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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Nondestructive Testing
Journal Basic Information
Journal DOI :
The Korean Society for Nondestructive Testing
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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
Virtual Reality Presentation of Moment Tensor Analysis by SiGMA
Ohtsu, Masayasu ; Shigeishi, Mitsuhiro ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 189~197
Nucleation of a crack is readily defected by acoustic emission (AE) method. One powerful technique for AE waveform analysis has been developed as SiGMh (Simplified Greens functions for Moment tensor Analysis), as crack kinematics of locations, types and orientations are quantitatively determined. Because these kinematical outcomes are obtained as three-dimensional (3-D) locations and vectors, 3-D visualization is definitely desirable. To this end, the visualization system has been developed by using VRML (Virtual Reality Modeling Language). As an application, failure protest of a reinforced concrete beam is discussed.
Characteristics of AE Signals from Plant according to the Environmental Variation
Nam, Ki-Woo ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 198~204
A basic experiment was performed to control tile plant growth using acoustic emission technique considering the environmental conditions for plant. At a dry soil condition, the signals due to the cavitation from xylem of angiosperm and gymnosperm were mainly detected. The strong signal from xylem and the weak signal from plasmodesmata and casparian strip were detected at the same time after distilled water was provided. Two signals after providing tile acid and distilled water were contrary to each other. The wind, number of leaf, music, temperature and humidity affected the acoustic emission count from plants but the frequency ranges of the detected signals were the same.
A Study of the Development of PC-Based Source Location System using Acoustic Emission Technique
Lee, M.R. ; Lee, J.H. ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 205~211
Acoustic emission (AE) technique has been applied to not only mechanical property testing but also on-line monitoring of the el)tire structure or a limit zone only. Although several AE devices have already been developed for the on-line monitoring, the price of these systems is very high and it is difficult for the field to apply yet. In this study, wc developed a specially designed PC-based source location system using the A/D board. The source location technique is very important to identify the source, such as crack, leak detection. However, since the AE waveforms obtained from transducers are very difficult to distinguish the defect signals, therefore, it is necessary to consider the signal analyses of the transient waveform. Wavelet Transform (WT) is a powerful tool for processing transient signals with temporally varying spectra that helps to resolve high and low frequency transients components effectively In this study, the analyses of the AE signals are presented by employing the WT analyses. AE results are compared the PC-based source location system using A/D board with the commercial AE system.
Characterization of Stress Corrosion Cracking at the Welded Region of High Strength Steel using Acoustic Emission Method
Na, Eui-Gyun ; Kim, Hoon ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 212~219
This study is to evaluate the characteristics of SCC at the welded region of high strength steel using acoustic emission(AE) method. Specimens were loaded by a slow strain rate method in synthetic seawater and the damage process was monitored simultaneously by AE method. Corrosive environment was controlled using the potentiostat, in which -0.8V and -1.1V were applied to the specimens. In the case of one-pass weldment subjected to -0.8V, much more AE counts were detected compared with the PWHT specimen. It was verified through the cumulative counts that coalescence of micro cracks and cracks for the one pass weldment with -0.8V were mostly detected. In case of the one pass weldment subjected to -1.1V, time to failure became shorter and AE counts were produced considerably as compared with that of the two pass weldment. It was shown that AE counts and range of AE amplitude have close relations with the number and size as well as width of the cracks which were formed during the SCC.
A Study on the Application of Acoustic Emission for the fatigue Test of Ship Welded Structure
An, Sung-Chan ; Kim, Dae-Soo ; Lee, Jin-Hee ; Park, Jin-Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 220~226
This paper presents the result of an investigation on the application of the acoustic emission method to the monitoring of fatigue crack initiation, growth and track location in welded joints. Fatigue test was carried out for a typical fillet welded joint of ship structure. AE parameter such as ring down count was analyzed in time domain and crack locations were examined by source location and cluster option which is one of the functions of AE signal processor The usability of AE mettled was confirmed for the detection of the initiation and location of through crack.
Leak Location Detection of Underground Water Pipes using Acoustic Emission and Acceleration Signals
Lee, Young-Sup ; Yoon, Dong-Jin ; Jeong, Jung-Chae ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 227~236
Leaks in underground pipelines can cause social, environmental and economical problems. One of relevant countermeasures against leaks is to find and repair of leak points of the pipes. Leak noise is a good source to identify the location of leak points of the pipelines. Although there have been several methods to detect the leak location with leak noise, such as listening rods, hydrophones or ground microphones, they have not been so efficient tools. In this paper, acoustic emission (AE) sensors and accelermeters are used to detect leak locations which could provide all easier and move efficient method. Filtering, signal processing and algorithm of raw input data from sensors for the detection of leak location are described. A 120m-long pipeline system for experiment is installed and the results with the system show that the algorithm with the AE sensors and accelerometers offers accurate pinpointing of leaks. Theoretical analysis of sound wave propagation speed of water in underground pipes, which is critically important in leak locating, is also described.
