• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.5
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• pp.580-585
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• 1988

In this paper, a low frequency acoustic microscope system has been built for the purpose of detecting subsurface defects in materials. The lateral resolution of acoustic microscope is studied and analyzed in order to evaluate that system performance. And a NDE technique is demonstrated by using this system. In the focused and defocused mode of operation, the acoustic microscope system showed in experiment that its lateral resolution was about 0.5 mm at a frequency of operation of 3MHz on a fused-quartz sample with seeded circular cracks ranged in size from 0.2 mm to 1.0 mm in diameter wihtin 1 mm of the surface. It also showed the acoustic image of 100 won coin with fine contrast.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1591-1594
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• 1987

The Scanning Acoustic Microscope(SAM) is an image device which can display the small opaque material or the interior of solid. This paper showed the design of the acoustic lens which is an important factor of the Scanning Acoustic Microscope, and analyzed the performance of the acoustic lens. Finally, I experimented the image processing of the interior of solid through the Scanning Acoustic Microscope and the change of the acoustic image (resolution,contrast) by the change of F/number.

• Proceedings of the Acoustical Society of Korea Conference
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• 1987.11a
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• pp.48-51
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• 1987

In this paper, acoustic reflection microscope system has been built for the purpose of detecting subsurface defects in materials and demonstrated for nondestructive testing application. 100 won coin, aluminuim, ceramics, and IC component employed as experimental samples and acoustic reflection microscope was operated in the focused and defocused mode at a frequency of operation of 3 MHz. It has been found that acoustic reflection icroscope has the resolution of 500 ${\mu}{\textrm}{m}$ and it has been an excellent tool for nondestructive testing.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.383-386
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• 1987

In this paper, a low frequency acoustic microscope system has been built for the purpose of detecting sub-surface defects in materials. 100 won coin, aluminium, ceramics, I.C. are used for experimental and the acoustic microscope is operated in the focused and defocused mode at a frequency of 3 MHz. In experiment, it has shown that acoustic microscope has the resolution of 0.5mm and the defects presented on the surface and near surface of samples are detected by a monitor.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.43-46
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• 1988

In this paper, a methodology for determination of the thickness of layer on a substrate using reflection acoustic microscope has been presented. It has been shown that the amplitude and the phase of reflection coefficient of the layer-substrate composite has been used for measurement of layer thickness, acoustic velosity, mass density of the layer material. The reflection acoustic microscope operating at a frequency of 15 MHz has been used for the experiment and the measured acoustic impedance value for aluminum sample has agreed with the published data, and the measured layer thickness for silver-glass composite has agreed with that measured using micrometer.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.336-341
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• 2004

This research investigates the feasibility of ultrasonic microscope for nondestructive assessment of thermal degradation in artificially aged commercial Co-base superalloy, FSX414. This alloy has been used for high temperature structure applications such as stationary gas turbine blade and nozzle chamber in fossil plant. Microstructural change was found that the fine carbides became coarser and spheroidized in matrix as aging time increased. The leaky surface acoustic wave velocity gradually decreases by a maximum of 4.7% with increasing aging time up to 4,000hours. However, the longitudinal wave velocity has a little change. Also, it has a good correlation between leaky surface acoustic wave velocity and Vickers hardness. Consequently, LSAW can be used to examine the degree of degradation in thermally aged Co-base superalloy.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.3
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• pp.118-123
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• 2019

The aim of this study investigates the feasibility of scanning acoustic microscope (SAM) with high frequency transducer for material degradation. The test specimen was prepared by artificial heat treatment of Co-base superalloy. The high frequency 200 MHz acoustic lens was used to generate the leaky surface acoustic wave (LSAW) on the test specimens. The matrix precipitates coarsened with thermal aging time, and then grow up to several tens of micrometers. The velocity of LSAW decreased with increasing aging time. Also, it has a good correlation between LSAW and hardness. Consequently, V(z) curve methods of SAM using high frequency transducer is useful tool to evaluate the heat treatment effects on microstructure.

• The Journal of the Acoustical Society of Korea
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• v.6 no.3
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• pp.23-30
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• 1987

In this paper, the characteristic response of reflected signals of acoustic reflection microscope, V(z) phenomenon, has been studied and a new type of NDE technique has been presented. 10 Won coin, aluminium, IC component, and kevlar-epoxy samples have been used for the experiment of NDE and the acoustic microscope operating at a center frequency of 3 MHz has been used in the focused or defocused mode of operation. In experiment, it has been shown that the acoustic microscope has the resolution of $500\mu m$ and the defects present on the surface and near surface of samples have been detected by acoustic transducer and imaged on a monitor, and the variation of the contrast of image for samples has been in good agreement with V(z) phenomenon.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.3
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• pp.227-236
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• 1994

The characteristics of the P(VDF-TrFE) acoustic microscope transducer were evaluated theoretically and experimentally by comparison with those of the PVDF and the ZnO acoustic microscope transducers. It was found that its insertion loss was about 5dB lower than that of the PVDF and about 13$\textbf{dB}$ higher than that of the ZnO. And its relative bandwidth was 20% which could produce the effective acoustic pulse waves having about 4 periods duration into water. Another finding was that the effective horizontal focusing resolution and the focal depth were $120\mu m and $1.5mm$, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.697-698
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• 2010