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  • Title/Summary/Keyword: 초음파/비파괴평가

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Evaluation of Mechanical Properties of Structural Ceramics (Al2O3) Using the High Frequency Ultrasonic C - Scan (초음파 C-Scan을 이용한 구조용 세라믹스의 기계적 특성평가)

  • Chang, Y.K.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.9 no.2
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    • pp.18-24
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    • 1989
  • Computer-aided high frequency ultrasonic is applied to aluminum oxide(85w%, 94w%, 96w%, and 99w%) MOR(modulus of rupture) samples to evaluate mechanical properties such as density variation, pore content, elastic modulus, shear modulus, and poisson's ratio. Ultrasonic wave velocity and attenuation measurement techniques were used as an evaluator of such properties. Pulse-echo C-Scan images with different fate setting method using 50MHz center frequency 1 inch focal length transducer allows evaluation of density variation and pore content. Elastic modulus calculated with the relation of density and ultrasonic velocity. It shows good reliability as compared with resonance method. Sintered density variation of 0.025g/cm3, that is 0.6% of theoretical density in Al2O3 samples can be observed by ultrasonic velocity measurement. Attenuation measurement method qualitatively agree with 4-point fracture testing result concerning of porosity content.

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Nondestructive Evaluation of Ceramic/Metal Interface Using the V(z) Curve of Scanning Acoustic Microscope (초음파현미경에서 V(z) 곡선을 이용한 세라믹/금속 접합계면의 비파괴평가)

  • Park Ik-Keun;Lee Chul-Ku;Cho Dong-Su;Kim Yong-Kwon
    • Journal of Welding and Joining
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    • v.23 no.2
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    • pp.59-65
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    • 2005
  • A leaky surface acoustic wave (LSAW) velocity was measured using a scanning acoustic microscope on the ceramic/metal interface in order to investigate material properties. The inverse Fourier transform (IFFT) of the V(z) curve contains the reflectance function of a liquid-specimen interface. So, the longitudinal, transverse, and Rayleigh wave velocities for each layer are obtained by the inversion of the V(z) curve at the same time. This paper contains mainly the experimental procedure for measurements of the LSAW velocity, and the results obtained for the velocity variation of individual layer after the thermal shock. It is shown that this method is useful in measuring the material properties under external stress.

A Study on Frequency and Time Domain Interpretation for Safety Evaluation of old Concrete Structure (노후된 콘크리트 구조물의 안전도 평가를 위한 초음파기법의 주파수 및 시간영역 해석에 관한 연구)

  • Suh Backsoo;Sohn Kwon-Ik
    • Tunnel and Underground Space
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    • v.15 no.5 s.58
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    • pp.352-358
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    • 2005
  • For non-destructive testing of concrete structures, time and frequency domain method were applied to detect cavity in underground model and pier model. To interpret the measured data, time domain method made use of tomography which was completed with first arrivaltime and inversion method. In this steady, frequency domain method using Fourier transform was tried. Maximum frequency in the frequency domain was analyzed to calculate location of cavity.

Analysis of Diffusion Bonded Parts Using Immersed UT Method (수침초음파를 이용한 확산접합부평가)

  • Park, J.C.;Oh, C.S.;Kim, Y.S.;Kim, J.G.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.12 no.3
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    • pp.33-39
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    • 1992
  • This paper presents a summary of the immersion ultrasonic test to analyze the quality of diffusion bonding parts. The most important property of diffusion bonding parts is bonding strength, and that can be obtained by shear test. By comparing among data obtained by ultrasonic test(C-Scan) and those by shear test (bonding strength), these data are shown to be in good relation. Therefore ultrasonic C-Scan test result can be used successfully in quantitative quality control for diffusion bonded parts.

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Spectral Backward Radiation Profile (주파수 대역별 후방복사 프로파일)

  • Kim, Hak-Joon;Kwon, Sung-Duk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.5
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    • pp.362-367
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    • 2005
  • Ultrasonic backward radiation profile is frequency-dependent when the incident region has deptional gradient of acoustical properties or multi-layers. Until now, we have measured the profiles of principal frequencies of an used transducers so that it was not easy to characterize the frequency dependence of the SAW(surface acoustic wave) from the backward radiation profile. We tried to measure the spectral backward radiation profiles using DFP(digital filer package) in a Lecroy DSO(digital storage oscilloscope). The measured spectral profiles showed that the steel specimen of #1200 surface treatment have 2% SAW velocity dispersion of the loaded case and the severly rusty steel specimen have the very big changes in the shape and pattern of the spectral profile. It is concluded that the spectral backward radiation profiles could be very effective tool to evaluate the frequency dependence of surface area.

Evaluation of Mass Variation of Aspheric Glass tens Using Resonant Ultrasound Spectroscopy (비구면 렌즈의 질량변화 평가를 위한 RUS의 적용)

  • Heo, Uk;Im, Kwang-Hee;Yang, In-Young;Kim, Ji-Hoon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.2
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    • pp.183-189
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    • 2007
  • Ultra precise processed parts are required together with the development of optoelectronics industry. As important parts of optoelectronics industry, there are ferrule of optical connector and lens for optical devices. In particular, the lens requires high reliability with high precision without including flaws. These optical modules need ultra precise processing in order to reduce the loss of light sources and various nondestructive inspections are carried out in the finishing stage to separate good and bad quality products. Therefore, it was analyzed through the characteristics of response of amplitude and resonant frequency according to the mass variations of aspheric lens that is used currently in laser printers.

