• Title/Summary/Keyword: 초음파/비파괴평가

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A Study on the Compressive Strength Prediction of Crushed Sand Concrete by Non-Destructive Method (부순모래 콘크리트의 비파괴 시험에 의한 압축강도 추정에 관한 연구)

  • Kim, Myung-Sik;Baek, Dong-Il;Kim, Kang-Min
    • Journal of the Korea Concrete Institute
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    • v.19 no.1
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    • pp.75-81
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    • 2007
  • Percentage that aggregate of materials that concrete composed about 7080 of whole volume, therefore influence that quality of aggregate gets in concrete characteristics are very important. Schmidt hammer and ultra-sonic velocity method are commonly used for crushed sand concrete compressive strength test in a construction field. At present, various equations for prediction of strength are present, which have been used in a construction field. The purpose of this study is to evaluate the correlation between prediction strength by present equations and destructive strength to test specimen, and find out which is a suitable equation for the construction site, a strength test was carried out destructive test by means of core sampling and traditional test. The experimental parameters were concrete age, curing condition, and strength level. It is demonstrated that the correlation behavior of crushed sand concrete strength in this study good due to the perform analysis of correlation between core, destructive strength and non-destructive strength.

Effect of Bonding Layer on Guided Wave Mode Behavior in FRP Plate Bonded on Concrete (FRP 보강판 부착 콘크리트에서 유도초음파 모드 거동에 대한 접착층의 영향)

  • Lee, Yong-Ju;Shin, Sung-Woo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.32 no.1
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    • pp.34-40
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    • 2012
  • In this study, effects of bonding agent, e.g. epoxy, on the behavior of fundamental guided wave modes propagated in FRP plate bonded on a concrete, are investigated. Global matrix model of multilayered FRP-epoxy-concrete system was constructed to obtain the velocity and attenuation dispersion curves of the fundamental A0 and S0 modes. Two variables, thickness and elastic modulus of epoxy layer, were considered in the dispersion analysis. It was found that both the thickness and the elastic modulus of epoxy layer greatly affect the phase velocity and attenuation of S0 mode while those are negligible for A0 mode. Based on the results, it was concluded that S0 mode is more effective than A0 mode for bonding condition assessment for FRP plate bonded concrete.

Assessment of Pipe Wall Loss Using Guided Wave Testing (유도초음파기술을 이용한 배관 감육 평가)

  • Joo, Kyung-Mun;Jin, Seuk-Hong;Moon, Yong-Sig
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.4
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    • pp.295-301
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    • 2010
  • Flow accelerated corrosion(FAC) of carbon steel pipes in nuclear power plants has been known as one of the major degradation mechanisms. It could have bad influence on the plant reliability and safety. Also detection of FAC is a significant cost to the nuclear power plant because of the need to remove and replace insulation. Recently, the interest of the guided wave testing(GWT) has grown because it allows long range inspection without removing insulation of the pipe except at the probe position. If GWT can be applied to detection of FAC damages, it will can significantly reduce the cost for the inspection of the pipes. The objective of this study was to determine the capability of GWT to identify location of FAC damages. In this paper, three kinds of techniques were used to measure the amplitude ratio between the first and the second welds at the elbow area of mock-ups that contain real FAC damages. As a result, optimal inspection technique and minimum detectability to detect FAC damages drew a conclusion.

Effects of Rubber Loading on the Ultrasonic Backward Radiation Profile of Leaky Lamb Wave (고무 접합이 후방복사된 리키 램파 프로파일에 미치는 영향)

  • Song, Sung-Jin;Kwon, Sung-Duk;Jung, Min-Ho;Kim, Young-H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.22 no.5
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    • pp.508-515
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    • 2002
  • The characterization of adhesive property in multi-layer materials has been hot issue for a long time. In order to evaluate adhesive properties, we constructed fully automated system for the backward radiation of leaky Lamb wave. The backward radiation profiles were obtained for the bare steel plate and plates with rubber-loading. The rf waveforms and frequency spectra of backward radiation show the characteristics of involved leaky Lamb wave modes. As the thickness of rubber-loading increased, the amplitude of profile at the incident angle of 13.4 exponentially decreased. Scanning the incident position over the partially rubber-loaded specimen shows good agreement with the actual rubber-loading. The backward radiation of leaky Lamb wave has great potential to evaluate the adhesive condition as well as material properties of plates.

Application of Ultrasound Tomography for Non-Destructive Testing of Concrete Structure (초음파 tomography를 응용한 콘크리트 구조물의 비파괴 시험에 관한 연구)

  • Kim, Young-Ki;Yoon, Young-Deuk;Yoon, Chong-Yul;Kim, Jung-Soo;Kim, Woon-Kyung;Song, Moon-Ho
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.37 no.1
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    • pp.27-36
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    • 2000
  • As a potential approach for non-destructive testing of concrete structures, we evaluate the time-of-flight (TOF) ultrasound tomography technique In conventional X ray tomography, the reconstructed Image corresponds to the internal attenuation coefficient However, in TOF ultrasound tomography, the reconstructed Image is proportional to the retractive index of the medium Because refractive effects are minimal for X-rays, conventional reconstruction techniques are applied to reconstruct the Image in X-ray tomography However, since ultrasound travels in curved path, due to the spatial variations in the refractive index of the medium, the path must be known to correctly reconstruct the Image. Algorithm for determining the ultrasound path is developed from a Geometrical Optics point view and the image reconstruction algorithm, since the paths are curved It requires the algebraic approach, namely the ART or the SIRT Here, the difference between the computed and the measured TOP data is used as a basis, for the iteration process First the initial image is reconstructed assuming straight paths. It then updates the path based on the recently reconstructed image This process of reconstruction and path determination repeats until convergence The proposed algorithm is evaluated by computer simulations, and in addition is applied to a real concrete structure.

