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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
Selecting the target year
Stochastic Estimation of Acoustic Impedance of Glass-Reinforced Epoxy Coating
Kim, Nohyu ; Nah, Hwan-Seon ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 119~127
DOI : 10.7779/JKSNT.2014.34.2.119
An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.
Detection of Subsurface Defects in Metal Materials Using Infrared Thermography; Image Processing and Finite Element Modeling
Ranjit, Shrestha ; Kim, Won Tae ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 128~134
DOI : 10.7779/JKSNT.2014.34.2.128
Infrared thermography is an emerging approach to non-contact, non-intrusive, and non-destructive inspection of various solid materials such as metals, composites, and semiconductors for industrial and research interests. In this study, data processing was applied to infrared thermography measurements to detect defects in metals that were widely used in industrial fields. When analyzing experimental data from infrared thermographic testing, raw images were often not appropriate. Thus, various data analysis methods were used at the pre-processing and processing levels in data processing programs for quantitative analysis of defect detection and characterization; these increased the infrared non-destructive testing capabilities since subtle defects signature became apparent. A 3D finite element simulation was performed to verify and analyze the data obtained from both the experiment and the image processing techniques.
Evaluation of Detectable Defect Size for Inner Defect of Pressure Vessel Using Laser Speckle Shearing Interferometry
Kim, Kyeong-Suk ; Seon, Sang-Woo ; Choi, Tae-Ho ; Kang, Chan-Geun ; Na, Man-Gyun ; Jung, Hyun-Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 135~140
DOI : 10.7779/JKSNT.2014.34.2.135
Pressure vessels are used in various industrial fields. If a defect occurs on the inner or outer surface of a pressure vessel, it may cause a massive accident. A defect on the outer surface can be detected by visual inspection. However, a defect on the inner surface is generally impossible to detect with visual inspection. Nondestructive testing can be used to detect this type of defect. Laser speckle shearing interferometry is one nondestructive testing method that can optically detect a defect; its advantages include noncontact, full field, and real time inspection. This study evaluated the detectable size for an internal defect of a pressure vessel. The material of the pressure vessel was ASTM A53 Gr.B. The internal defect was detected when the pressure vessel was loaded by internal pressure controlled by a pneumatic system. The internal pressure was controlled from 0.2 MPa to 0.6 MPa in increments of 0.2 MPa. The results confirmed that an internal defect with a 25 % defect depth could be detected even at 0.2 MPa pressure variation.
Degradation Assessment of Thermoplastic Synthetic Resin Using Propagation Characteristics of Ultrasound
Jeon, Woo-Sang ; Kim, Gi-Jin ; Kwon, Sung-Duk ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 141~147
DOI : 10.7779/JKSNT.2014.34.2.141
A nondestructive ultrasonic technique was applied to evaluate the thermal characteristics and degradation of synthetic polymer resin (plastics) with better cost-effectiveness and functionality than glass and metal. Thermoplastic and transparent acrylic resin (PMMA) specimens were annealed at below the glass transition temperature (
), and the propagation characteristics (attenuation and velocity) were measured. The attenuation increased and the velocity decreased with thermal degradation. The results showed that the thermal aging of the specimens could be evaluated quantitatively and that the Tg could be evaluated qualitatively.
Photoelastic Stress Analysis for a Rhombus Plate under Compressive Load Using Image Processing Technique
Liu, Guan Yong ; Kim, Myung Soo ; Baek, Tae Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 148~154
DOI : 10.7779/JKSNT.2014.34.2.148
Photoelasticity is a useful technique for obtaining the differences and directions of principal stresses in a model. In conventional photoelasticity, the photoelastic parameters are measured manually point by point. Identifying and measuring photoelastic data is time-consuming and requires skill. The fringe phase shifting method was recently developed and has been found to be convenient for measuring and analyzing fringe data in photo-mechanics. This paper presents an experimental study on the stress distribution along a horizontal line that passes the central point of a rhombus plate made of Photoflex (i.e., type of urethane rubber). The isoclinic fringe and/or principal stress direction is constant on this horizontal line, so a four-bucket phase shifting method can be applied. The method requires four photoelastic fringes that are obtained from a circular polariscope by rotating the analyzer at
. Experimental measurements using the method were quantitatively compared with the results from FEM analysis; the results from the two methods showed comparable agreement.
