• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.5
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• pp.321-331
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• 2015

A study on the application of cooling defect detection was performed on the basis of a preceding study on the heated defect detection in nuclear piping loop system, using lock-in infrared thermography. A loop system with piping defects was made by varying the wall-thinning length, the circumference orientation angle, and the wall-thinning depth. The test was performed using an IR camera and a cooling device. Distance between the cooling device and the target loop system was fixed at 2 m. For analyzing experimental results, the temperature distribution data for cooling, and phase data were obtained. Through the analysis of this data, the defect length was measured. The reliability of the measurements for cooling defect conditions was shown to be higher in the lock-in infrared thermography data than the infrared thermography data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1175-1182
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• 2013

The lock-in mode infrared thermography (IRT) technique has been developed to improve the detection capability of defects in materials with high thermal conductivity, and it has been shown to provide better detection capability than conventional active IRT. Therefore, to investigate the application of this technique to nuclear piping components, lock-in mode IRT tests were conducted on pipe specimens containing simulated wall-thinning defects. Phase images of the wall-thinning defects were obtained from the tests, and they were compared with thermal images obtained from conventional active IRT tests. It showed that the ability to size the detected wall-thinning defects in piping components was improved by using lock-in mode IRT. The improvement was especially apparent when detecting short and narrow defects and defects with slanted edges. However, the detection capability for shallow wall-thinning defects did not improve much when using lock-in mode IRT.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.121-125
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• 2010

The infrared thermography technology rather than traditional nondestructive methods has benefits with non-contact and non-destructive testings in measuring for the fault diagnosis of the rotating machine. In this work, condition monitoring measurements using this advantage of thermography were proposed. From this study, the novel approach for the damage detection of a rotating machine was conducted based on the spectrum analysis. As results, by adopting the ball bearing used in the rotating machine applied extensively, an spectrum analysis with thermal imaging experiment was performed. Also, as analysing the temperature characteristics obtained from the infrared thermography for in-situ rotating ball bearing under the lubrication condition, it was concluded that infrared thermography for condition monitoring in the rotating machine at real time could be utilized in many industrial fields.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.5
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• pp.525-531
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• 2004

In this paper, the concept of infrared thermography(IRT), the principle of measurement of IRT and how to set up the IR camera for the nondestructive testing are described in detail. Also, its utilization and non-destructive testing(NDT) diagnosis are reviewed. By performing the periodic non-touched WDT through the estimation of thermal patterns related with the temperature for the surface targeted, IRT can be applied to the early prevention of the device failure. For the diagnosis utilization, thermal imaging patterns obtained from IRT for heated blocks with internal defects were estimated through the lion-destructive method and discussed the way of IRT estimation from the analysis of characteristics between material defects and thermal imaging patterns.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.110-115
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• 2010

This study was conducted to estimate the feasibility using thermal image measurement that is applicable to internal leak diagnosis for the power plant valve. Abnormal heating of valve surface associated with high temperature steam f10w toward valve outlet side in the condition of low temperature is a primary indicator of leakage problems in high temperature and pressure valves. Thermal imaging enables to see the invisible thermal radiation that may portend impending damage before their condition becomes critical. When steam flow in valve outlet side in the condition of low temperature is converted into heat transmitted through the valve body due to the internal leakage in valve. The existence of abnormally increasable leakage rate in the valve will result in abnormally high levels of heat to be generated that can be quickly identified with a thermal image avoiding energy loss or damage of valve component. From the experimental results, it was suggested that the thermal image measurement could be an effective way to precisely diagnose and evaluate internal leak situation of valve.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.104-109
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• 2010

Lap joint friction stir welding(LFSW) is an relatively new solid state joining process. A6061-T6 aluminium alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength to weight ratio and good corrosion resistance. Test methods used in this paper, lock-in thermography, a phase difference between the defect area and the healthy area indicates the qualitative location and size of the defect. In this paper, the defects detected from the thermal image of mechanical properties for weld were evaluated and compared by the lock-in infrared thermography technique.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.34-39
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• 2013

In the advanced research deducted infrared thermography (IRT) test using 4 inch pipe with artificial wall-thinning defect to measure on the wall-thinned nuclear pipe components. This study conducted for defect detection condition of nuclear small-bore pipe research using deducted condition in the advanced research. Defect process is processed by change for defect length, circumferential direction angle, wall-thinning depth. In the used equipment IR camera and two halogen lamps, whose full power capacitany is 1 kW, halogen lamps and Target pipe experiment performed to the distance of the changed 1 m, 1.5 m, 2 m. To analysis of the experimental results ensure for the temperature distribution data, by this data measure for defect length. artificial defect of 4 inch pipe is high reliability in the 2 m, but small-bore pipe is in the 1.5 m from the defect clearly was detected.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.91-97
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• 2010

This paper proposes method to evaluate the location and size of the internal defects of metallic specimens by the shearing phase lock-in infrared thermography. Until now, infrared thermography test for metal specimen of STS304 and Cu-Zn were conducted to find the best test conditions. However, In unspecified situation of the form and existence of defects, there was a disadvantage to takes a long time for finding the optimal experimental conditions. The defect detection and evaluation was performed at 60 MHz signal using lock-in and shearing-phase method under limited heating conditions. By shearing-phase distribution method, Defects for the maximum, minimum and zero points were quantitatively detected at the size and location of the subsurface. As results, application of the proposed technique was verified for STS304 and Cu7-Zn3 with artificial defect and factors affected defect evaluation were searched and analyzed.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.139-143
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• 2011

The problem of delamination of composite tubes by impact has been acknowledged in aerospace and automobile industry. Non-destructive testing(NDT) methods in composite material structure are important to evaluate reliability of composite structure. There are many kinds of NDT methods which can detect the inside defect of the composite material such as Infrared Thermography(IRT). Infrared thermal imaging of object is different from that of a defect, in heated composite tubes with an internal defect, and then location and size of a defect can be measured by the analysis of thermal imaging pattern. In this study, Lock-in Infrared thermography detect internal defects of Impacted composite tubes by the inspection of infrared lay radiated from the surface of composite tubes.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.40-45
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• 2013

The purpose of this study was to detect the pin hole defect of dental composite restoration using lock-in thermography method. Amplitude and phase images of the composite resin specimens were analyzed according to the lock-in frequency and the diameter of defect area. Through the amplitude image analysis, at lock-in frequency of 0.05 Hz, defect diameters 2-5 mm exhibited the highest amplitude contrast value between defective area and sound area. The lock-in frequency range of 0.3-0.5 Hz provided good phase angle contrast for the defect area. At lock-in frequency range of 0.5 Hz, defect diameter of 5 mm exhibited the highest phase contrast value. It is concluded that the infrared lock-in thermography method verified the effectiveness for detecting the pin hole defect of dental composite restoration.