• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.1
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• pp.25-29
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• 2006

In this paper, the eddy current signals come from a pair oi transmit-receive (T/R) pancake coil on ECT array Probe are analyzed with the variations of the lift-of and of the distance between transmit and receive coils. To obtain the electromagnetic characteristics of the probes, the governing equation describing the eddy current problems is derived from Maxwell's equation and is solved using three-dimensional finite element method. Eddy current signals from T/R coils on ECT array probe have quite different characteristics compared with ones from impedance coil on rotating pancake coil probe. The results in this paper ran be helpful when the field eddy current signals from ECT array probe are evaluated.

• Journal of Power System Engineering
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• v.14 no.2
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• pp.60-64
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• 2010

This paper introduces reliability improvement and time saving in eddy current inspection by signal characteristic optimization of multi-coil eddy current array probe. In the past, Multi-coil array probe and single probe were used for the gas turbine rotor surface inspection & defect evaluation. The multi-coil array probe was used for the broad area inspection. But the signal deviations among multi-coil array probe are maximum 28% in commercial probe. This differences were considered to impedance differences among coils, so it is very difficult to evaluate exact defect size. The signal deviations among multi-coil array probe are maximum 28% in commercial probe. So, single coil inspection was used for exact defect sizing. The purpose of this study is to improve signal deviations of multi-coil array probe. The introduced new technology can improves this deviation by adjusting input voltage in each coil. At first, apply same voltage in each coil and collect signal amplitude of each coil. And calculate new input voltage based on signal amplitude of each coil. If the signal amplitude deviation is within 5% among multi-coil array probe, the signal amplitude of multi-coil array probe is reliable. The proposed technology gives 2% signal deviation among multi-coil array probe. The proposed new technology gives reliability improvement and inspection time saving in eddy current inspection.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.449-450
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• 2008

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.1
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• pp.25-31
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• 2009

Steam Generator(SG) tube is an important component of Nuclear Power Plant(NPP), which comprises of the pressure boundary of primary system. The integrity of SG tube has been confirmed by the eddy current test every outage. In Korea, Bobbin probe and MRPC probe have been generally used for the eddy current test. Meanwhile the usage of Array probe has gradually increased in U.S., Japan and other countries. In this study, we investigated the defect detection capability of the Array probe through its preliminary application to SG tube inspection. The Array probe has the equivalent capability in the defect detection and sizing as the conventional methods. Thus it is desirable that the Array probe is generally applied to SG tube inspection in the domestic NPPs.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.241-245
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• 2006

In the examination of Steam Generator (SG) tube in Nuclear Power Plant (NPP) Eddy Current Testing (ECT) probes play an Important role in detecting the defects. Bobbin probe and Rotating Pancake Coil (RPC) probe is usually used for the inspection of SG tube. Bobbin probe is good at high speed inspection, but ability of detection of circumferential defect is very weak. On the contrary RPC probe, which moves for inspection in the direction of axial and circumferential simultaneously, has very slow inspection speed, but it was excellent detection capability fur small cracks, which is hardly detected by bobbin probe. Many examinations of SG tube examination of NPP are achieved during short period. Therefore, solution about this must develop probe of new form for examination performance and examination time shortening of other probe. In this paper, analyzed technological present condition of Bob-bin probe and RPC probe been using in Nondestructive Testing (NDT) for SG tube defect detection and Appeared about background theory and view of developed probe newly.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.289-292
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• 2009

This paper describes the analysis for ground impedance measurement influenced by distance of current probe and frequency using the fall-of-potential method and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position of auxiliary probes. In order to analyze the effects of ground impedance due to the distance of the current probe and frequency, ground impedances were measured in case that the distance of current probe was located from 5[m] to 20[m] and the measuring frequency was ranged in 55[Hz], 128[Hz], 342[Hz], and 513[Hz]. The results could be help to determine the position of current probe when the ground impedance was measured at grounding system.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.46-50
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• 2015

This paper describes the measurement and analysis of ground impedance according to arrangement of auxiliary probe around ground grid using the fall-of-potential method and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method involves passing a current between a ground electrode and a current probe, and then measuring the voltage between a ground electrode and a potential probe. To minimize interelectrode influences due to mutual resistances, the current probe is a generally placed at a substantial distance from the ground electrode under test. In order to analyze the effects of ground impedance due to the arrangement of auxiliary probe and frequency, ground impedances were measured in case that the arrangements of auxiliary probe were straight line, perpendicular line, and horizontal line. The distance of current probe was located from 10[m] to 200[m] and the measuring frequency was ranged from 55[Hz] to 513[Hz]. As a consequence, the ground impedance increases with increasing the distance from the ground electrode to the point to be tested, but the ground impedance decreases with increasing the frequency.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.52-57
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• 2008

Most of the electrons emitted from the filament, are captured by the anode. The portion of the electron current that leaves the gun through the hole in the anode is called the beam current. Electron beam probe is called the focused beam on the specimen. Because of the lenes and aperture, the probe current becomes smaller than the beam current. It generate various signals(backscattered electron, secondary electron) in an interaction with the specimen atoms. Backscattered electron provide an useful signal for composition and local specimen surface inclination. Secondary electron is used far the formation of surface imagination. The steady electron beam probe is very important for the imagination formation and the brightness. In this paper, we show the results of developed elements that create electron beam probe and the measured beam probe in various acceleration voltages by Faraday cup. These data are used to analysis and improve the performance of the system in the development.

• Progress in Superconductivity
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• v.13 no.1
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• pp.28-33
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• 2011

Distribution of the local critical temperature and current density in YBCO coated conductors were analyzed using Low-temperature Scanning Laser and Hall Probe Microscopy (LTSLHPM). We prepared YBCO coated conductors of various bridge types to study the spatial distribution of the critical temperature and the current density in single and multi bridges. LTSLHPM system was modified for detailed linescan or two-dimensional scan both scanning laser and scanning Hall probe method simultaneously. We analyzed the local critical temperature of single and multi bridges from series of several linescans of scanning laser microscopy. We also investigated local current density and hysteresis curve of single bridge from experimental results of scanning Hall probe microscopy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.12-12
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• 2010

The hall probe measurement system was used to measure the critical current distribution of superconducting coated conductor. The system consists of reel to reel moving apparatus, 7 array hall probe, a rotary encoder and permanent magnet. The magnetic field profile across the width of superconducting coated conductor using Bean's critical state model was calculated. The effect of various parameters of the formulas on the magnetic field distribution and the effect of shape and size of artificial defects, which were formed on the surface of SmBa2Cu3O7-d(SmBCO) coated conductor using laser marking system, on the hall probe magnetic field signal of the hall probe measurement system was investigated.