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Characterization of TiN Layered Substrate using Leaky Rayleigh Surface Wave (누설 레일리 표면파를 이용한 TiN 코팅 부재의 특성평가)

  • Kwon, Sung-Duk;Kim, Hak-Joon;Song, Sung-Jin
    • Journal of the Korean Society for Nondestructive Testing
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    • v.26 no.1
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    • pp.7-11
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    • 2006
  • Since ceramic layers coated on machinery components inevitably experience the changes in their properties it is necessary to evaluate the characteristics of ceramic coating layers nondestructively for a reliable use of coated components and 4heir remaining life prediction. To address such a need, in the present study, an ultrasonic backward radiation technique is applied to investigate the characteristics of leaky Rayleigh surface waves propagating through the very thin TiN ceramic layers coated on AISI 1045 steel or austenitic 304 steel substrate with three different conditions of surface roughness, coating layer thickness and wear condition. In the experiments performed in the present work, the peak angle and the peak amplitude of ultrasonic backward radiation profile varied sensitively according to three specimen preparation renditions. in fact, this result demonstrates a high possibility of the ultrasonic backward radiation as an effective tool for the nondestructive characterization of the resting layers even in such a thin regime.

Evaluation of Ultrasonic Nonlinear Characteristics in Heat-Treated Aluminum Alloy (열처리된 알루미늄 합금의 초음파 비선형 특성 평가)

  • Kim, JongBeom;Cheon, Chung;Jhang, Kyung-Young;Kim, Chung-Seok
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.2
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    • pp.193-197
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    • 2013
  • In this study, ultrasonic nonlinear characteristics in the heat-treated aluminum alloy have been evaluated. The nonlinearity of ultrasonic wave has been measured as the acoustic nonlinear parameter β, depending upon the amplitude ratio of the second-order harmonic and the fundamental frequency component of ultrasonic wave propagating through the materials. The parameter β measurement has been carried out with the reflected signals from the back-wall of specimens at the same plane using the contact-type transducers. The heat-treatment, aging, has been achieved at 300C for various durations in the range of 1 to 50 hours. The tensile strength and elongation are obtained by the tensile test and then compared with the parameter β. There is a peak of the acoustic nonlinear parameter β on 5 hours aging and the β decreases thereafter, exhibiting closed relations with tensile strength and elongation. Also, the heat-treatment time showing peak in the parameter β was identical to that showing severe change in the σε curve. These results suggest that the acoustic nonlinear parameter β can be used for monitoring the strength variations with aging of aluminum alloys.

The Experience of Inservice Inspection for Yonggwang Nuclear Power Plant Unit 6 (영광 원자력발전소 6호기 가동중검사 수형 경험)

  • Kim, Young-Ho;Nam, Min-Woo;Yang, Seung-Han;Yoon, Byung-Sik;Kim, Yong-Sik
    • Journal of the Korean Society for Nondestructive Testing
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    • v.24 no.4
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    • pp.384-389
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    • 2004
  • As the increase of the operation year of nuclear power plants, the probabilities of the degradation of the major facilities and materials in the nuclear power plants are increased. The integrity of those facilities shall be monitored and verified by the non-destructive examination methods with the regulation codes, so called inservice inspection(ISI). The ISI of Yonggwang unit 6 was performed in four different parts, 1) non-destructive examinations for the components, piping weldments and structures, 2) automated ultrasonic examinations for pressure vessels, 3) visual examinations for the interior structures of the reactor, 4) eddy current examinations for the steam generator tubes. As the results, there was no severe indication and all detected indications were evaluated as non-relavent. Especially for the examinations of the piping weldments, PD(Performance Demonstration) was applied as a W examination method defined in the 1995 edition of ASME Code Sec. XI. The implementation of the PD for the piping weld results in an improvement of the reliability of the UT examinations.

Evaluation of Adhesive Properties in Polymeric Thin Film by Ultrasonic Atomic Force Microscopy (UAFM을 이용한 폴리머 박막의 접합 특성 평가)

  • Kwak, Dong-Ryul;Park, Tae-Sung;Park, Ik-Keun;Miyasaka, Chiaki
    • Journal of the Korean Society for Nondestructive Testing
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    • v.32 no.2
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    • pp.142-148
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    • 2012
  • This study presents the assessment results of adhesive properties on the interface between a silicon wafer and nano-scale polymer thin film pattern through UAFM images by using the contact resonance frequency of the cantilever. For the experiment, we varied surface treatment processes for the silicon wafer and fabricated a 300nm polymer thin film pattern through lithography. Images from the optical microscope were used to compare the produced test specimens for adhesive condition and the critical load value from the nano scratch test was used to verify the adhesive condition of the nano pattern. Each test specimen resulted in a 1μm×1μm surface image and subsurface adhesive image. Adhesive condition was evaluated by image contrast differences on the interface according to the changing amplitudes and phases of contact resonance frequency.

Ultrasonic Flaw Detection in Turbine Rotor Disc Keyway Using Neural Network (신경회로망을 이용한 터빈로타 디스크 키웨이의 결함 검출)

  • 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
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    • v.23 no.1
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    • pp.45-52
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    • 2003
  • 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.