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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Nondestructive Testing
Journal Basic Information
Journal DOI :
The Korean Society for Nondestructive Testing
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Volume & Issues
Volume 27, Issue 6 - Dec 2007
Volume 27, Issue 5 - Oct 2007
Volume 27, Issue 4 - Aug 2007
Volume 27, Issue 3 - Jun 2007
Volume 27, Issue 2 - Apr 2007
Volume 27, Issue 1 - Feb 2007
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NDT of a Nickel Coated Inconel Specimen Using by the Complex Induced Current - Magnetic Flux Leakage Method and Linearly Integrated Hall Sensor Array
Jun, Jong-Woo ; Lee, Jin-Yi ; Park, Duk-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 375~382
Nondestructive testing (NDT) by using the electromagnetic methods are useful for detecting cracks on the surface and subsurface of the metal. However, when the material contains both ferromagnetic and paramagnetic materials, it is difficult for NDT to detect and analyze cracks using this method. In addition the existence of a partial ferromagnetic material can be incorrectly characterized as a crack in the several cases. On the other hand a large crack has sometimes been misunderstood as a partially magnetized region. Inconel 600 is an important material in atomic energy plant. A nickel film is coated when a crack a appears on an Inconel substrate. Cracks are difficult to detect on the combined material of an Inconel substrate with a nickel film, which are paramagnetic and ferromagnetic material respectively. In this paper, a scan type magnetic camera, which uses a complex induced current-magnetic flux leakage (CIC-MFL) method as a magnetic source and a linearly integrated Hall sensor array (LIHaS) on a wafer as the magnetic sensors, was examined for its ability to detect cracks on the combined material. The evaluation probability of a crack is discussed. In addition the detection probability of the minimum depth was reported.
Prediction of Defect Size of Steam Generator Tube in Nuclear Power Plant Using Neural Network
Han, Ki-Won ; Jo, Nam-Hoon ; Lee, Hyang-Beom ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 383~392
In this paper, we study the prediction of depth and width of a defect in steam generator tube in nuclear power plant using neural network. To this end, we first generate eddy current testing (ECT) signals for 4 defect patterns of SG tube: I-In type, I-Out type, V-In type, and V-Out type. In particular, we generate 400 ECT signals for various widths and depths for each defect type by the numerical analysis program based on finite element modeling. From those generated ECT signals, we extract new feature vectors for the prediction of defect size, which include the angle between the two points where the maximum impedance and half the maximum impedance are achieved. Using the extracted feature vector, multi-layer perceptron with one hidden layer is used to predict the size of defects. Through the computer simulation study, it is shown that the proposed method achieves decent prediction performance in terms of maximum error and mean absolute percentage error (MAPE).
Development and Calibration of a Plate Type Eddy Current Standard
Kim, Young-Joo ; Kim, Young-Gil ; Ahn, Bong-Young ; Yoon, Dong-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 393~397
Eddy current standard including an artificial slot for the calibration of absolute type surface probe was fabricated. Developed eddy current standard has the electric conductivity and dimensions, and contains artificial slot as established in ASTM E 1629. The width and depth of artificial slot are 0.1 mm and 0.5 mm respectively. This slot was only possible to measure the depth on the two side edges, and impossible for the middle part with general measurement tools. The ultrasonic test method was applied for measuring depth of the middle part of the artificial slot in the standard. Using this method the dimension could be measured successfully with uncertainty about
. Calibration of eddy current standard for the absolute probe can be performed by this technique.
Design of a Shielded Reflection Type Pulsed Eddy Current Probe for the Evaluation of Thickness
Shin, Young-Kil ; Choi, Dong-Myung ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 398~408
For better evaluation of material thickness by using the reflection type pulsed eddy current method, various probe models are designed and their response signals, characteristics, and sensitivities to thickness variation are investigated by a numerical analysis method. Since the sensor needs to detect magnetic fields from eddy currents induced in a test material, not from the exciter coil, two types of models that are shielded by the combination of copper and ferrite and only by ferrite are considered. By studying response signals from these shielded probe models, the peak value and the zero crossing time are selected as useful signal features for the evaluation of material thickness. Investigation of sensitivities of these two features shows that the sensitivity of peak value is more useful than that of zero crossing time and that the probe shielded only by ferrite gives much better sensitivity to thickness variation.
Delamination Detection of Retrofitted Concrete Using Horn Antenna
Rhim, Hong-Chul ; Cho, Young-Sik ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 409~416
In accordance with the increased usage of reinforcing materials such as carbon fibers and glass fibers, delamination detection between concrete and the reinforcing material is needed as such delaminations may be a major cause for strength reduction or failure of a structure. In this work, 15 GHz center frequency with 10 GHz band width horn antenna was used to detect delamination between concrete and carbon fibers or glass fibers. The specimens measured
, and glass fibers and carbon fibers with a thickness of 1.5 mm were attached on the specimens' surfaces using epoxy. In addition, artificial delaminations of size
were placed in the middle of the specimen with thickness of 2, 4, 6 mm respectively together with a 2 mm delamination projecting upwards from the surface of the concrete. Therefore a total of 8 specimens were used, 4 specimens for glass fiber reinforced concrete and 4 for carbon fiber reinforced concrete, containing delaminations as described above. The experiment results were derived by using the difference of area under the curved graph. According to experimental results artifical delaminations were identified in both fiber reinforced and carbon reinforced specimens and these results could contribute to further development of delamination detection technology.
