• 제목/요약/키워드: V(z) 곡선

검색결과 31건 처리시간 0.026초

A study on the characteristic of material using V(z) curve of acoustic microscope (음향현미경의 V(z)곡선을 이용한 재료의 특성에 관한 연구)

  • Moon, G.;Ko, D.S.;Jun, K.S.
    • The Journal of the Acoustical Society of Korea
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    • 제7권2호
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    • pp.65-73
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    • 1988
  • In this paper, V(z) curve has been analyzed theoretically and compared with the experimental result, and the relation between the V(z) curve and the material characteristic has been studied. Angular spectrum and ray optics theory have been used for theoretical analysis and the acoustic microscope operating at a center frequency of 3 MHz has been used for experiment. In experiment, it has been shown that each material has a V(z) curve of a unique form and the interval of dips appearing in the V(z) curves have been used to determine the Rayleigh wave velocity.

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Simulation of V(z) curve at the Acoustic Microscope (초음파현미경에서 V(z)곡선의 시뮬레이션)

  • 박익근;임재생;윤종학;노승남;서성원
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 한국공작기계학회 2003년도 추계학술대회
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    • pp.426-430
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    • 2003
  • 본 연구에서는 초음파현미경의 기하학적 원리와 초음파현미경의 특징중 하나인 V(z)곡선의 간섭파형을 시뮬레이션 하였고, 실제 초음파현미경의 V(z)곡선법을 이용하여 미소영역에서의 누설탄성표면파 음속을 측정하였다. 초음파현미경을 이용한 V(z)곡선법의 음속측정결과가 시뮬레이션 음속값과 큰차이를 보이지 않으므로 미소영역에 초음파현미경의 V(z)곡선법을 적용하여 초음파의 음속측정이 가능함을 확인하였다. 이는 향후 초음파현미경을 이용하여 미세한 재료의 물성평가에 적용할 수 있을 것으로 기대된다.

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A Study on the Distinction of Solid Characteristics Using Focused Acoustic Wave (집속음향파를 이용한 고체특성 판별에 관한 연구)

  • Moon, Gun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제18권1호
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    • pp.92-99
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    • 1993
  • On this study. Constructed the system detecting the reflective acoustic waves from the solid-samples using the 3MHZ focused-acoustic transducer and detected the V(Z) charateristics curves varied by the distance between the focusing position and the solid surface. The results of the experimental detection to various solid materials showed that the materials have their own unique shape of V(Z) curves. This paper suggested the possibility distinguishing the solid characteristics by analysing the V (Z) curves.

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Nondestructive Evaluation of Nanostructured Thin Film System Using Scanning Acoustic Microscopy (초음파현미경을 이용한 나노 구조 박막 시스템의 비파괴평가)

  • Miyasaka, Chiaki;Park, Ik-Keun;Park, Tae-Sung
    • Journal of the Korean Society for Nondestructive Testing
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    • 제30권5호
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    • pp.437-443
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    • 2010
  • In recent years, as nano scale structured thin film technology has emerged in various fields such as the materials, biomedical and acoustic sciences, the quantitative nondestructive adhesion evaluation of thin film interfaces using ultra high frequency scanning acoustic microscopy(SAM) has become an important issue in terms of the longevity and durability of thin film devices. In this study, an effective technique for investigating the interfaces of nano scale structured thin film systems is described, based on the focusing of ultrasonic waves, the generation of leaky surface acoustic waves(LSAWs), V(z) curve simulation and ultra high frequency acoustical imaging_ Computer simulations of the V(z) curve were performed to estimate the sensitivity of detection of micro flaws(i.e., delamination) in a thin film system. Finally, experiments were conducted to confirm that a SAM system operating at a frequency of 1 GHz can be useful to visualize the micro flaws in nano structured thin film systems.

Evaluation of the Thermal Degradation in Co-based Superalloy using High frequency Transducer of Scanning Acoustic Microscope (초음파현미경의 고주파 초음파 탐촉자를 이용한 코발트기 초내열합금강의 열화평가)

  • Park, Ik-Keun;Cho, Dong-Su;Kim, Yong-Kwon;Lim, Jae-Seang;Kim, Chung-Seok
    • Journal of the Korean Society for Nondestructive Testing
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    • 제24권5호
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    • pp.518-524
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    • 2004
  • The feasibility of Y(z) curve method of scanning acoustic microscope using high frequency transducer was experimentally studied for assessment of the thermal degradation in Co-based superalloy. Thermal degradation was performed to simulate the microstructural changes in Co-based superalloy arising from long term exposure at high temperature. Longitudinal wave velocity measured by pulse echo method using 10MHz transducer and leaky surface acoustic wave (LSAW) velocity measured by V(z) curve method using 200MHE transducer were measured to investigate the effect on thermal degradation. Ultrasonic velocity decreased as the aging time increased in both ultrasonic waves. Moreover, the low frequency longitudinal wave velocity decreased a little. Otherwise, the high frequency LSAW velocity drastically decreased up to a maximum of 4.7% at the aging time of 4,000hours. A good correlation was found between LSAW and Vickers hardness. Consequently, V(z) curve method of SAM using high frequency transducer could be a potential tool for assessing thermal degradation.

