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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 19, Issue 6 - Dec 1999
Volume 19, Issue 5 - Oct 1999
Volume 19, Issue 4 - Aug 1999
Volume 19, Issue 3 - Jun 1999
Volume 19, Issue 2 - Apr 1999
Volume 19, Issue 1 - Feb 1999
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The Study on Scattered Far-Field Analysis of Ultrasonic SH-Wave Using Boundary Element Method
Lee, Joon-Hyun ; Lee, Seo-Il ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 5, 1999, Pages 333~339
It is well recognized that ultrasonic technique is one of the most common and reliable nondestructive evaluation techniques for quantitative estimation of defects in structures. For the quantitative and accurate estimation of internal defects. the characteristics of scattered ultrasonic wavefields must be understood. In this study. the scattered near-field and far-field due to a circular cavity embedded in infinite media subjected to incident SH-waves were calculated by the boundary element method. The frequency response of the scattered ultrasonic far-field was transformed into the time-domain signal by obtaining its inverse Fourier transform. It was found that the amplitude of time-domain signal decreases and its time delay increases as the distance between the detecting point of ultrasonic scattered field and the center of internal cavity increases.
The Effect of Dispersion Relations on the Determination of Surface Acoustical Wave Velocity
Kwon, Sung-D. ; Yoon, Seok-S. ; Lee, Seung-H. ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 5, 1999, Pages 340~346
Minimum reflection and backward radiation methods on liquid/solid interrace were used to determine the velocity dispersion relation of acoustical surface wave for brass and aluminum substrates and copper/stainless steel nickel/brass, and nickel/aluminum layered substrates. Dispersion data agreed to dispersion characteristics of a generalized Lamb wave. The difference between velocities determined by two phenomena was closely related to the dispersion characteristics. This correspondence was explained by considering the generation mechanism of surface waves and the concept of group velocity.
Vibration-Based Nondestructive Evaluation of Thermal Stress-Induced Damage in Thin Composite Laminates
Lee, Sung-Hyuk ; Choi, Nak-Sam ; Lee, Jong-Ki ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 5, 1999, Pages 347~355
A feasibility investigation on vibration-based nondestructive evaluation of thermal stress-induced micro-failure in the free edge region of thin composite laminates(1mm thick) has been carried out. The failure occurrence and damage zone, which were predicted by the three-dimensional finite-element thermal stress analysis, were observed using the ultrasonic C-scan and optical microscopy. Analysis of the vibration spectrum measured from the laminate beam specimens by the vibration sweep test exhibited that the obvious decrease in resonancy frequency and some considerable increase in damping factor were associated with the micro-failure formation. The vibration technique utilizing short beam and high resonant frequency was found to be very sensitive to the thermal stress-induced damage in the thin laminates.
A Study on Quantitative Thickness Evaluation Using Film Density Variation in Film Radiography
Lee, Sung-Sik ; Lee, Jeong-Ki ; Kim, Young-H. ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 5, 1999, Pages 356~362
Based on the assumption that film density increases exponentially with exposure in the industrial radiographic film. an equation representing the characteristic curves of industrial radiographic films and a new density-thickness relation are suggested. The accuracy and reliability of the suggested relation has been tested using radiographs of a carbon steel step wedge with known thickness variation by polychromatic X-ray and
). The experimental results were well agreed to the proposed relation in the range of film densities from 1.0 to 3.5 and it was more accurate than the conventional relation. It is also found that
-ray is more effective in this purpose than polychromatic X-ray, which results in variation of effective linear absorption coefficient due to beam hardening effect as thickness increases. Therefore using the equation and experimentally determined parameters the quantitative evaluation of thickness variation is possible and it can be used to evaluate the depth of local corrosion of pressure vessels in plants.
Simultaneous Measurement of Ultrasonic Velocity and Thickness of Isotropic and Homogeneous Solids Using Two Transducers
Lee, Jeong-Ki ; Kwon, Jin-O ; Kim, Young-H. ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 5, 1999, Pages 363~368
Ultrasonic pulse-echo methods measuring the transit time through specimens have been widely used in determination of ultrasonic velocity and thickness of specimens. Usually, to determine the velocity of the ultrasonic. the transit time of the ultrasonic pulse through specimen is measured by using the ultrasonic measuring equipment such as the oscilloscope including ultrasonic pulser/receiver and the thickness of the specimen is measured by using the length measuring instrument such as micrometer or vernier calipers etc., i. e. each parameter is measured by using each measuring method. In the case of the measuring the thickness of a specimen by using the ultrasonics. the ultrasonic equipments, which measure the thickness, such as the ultrasonic thickness gauge must be calibrated by using the reference block of which the ultrasonic velocity is known beforehand. In the present work, we proposed a new method for simultaneous measurement of ultrasonic velocity and thickness without reference blocks. Experimental results for several specimens show that proposed method have good agreements with those by traditional ultrasonic method.
A Study on the Detection of Interfacial Defect to Boundary Surface in Semiconductor Package by Ultrasonic Signal Processing
Kim, Jae-Yeol ; Hong, Won ; Han, Jae-Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 5, 1999, Pages 369~377
Recently, it is gradually raised necessity that thickness of thin film is measured accuracy and managed in industrial circles and medical world. Ultrasonic signal processing method is likely to become a very powerful method for NDE method of detection of microdefects and thickness measurement of thin film below the limit of ultrasonic distance resolution in the opaque materials, provides useful information that cannot be obtained by a conventional measuring system. In the present research. considering a thin film below the limit of ultrasonic distance resolution sandwiched between three substances as acoustical analysis model, demonstrated the usefulness of ultrasonic signal processing technique using information of ultrasonic frequency for NDE of measurements of thin film thickness. Accordingly, for the detection of delamination between the junction condition of boundary microdefect of thin film sandwiched between three substances the results from digital image processing.
Nondestructive Flaw Classification by Pattern Recognition Approach
Song, Sung-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 5, 1999, Pages 378~391