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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
Editor in Chief :
Volume & Issues
Volume 24, Issue 6 - Dec 2004
Volume 24, Issue 5 - Oct 2004
Volume 24, Issue 4 - Aug 2004
Volume 24, Issue 3 - Jun 2004
Volume 24, Issue 2 - Apr 2004
Volume 24, Issue 1 - Feb 2004
Selecting the target year
Ultrasonic Backscattering on Painted Rough Surface at near Rayleigh Angle
Kwon, Sung-D. ; Kwon, Yong-G. ; Yoon, Seok-S. ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 1~7
The angular dependence (or profile) of backscattered ultrasound was measured for steel specimens with a range of surface roughness,
. Backscattering profiles at or near the Rayleigh angle still showed roughness dependence while the assessment of surface roughness via normal profile became impossible due to the paint layer masking the roughness. The peak amplitude directly radiated at the Rayleigh angle was proportional to the surface roughness, while the averaged peak amplitude radiated from the backward propagating Rayleigh wave, produced by reflection at a corner, was inversely proportional. In the painted specimens, the linearity of direct backward radiation with the roughness was observed even at the roughness of less than three hundredths of a wavelength, and the abnormal multiple bark reflection caused by periodic roughness disappeared.
Model-Based Interpretation and Experimental Verification of ECT Signals of Steam Generator Tubes
Song, Sung-Jin ; Kim, Eui-Lae ; Yim, Chang-Jae ; Lee, Jin-Ho ; Kim, Young-H. ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 8~14
Model-based inversion tools for eddy current signals have been developed by combining neural networks and finite element modeling, for quantitative flaw characterization in steam generator tubes. In the present work, interpretation of experimental eddy current signals was carried out in order to validate the developed inversion tools. A database was constructed using the synthetic flaw signals generated by the finite element model. The hybrid neural networks composed of a PNN classifier and BPNN size estimators were trained using the synthetic signals. Experimental eddy current signals were obtained from axisymmetric artificial flaws. Interpretation of flaw signals was conducted by feeding the experimental signals into the neural networks. The interpretation was excellent, which shows that the developed inversion tools would be applicable to the Interpretation of real eddy current signals.
Development of an EMAT System for Detecting flaws in Pipeline
Ahn, Bong-Young ; Kim, Young-Joo ; Kim, Young-Gil ; Lee, Seung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 15~21
It is possible to detect flaws in pipelines without interruption using all EMAT transducer because it is a non-contact transducer which can transmit ultrasonic waves into specimens without couplant. And it ran easily generate guided waves desired in each specific problem by altering the design of coil and magnet. In the present work, EMAT systems have been fabricated to generate surface waves, and selectively the plate wave of
mode. The surface wave of 1.5MHz showed a good signal-to-noise ratio without distortion in its propagation along a pipeline, while the
mode of 800kHz and the
mode of 940kHz were distorted according to their dispersive properties. The wider the excitation pulse becomes, the better the mode selectivity of the plate waves becomes. A pipe of 256mm inner diameter and 5.5m thickness with 5 flaws was used for comparing the flaw detectability among the modes under consideration.
Magnetic Susceptibility depending on the Thermal Degradation of HK-40 Steel
Kim, Jeong-Min ; Son, De-Rac ; Park, Jong-Seo ; Nahm, Seung-Hoon ; Kim, Dong-Gyun ; Han, Sang-In ; Choi, Song-Chun ; Ryu, Dae-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 22~28
Since the used materials of furnace heater tube with different kinds of thermal degradation were not commonly available, the HK-40 steel specimens were heat-treated isothermally at elevated temperature to simulate the microstructure at the service temperature. HK-40 steel specimens with five different aging time were prepared by isothermal heat treatment at
. The characteristics of the magnetic susceptibility have been investigated for the degradation evaluation of HK-40 steel. The magnetic susceptibility at room temperature increases as the extent of degradation of the materials increases. The variation of magnetic susceptibility was compared with the variation of tensile properties and Vickers hardness. To investigate the effect of the microsturctural change on the characteristics of tensile properties, hardness and magnetic susceptibility, the microstructures were examined by a scanning electron microscope(SEM) and the chemical compositions were analyzed by a energy spectrometer of SEM. As a result, the magnetic susceptibility method can be suggested as one of the nondestructive evaluation methods for the degradation of the HK-40 steel.
