• Applied Microscopy
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• 제50권
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• pp.25.1-25.11
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• 2020

Scanning acoustic microscopy (SAM) or Acoustic Micro Imaging (AMI) is a powerful, non-destructive technique that can detect hidden defects in elastic and biological samples as well as non-transparent hard materials. By monitoring the internal features of a sample in three-dimensional integration, this technique can efficiently find physical defects such as cracks, voids, and delamination with high sensitivity. In recent years, advanced techniques such as ultrasound impedance microscopy, ultrasound speed microscopy, and scanning acoustic gigahertz microscopy have been developed for applications in industries and in the medical field to provide additional information on the internal stress, viscoelastic, and anisotropic, or nonlinear properties. X-ray, magnetic resonance, and infrared techniques are the other competitive and widely used methods. However, they have their own advantages and limitations owing to their inherent properties such as different light sources and sensors. This paper provides an overview of the principle of SAM and presents a few results to demonstrate the applications of modern acoustic imaging technology. A variety of inspection modes, such as vertical, horizontal, and diagonal cross-sections have been presented by employing the focus pathway and image reconstruction algorithm. Images have been reconstructed from the reflected echoes resulting from the change in the acoustic impedance at the interface of the material layers or defects. The results described in this paper indicate that the novel acoustic technology can expand the scope of SAM as a versatile diagnostic tool requiring less time and having a high efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1985년도 하계학술회의논문집
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• pp.337-340
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• 1985

• 비파괴검사학회지
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• 제29권6호
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• pp.534-549
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• 2009

As the thin film technology has emerged in various fields, adhesion of the film interface becomes an important issue in terms of the longevity and durability of thin film devices. Diverse nondestructive methods utilizing acoustic techniques have been developed to assess the interfacial integrity. As an effective technique based on the ultrasonic wave focusing and the surface acoustic wave(SAW) generation, scanning acoustic microscopy(SAM) has been investigated for adhesion evaluation. Visualization of film microstructures and quantification of adhesion weakness levels by SAW dispersion are the recent achievements of SAM. To overcome the limitations in the theoretical dispersion model only suitable for perfectly elastic and isotropic materials, a new model has been more recently developed in consideration of film anisotropy and viscoelasticity and applied to the adhesion evaluation of polymeric films fabricated on semiconductive wafers.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.899-900
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• 2009

• 한국공작기계학회논문집
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• 제10권5호
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• pp.9-16
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• 2001

Turning experiments are conducted to investigate characteristics of acoustic emission due to wear of the coated tool. The AE signals are obtained with a sensor attached to tool holder side. Tool states are identified with scanning electron microscopy and optical microscopy. It is demonstrated that the AE signals provide reliable informations about the cutting processes and tool states. Moreover, tool wear can be detected successfully using the AE-RMS.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1133-1134
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• 2010

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 학술발표대회 논문집 제17권 2호
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• pp.259-262
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• 1998

In this paper, we have studied measurement technique for inhomogeneous residual stress using acoustic microscopy with quadrature detector. In experiment, aluminum tensile specimen with the flaw has been made and loaded by Instrone. A spherical typed acoustic transducer of center frequency 5MHz has been used for sending a longitudinal acoustic wave into a stressed specimen. It has been shown in experimental results that the phase has largely changed around the flaw that residual stress has been largely distributed and acoustic microscopy has been used in the field of residual stress measurement.

• International Journal of Precision Engineering and Manufacturing
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• 제9권2호
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• pp.28-33
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• 2008

In a scanning electron microscope (SEM), outside acoustic noise causes image noise that distorts observations of the specimen being examined. A SEM that is less sensitive to acoustic noise is highly desirable. This paper investigates the image noise problem by addressing the mode shapes of the base plate and the transmission path of the acoustic noise and vibration. By arranging the position of the rib, a new SEM base plate was developed that had twisting as the 1st and 2nd modes. In those two twisting modes, vibration nodes existed near the center of the base plate where the specimen chamber is placed. Less vibration was transmitted to the chamber and to the specimen by the twisting modes compared to bending ones, which are the 2nd and 3rd modes for a rectangular plain base plate. An SEM with the developed base plate installed exhibited a significant reduction of image noise when exposed to acoustic noises below 250 Hz.

• 한국재료학회지
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• 제6권9호
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• pp.963-971
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• 1996

세라믹 강화 복합 재료의 모재로서 사용되는 무정형 PEEK가 보여주는 self-bonding 현상의 주 기구인 PEEK체인들의 확산(interdiffusion)과 뒤엉킴(entanglement)이 일어나기 위하여 PEEK의 접합 면에서 반드시 선행되어 일어나야 하는 젖음성의 정도에 미치는 접합 공정 변수의 영향을 C-mode acoustic microscopy를 이용하여 고찰하였다. 또한 self-bonding 된 PEEK시편들의 전단 변형시 전단 하중의 증가에 따라 일어나는 접합 면에서의 debonding 정도를 측정함으로써 접합 면에서 일어나는 파괴 거동을 관찰하였다. 각각의 접합 조건에서의 젖음성의 정도는 시간과 압력의 증가에 따라 다소 증가함을 보여 주었으나, 접합 온도와는 거의 무관함을 보여 주었다. 또한 전단 파괴 시험시 각각의 접합 조건 하에서 개발된 self-bonding강도의 80%-90%이상의 전단 하중이 가해진 후부터 debonding이 시작되어, 이 후 하중이 증가함에 따라 급속도로 진행되어 파괴가 일어남을 알 수 있었다.

• 한국안전학회지
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• 제16권4호
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• pp.7-13
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• 2001

Wire electrical discharge machining experiments in conducted to investigate characteristics of acoustic emission (AE) and electrical discharge energy due to current peak (I$_{p}$), pulse on time($\tau$/on/). The AE signals are obtained with a sensor attached to workpiece side. Machining states are identified with scanning electron microscopy and residual stress analyzer. It is demonstrated that the residual stress provide reliable informations about the machining states. Moreover, machining states can be detected successfully using both the residual stress and AE count rate.e.