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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    • 제23권2호
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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.

Evaluation of Adhesive Strength for Nano-Structured Thin Film by Scanning Acoustic Microscope (초음파 현미경을 이용한 나노 박막의 접합 강도 평가)

  • Park, Tae-Sung;Kwak, Dong-Ryul;Park, Ik-Keun;Miyasaka, Chiaki
    • Journal of the Korean Society for Nondestructive Testing
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    • 제32권4호
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    • pp.393-400
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    • 2012
  • In recent years, nano-structured thin film systems are often applied in industries such as MEMS/NEMS device, optical coating, semiconductor or like this. Thin films are used for many and varied purpose to provide resistance to abrasion, erosion, corrosion, or high temperature oxidation and also to provide special magnetic or dielectric properties. Quite a number of articles to evaluate the characterization of thin film structure such as film density, film grain size, film elastic properties, and film/substrate interface condition were reported. Among them, the evaluation of film adhesive to substrate has been of great interest. In this study, we fabricated the polymeric thin film system with different adhesive conditions to evaluate the adhesive condition of the thin film. The nano-structured thin film system was fabricated by spin coating method. And then V(z) curve technique was applied to evaluate adhesive condition of the interface by measuring the surface acoustic wave(SAW) velocity by scanning acoustic microscope(SAM). Furthermore, a nano-scratch technique was applied to the systems to obtain correlations between the velocity of the SAW propagating within the system including the interface and the shear adhesive force. The results show a good correlation between the SAW velocities measured by acoustic spectroscope and the critical load measured by the nano-scratch test. Consequently, V(z) curve method showed potentials for characterizing the adhesive conditions at the interface by acoustic microscope.

Nondestructive Evaluation of Seramics/Metals Interface Using V(z) Curve of Scanning Acoustic Microscopy(SAM) (초음파현미경에서 V(z)곡선을 이용한 세라믹/금속 접합계면의 비파괴 평가)

  • 조동수;박익근;김용권;이철구
    • Proceedings of the KWS Conference
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    • 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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    • pp.321-323
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    • 2004
  • 전자 제품에 사용되는 부품 ㆍ소재의 신뢰성 품질 평가를 위해 정밀한 모터의 제어기술, 첨단신호처리 기술, 압전소자 기술의 발달로 미세변화 계측의 재현성, 고분해능, 표면과 내부의 이미지관찰, 또한 미소부위에서 재료의 누설탄성표면파의 음속측정이 가능한 초음파현미경에 대한 연구가 최근 들어 활발히 진행되고 있다. (중략)

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Computing Intersection between Freeform Surfaces (자유곡면 간의 교차곡선 계산)

  • Kim, Ku-Jin;Seong, Joon-Kyung;Kim, Myung-Soo
    • Journal of the Korea Computer Graphics Society
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    • 제10권3호
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    • pp.28-33
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    • 2004
  • 본 논문에서는 자유곡면 간의 교차곡선이 갖는 위상 구조를 분석하는 방법을 제시하며, 또한 이를 이용하여 교차곡선을 효율적이고 안정적으로 계산하는 알고리즘을 제안한다. 자유곡면 간의 교차곡선 계산은 현재까지 난문제로 알려져 있으며, 그러한 가장 큰 원인 중의 하나로서 교차곡선의 위상 구조를 분석하기 어렵다는 점을 들 수 있다. 본 논문에서는 입력으로 주어지는 자유곡면 중의 하나가 매개변수 곡면 F(u, v) 이라는 가정 하에 음함수 곡면 g(x, y, z) = 0 과의 교차곡선, 그리고 또 다른 매개변수 곡면 G(s, t)와의 교차곡선 계산방법을 제시한다. 교차곡선은 uv-평면 상의 평면 곡선으로 고려되며, 이 평면곡선에서 u-방향에 대한 극점(critical point)을 먼저 계산한 뒤 이를 이용하여 위상구조를 분석한다. 또한, 분석된 위상구조를 기반으로 전체 교차곡선을 추적(tracing)하는 알고리즘을 제시한다.

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