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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
Editor in Chief :
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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Detection of the Defect on the Metal Surface Using the Modulated Microwave
Joo, G.T. ; Jung, S.H. ; Song, K.Y. ; Kim, J.O. ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 3, 1999, Pages 173~179
The defects on the metal surface. such as the ended circular pressed hole. the penetrated circular drilled hole, and the linear hollow lanes have been investigated by means of the microwave. In this experiment, frequency was set at 9.2GHz with 3kHz modulation, and the methods of reflection, transmission, fixed carrier frequency, and mod-demodulated technique have been used for investigating defects. The magnitudes of the microwave signals have been changed at the ended circular pressed hole and the penetrated circular drilled hole. The defect sizes that were estimated from the reflected microwave signals had the dimensions enlarged by twice the original size of the penetrated circular drilled hole and 2.5 times the original size of the ended circular pressed hole. The magnitudes of the reflected microwave signals from the linear hollow lane have increased with expansion of the width of the notch. In the linear hollow lane with the depth of 2.4mm, the reflected microwave signals versus the defect widths had a maximum value at the defect width of 50mm, and in the linear hollow lanes with the depths of 1.2mm and 0.45mm, the reflected microwave signals versus the defects widths had the maximum values each at the defect depths of 55mm.
Analysis of Elastic Constants in SiC Particulate Reinforced Al Matrix Composites by Resonant Ultrasound Spectroscopy
Jung, Hyun-Kyu ; Cheong, Yong-Moo ; Joo, Young-Sang ; Hong, Soon-Hyung ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 3, 1999, Pages 180~188
The dynamic elastic properties of metal matrix composites were investigated by resonant ultrasound spectroscopy(RUS). The composites used in this study consisted of 2124 aluminum alloy reinforced with different concentrations of SiC particles. RUS can determine the nine independent elastic stiffness(
) for the orthorhombic symmetry on a small specimen simultaneously. The elastic constants were determined as a function of the volume fraction. A concept of effective aspect ratio. which combine the aspect ratio and the orientation of reinforcement. was used to calculate the initial moduli from Mori-Tanaka theory for the input of RUS minimization code. Young's moduli can be obtained from the measured stiffnesses. The results show that the elastic stiffness increases with increment of the particle content. The behavior of elastic stiffness indicates that the particle redistribution induced by the extrusion process enlarges the transversely isotropic symmetry as the fraction of reinforced particles increase. This relationship could be used for determination of the volume fractions of reinforcement as a potential tool of nondestructive material characterization.
Analysis on Propagation Characteristics and Experimental Verification of
Circumferential Waves in Nuclear Fuel Rods Coated with Oxide Layers
Joo, Young-Sang ; Ih, Jeong-Guon ; Jung, Hyun-Kyu ; Cheong, Yong-Moo ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 3, 1999, Pages 189~199
The resonance scattering of acoustic waves from the cylindrical shells of nuclear fuel rods coated with oxide layers has been theoretically modeled and numerically analyzed for the propagation characteristics of the circumferential waves. The normal mode solutions of the scattering pressure of the coated shells have been obtained. The pure resonance components have been isolated using the newly proposed inherent background coefficients. The propagation characteristics of resonant circumferential waves for the shells coated with oxide layers are affected by the presence and the thickness of an oxide layer. The characteristics have been experimentally confirmed through the method of isolation and identification of resonances. The change of the phase velocity of the
circumferential wave mode for the coated shell is negligible at the specified partial waves in spite of the presence of the oxide layer and the increase in coating thickness. Utilizing the invariability characteristics of the phase velocity of the
mode, the oxide layer thickness of the coated shells can be estimated. A new nondestructive technique for the relative measurement of the coating thickness of coated shells has been proposed.
Analysis of Stress Distribution of a Curved Beam Using Photoelasticity
Baek, Tae-Hyun ; Kim, Myung-Soo ; Kim, Soo-Il ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 3, 1999, Pages 200~206
This paper describes the stress analysis of a curved beam by using photoelasticity. In order to measure accurate isochromatic fringe orders at certain locations. fringes are doubled and sharpened by digital image processing. After fringe multiplication and sharpening. fringe orders can be read as a quarter order interval (N=0, 1/4, 2/4, 3/4,...). The results obtained from photoelastic experiment are compared with those calculated by using theory. Two results are agreed well even though there are some scatter bands with maximum 8 percent for the results of photoelastic measurements and theoretical calculation. Difference may be occurred due to the slight misalignment of the direction to which axial load is applied in photoelastic experiment. It is confirmed that accurate measurement of stress distribution can be possible by using the techniques of fringe multiplication and sharpening in photoelasticity.
Numerical Analysis of Ultrasonic Beam Profile Due to the Change of the Number of Piezoelectric Elements for Phased Array Transducer
Choi, Sang-Woo ; Lee, Joon-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 3, 1999, Pages 207~216
A phased array is a multi-element piezoelectric device whose elements are individually excited by electric pulses at programmed delay time. One of the advantages of using phased array in nondestructive evaluation (NDE) application over conventional ultrasonic transducers is their great maneuverability of ultrasonic beam. There are some parameters such as the number and the size of the piezoelectric elements and the inter-element spacing of the elements to design phased array transducer. In this study, the characteristic of ultrasonic beam for phased array transducer due to the variation of the number of elements has been simulated for ultrasonic SH-wave on the basis of Huygen's principle. Ultrasonic beam directivity and focusing due to the change of time delay of each element were discussed due to the change of the number of piezoelectric elements. It was found that ultrasonic beam was much more spreaded and hence its sound pressure was decreased as steering angle of ultrasonic beam was increased. In addition, the ability of ultrasonic bean focusing decreased gradually with the increase of focal length at the same piezoelectric elements. However, the ability of beam focusing was improved as the number of consisting elements was increased.
A Diagnostic Ultrasound Imaging System
Lee, Seong-Woo ;
Journal of the Korean Society for Nondestructive Testing, volume 19, issue 3, 1999, Pages 217~232
The ability to see the internal organs of the human body in a noninvasive way is a powerful diagnostic tool of modern medicine. Among these imaging modalities such as X-ray, MRI, and ultrasound. MRI and ultrasound are presenting much less risk of undesirable damage of both patient and examiner. In fact, no deleterious effects have been reported as a result of clinical examination by using MRI and ultrasound diagnostic equipment. As a result. their market volume has been rapidly increased. MRI has a good resolution. but there are a few disadvantages such as high price. non-real-time imaging capability. and expensive diagnostic cost. On the other hand, the ultrasound imaging system has inherently poor resolution as compared with X-ray and MRI. In spite of its poor resolution, the ultrasound diagnostic equipment is lower in price and has an ability of real-time imaging as compared with the others. As a result. the ultrasound imaging system has become general and essential modality for imaging the internal organs of human body. In this review various researches and developments to enhance the resolution of the ultrasound images are explained and future trends of the ultrasound imaging technology are described.