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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 30, Issue 6 - Dec 2010
Volume 30, Issue 5 - Oct 2010
Volume 30, Issue 4 - Aug 2010
Volume 30, Issue 3 - Jun 2010
Volume 30, Issue 2 - Apr 2010
Volume 30, Issue 1 - Feb 2010
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Frequency-Based Image Analysis of Random Patterns: an Alternative Way to Classical Stereocorrelation
Molimard, J. ; Boyer, G. ; Zahouani, H. ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 181~193
The paper presents an alternative way to classical stereocorrelation. First, 2D image processing of random patterns is described. Sub-pixel displacements are determined using phase analysis. Then distortion evaluation is presented. The distortion is identified without any assumption on the lens model because of the use of a grid technique approach. Last, shape measurement and shape variation is caught by fringe projection. Analysis is based on two pin-hole assumptions for the video-projector and the camera. Then, fringe projection is coupled to in-plane displacement to give rise to 3D measurement set-up. Metrological characterization shows a resolution comparable to classical (stereo) correlation technique (
pixel). Spatial resolution seems to be an advantage of the method, because of the use of temporal phase stepping (shape measurement, 1 pixel) and windowed Fourier transform (in plane displacements measurement, 9 pixels). Two examples are given. First one is the study of skin properties; second one is a study on leather fabric. In both cases, results are convincing, and have been exploited to give mechanical interpretation.
Prediction of the Fundamental Mode Lamb Wave Reflection from a Crack-Like Discontinuity Using Eigen-Mode Expansion
Park, Jae-Seok ; Jang, Chang-Heui ; Lee, Jong-Po ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 194~199
Based on the idea of eigen-mode expansion, a method to analyze the reflection of Lamb wave from a finite vertical discontinuity of plate is theoretically derived and verified by experiment. The theoretical prediction is in good agreement with the experimental result, and this strongly suggests that eigen-mode expansion method could be used for solution of inverse scattering problem for ultrasonic testing using Lamb wave.
Characteristics on Temperature Evolution in the Metallic Specimen by Ultrasound-Excited Thermography
Choi, M.Y. ; Park, J.H. ; Kang, K.S. ; Kim, W.T. ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 200~206
In ultrasound-excited thermography, the injected ultrasound to an object is transformed to heat and the appearance of defects can be visualized by thermography camera. The advantage of this technology is selectively sensitive to thermally active defects. Despite the apparent simplicity of the scheme, there are a number of experimental considerations that can complicate the implementation of ultrasound excitation thermography inspection. Factors including acoustic horn location, horn-crack proximity, horn-sample coupling, and effective detection range all significantly affect the detect ability of this technology. As conclusions, the influence of coupling pressures between ultrasound exciter and specimen was analyzed, which was dominant factor in frictional heating model.
Measurement of Sound Speed Following the Fluid Temperature Using Acoustic Inspection Device
Jeon, E.S. ; Kim, W.T. ; Kim, I.S. ; Park, H. ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 207~211
In this paper, the fluid AID(acoustic inspection device) was developed to measure SOS(speed of sound) since fluids used in most of industrial fields have different properties and its equipment is highly expensive. From AID developed, it is intended to get potentially the capability to distinguish the kind of fluid using the measurement by the SOS at various fields. In order to measure the sound speed of specific fluids, the measurement system and ultrasonic sensors are composed. The fluid used in the experimental work are soybean oil, glycerin, diesel oil and the error of time difference due to the container wall is extracted for preliminary experiment. As results, the variations of sound speed according to the temperature change of target fluid were analyzed and the polynomial equations were proposed.
An Application of a Magnetic Camera for an NDT System for Aging Aircraft
Kim, Jung-Min ; Jun, Jong-Woo ; Lee, Jae-Sun ; Lee, Jin-Yi ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 212~224
The usefulness of the magnetic camera for non-destructive testing of aging aircraft is discussed in this paper. The magnetic camera can be used f magnetic particle testing(MT), magnetic flux leakage testing(MFLT), eddy current testing(ECT) and penetration testing(PT). It measures the distribution of a magnetic field and visualizes the magnetic pattern. Near and far side cracks, fatigue, thickness degradation, and cracks under rivets have been detected. The possibility of quantitative evaluation was also examined. Using indirect experiments, we verified the detection ability of the sensor for cracks in titanium and advanced composite materials.
A Study on 3-Dimensional Profilometry of Steam Generator Tube Using a New Eddy Current Probe
Kim, Young-Kyu ; Song, Myung-Ho ; Choi, Myung-Sik ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 225~235
There are many types of the geometric transitions such as dent, bulge, protrusion, expansion, etc, on the inner and outer surfaces of heat exchanger tubes, steam generator tubes, and condenser tubes of nuclear power plants. Such geometric transition causes a local residual stress in heat exchanger tubes and acts as a structural factor accelerating the evolution of defects, in particular stress corrosion cracks. In the conventional eddy current test methods, the bobbin coil profilometry can provide 2-dimensional geometric information on the variation of the average inner diameter along the tube length, but the 3-dimensional distribution and the quantitative size of a local geometric transition existing in the tube cannot be measured. In this paper, a new eddy current probe, developed for the 3-dimensional profile measurement, is introduced and its superior performance is compared with that from the conventional bobbin coil profilometry for the various types of geometric transition. Also, the accuracy of the probe for the quantitative profile measurement is verified by comparing the results with that from the laser profilometry. It is expected that the new eddy current probe and techniques can be effectively used for an optimization of the tube expansion process, and the management of tubes with geometric transitions in service.
