution system. We developed the new and best algorithms of high impedance ground fault detection. This algorithms are 'the even order power method, even order ratio method', 'and even order ratio varience method'. Using this algorithms, a detection device for high impedance faults is constructed and tested in the laboratory. And continually, it is installed and has been tested in KEPCO substations.