Pigment Analysis and Nondestructive Deterioration Diagnosis of the Wall Paintings in Gwanyongsayaksajeon (Yaksajeon Hall of Gwanyongsa Temple), Changnyeong, Korea (창녕 관룡사 약사전 벽화의 안료분석 및 비파괴 훼손도 진단)

  • Chun, Yu-Gun;Kim, Won-Kuk;Jo, Young-Hoon;Han, Doo-Roo;Kim, Sun-Duk;Lee, Chan-Hee
    • Journal of Conservation Science
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    • v.25 no.4
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    • pp.383-398
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    • 2009
  • We have investigated chemical properties of the pigments and carried out the deterioration diagnosis using nondestructive techniques of the wall painting in Yaksajeon Hall of Gwanyongsa Temple. As the results of pigments analysis, it was unusual that the cobalt was detected in the blue and green colors used to traditional paint background. According to the deterioration diagnosis, ultrasonic measurement and infrared thermography, dominant cracks and exfoliation caused by high content of moisture. Therefore, it should be devised effective plan to prevent penetration of water for the long term this wall painting.

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Fabrication of Mechanical fatigue flawed Specimen and Evaluation of Flaw Size (기계적 피로결함 시험편 제조 및 결함 크기 평가)

  • Hong, Jae-Keun;Kim, Woo-Sung;Son, Young-Ho;Park, Ban-Uk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.1
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    • pp.38-44
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    • 2003
  • Performance demonstration with real flawed specimens has been strongly required for nondestructive evaluation of safety class components in nuclear power plant. Mechanical or thermal fatigue crack and intergranular stress corrosion cracking could be occured in the in-service nuclear power plant and mechanical fatigue crack was selected to study in this paper. Specimen was designed to produce mechanical fatigue flaw under tensile stress. The number of cycles and the level of stress were controlled to obtain the desired flaw roughness. After the accurate physical measurement of the flaw size and location, fracture surface was seal-welded in place to ensure the designed location and site. The remaining weld groove was then filled by using gas-tungsten are welding(GTAW) and flux-cored arc welding(FCAW). Results of radio graphic and ultrasonic testing showed that fatigue cracks were consistent with the designed size and location in the final specimens.

Comparative Study on NDT Techniques for Evaluation of Concrete Quality Exposed to Marine Environment (항만 상치 콘크리트 품질 관리를 위한 비파괴 스캐닝 기법 비교 연구)

  • Homin Song;Jiyoung Min
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.36 no.5
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    • pp.177-184
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    • 2024
  • Concrete, the primary material used in quay walls, is directly exposed to saline environments. Coping concrete, particularly in areas where periodic berthing and loading/unloading occur, is prone to rapid quality deterioration. Current facility safety and maintenance guidelines assess concrete durability at specific points through sampling, which are intended to represent the entire inspection unit. This paper explores quality management strategies from an areal perspective by applying various non-destructive scanning methods to extensive areas of coping concrete. Ultrasonic array imaging and ground-penetrating radar scanning images revealed significant quality degradation in berthing operation areas, whereas sampling-based ultrasonic pulse velocity and rebound hardness values were less effective in detecting this degradation.

Correlation between Probe Frequency and Echo-Pulse Velocity for Ultrasonic Testing of a Fiber-Reinforced Plastic Hull Plate (복합소재 선체 외판의 초음파 탐상을 위한 탐촉자 주파수와 수신기 음향 속력의 상관관계)

  • Lee, Sang-gyu;Han, Zhiqiang;Lee, Chang-woo;Oh, Daekyun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.2
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    • pp.219-226
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    • 2020
  • Nondestructive testing is one of the most commonly used quality inspection methods for evaluating ship structures. However, accurate evaluation is dif icult because various composite materials, such as reinforcements, resin, and fiber-reinforced plastics (FRPs), are used in hulls, and manufacturing quality differences are likely to exist owing to the fabrication environment and the skill level of workers. This possibility is especially true for FRP ships because they are significantly thicker than other structures, such as automobiles and aircraft, and are mainly manufactured using the hand lay-up method. Because the density of a material is a critical condition for ultrasonic inspection, in this study, a hull plate was selected from a vessel manufactured using e-glass fiber, which is widely used in the manufacture of FRP vessels with the weight fraction of the glass content generally considered. The most suitable ultrasonic testing conditions for the glass FRP hull plate were investigated using a pulse-echo ultrasonic gauge. A-scans were performed with three probes (1.00, 2.25, and 5.00 MHz), and the results were compared with those of the hull plate thickness measured using a Vernier caliper. It was found that when the probe frequency was higher, the eco-pulse velocity of the receiver had to be lowered to obtain accurate measurement results, whereas fewer errors occurred at a relatively low probe frequency.