Strain Transmission Characteristics of Packaged Fiber Bragg Grating Sensors for Structural Health Monitoring
Cho, Sung-In ; Yoo, Seung-Jae ; Kim, Eun-Ho ; Lee, In ; Kwon, Il-Bum ; Yoon, Dong-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 236~243
Fiber Bragg grating(FBG) sensor arrays can be used to monitor the mechanical behavior of the large composite structures such as wind turbine rotor blades and aircrafts. However, brittle FBG sensors, especially multiplexed FBG sensors are easily damaged when they are installed in the flexible structures. As a protection of brittle FBG sensors, epoxy packaged FBG sensors have been presented in this paper. Finite element analysis and experiments were performed to evaluate the effects of adhesives, packaging materials and the bonding layer thickness on the strain transmission. Two types of epoxy were used for packaging FBG sensors and the sensor probes were attached with various bonding layer thickness. It was observed that thin bonding layer with high elastic modulus ratio of the adhesive to packaging provided good strain transmission. However, the strain transmission was significantly decreased when elastic modulus of the adhesive was much lower than the packaged FBG sensor probe's one.
Review of Radio Frequency Identification and Wireless Technology for Structural Health Monitoring
Dhital, Dipesh ; Chia, Chen Ciang ; Lee, Jung-Ryul ; Park, Chan-Yik ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 244~256
Radio frequency identification(RFID) combined with wireless technology has good potential for structural health monitoring(SHM). We describe several advantages of RFID and wireless technologies for SHM, and review SHM examples with working principles, design and technical details for damage detection, heat exposure monitoring, force/strain sensing, and corrosion detection in concrete, steel, carbon fiber reinforced polymer(CFRP), and other materials. Various sensors combined with wireless communication are also discussed. These methodologies can be readily developed, implemented, and customized. There are some technical difficulties, but solutions are being addressed. Lastly, a surface acoustic wave-based RFID system is presented, and possible future trends of SHM based on RFID and wireless technology are presented.
Micro-Structure Measurement and Imaging Based on Digital Holography
Kim, Kyeong-Suk ; Jung, Hyun-Chul ; Chang, Ho-Seob ; Kee, Chang-Doo ; Akhter, Naseem ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 257~260
Advancements in the imaging and computing technology have opened the path to digital holography for non-destructive investigations of technical samples, material property measurement, vibration analysis, flow visualization and stress analysis in aerospace industry which has widened the application of digital holography in the above fields. In this paper, we demonstrate the non-destructive investigation and micro-structure measurement application of digital holography to the small particles and a biological sample. This paper gives a brief description of the digital holograms recorded with this system and illustratively demonstrated.
Imaging of a Defect in Thin Plates Using the Time Reversal of Single Mode Lamb Wave: Simulation
Jeong, Hyun-Jo ; Lee, Jung-Sik ; Bae, Sung-Min ; Lee, Hyun-Ki ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 261~270
This paper presents an analytical investigation for a baseline-free imaging of a defect in plate-like structures using the time-reversal of Lamb waves. We first consider the flexural wave (A0 mode) propagation in a plate containing a defect, and reception and time reversal process of the output signal at the receiver. The received output signal is then composed of two parts: a directly propagated wave and a scattered wave from the defect. The time reversal of these waves recovers the original input signal, and produces two additional side bands that contain the time-of-flight information on the defect location. One of the side band signals is then extracted as a pure defect signal. A defect localization image is then constructed from a beamforming technique based on the time-frequency analysis of the side band signal for each transducer pair in a network of sensors. The simulation results show that the proposed scheme enables the accurate, baseline-free detection of a defect, so that experimental studies are needed to verify the proposed method and to be applied to real structure.
A Special Pre-Service-Inspection Using Radiographic Testing(RT) for Brazing Fitting Uused in Aircraft Hydraulic System
Kim, Gyu-Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 271~281
Brazing fitting which is one of the aircraft hydraulic power system components is widely used for saving weight and achieving higher reliability. Any inherent defects or damage of fitting can cause system failure and/or physical damage of human body due to highly pressurized fluid. Radiographic testing(RT) technique and additional micro-structure investigation on cut-away surfaces have been accomplished to find out some defect-like-inhomogeneity in the fittings. The radiography results showed that some defect-like-inhomogeneity existed inside body. Additional micro-structure investigation on cut-away surface reveals that the inhomogeneity is due to internal voids. In this study, it can be is said that RT technique can be a useful tool for field acceptance test of hydraulic brazing fitting in short time.
Detection of Damages in Concrete Structures Using Non-Contact Air-Coupled Sensing Methods
Shin, Sung-Woo ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 3, 2010, Pages 282~289
Most nondestructive testing techniques require good contact between the sensor and tested concrete surface to obtain reliable data. But the surface preparation is often very time and labor consuming due to the rough surface or limited access of concrete structures. One approach to speed up the data collection process is to eliminate the need for physical contact between the sensor and tested structure. Non-contact air-coupled sensing technique can be a good solution to this problem. An obvious advantage of the non-contact air-coupled sensing technique is which can greatly speed up the data collection in field and thus the damage detection process can be completed very rapidly. In this article, recent developments in non-contact air-coupled sensing technique for rapid detection of damages in concrete structures are summarized to evoke interest, discussion and further developments on this technique to a NDT research community in Korea. It is worth noting that the works in this article have been published in the types of thesis, proceedings, and journals. All published sources are cited in the text and listed in reference.