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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Nondestructive Testing
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Journal DOI :
The Korean Society for Nondestructive Testing
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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
Guided Wave Calculation and Its Applications to NDE
Hayashi, Takahiro ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 125~135
This paper describes the calculation technique for guided wave propagation with a semi-analytical finite element method (SAFEM) and shows some results of numerical calculation and guided wave simulation for plates, pipes and railway rails. The SAFEM calculation gives dispersion curves and wave structures for bar-like structures. Dispersion curve software for a pipe is introduced, and also dispersion corves for a rail are given and experimentally verified. The mode conversions in a plate with a defect and in a pipe with an elbow or a defect are shown as examples of our guided wave simulations.
Detection of Cracks in feeder Pipes of Pressurized Heavy Water Reactor Using an EMAT Torsional Guided Wave
Cheong, Yong-Moo ; Kim, Sang-Soo ; Lee, Dong-Hoon ; Jung, Hyun-Kyu ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 136~141
A torsional guided wave mode was applied to detect a crack in a pipe. An array of electromagnetic acoustic transduce. (EMAT that can generate and receive torsional guided ultrasound with the frequency of 200kHz was designed and fabricated for testing a pipe of 2.5 inch diameter Artificial notches with various depths were fabricated in a bent feeder pipe mock-up and the detectability was examined from the distance of 2m of the specimen. The axial notches with the depth of 5% of wall thickness were successfully detected by a torsional mode (T(0,1)) generated by the EMAT However, it was found that the depth of defects was not related to the signal amplitude.
A Study on the Behavior of Ultrasonic Guided Wave Mode in a Pipe Using Comb Transducer
Park, Ik-Keun ; Kim, Yong-Kwon ; Cho, Youn-Ho ; Ahn, Yeon-Shik ; Cho, Yong-Sang ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 142~150
A preliminary study of the behavior of ultrasonic guided wave mode in a pipe using a comb transducer for maintenance inspection of power plant facilities has been verified experimentally. The mode identification has been carried out in a pipe using the time-frequency analysis methods such as the wavelet transform(WT) and the short time Fourier transform (STFT), compared with theoretically calculated group velocity dispersion curves for longitudinal and flexural modes. The results are in good agreement with analytical predictions and show the effectiveness of using the time-frequency analysis method to identify the individual modes. It was found out that the longitudinal mode(0,1) is less affected by mode conversion compared with the other modes. Therefore, L(0,1) is selected as an optimal mode for the evaluation of the surface defect in a pipe.
A Study on a Crack Evaluation Technique for Turbine Blade Root Using Phased Array Ultrasonics
Cho, Yong-Sang ; Jung, Gye-Jo ; Park, Sang-Ki ; Kim, Jae-Hoon ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 151~157
Ultrasonic testing is a kind of nondestructive test to detect a crack or discontinuity in materials or on material surfaces by sending ultrasound to it. This conventional ultrasonic technique has some limitations in reliably detecting crack or accurately assessing materials in the case of complex-shaped power plant components such as a turbine blade root. An alternative method for such a difficult inspection is highly needed. In this study, application of a phased array ultrasonic testing (UT) system to a turbine blade, one of the critical power plant components, has been considered, and the particular incident angle has been determined so that the greatest track detectability and the most accurate crack length evaluation nay be achieved. The response of ultrasonic phased array was also analyzed to establish a special method to determine the track )ength without moving the transducer. The result showed that the developed method for crack length assessment is a more accurate and effective method, compared with the conventional method.
Application of Continuous Indentation Technique for Reliability Evaluation in Power Plant Facilities
Park, Sang-Ki ; Ahn, Yeon-Shik ; Jung, Gye-Jo ; Cho, Yong-Sang ; Choi, Yeol ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 158~162
Reliability of welded structures in power plant facilities is very important, and their reliability evaluation requires exact materials properties. But, the conventional PQR (Procedure Qualification Record) can hardly reflect the real material properties in the field because the test is only done on specimens with simulated welding. Therefore, a continuous indentation technique is proposed in this study for simple and non-destructive testing of in-field structures. This test measures the indentation load-depth curve during indentation and analyzes the mechanical properties such as the yield strength, tensile strength and work hardening index. This technique has been applied to evaluate the tensile properties of the weldment in the main steam pipe and hot reheater pipe in power plants under construction and in operation.
