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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Nondestructive Testing
Journal Basic Information
Journal DOI :
The Korean Society for Nondestructive Testing
Editor in Chief :
Volume & Issues
Volume 7, Issue 1 - Oct 1987
Volume 6, Issue 2 - Apr 1987
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A study on the Relationship between the Size of Defect and the Intensity of Eddy Current Signal in Heat Exchanging Tube made of STS 304.
Han, E.K. ; Eom, H.S. ; Park, I.G. ; Choi, M.S. ;
Journal of the Korean Society for Nondestructive Testing, volume 6, issue 2, 1987, Pages 7~16
Eddy Current Examination is expected as the effective technique for nondestructive inspection of steam generator and various kinds of heat exchanging tubes made of STS - 304. In Case of E. C. T, a study on the various factors which have an effect on coil impedance is very important to the sensitivity of defect detection and the ratio of signal to noise. Therefore, this study analyzed coil impedance by means of the variational principle, the minimized theory of energy functional and the application of Finite Element Method. Really by using E. C. T, the relationship between the size of defects and the intensity of Eddy Current Signals can be obtained. Signal intensity becomes maximum at certain frequency. This frequency is affected by the characteristics and the position of signal sources.
An Investigation of Fracture Mechanism of Spheroidal Graphite Cast Iron by Acoustic Emission Method
Kim, S.C. ; Ham, K.C. ; Oh, B.S. ;
Journal of the Korean Society for Nondestructive Testing, volume 6, issue 2, 1987, Pages 17~36
In this experimental research, fracture mechanisms of spheroidal graphite cast iron (As Cast, annealed and normalized) were investigated by using Acoustic Emission (AE) technique. In this study, the data (AE signal) are digitized and processed with the 8 bits micro-computer (APPLE II) connected to the AE measuring device without data processing unit. The source of AE signal was estimated by fractography analysis. The results obtained in this experimental study are summarized as follows : For the heterogeneous materials (spheroidal graphite cast iron) with inclusions which may considered as cracks, it is found that low and high AE amplitude appear simultaneously and the load is found to be fluctuated in the final stage of deformation. But the lad is not fluctuated in tension test with low AE amplitude only. AE is measured within elastic region and it is confirmed that 0.2% offset yield load agrees approximately with the load point where AE counts decrease steeply after the point of maximum AE counts.
Measurement of In- plane Displacement by Speckle Photography and Image Processing
Han, Eung-Kyo ; Sumi, Seinosuke ; Kim, Koung-Suk ;
Journal of the Korean Society for Nondestructive Testing, volume 6, issue 2, 1987, Pages 37~45
Speckle photography is a very useful method for measuring in-plane surface displacement. In its basic form, the object to be studied is illuminated with a divergent laser beam, and a double exposure photograph of the object is recorded, on a fine-grain film or plate, before and after the object is deformed, The magnitude and the direction of the displacement can then be obtained by measuring the spacing and the direction of the Young's fringe, which is produced by probing the developed negative with an unexpaned laser beam, and consists of a pattern of parallel equi-spaced dark bands. In this paper, a hybrid optical and electronic image processing is described-Young's fringe on the viewing screen is observed by a TV-camera and the 2-D video signal is converted from analog to digital and transfered to the computer where the spacing and direction of the fringes are calculated. Several examples of application show that the displacement magnitude and direction can be determined with an accuracy of
The effect of ultrasonic search units on the detectability and size evaluation of planar flaws
Lee, J.P. ; Kim, B.C. ; Lim, H.T. ; Joo, Y.S. ;
Journal of the Korean Society for Nondestructive Testing, volume 6, issue 2, 1987, Pages 46~56
The effect of ultrasonic search units on the detectability and size evaluation of planar flaws was studied for thicker ferritic material using the technique of the DAC curve and reference level. Cylindrical holes were used as calibration reflectors. The planar flaws such as disc and band types were machined. They were detected and evaluated with different search units and sizing criteria. The value evaluated was compared with the actual dimension of planar flaws.
The Technology of Mechanized Ultrasonic Test for the React or Vessel of PWR Power Plant in Korea.
Park, Moon-Ho ; Park, Kwang-Hee ; Koo, In-Soo ; Park, Dae-Young ;
Journal of the Korean Society for Nondestructive Testing, volume 6, issue 2, 1987, Pages 57~70