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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Nondestructive Testing
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Journal DOI :
The Korean Society for Nondestructive Testing
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Volume & Issues
Volume 16, Issue 3 - Dec 1996
Volume 16, Issue 2 - Sep 1996
Volume 16, Issue 1 - Apr 1996
Volume 15, Issue 4 - Feb 1996
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A Study on Hybrid Split-Spectrum Processing Technique for Enhanced Reliability in Ultrasonic Signal Analysis
Huh, H. ; Koo, K.M. ; Kim, G.J. ;
Journal of the Korean Society for Nondestructive Testing, volume 16, issue 1, 1996, Pages 1~9
Many signal-processing techniques have been found to be useful in ultrasonic and nondestructive evaluation. Among the most popular techniques are signal averaging, spatial compounding, matched filters and homomorphic processing. One of the significant new process is split-spectrum processing(SSP), which can be equally useful in signal-to-noise ratio(SNR) improvement and grain characterization in several specimens. The purpose of this paper is to explore the utility of SSP in ultrasonic NDE. A wide variety of engineering problems are reviewed, and suggestions for implementation of the technique are provided. SSP uses the frequency-dependent response of the interfering coherent noise produced by unresolvable scatters in the resolution range cell of a transducer. It is implemented by splitting the frequency spectrum of the received signal by using gaussian bandpass filter. The theoretical basis for the potential of SSP for grain characterization in SUS 304 material is discussed, and some experimental evidence for the feasibility of the approach is presented. Results of SNR enhancement in signals obtained from real four samples of SUS 304. The influence of various processing parameters on the performance of the processing technique is also discussed. The minimization algorithm, which provides an excellent SNR enhancement when used either in conjunction with other SSP algorithms like polarity-check or by itself, is also presented.
A Study on the Fatigue-Fractured Surface of Normalized SS41 Steel and M.E.F. Dual Phase Steel by an X-ray Diffraction Technique
Oh, Sae-Wook ; Park, Young-Chul ; Park, Soo-Young ; Kim, Deug-Jin ; Hue, Sun-Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 16, issue 1, 1996, Pages 10~18
This study verified the relationship between fracture mechanics parameters and X-ray parameters for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). The fatigue crack propagation test were carried out and X-ray diffraction technique was applied to fatigue fractured surface. The change in X-ray parameters(residual stress, half-value breadth) according to the depth of fatigue fractured surface were investigated. The depth of maximum plastic zone,
, were determined on the basis of the distribution of the half-value breadth for normalized SS41 steel and that of the residual stress for M.E.F. dual phase steel.
could be estimated by the measurement of
The Optimization of NDT Method for Real Time X-ray Imaging
Na, Sung-Youb ; Choi, Yong-Kyu ;
Journal of the Korean Society for Nondestructive Testing, volume 16, issue 1, 1996, Pages 19~28
This study has investigated the optimization of NDT method and the minimum detectable defect size for complex structures such as the solid propellant rocket motor using real time X-ray imaging system. Test specimens were made of steel plates with various defect size, and installed with proper thickness for which solid propellant, rubber, and case converted to the steel equivalent thickness according to the radiographic equivalent theory. As the results, this examination obtained optimum magnification and X-ray energy, dose rate according to steel equivalent thickness, also, obtained the relationship between minimum detectable defect size and the ratio(defect depot/object thickness). Thus, this simulated test is the preliminary procedure before performing NDT for real objects, and is possibly applied for NDT of other complex structures.
The Defect Inspection on the Irradiated Fuel Rod by Eddy Current Test
Koo, D.S. ; Park, Y.K. ; Kim, E.K. ;
Journal of the Korean Society for Nondestructive Testing, volume 16, issue 1, 1996, Pages 29~33
The eddy current test(ECT) probe of differential encircling coil type was designed and fabricated, and the optimum condition of ECT was derived for the examination of the irradiated fuel rod. The correlation between ECT test frequency and phase & amplitude was derived by performing the test of the standard rig that includes inner notches, outer notches and through-holes. The defect of through-hole was predicted by ECT at the G33-N2 fuel rod irradiated in the Kori-1 nuclear power reactor. The metallographic examination on the G33-N2 fuel rod was Performed at the defect location predicted by ECT. The result of metallographic examination for the G33-N2 fuel rod was in good agreement with that of ECT. This proves that the evaluation for integrity of irradiated fuel rod by ECT is reliable.
Development of Adaptive Signal Pattern Recognition Program and Application to Classification of Defects in Weld Zone by AE Method
Lee, K.Y. ; Lim, J.M. ; Kim, J.S. ;
Journal of the Korean Society for Nondestructive Testing, volume 16, issue 1, 1996, Pages 34~45
The signal pattern recognition program which can perform signal acquisition and processing, the extraction and selection of features, the classifier design and the evaluation, is developed and applied to the classification of artificial defects in the weld zone of Austenitic STS304. The neural network classifier is compared with the linear discriminant function classifier and the empirical Bayesian classifier. The signal through a broadband sensor is compared with that through a resonance type sensor. In recognition rate, the neural network classifier is best, and the signal through a broadband sensor is better.
Ultrasonic Inspection of RPV Internal Structures
Sim, C.M. ; Choi, H.L. ;
Journal of the Korean Society for Nondestructive Testing, volume 16, issue 1, 1996, Pages 46~51