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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 23, Issue 6 - Dec 2003
Volume 23, Issue 5 - Oct 2003
Volume 23, Issue 4 - Aug 2003
Volume 23, Issue 3 - Jun 2003
Volume 23, Issue 2 - Apr 2003
Volume 23, Issue 1 - Feb 2003
Selecting the target year
A Study of the Guided Wave Propagation in the Water Supplying Pipes with Scale
Song, Sung-Jin ; Lee, Dong-Hoon ; Lee, Hyun-Dong ; Bae, Cheol-Ho ; Park, Jung-Hoon ; Kim, Young-H. ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 1, 2003, Pages 1~6
Since the scale in pipes reduces the flow rate, a quantitative evaluation of the scale is essential for the proper maintenance of pipes. Guided waves were employed to estimate the amount of scale in water supplying pipes. Using variable angle wedge, several modes of guided waves wire generated and their propagation charcteristics along the pipes with stale were analyzed. It was experimentally observed that the amplitude of F(M,2) modes at
decreased significantly with increasing amount of scale. The present study showed that F(M,2) modes were optima) to evaluate the scale in water supplying pipes.
Development of On-line Monitoring System for Shape Memory Alloy Composite
Lee, Jin-Kyung ; Park, Young-Chul ; Lee, Min-Rae ; Lee, Dong-Hwa ; Lee, Kyu-Chang ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 1, 2003, Pages 7~13
A hot press method was use for the optimal manufacturing condition for a shape memory alloy(SMA) composite. The bonding between the matrix and the reinforcement within the SMA composite by the hot press method was strengthened by cold rolling. In this study, the objective was to develop an on-line monitoring system for the prevention of the crack initiation and propagation by shape memory effort of SMA composite. Shape memory effect was used to prevent the SMA composite from cracking. For the system to be developed, an optimal hE parameter should be determined based on the degree of damage and crack initiation. When the SHA composite was heated by the plate heater attached at the composite, the propagating cracks appeared to be controlled by the compressive force of SMA.
Development and Characterization of Ultrasonic transducers for High Temperature Contact Measurement
Kim, Ki-Bok ; Kim, Byoung-Geuk ; Lee, Seung-Seok ; Yoon, Nam-Won ; Yoon, Dong-Jin ; Ahn, Yoon-Kook ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 1, 2003, Pages 14~20
Piezoelectric ultrasonic transducers for high temperature contact measurement were developed. These high temperature ultrasonic transducers (HTUT) consisted of bismuth titanate piezoceramic element whose Curie temperature is higher than
, a backing material of the mixture of tungsten powder and inorganic binder, an inner alumina tube, a wear Plate and a housing. The operational frequencies or the HTUT were 1.04 and 2.08 MHz, respectively. Various commercially available couplants for high temperature were evaluated and compared. As a couplant for high temperature ultrasonic testing between HTUT and test specimen, gold epoxy was selected. The peak amplitude of pulse-echo signals from steel test specimen decreased with increasing temperature. The operational temperature of the HTUT reached up to
at which the continuous contact measurement was possible.
Development of Vision Control Scheme of Extended Kalman filtering for Robot's Position Control
Jang, W.S. ; Kim, K.S. ; Park, S.I. ; Kim, K.Y. ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 1, 2003, Pages 21~29
It is very important to reduce the computational time in estimating the parameters of vision control algorithm for robot's position control in real time. Unfortunately, the batch estimation commonly used requires too murk computational time because it is iteration method. So, the batch estimation has difficulty for robot's position control in real time. On the other hand, the Extended Kalman Filtering(EKF) has many advantages to calculate the parameters of vision system in that it is a simple and efficient recursive procedures. Thus, this study is to develop the EKF algorithm for the robot's vision control in real time. The vision system model used in this study involves six parameters to account for the inner(orientation, focal length etc) and outer (the relative location between robot and camera) parameters of camera. Then, EKF has been first applied to estimate these parameters, and then with these estimated parameters, also to estimate the robot's joint angles used for robot's operation. finally, the practicality of vision control scheme based on the EKF has been experimentally verified by performing the robot's position control
Position Control Technique of Ultrasonic Scanner for an Automated Ultrasonic Testing Using Surface Wave
Lee, Jong-Po ; Park, Chul-Hoon ; Um, Byong-Guk ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 1, 2003, Pages 30~37
In order to replace the manual ultrasonic testing(UT) with an automated UT(AUT), a scanner which enables us to control the positions of a transducer is essential. Encoders have been commonly used to obtain the position information from the conventional scanners controlled by motor. Encoders have various advantages in many aspects. However, if the slip of motor wheel occurs during scanning, various errors are involved in the position accuracy. Thus, the position information of encoders becomes meaningless in case of slip. The reliability of AUT results nay become serious problem. Hence, slip must be avoided, but it can not be completely avoided at present time. In this paper, a new idea that surface wave is used to solve this problem and replace encoders has been proposed. It is shown that this idea can be employed in AUT scanner without encoders. That is, one transducer transmitting surface wave is fixed and the other transducer attached to the scanner receives UT signal. Then, computer calculates the present position of scanner based on the information given by surface wave. Thus, the movement of a scanner can be controlled by the amount of input based on the information obtained.
Fabrication of Mechanical fatigue flawed Specimen and Evaluation of Flaw Size
Hong, Jae-Keun ; Kim, Woo-Sung ; Son, Young-Ho ; Park, Ban-Uk ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 1, 2003, Pages 38~44
Performance demonstration with real flawed specimens has been strongly required for nondestructive evaluation of safety class components in nuclear power plant. Mechanical or thermal fatigue crack and intergranular stress corrosion cracking could be occured in the in-service nuclear power plant and mechanical fatigue crack was selected to study in this paper. Specimen was designed to produce mechanical fatigue flaw under tensile stress. The number of cycles and the level of stress were controlled to obtain the desired flaw roughness. After the accurate physical measurement of the flaw size and location, fracture surface was seal-welded in place to ensure the designed location and site. The remaining weld groove was then filled by using gas-tungsten are welding(GTAW) and flux-cored arc welding(FCAW). Results of radio graphic and ultrasonic testing showed that fatigue cracks were consistent with the designed size and location in the final specimens.
Ultrasonic Flaw Detection in Turbine Rotor Disc Keyway Using Neural Network
Son, Young-Ho ; Lee, Jong-O ; Yoon, Woon-Ha ; Lee, Byung-Woo ; Seo, Won-Chan ; Lee, Jong-Kyu ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 1, 2003, Pages 45~52
A number of stress corrosion cracks in turbine rotor disk keyway in power plants have been found and the necessity has been raised to detect and evaluate the cracks prior to the catastrophic failure of turbine disk. By ultrasonic RF signal analysis and using a neural network based on bark-propagation algorithm, we tried to evaluate the location, size and orientation of cracks around keyway. Because RF signals received from each reflector have a number of peaks, they were processed to have a single peak for each reflector. Using the processed RF signals, scan data that contain the information on the position of transducer and the arrival time of reflected waves from each reflector were obtained. The time difference between each reflector and the position of transducer extracted from the scan data were then applied to the back-propagation neural network. As a result, the neural network was found useful to evaluate the location, size and orientation of cracks initiated from keyway.