Characterization of Water Absorption by CFRP Using Air-Coupled Ultrasonic Testing
Lee, Joo-Min ; Lee, Joo-Sung ; Kim, Yong-Kwon ; Park, Ik-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 155~164
DOI : 10.7779/JKSNT.2014.34.2.155
Carbon-fiber-reinforced plastic (CFRP) composites are increasingly being used in a variety of industry applications, such as aircraft, automobiles, and ships because of their high specific stiffness and high specific strength. Aircraft are exposed to high temperatures and high humidity for a long duration during flights. CFRP materials of the aircraft can absorb water, which could decrease the adhesion strength of these materials and cause their volumes to change with variation in internal stress. Therefore, it is necessary to estimate the characteristics of CFRP composites under actual conditions from the viewpoint of aircraft safety. In this study air-coupled ultrasonic testing (ACUT) was applied to the evaluation of water absorption properties of CFRP composites. CFRP specimens were fabricated and immersed in distilled water at
for 30, 60, and 120 days, after which their ultrasonic images were obtained by ACUT. The water absorption properties were determined by quantitatively analyzing the changes in ultrasonic signals. Further, shear strength was applied to the specimens to verify the changes in their mechanical properties for water absorption.
Application of a Fiber Fabry-Pérot Interferometer Sensor for Receiving SH-EMAT Signals
Lee, Jin-Hyuk ; Kim, Dae-Hyun ; Park, Ik-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 165~170
DOI : 10.7779/JKSNT.2014.34.2.165
Shear horizontal (SH) waves propagate as a type of plate wave in a thin sheet. The dispersion characteristics of SH waves can be used for signal analysis. Therefore, SH-waves are useful for monitoring the structural health of a thin-sheet-structure. An electromagnetic acoustic transducer (EMAT), which is a non-contact ultrasonic transducer, can generate SH-waves easily by varying the shape and array of magnets and coils. Therefore, an EMAT can be applied to an automated ultrasonic testing system for structural health monitoring. When used as a sensor, however, the EMAT has a weakness in that electromagnetic interference (EMI) noise can occur easily in the automated system because of motors and electric devices. Alternatively, a fiber optic sensor works well in the same environment with EMI noise because it uses a light signal instead of an electric signal. In this paper, a fiber Fabry-P
rot interferometer (FFPI) was proposed as a sensor to receive the SH-waves generated by an EMAT. A simple test was performed to verify the performance of the FFPI sensor. It is thus shown that the FFPI can receive SH-wave signals clearly.
Thickness Measurement of Ni Thin Film Using Dispersion Characteristics of a Surface Acoustic Wave
Park, Tae-Sung ; Kwak, Dong-Ryul ; Park, Ik-Keun ; Kim, Miso ; Lee, Seung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 171~175
DOI : 10.7779/JKSNT.2014.34.2.171
In this study, we suggest a method to measure the thickness of thin films nondestructively using the dispersion characteristics of a surface acoustic wave propagating along the thin film surface. To measure the thickness of thin films, we deposited thin films with different thicknesses on a Si (100) wafer substrate by controlling the deposit time using the E-beam evaporation method. The thickness of the thin films was measured using a scanning electron microscope. Subsequently, the surface wave velocity of the thin films with different thicknesses was measured using the V(z) curve method of scanning acoustic microscopy. The correlation between the measured thickness and surface acoustic wave velocity was verified. The wave velocity of the film decreased as the film thickness increased. Therefore, thin film thickness can be determined by measuring the dispersion characteristics of the surface acoustic wave velocity.
Study of Quantitative Assessment Standard for Type 1 and Type 2 Gas Cylinders Using Acoustic Emission Testing
Kim, Dong-Hyun ; Lee, Sang-Bum ; Kim, Kyung-Hoon ; Yoon, Dong-Jin ; Bae, Dong-Myung ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 176~183
DOI : 10.7779/JKSNT.2014.34.2.176
Acoustic emission testing (AET) of cylinders is advantageous in that it can be directly conducted on cylinders installed in a car, without needing to dissemble them on a real-time basis. Therefore, users prefer AET over other nondestructive testing methods. Owing to these advantages of AET, it has been approved by the Department of Transportation of the U.S. as a safety evaluation method for pressure containers or as an alternative to the hydroproof testing method. This paper presents a study of the quantitative evaluation criteria for a container having ultrasonic testing defects and also for Type 1 and Type 2 gas cylinders, which are defective seamless pressure containers provided by NK, a manufacturer of pressure containers. For the Type 1 cylinder, the process from crack growth to leak was observed in a repetitive fatigue test using a 113 L container according to ASTM E 1419-02. Further, for the Type 2 cylinder, integrity was evaluated using a 119 L sound container and a container damaged by hydraulic pressure, by the slow-fill method according to ASTM E 2191-02. Based on the AET results of the Type 1 and Type 2 cylinders, quantitative evaluation criteria were established for a defective and non-defective container.
Test Technologies of the Leak and Water Absorption for Water-Cooled Generator Stator
Bae, Sung Won ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 184~189
Digital Holographic Tomography
Jung, Hyunchul ;
Journal of the Korean Society for Nondestructive Testing, volume 34, issue 2, 2014, Pages 190~195