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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 26, Issue 6 - Dec 2006
Volume 26, Issue 5 - Oct 2006
Volume 26, Issue 4 - Aug 2006
Volume 26, Issue 3 - Jun 2006
Volume 26, Issue 2 - Apr 2006
Volume 26, Issue 1 - Feb 2006
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Nondestructive Measurement of the Coating Thickness in the Simulated TRISO-Coated Fuel Particle Using Micro-Focus X-ray Radiography
Kim, Woong-Ki ; Lee, Young-Woo ; Park, Ji-Yeon ; Park, Jung-Byung ; Ra, Sung-Woong ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 2, 2006, Pages 69~76
TRISO(tri-isotropic)-coated fuel particle technology is utilized owing to its higher stability at a high temperature and Its efficient retention capability for fission products In the HTGR(high temperature gas-reeled reactor). The typical spherical TRISO fuel panicle with a diameter of about 1mm is composed of a nuclear fuel kernel and outer coating layers. The outer coating layers consist of a buffer PyC(pyrolytic carbon) layer, Inner PyC(1-PyC) layer, SiC layer, and outer PyC(O-PyC) layer Most of the Inspection Items for the TRTSO-coated fuel particle depend on destructive methods. The coating thickness of the TRISO fuel particle can be nondestructively measured by the X-ray radiography without generating radioactive wastel. In this study, the coaling thickness for the simulated TRISO-coated fuel particle with
kernel Instead of
kernel was measured by using micro-focus X-ray radiography with micro-focus X-ray generator and flat panel detector The radiographic image was also enhanced by image processing technique to acquire clear boundary lines between coating layers. The coaling thickness wat effectively measured by applying the micro-focus X-ray radiography The inspection process for the TRISO-coated fuel particles will be improved by the developed micro-focus X-ray radiography and digital image processing technology.
Precise Estimation of Nonlinear Parameter in Pulse-Like Ultrasonic Signal
Ha, Job ; Jhang, Kyung-Young ; Sasaki, Kimio ; Tanaka, Hiroaki ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 2, 2006, Pages 77~83
Ultrasonic nonlinearity has been considered as a solution for the detection of microcracks or interfacial delamination in a layered structure. The distinguished phenomenon in nonlinear ultrasonics is the generation of higher-order harmonic waves during the propagation. Therefore, in order to quantify the nonlinearity, the conventional method measures a parameter defined as the amplitude ratio of a second-order harmonic component and a fundamental frequency component included in the propagated ultrasonic wave signal. However, its application In field inspection is not easy at the present stage because no standard methodology has yet been made to accurately estimate this parameter. Thus, the aim of this paper is to propose an advanced signal processing technique for the precise estimation of a nonlinear ultrasonic parameter, which is based on power spectral and bispectral analysis. The method of estimating power spectrum and bispectrum of the pulse-like ultrasonic wave signal used in the commercial SAM (scanning acoustic microscopy) equipment is especially considered in this study The usefulness of the proposed method Is confirmed by experiments for a Newton ring with a continuous air gap between two glasses and a real semiconductor sample with local delaminations. The results show that the nonlinear parameter obtained tv the proposed method had a good correlation with the delamination.
Detection of a Surface-Breaking Crack Using the Surface Wave of a Laser Ultrasound
Park, Seung-Kyu ; Jung, Hyun-Kyu ; Baik, Sung-Hoon ; Lim, Chang-Hwan ; Joo, Young-Sang ; Kang, Young-June ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 2, 2006, Pages 84~89
A laser ultrasonic inspection system is a non-contact inspection device which generates and measures ultrasounds by using laser beams. A laser ultrasonic inspection system provides a high measurement resolution because the ultrasonic signal generated by a pulse laser beam has a wide-band spectrum and the ultrasonic signal is measured from a small focused spot of a measuring laser beam. In this paper, we have investigated the detection techniques of a surface-breaking crack by using the laser ultrasonic surface waves. A crack acts as a low pass filter whose cut-off frequency is lowered in proportion to the depth of a crack. And, the center frequency value of a spectrum is decreased in proportion to the depth of a crack. In this paper, we extracted the crack information by using the frequency attenuation from the normalized transfer function spectrum of a surface-breaking crack. Also, we effectively measured the crack depth by using the decreasing value of the center frequency from a crack passed ultrasonic signal. The proposed measuring techniques of crack depths provided more precise information than the amplitude measuring technique.
