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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
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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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A Study on AE Signal Analysis of Composite Materials Using Matrix Piezo Electric Sensor
Yu, Yeun-Ho ; Choi, Jin-Ho ; Kweon, Jin-Hwe ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 1, 2007, Pages 1~7
As fiber reinforced composite materials are widely used in aircraft, space structures and robot arms, the study on non-destructive testing methods has become an important research area for improving their reliability and safety. AE (acoustic emission) can evaluate the defects by detecting the emitting strain energy when elastic waves are generated by the initiation and growth of crack, plastic deformation, fiber breakage, matrix cleavage, or delamination. In the paper, AE signals generated under uniaxial tension were measured and analyzed using the
matrix piezo electric sensor. The electronic circuit to control the transmitting distance of AE signals was designed and constructed. The optical data storage system was also designed to store the AE signal of 64channels using LED (light emitting diode) elements. From the tests, it was shown that the source location and propagation path of AE signals in composite materials could be detected effectively by the
matrix piezo electric sensor.
Enhancement of Image Sharpness in X-ray Digital Tomosynthesis Using Self-Layer Subtraction Backprojection Method
Shon, Cheol-Soon ; Cho, Min-Kook ; Lim, Chang-Hwy ; Cheong, Min-Ho ; Kim, Ho-Kyung ; Lee, Sung-Sik ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 1, 2007, Pages 8~14
X-ray digital tomosynthesis is widely used in the nondestructive testing and evaluation, especially for the printed circuit boards (PCBs). In this study, we propose a simple method to reduce the blur artefact, frequently claimed in the conventional digital tomosynthesis based on SAA (shift-and-add) algorithm, and thus restore the image sharpness. The proposed method is basically based on the SAA, but has a correction procedure by finding blur artefacts from the forward-and back-projection for the firstly obtained, manipulated backprojection data. The manipulation is the replacement of the original data at the POI (plane-of-interest) by zeros. This method has been compared with the conventional SAA algorithm using the experimental measurements and Monte Carlo simulation for the designed PCB phantom. The comparison showed a much enhancement of sharpness in the images obtained from the proposed method.
Hybrid Stress Analysis around a Circular Hole in a Tensile Plate by Use of Phase Shifting Photoelasticity
Baek, Tae-Hyun ; Lee, Choon-Tae ; Yang, Min-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 1, 2007, Pages 15~22
A hybrid experimental-numerical method is presented for determining the stresses around a circular hole in a finite-width, tensile loaded plate. Measured fringe orders along straight lines provided the input information on the external boundary of the hybrid element. In order to see the effects of varying stress field, different numbers of terms in a power-series representation of the complex type conformal mapping stress function were tested. For qualitative comparison, actual isochromatic fringes were compared with reconstructed theoretical fringes using stress-optic law. For quantitative comparison, relative errors and standard deviations with respective to relative errors were analyzed for all measured points by changing the number of terms of stress function. The hybrid results are highly comparable with those predicted by FEA. The results show that this approach is effective and promising because isochromatic data along the straight lines in photoelasticity can be conveniently measured by use of phase shifting photoelasticity.
Concentration of Sodium Chloride Solutions Sensing by Using a Near-Field Microwave Microprobe
Kim, Song-Hui ; Yoon, Young-Woon ; Babajanyan, Arsen ; Kim, Jong-Chul ; Lee, Kie-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 1, 2007, Pages 23~30
We observed the NaCl concentration of solutions using a near-field microwave microprobe(NFMM). Instead of the usual technique, we take advantage of the noncontact evaluation capabilities of a NFMM. A NFMM with a high Q dielectric resonator allows observation of small variations of the permittivity due to changes in the NaCl concentration. The changes of NaCl concentration due to a change of permittivity of the NaCl solution were investigated by measuring the microwave reflection coefficient
of the resonator. The NaCl sensor consisted of a dielectric resonator coupled to a probe tip at an operating frequency of about f=4 GHz. The change of the NaCl concentration is directly related to the change of the reflection coefficient due to a near field electromagnetic interaction between the probe tip and the NaCl solution. In order to determine the probe selectivity, we measured a mixture solution of NaCl and glucose.
Small-Focal Source for Non-Destructive Testing Application by Using Enriched Target Material
Son, K.J ; Hong, S.B. ; Jang, K.D. ; Han, H.S. ; Park, U.J. ; Lee, J.S. ; Kim, D.H. ; Han, K.D. ; Park, C.D. ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 1, 2007, Pages 31~37
small-focal source has been developed by using the HANARO reactor and the radioisotope production facility at the Korea Atomic Energy Research Institute (KAERI). The small-focal source with the dimension of 0.5 mm in diameter and 0.5 mm in length was fabricated as an aluminum-encapsulated form by a specially designed pressing equipment. For the estimation of the radioactivity, neutron self-shielding and
self-absorption effects on the measured activity was considered. From this estimation, it is realized that
small-focal sources over 3 Ci activities can be produced from the HANARO. Field performance tests were performed by using a conventional source and the developed source to take images of a computer CPU and a piece of a carbon steel. The small-focal source showed better penetration sensitivity and geometrical sharpness than the conventional source does. It is concluded from the tests that the focal dimension of this source is small enough to maximize geometrical sharpness in the image taking for the close proximity shots, pipeline crawler applications and contact radiography.
Detection and Sizing of Fatigue Cracks in Thin Aluminum Panel with Rivet Holes
Kim, Jung-Chan ; Kwon, Oh-Yang ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 1, 2007, Pages 38~47
The initiation of fatigue cracks in a simulated aircraft structure with a series of rivet holes was detected by acoustic emission(AE), then the crack length was determined by surface acoustic wave(SAW) technique. With the initiation and growth of fatigue cracks, AE events increased intermittently to form a stepwise incremental curve of cumulative AE events whereas the crack length increased more or less monotonically. With the SAW technique employed, the crack sizing for 13 different cracks including some short cracks was performed. With the reference to the measurement by traveling microscope, cracks in the range of
long were reliably sized by the SAW technique. Although it was impossible to size the short fatigue cracks in the range shorter than 1 mm, the SAW technique still appeared practically useful for a range of crack lengths often found in aircraft structures.
Fatigue Crack Growth Behavior of and Recognition of AE Signals from Composite Patch-Repaired Aluminum Panel
Kim, Sung-Jin ; Kwon, Oh-Yang ; Jang, Yong-Joon ;
Journal of the Korean Society for Nondestructive Testing, volume 27, issue 1, 2007, Pages 48~57
The fatigue crack growth behavior of a cracked and patch-repaired Ah2024-T3 panel has been monitored by acoustic emission(AE). The overall crack growth rate was reduced The crack propagation into the adjacent hole was also retarded by introducing the patch repair. AE signals due to crack growth after the patch repair and those due to debonding of the plate-patch interface were discriminated by usiag the principal component analysis. The former showed high center frequency and low amplitude, whereas the latter showed long rise tine, low frequency and high amplitude. This type of AE signal recognition method could be effective for the prediction of fatigue crack growth behavior in the patch-repaired structures with the aid of AE source location.