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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Nondestructive Testing
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Journal DOI :
The Korean Society for Nondestructive Testing
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Volume & Issues
Volume 34, Issue 6 - Dec 2014
Volume 34, Issue 5 - Oct 2014
Volume 34, Issue 4 - Aug 2014
Volume 34, Issue 3 - Jun 2014
Volume 34, Issue 2 - Apr 2014
Volume 34, Issue 1 - Feb 2014
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FEM Model-Based Investigation of Ultrasonic TOFD for Notch Inspection
Tang, Ziqiao ; Yuan, Maodan ; Wu, Hu ; Zhang, Jianhai ; Kim, Hak-Joon ; Song, Sung-Jin ; Kang, Sung-Sik ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 1~9
DOI : 10.7779/JKSNT.2014.34.1.1
A two-dimensional numerical model based on the finite element method was built to simulate the wave propagation phenomena that occur during the ultrasonic time of flight diffraction (TOFD) process. First, longitudinal-wave TOFD was simulated, and the numerical results agreed well with the theoretical results. Shear-wave TOFD was also investigated because shear waves have higher intensity and resolution. The shear wave propagation was studied using three models with different boundary conditions, and the tip-diffracted shear-to-longitudinal wave was extracted from the A-scan signal difference between the cracked and non-cracked specimens. This signal showed very good agreement between the geometrical and numerical arrival times. The results of this study not only provide better understanding of the diffraction phenomena in TOFD, but also prove the potential of shear-wave TOFD for practical application.
Prediction of the Effect of Defect Parameters on the Thermal Contrast Evolution during Flash Thermography by Finite Element Method
Yuan, Maodan ; Wu, Hu ; Tang, Ziqiao ; Kim, Hak-Joon ; Song, Sung-Jin ; Zhang, Jianhai ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 10~17
DOI : 10.7779/JKSNT.2014.34.1.10
A 3D model based on the finite element method (FEM) was built to simulate the infrared thermography (IRT) inspection process. Thermal contrast is an important parameter in IRT and was proven to be a function of defect parameters. Parametric studies were conducted on internal defects with different depths, thicknesses, and orientations. Thermal contrast evolution profiles with respect to the time of the defect and host material were obtained through numerical simulation. The thermal contrast decreased with defect depth and slightly increased with defect thickness. Different orientations of thin defects were detected with IRT, but doing so for thick defects was difficult. These thermal contrast variations with the defect depth, thickness, and orientation can help in optimizing the experimental process and interpretation of data from IRT.
Evaluation of Residual Stress on Pipe Welded Joints Using Laser Interferometry
Chang, Ho-Seob ; Na, Man-Gyun ; Kim, Koung-Suk ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 18~22
DOI : 10.7779/JKSNT.2014.34.1.18
Residual stresses that occur during the welding process, are the main cause of failure and defects in welded structures. This paper, presents the use of an electronic processing laser speckle interferometer to measure the residual stress of a welded pipe for a nuclear power plant. A tensile testing machine was used to evaluate a welded pipe that failed in compression. The inform plane deformation and modulus of elasticity of the base metal and welds were measured using an interferometer. Varying the load on the welded pipe had a larger effect on the deformation of the base metal the other properties of the base metal and welds. The elastic moduli of the base metal and weld of the welded pipe were 202.46 and 212.14 GPa, respectively, the residual stress was measured to be 6.29 MPa.
Characteristics of Elastic Wave Generated by Wear and Friction of SiC
Moon, Chang-Kwon ; Nam, Ki-Woo ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 23~30
DOI : 10.7779/JKSNT.2014.34.1.23
The wear characteristics of
/SiC composites were evaluated according to the alignment direction of the fibers, and the elastic wave-generated friction was detected and analyzed in wearing. The friction coefficient and wear loss were similar in the longitudinal and the transverse direction of the fibers. However, these values were lower in the vertical direction of the fibers because of the brittle nature of the fiber. The friction coefficient and the wear loss were directly proportional to each other. The dominant frequencies were 58.6 kHz for monolithic SiC and 117.2 and 136.7 kHz for
/SiC composites, respectively.
Development of Nondestructive Sorting Method for Brown Bloody Eggs Using VIS/NIR Spectroscopy
Lee, Hong-Seock ; Kim, Dae-Yong ; Kandpal, Lalit Mohan ; Lee, Sang-Dae ; Mo, Changyeun ; Hong, Soon-Jung ; Cho, Byoung-Kwan ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 31~37
DOI : 10.7779/JKSNT.2014.34.1.31
The aim of this study was the non-destructive evaluation of bloody eggs using VIS/NIR spectroscopy. The bloody egg samples used to develop the sorting mode were produced by injecting chicken blood into the edges of egg yolks. Blood amounts of 0.1, 0.7, 0.04, and 0.01 mL were used for the bloody egg samples. The wavelength range for the VIS/NIR spectroscopy was 471 to 1154 nm, and the spectral resolution was 1.5nm. For the measurement system, the position of the light source was set to
, and the distance between the light source and samples was set to 100 mm. The minimum exposure time of the light source was set to 30 ms to ensure the fast sorting of bloody eggs and prevent heating damage of the egg samples. Partial least squares-discriminant analysis (PLS-DA) was used for the spectral data obtained from VIS/NIR spectroscopy. The classification accuracies of the sorting models developed with blood samples of 0.1, 0.07, 0.04, and 0.01 mL were 97.9%, 98.9%, 94.8%, and 86.45%, respectively. In this study, a novel nondestructive sorting technique was developed to detect bloody brown eggs using spectral data obtained from VIS/NIR spectroscopy.