Evaluation of Creep Properties of W-substituted 2205 Duplex Stainless Steel
Kim, Gi-Yeob ; Choi, Byong-Ho ; Nam, Ki-Woo ; Ahn, Yong-Sik ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 29~37
The effect of the substitution of Tungsten(W) for Molybdenum(Mo) on the creep behaviour of 22Cr-5Ni duplex stainless steel(DSS) has been investigated. Creep tests were carried out at
phase is precipitated during creep at
, at which creep rupture time was much lower compared with at
. The substitution of W for Mo in the duplex stainless steel was known to retard the formation of
phase. Minimum creep rate and creep rupture time, however, were hardly influenced by the substitution of 2wt.% W. An ultrasonic measurement for the creep specimens has been carried out for the evaluation of creep damage. The sound velocity increases propotionally with the increase of creep rupture time at
of creep temperature. On the contrary, the sound velocity decreases with the increase of rupture time at
, which can be correlated with the microstructural evolution during creep.
Stress Distribution of a Crane Hook by Photoelasticty Using 4-step Phase Shifting Method and finite Element Method
Baek, Tae-Hyun ; Kim, Whan ; Lee, Chun-Tae ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 38~44
An experimental study for a crane hook was performed to investigate the stress distribution along a certain line where the maximum and minimum stresses to be developed. On this line, the isoclinic fringe and/or principal stress direction is constant. The crane hook was modeled into a 2-dimensional plate made of urethane rubber called 'Photoflex' The Photoflex is very sensitive to a load and has low photoelastic fringe constant. The Tardy compensation method with the fringe sharpening process and the 4-step phase shifting method, was used for the photoelastic technique. Experimental results by photoelasticity were compared with the calculated stresses from the simple curved beam theory and tile finite element analysis. Ail the results were close to each other.
Leak Detection and Evaluation for Power Plant Boiler Tubes Using Acoustic Emission
Lee, Sang-Guk ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 45~51
Boiler tubes in power plants are often leaked due to various material degradations including creep and thermal fatigue damage under severe operating conditions such as high temperature and high pressure over an extended period of time. To monitor and diagnose the tubes on site and in real time, the acoustic emission (AE) technology was applied. We developed an AE leak detection system, and used it to study the variation of AE signal from the on-site tubes in response to the changes in the boiler operation condition and to detect the locations of leakage based on it. Detection of leak was performed by acquiring and evaluating the signals in separate regimes of high and low frequency signal. As a result of these studies, we found that on-line monitoring and detection of leak location for boiler tubes is possible using the developed system. Thus, the system is expected to contribute to the safe operation of power plants, and prevent economic losses due to potential leak.
The Status of ISO/TC 135 and the major revisions of ISO 9712 to be included in 2004 edition
Lee, Jong-Po ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 52~63
The importance of nondestructive testings and its international standardization are well recognized not only in the developed countries and but also in the developing countries in recent years. In order to deal with the international standardization for nondestructive testing, the ISO/TC 135 meeting was held in Cheju island, Republic of Korea from 28th to 31st, October, 2003. In this period, the meetings of subcommittee 2, 5, 6, 7, and SC 7 WG 7 were also held. Here summarized are the results of the meetings and the status of ISO/TC 135. In addition, the major revisions of ISO 9712 to be included in 2004 edition are discussed in detail.
Recent Research Trend for Nondestructive Testing Technology
Lee, Seung-Seok ; Kim, Ki-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 1, 2004, Pages 64~85