A Practical Method of Acoustic Emission Source Location in Anisotropic Composite Laminates
Kim, Jeong-Kon ; Kang, Yong-Kyu ; Kwon, Oh-Yang ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 237~245
Since the velocity is dependent on the fiber orientation in anisotropic composites, the application of traditional acoustic emission (AE) source location techniques based on the constant velocity to composite structures has been practically impossible. The anisotropy makes the source location procedure complicated and deteriorates the accuracy of the location. In this study, we have divided the region of interest(ROI) into a set of finite elements, taken each element as a virtual source, and calculated the arrival time differences between sensors by using the velocities at every degree from 0 to 90. The calculated and the experimentally measured values of the arrival time difference aye then compared to minimize the location error. The results from two different materials, namely AA6061-T6 and CFRP(uni-directional; UD,
) laminate confirmed the practical usefulness of the proposed method.
Detection of Fatigue Damage in Aluminum Thin Plates with Rivet Holes by Acoustic Emission
Kim, Jung-Chan ; Kim, Sung-Jin ; Kwon, Oh-Yang ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 246~253
The initiation and growth of short fatigue cracks in the simulated aircraft structure with a series of rivet holes was detected by acoustic emission (AE). The location and the size of short tracks were determined by AE source location techniques and the measurement with traveling microscope. AE events increased intermittently with the initiation and growth of short cracks to form a stepwise increment curve of cumulative AE events. For the precise determination of AE source locations, a region-of-interest (ROI) was set around the rivet holes based on the plastic zone size in fracture mechanics. Since the signal-to-noise ratio (SNR) was very low at this early stage of fatigue cracks, the accuracy of source location was also enhanced by the wavelet transform do-noising. In practice, the majority of AE signals detected within the ROI appeared to be noise from various origins. The results showed that the effort of structural geometry and SNR should be closely taken into consideration for the accurate evaluation of fatigue damage in the structure.
Analysis and Classification of Acoustic Emission Signals During Wood Drying Using the Principal Component Analysis
Kang, Ho-Yang ; Kim, Ki-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 254~262
In this study, acoustic emission (AE) signals due to surface cracking and moisture movement in the flat-sawn boards of oak (Quercus Variablilis) during drying under the ambient conditions were analyzed and classified using the principal component analysis. The AE signals corresponding to surface cracking showed higher in peak amplitude and peak frequency, and shorter in rise time than those corresponding to moisture movement. To reduce the multicollinearity among AE features and to extract the significant AE parameters, correlation analysis was performed. Over 99% of the variance of AE parameters could be accounted for by the first to the fourth principal components. The classification feasibility and success rate were investigated in terms of two statistical classifiers having six independent variables (AE parameters) and six principal components. As a result, the statistical classifier having AE parameters showed the success rate of 70.0%. The statistical classifier having principal components showed the success rate of 87.5% which was considerably than that of the statistical classifier having AE parameters.
Effect of Ear and Near-side Single Circular Pit Depth and Bulk Stress on Magnetic Flux Leakage at ferromagnetic Pipeline
Ryu, Kwon-Sang ; Park, Young-Tae ; Atherton, D.L. ; Clapham, L. ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 263~269
Magnetic flux leakage (MFL) signals were used for corrosion inspection of buried oil and gas pipeline. 3D finite element analysis was used to examine the effects of far and near-side pit depth and tensile stress on MFL signals. Anisotropci materials were used, and the effects of simulated tensile stress on MFL were investigated. The axial and radial MFL signals depended on far and near-side single pit depth and on the bulk stress, but the circumferential MFL signal did not depend on them. The axial and radial MFL signals increased with increasing pit depth and the bulk stress, but the circumferential MFL signal was scarcely changed.
Studies on the Influence of Various factors in Ultrasonic Flaw Detection in Ferrite Steel Butt Weld Joints
Baby, Sony ; Balasubramanian, T. ; Pardikar, R.J. ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 270~279
Parametric studies have been conducted into the variability of the factors affecting the ultrasonic testing applied to weldments. The influence of ultrasonic equipment, transducer parameters, test technique, job parameters, defect type and characteristics on reliability far defect detection and sizing was investigated by experimentation. The investigation was able to build up substantial bank of information on the reliability of manual ultrasonic method for testing weldments. The major findings of the study separate into two parts, one dealing with correlation between ultrasonic techniques, equipment and defect parameters and inspection performance effectiveness and other with human factors. Defect detection abilities are dependent on the training, experience and proficiency of the UT operators, the equipment used, the effectiveness of procedures and techniques.
Pre-service Acoustic Emission Testing for Metal Pressure Vessel
Lee, Jong-O ; Yoon, Woon-Ha ; Lee, Tae-Hee ; Lee, Jong-Kyu ;
Journal of the Korean Society for Nondestructive Testing, volume 23, issue 3, 2003, Pages 280~284
The field application of acoustic emission(AE) testing for brand-new metal pressure vessel were performed. We will introduce the test procedure for acoustic emission test such as instrument check distance between sensors, sensor location, whole system calibration, pressurization sequence, noise reduction and evaluation. The data of acoustic emission test contain many noise signal, these noise can be reduced by time filtering which based on the description of observation during AE test.