Microstructural Evolution and Magnetic Property of Creep-Fatigued Ferritic 9Cr Heat-Resisting Steel
Kim, Chung-Seok ; Kwun, S.I. ; Park, Ik-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 417~425
The ferritic 9Cr-1Mo-V-Nb heat-resisting steel was experimentally studied in order to characterize its microstructural evolution during creep-fatigue by coercivity measurement. The creep-fatigue test was conducted at
with the tensile holding time of 60s and 600s, respectively. The coercivity decreased until the failure and the hardness monotonously decreased for the whole fatigue life. As the life fraction of creep-fatigue increased, the
carbide coarsened following the Ostwald ripening mechanism. However, the MX carbonitrides did not grow during creep-fatigue due to so stable at
. The width of martensite lath increased because of the dislocation recovery at the lath boundaries. The magnetic coercivity has an influence on the microstructural properties such as dislocation, precipitates and martensite lath boundaries, which interpreted in relation to microstructural changes. Consequently, this study proposes a magnetic coercivity to quantify the level of damage and microstructural change during the creep-fatigue of ferritic 9Cr-1Mo-V-Nb steel.
A Brazing Defect Detection Using an Ultrasonic Infrared Imaging Inspection
Cho, Jai-Wan ; Choi, Young-Soo ; Jung, Seung-Ho ; Jung, Hyun-Kyu ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 426~431
When a high-energy ultrasound propagates through a solid body that contains a crack or a delamination, the two faces of the defect do not ordinarily vibrate in unison, and dissipative phenomena such as friction, rubbing and clapping between the faces will convert some of the vibrational energy to heat. By combining this heating effect with infrared imaging, one can detect a subsurface defect in material in real time. In this paper a realtime detection of the brazing defect of thin Inconel plates using the UIR (ultrasonic infrared imaging) technology is described. A low frequency (23 kHz) ultrasonic transducer was used to infuse the welded Inconel plates with a short pulse of sound for 280 ms. The ultrasonic source has a maximum power of 2 kW. The surface temperature of the area under inspection is imaged by an infrared camera that is coupled to a fast frame grabber in a computer. The hot spots, which are a small area around the bound between the two faces of the Inconel plates near the defective brazing point and heated up highly, are observed. And the weak thermal signal is observed at the defect position of brazed plate also. Using the image processing technology such as background subtraction average and image enhancement using histogram equalization, the position of defective brazing regions in the thin Inconel plates can be located certainly.
Study on an Extraction Method for a Fuel Rod Image and a Visualization of the Color Information in a Sectional Image of a Spent Fuel Assembly
Jang, Ji-Woon ; Shin, Hee-Sung ; Youn, Cheung ; Kim, Ho-Dong ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 432~441
Image processing methods for an extraction of a nuclear fuel rod image and visualization methods of the RGB color data were studied with a sectional image of spent fuel assembly. The fuel rod images could be extracted by using a histogram analysis, an edge detection and RGB rotor data. In these results, a size of the spent fuel assembly could be measured by using a histogram analysis method and a shape of the spent fuel rod could be observed by using an edge detection method. Finally, a various analyses were established for status of the spent fuel assembly by realized various 3D images for the color data in an image of a spent fuel assembly.
Development of Steam-Generator UT System and Experimental Verification
Park, Jae-Seok ; Hong, Soon-Sin ; Park, Chi-Seung ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 442~448
The ultrasonic inspection system for the expansion/transition area of steam generator tube was successfully developed. Variety of artificial flaw and real track specimen was tested using the UT system to verify the performance of the system. All artificial flaws of which through-wall depth larger than 10% was clearly detected by UT system. Measurement results of through-wall depth of flaws larger than 20% had good linearity and reproducibility with 3.27 of standard deviation. Results of real crack specimen test suggested that the detection limit of real crack strongly depends on the track morphology. A potential for measurement of PRL(percentage of remaining ligament) was recognized by the real crack specimen test.
Comparative Analysis of the Weight Functions for the Reconstruction of a Gamma-ray CT based on the EM Technique
Lee, Na-Young ; Jung, Sung-Hee ; Kim, Jong-Bum ; Kim, Jin-Sup ; Kim, Jae-Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 5, 2007, Pages 449~458
In this paper, we reconstructed the cross-sectional images of two phantoms simulating a petrochemical process from gamma radiation measurements. Three different weight functions for EM image reconstruction algorithm were built and compared with histograms representing the variance of the homogeneity of the phantom material, The radiation source,
, collimated by a lead with 5 mm diameter aperture and the measurement was made with a lead shielded 1inch NaI detector. As a result, the method taking into account the beam area in each pixel for a weight function showed the best resolution among the three methods.