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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
Editor in Chief :
Volume & Issues
Volume 25, Issue 6 - Dec 2005
Volume 25, Issue 5 - Oct 2005
Volume 25, Issue 4 - Aug 2005
Volume 25, Issue 3 - Jun 2005
Volume 25, Issue 2 - Apr 2005
Volume 25, Issue 1 - Feb 2005
Selecting the target year
Health Monitoring for Large Structures using Brillouin Distributed Sensing
Thevenaz, L. ; Chang, KT. ; Nikles, M. ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 421~430
Brillouin time-domain analysis in optical fibres is a novel technique making possible a distributed measurement of temperature and strain over long distance and will deeply modify our view about monitoring large structures, such as dams, bridges, tunnels and pipelines, Optical fibre sensing will certainly be a decisive tool for securing dangerous installations and detecting environmental and industrial threats.
Experimental Analysis of Unsteady Bubble Behaviors Using Three-Dimensional Tomography
Ko, Han-Seo ; Kim, Yong-Jae ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 431~438
Bubble behaviors in a circular tube have been analyzed numerically and experimentally by a three-dimensional tomography method, Initially, a multiplicative algebraic reconstruction technique (MART) which showed better results for previous studies of numerical simulations has been performed to confirm the accuracy of the three-dimensional reconstruction for the two-phase flow using a computer-synthesized phantom, Then, bubble behaviors have been investigated experimentally by the three-dimensional MART method using real projected data captured simultaneously by a laser and three CCD cameras for three angles of view, Also, the transient reconstructions have been attempted to analyze the real-time oxygen-bubble movements in water by the interval of 1/30 second.
Ultrasonic Inspection of Cracks in Stud Bolts of Reactor Vessels in Nuclear Power Plants by Signal Processing of Differential Operation
Choi, Sang-Woo ; Lee, Joon-Hyun ; Oh, Won-Deok ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 439~445
The stud bolt is one of crucial parts for safe operation of reactor vessels in nuclear power plants, Crack initiation and propagation were reported in stud bolts that arc used for closure of reactor vessel and head, Stud bolts are inspected by ultrasonic technique during overhaul periodically for the prevention of stud bolt failure which could induce radioactive leakage from nuclear reactor, In conventional ultrasonic testing for inspection of stud bolts, cracks are detected by using shadow effect It takes too much time to inspect stud bolts by using conventional ultrasonic technique. In addition, there were numerous spurious signals reflected from every oblique surfaces of thread, In this study, the signal processing technique for enhancing conventional ultrasonic technique was introduced for inspecting stud bolts. The signal processing technique provides removing spurious signal reflected from every oblique surfaces of thread and enhances detectability of defects. Detectability for small crack was enhanced by using this signal processing in ultrasonic inspection of stud bolts in Nuclear Power Plants.
Development of a Spherically Focused Capacitive-film Air-coupled Ultrasonic Transducer
Song, Jun-Ho ; Chimenti Dale E. ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 446~450
We have built a spherically focused, not using acoustic mirrors, capacitive micromachined air-coupled ultrasonic transducer. A flexible backplate of a copper/polyimide backplate is used, permitting it to conform to a spherically shaped substrate. The backplate is patterned with
center-to-center spacing. A
thick aluminized Mylar film completing the transducer is deformed to allow it to conform to the spherical backplate. The device's frequency spectrum is centered at 805kHz with -6dB points at 440 and 1210kHz.
Fiber Orientation Effects on the Fracture Process and Acoustic Emission Characteristics of Composite Laminates
Woo, Sung-Choong ; Kim, Jung-Heun ; Choi, Nak-Sam ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 451~458
The effects of fiber orientation on acoustic emission(AE) characteristics have been studied for various composite laminates. Reflection and transmission optical microscopy were used to investigate the damage zone of specimens. AE signals were classified through short time Fourier transform(STFT) as different types: AE signals with a high intensity and high frequency band were due to fiber fracture, while weak AE signals with a low frequency band were due to matrix cracking and/or interfacial cracking. Characteristic feature in the rate of hit-events having high amplitudes showed a procedure of fiber breakages, which expressed the characteristic fracture processes of notched fiber-reinforced plastics with different fiber orientations. As a consequence, the behavior of fracture in the continuous composite laminates could be monitored through nondestructive evaluation(NDE) using the AE technique.
Fabrication of Microcantilever Ultrasound Sensor and Its Application to the Scanning Laser Source Technique
Sohn, Young-Hoon ; Krishnaswamy, Sridhar ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 459~466
The scanning laser source (SLS) technique has been proposed recently as an effective way to investigate small surface-breaking defects, By monitoring the amplitude and frequency changes of the ultrasound generated as the SLS scans over a defect, the SLS technique has provided enhanced signal-to-noise performance compared to the traditional pitch-catch or pulse-echo ultrasonic methods, An extension of the SLS approach to map defects in microdevices is proposed by bringing both the generator and the receiver to the near-field scattering region of the defects, To facilitate near-field ultrasound measurement, silicon microcantilever probes are fabricated using microfabrication technique and their acoustical characteristics are investigated, Then, both the laser-generated ultrasonic source and the microcantilever probe are used to monitor near-field scattering by a surface-breaking defect.
Modeling Phased Array Ultrasonic Testing of a Flat-Bottom Hole in a Single Medium
Park, Joon-Soo ; Kim, Hak-Joon ; Song, Sung-Jin ; Seong, Un-Hak ; Kang, Suk-Chull ; Choi, Young-Hwan ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 467~474
The expanded multi-Gaussian beam model has recently been developed that can calculate the radiation beam field from a single, rectangular transducer with great computational efficiency. In this study, this model is adopted to calculate the radiation beam field for a phased array transducer with various time delays to achieve steering and/or focusing. The calculation beam fields are compared to those obtained by well known Rayleigh-Sommerfeld integral that provides the exact solution in order to explore the validity of the expanded multi-Gaussian beam model And then, this study proposes a complete ultrasonic measurement model including the expanded beam model, far-field scattering model and system efficiency, Using the proposed model, phased array ultrasonic testing signals for a flat-bottomed hole with/without focusing were performed.
Application of Neural Network to Determine the Source Location in Acoustic Emission
Lee, Sang-Eun ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 475~482
The iterative calculation by least square method was used to determine the source location of acoustic emission in rock, as so called "traditional method". The results were compared with source coordinates infered from the application of neural network system for new input data, as so called "new method". Input data of the neural network were based on the time differences of longitudinal waves arrived from acoustic emission events at each transducer, the variation of longitudinal velocities at each stress level, and the coordinates of transducer as in the traditional method. The momentum back propagation neural network system adopted to determine source location, which consists of three layers, and has twenty-seven input processing elements. Applicability of the new method were identified, since the results of source location by the application of two methods were similarly concordant.
A Relationship between UT Reported Sizes and Actual Sizes of Defects in Rotor Forgings
Seong, Un-Hak ; Kim, Jeong-Tae ;
Journal of the Korean Society for Nondestructive Testing, volume 25, issue 6, 2005, Pages 483~486
The relationship between the EFBH (Equivalent Flat-Bottom Hole) size measured by non-destructive method and the actual size by destructive method in many rotors manufactured at Doosan Heavy Industries & Construction Co. Ltd. was investigated. In this investigation. "the Master Curve" compensating the differences between UT reported sizes and actual sizes of defects in our rotor forgings were obtainable. The applicability of this "Master Curve" as a way of calculating the actual defect size was also investigated. For the evaluation of rotor forgings, it is expected that this "Master Curve" may be used to determine the accurate actual sizes of defects.