Simulation and Evaluation of ECT Signals From MRPC Probe in Combo Calibration Standard Tube Using Electromagnetic Numerical Analysis
Yoo, Joo-Young ; Song, Sung-Jin ; Jung, Hee-Jun ; Kong, Young-Bae ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 2, 2006, Pages 90~98
Signals captured from a Combo calibration standard tube paly a crucial role in the evaluation of motorized rotating pancake coil (MRPC) probe signals from steam generator (SG) tubes in nuclear power plants (NPPs). Therefore, the Combo tube signals should be consistent and accurate. However, MRPC probe signals are very easily affected by various factors around the tubes so that they can be distorted in their amplitudes and phase angles which are the values specifically used in the evaluation. To overcome this problem, in this study, we explored possibility of simulation to be used as a practical calibration tool far the evaluation of real field signals. For this purpose, we investigated the characteristics of a MRPC probe and a Combo tube. And then using commercial software (VIC-3D) we simulated a set of calibration signals and compared to the experimental signals. From this comparison, we verified the accuracy of the simulated signals. Finally, we evaluated two defects using the simulated Combo tube signals, and the results were compared with those obtained using the actual field calibration signals.
A Study of the Exclusive Embedded A/D Converter Using the Microprocessor and the Noise Decrease for the Magnetic Camera
Lee, Jin-Yi ; Hwang, Ji-Seong ; Song, Ha-Ryong ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 2, 2006, Pages 99~107
Magnetic nondestructive testing is very useful far detecting a crack on the surface or near of the surface of the ferromagnetic materials. The distribution of the magnetic flux leakage (DMFL) on a specimen has to be obtained quantitatively to evaluate the crack. The magnetic camera is proposed to obtain the DMFL at the large lift-off. The magnetic camera consists of a magnetic source, magnetic lens, analog to digital converters (ADCs), interface, and computer. The magnetic leakage fields or the distorted magnetic fields from the object, which are concentrated on the magnetic lens, are converted to analog electrical signals tv arrayed small magnetic sensors. These analog signals are converted to digital signals by the ADCs, and are stored, imaged, and processed by the interface and computer. However the magnetic camera has limitations with respect to converting and switching speed, full range and resolution, direct memory access (DMA), temporary storage speed and volume because common ADCs were used. Improved techniques, such as those that introduce the operational amplifier (OP-Amp), amplify the signal, reduce the connection line, and use the low pass filter (LPF) to increase the signal to noise ratio are necessary. This paper proposes the exclusive embedded ADC including OP-Amp, LPF, microprocessor and DMA circuit for the magnetic camera to satisfy the conditions mentioned above.
Development of Signal Processing Technique of Digital Speckle Tomography for Analysis of Three-Dimensional Density Distributions of Unsteady and Asymmetric Gas Flow
Baek, Seung-Hwan ; Kim, Yong-Jae ; Ko, Han-Seo ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 2, 2006, Pages 108~114
Transient and asymmetric density distributions of butane flow have been investigated from laser image signals by developed three-dimensional digital speckle tomography. Moved signals of speckles have been captured by multiple CCD images in three angles of view simultaneously because the flows were asymmetric and transient. The signals of speckle movements between no flow and downward butane flow from a circular half opening have been calculated by a cross-correlation tracking method so that those distances can be transferred to deflection angles of laser rays fur density gradients. The three-dimensional density fields have been reconstructed from the fringe shift signal which is integrated from the deflection angle by a real-time multiplicative algebraic reconstruction technique (MART).
Generation of the FE Model of a Korean Young Male Adults and Determination of Mechanical Properties for Engineering Analysis
Yoo, Seung-Hyun ; Kim, Hak-Kyun ; Kim, Jong-Bum ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 2, 2006, Pages 115~121
Geometries, boundary renditions, loading renditions and mechanical properties are essential for finite element analysis. However it is a very difficult task to obtain In-vivo geometry and mechanical properties of human body. In this study totally 38 kinds of inner organs are segmented using MRI of young male with Korean standard body shape to make a finite element model. And RUS has been used to acquire anisotropic elasticity matrix of the femoral head.
Influence of Shearing Amount on Detection of Internal Defect of Pressure Pipeline by Shearography
Kim, Koung-Suk ; Kang, Ki-Soo ; Choi, Man-Yong ; Kang, Young-June ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 2, 2006, Pages 122~129
Shearography is one of optical methods that has been applied to nondestructive testing (NDT) and strain/stress analysis. The technique has the merit of the directly measuring relative displacement, which is insensitive to environmental vibration disturbance. Previous studies about the method have emphasized on extending its application to new fields and lack insufficient research on effective parameters for qualitative and quantitative evaluation of defects. In this paper, the influence of shearing amount on the detection of an internal defect is investigated. In experiment, slender defects along longitudinal direction of pipeline are artificially designed and detection results according to the change of shearing amount are analyzed. Based on the investigation, we propose the technique for the determination of defect size and accurate source location.