Remote field Eddy Current Technique Development for Gap Measurement of Neighboring Tubes of Nuclear Fuel Channel in Pressurized Heavy Water Reactor
Jung, H.K. ; Lee, D.H. ; Lee, Y.S. ; Huh, H ; Cheong, Y.M. ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 164~170
Liquid Injection Nozzle(LIN) tube and Calandria tube(CT) in pressurized Heavy Water Reactor (PHWR) are .ross-aligned horizontally. These neighboring tubes can contact each other due to the sag of the calandria tube resulting from the irradiation creep and thermal creep, and fuel load, etc. In order to judge the contact which might be the safety concern, the remote field eddy current (RFEC) technology is applied for the gap measurement in this paper. LIN can be detected by inserting the RFEC probe into pressure tube (PT) at the crossing point directly. To obtain the optimal conditions of the RFEC inspection, the sensitivity, penetration and noise signals are considered simultaneously. The optimal frequency and coil spacing are 1kHz and 200mm respectively. Possible noises during LIN signal acquisition are caused by lift-off, PT thickness variation, and gap variation between PT and CT. The simulated noise signals were investigated by the Volume Integral Method(VIM). Signal analysis on the voltage plane describes the amplitude and shape of LIN and possible defects at several frequencies. All the RFEC measurements in the laboratory were done in variance with the CT/LIN gap and showed the relationship between the LIN gap and the signal parameters by analyzing the voltage plane signals.
Conceptual Design of In-Service Inspection and Maintenance of tiquid Metal Reactor KALIMER
Joo, Young-Sang ; Kim, Seok-Hoon ; Lee, Jae-Han ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 171~179
The design concepts of in-service inspection and maintenance are very important for the reactor system design of the nuclear power plant. The strategy of in-service inspection and maintenance should be reflected in the mechanical system design for the verification of the operability of liquid metal reactor KALIMER. In this paper the fundamental approaches of the in-service inspection and maintenance of the KALIMER are established to ensure the safety and reliability of the reactor system. The general method and requirement of the in-service inspection and maintenance for the reactor system and components are proposed and described to satisfy the intents of the ASME Section XI Division 3 and the design characteristics of KALIMER.
Evaluation of the Surface Crack by a Large Aperture Ultrasonic Probe
Cho, Yong-Sang ; Kim, Jae-Hoon ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 180~185
Conventional ultrasonic examination to detect micro and small surface cracks is based on the pulse-echo technique using a normal immersion focused transducer with high frequency, or an angle-beam transducer generating surface waves. It is difficult to make an automatic ultrasonic system that can detect micro and small surface cracks and position in a large structure like steel and ceramic rolls, because of the huge data of inspection and the ambiguous position data of the transducer. In this study, a high-precision scanning acoustic microscope with a 10MHz large-aperture transducer has been used to assess the existence, position and depth of a surface crack from the real-time A, B, C scans obtained by exploiting the ultrasonic diffraction. The ultrasonic method with large aperture transducer has improved the accuracy of the crack depth assessment and also the scanning speed by ten times, compared with the conventional ultrasonic methods.
Comparative Study on the Technical Standards for the In-Service Inspection of Nuclear Power Plant Components in Several Countries
Shin, Ho-Sang ; Kim, Kyung-Jo ; Jang, Chang-Heui ; Kang, Suk-Chull ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 186~196
In each country, the periodic ISI(In-Service Inspection) is required by the law to protect the public health and property from the potential accident of the nuclear facilities. To support the implementation of ISI program, the prescriptive ISI technical standards have been established. As the key parts of the ISI program, the non-destructive examination techniques are widely used to identify the degree of degradation of the pressure boundary components and welds. Recently, the risk informed-ISI program has been developed and implemented in several countries. Nonetheless, the existing ISI program which prescriptively decides the scope of inspection still has its own significance. In this article, the technical standards of ISI in leading countries like US, france, Canada, and Japan are reviewed and compared with the safety guide by IAEA. An outline to revise the domestic technical standards of ISI has been suggested.
Maintenance of Power Plant facilities and Nondestructive Inspection(I) - Thermoelectric Power Plant -
Park, Ik-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 2, 2004, Pages 197~210