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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 18, Issue 6 - Dec 1998
Volume 18, Issue 5 - Oct 1998
Volume 18, Issue 4 - Aug 1998
Volume 18, Issue 3 - Jun 1998
Volume 18, Issue 2 - Apr 1998
Volume 18, Issue 1 - Feb 1998
Selecting the target year
Improvement of Signal to Noise Ratio by Synthetic Aperture Focusing Technique in Ultrasonic Testing
Lee, S.L. ; Chang, K.O. ; Kim, B.C. ; Kim, G.G. ;
Journal of the Korean Society for Nondestructive Testing, volume 18, issue 4, 1998, Pages 271~277
Nondestructive method can include both testing itself and analysis or evaluation of the testing results. Although vast amount of testing can be accomplished in a fairly short amount of time due to the advancement of electronic technology. it is really difficult matter to identify whether the indication found during testing corresponds to be a real defect. Thus, in ultrasonic testing, advanced digital signal processing techniques have been widely studied in order to identify the shape of the defect during testing, and one of the signal processing techniques, synthetic aperture focusing technique(SAFT) was tried for holes machined in carbon steel plate in this study. Result showed that signal to noise ratio has been improved considerably compared to the result from original RF signals.
Development of Fracture Toughness Evaluation Method for Composite Materials by Non-Destructive Testing Method
Lee, Y.T. ; Kim, K.S. ;
Journal of the Korean Society for Nondestructive Testing, volume 18, issue 4, 1998, Pages 278~291
Fracture process of continuous fiber reinforced composites is very complex because various fracture mechanisms such as matrix cracking, debonding, delamination and fiber breaking occur simultaneously during crack growth. If fibers cause crack bridging during crack growth, the stable crack growth and unstable crack growth appear repeatedly. Therefore, it is very difficult to exactly determine tile starting point of crack growth and the fracture toughness at the critical crack length in composites. In this research, fracture toughness test for CFRP was accomplished by using acoustic emission(AE) and recording of tile fracture process in real time by video-microscope. The starting point of crack growth, pop-in point and the point of unstable crack growth can be exactly determined. Each fracture mechanism can be classified by analyzing the fracture process through AE and video-microscope. The more reliable method ior the fracture toughness measurement of composite materials was proposed by using the combination of R-curve method, AE and video microscope.
Effects of Microstructural States on Magnetic Barkhausen Noise Behavior in the Weld Heat-Affected Zone of Reactor Pressure Vessel Steel
Kim, Joo-Hag ; Yoon, Eui-Pak ; Moon, Jong-Gul ; Park, Duck-Gun ; Hong, Jun-Hwa ;
Journal of the Korean Society for Nondestructive Testing, volume 18, issue 4, 1998, Pages 292~303
Recent study has demonstrated that some magnetic properties are sensitive to the microstructural state of material. The ASTM A 508 Gr. 3 reactor pressure vessel steel has various microstructural changes including martensitic and bainitic phases, and various sizes of grain and precipitates in the weld heat-affected zone (HAZ). To correlate the microstructural state with Barkhausen noise (BN), specimens were prepared through simulating various weld thermal cycles using a thermal simulator. The conventional magnetic properties, i.e. coercive force, remanence and maximum induction, did not change significantly, whereas the BN amplitude and energy during a magnetization cycle changed markedly with microstructural state. The BN increased with increasing grain and carbide sizes, and the tempered bainite structure showed higher BN parameter than tempered martensite.
Numerical Analysis of Scattered Fields of Ultrasonic SH-Wave by Multi-Defects
Lee, Joon-Hyun ; Lee, Seo-Il ; Cho, Youn-Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 18, issue 4, 1998, Pages 304~312
In order to assure the reliability and integrity of structures such as bridges, Power and petrochemical plants, nondestructive evaluation techniques are recently playing more important roles. Among the various kinds of nondestructive evaluation techniques, ultrasonic technique is one of the most widely used methods for nondestructive inspection of internal defects in structures. For the reliable quantitative evaluation of internal defects from the experimental ultrasonic signals, a numerical analysis of ultrasonic scattering field due to a defect distribution is absolutely required. In this paper, the SH-wave scattering by multi-cavity defects using elastodynamic boundary element method is studied. The effects of shape of defects on transmitted and reflected fields are considered. The interaction of multi-cavity defects in 50-wave scattering is also investigated. Numerical calculation by the boundary element method has been carried out to predict near field solution of scattered fields of ultrasonic SH-wave. The presented results would be useful to improve the sensitivity of flaw defection for inverse analysis and pursue quantitative nondestructive evaluation for inverse problem.
Flaw Sizing by ASME and CSA Code
Park, Moon-Ho ; Kang, Suk-Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 18, issue 4, 1998, Pages 313~320
To record and evaluate the flaws which were found during pre-service/in-service inspection performance of nuclear power plants in Korea, the center line beam method described in ASME code and 6 dB drop method stated in CSA code were used. The measured through wall dimensions and lengths by these methods were compared and analyzed in this report. With the measured data analysis, the ekact understanding and use of these methods improves the reliability of flaw sizing and assures the integrity of nuclear power plant components.
ISI NDE Total Support System for Korean Nuclear Power Plants
Jeong, Yi-Hwan Peter ;
Journal of the Korean Society for Nondestructive Testing, volume 18, issue 4, 1998, Pages 321~329
Structural integrity of nuclear components is important for a safe operation of nuclear power plants. Therefore, nuclear power plants require to perform reliable, periodic inservice inspections. Korea Electric Power Company(KEPCO) operates the entire Korean nuclear power plants. Since nuclear power plant safety and the associated inservice inspection(ISI) are under the plant owner's responsibility, Korea Electric Power Research Institute(KEPRI), the R&D division of KEPCO, has established the ISI NDE Total Support system(TSS) for an efficient performance of ISI tasks, and initiated both key ISI NDE technology development program and traing & qualification system development program for an independent ISI operation. This paper describes details of these programs.