Identification of Structural Defects in Rail Fastening Systems Using Flexural Wave Propagation
Park, Jeongwon ; Park, Junhong ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 38~43
DOI : 10.7779/JKSNT.2014.34.1.38
An experimental method based on flexural wave propagation is proposed for identification of structural damage in rail fastening systems. The vibration of a rail clamped and supported by viscoelastic pads is significantly influenced by dynamic support properties. Formation of a defect in the rail fastening system induces changes in the flexural wave propagation characteristics owning to the discontinuity in the structural properties. In this study, frequency-dependent support stiffness was measured to monitor this change by a transfer function method. The sensitivity of wave propagation on the defect was measured from the potential energy stored in a continuously supported rail. Further, the damage index was defined as a correlation coefficient between the change in the support stiffness and the sensitivity. The defect location was identified from the calculated damage index.
Improved Estimation of Leak Location of Pipelines Using Frequency Band Variation
Lee, Young-Sup ; Yoon, Dong-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 44~52
DOI : 10.7779/JKSNT.2014.34.1.44
Leakage is an important factor to be considered for the management of underground water supply pipelines in a smart water grid system, especially if the pipelines are aged and buried under the pavement or various structures of a highly populated city. Because the exact detection of the location of such leaks in pipelines is essential for their efficient operation, a new methodology for leak location detection based on frequency band variation, windowing filters, and probability is proposed in this paper. Because the exact detection of the leak location depends on the precision of estimation of time delay between sensor signals due to leak noise, some window functions that offer weightings at significant frequencies are applied for calculating the improved cross-correlation function. Experimental results obtained by applying this methodology to an actual buried water supply pipeline, ~ 253.9 m long and made of cast iron, revealed that the approach of frequency band variation with those windows and probability offers better performance for leak location detection.
Safety Evaluation of Molten Steel Carrier by Using Instrument Indentation Technique
Lee, Jeong-Ki ; Kim, Yi-Gon ; Yoo, Dae-Wha ; Kim, Kwang-Ho ; Lee, Kyeong-Ro ; Kim, Chung-Youb ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 53~59
DOI : 10.7779/JKSNT.2014.34.1.53
Because a molten steel carrier is used in high-temperature and corrosive environments, erosion and corrosion decrease the thickness of the structure and expand the vent hole for emitting gas generated from refractory bricks. This increases the stress throughout the structure and introduces a significant stress concentration around the vent hole. In addition, the high-temperature environment degrades mechanical properties such as the yield and tensile strengths. These problems seriously affect the safety of the structure. In this study, the safety of a 10-year-old structure was evaluated by analyzing the stress distribution and measuring the mechanical properties of the structure. The mechanical properties were directly measured on the structure surface using the instrument indentation technique.
Field Application of a Cable NDT System for Cable-Stayed Bridge Using MFL Sensors Integrated Climbing Robot
Kim, Ju-Won ; Choi, Jun-Sung ; Lee, Eun-Chan ; Park, Seung-Hee ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 60~67
DOI : 10.7779/JKSNT.2014.34.1.60
In this study, an automated cable non-destructive testing(NDT) system was developed to monitor the steel cables that are a core component of cable-stayed bridges. The magnetic flux leakage(MFL) method, which is suitable for ferromagnetic continuum structures and has been verified in previous studies, was applied to the cable inspection. A multi-channel MFL sensor head was fabricated using hall sensors and permanent magnets. A wheel-based cable climbing robot was fabricated to improve the accessibility to the cables, and operating software was developed to monitor the MFL-based NDT research and control the climbing robot. Remote data transmission and robot control were realized by applying wireless LAN communication. Finally, the developed element techniques were integrated into an MFL-based cable NDT system, and the field applicability of this system was verified through a field test at Seohae Bridge, which is a typical cable-stayed bridge currently in operation.
Introduction to Terahertz Wave Technology and Its Usage for Nondestructive Testing Evaluation
Kim, Hak-Sung ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 68~76
Capacitive Micromachined Ultrasonic Transducer (CMUT) for Ultrasound Imaging Application
Park, Kwan Kyu ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 1, 2014, Pages 77~84