• Title/Summary/Keyword: 레이저 유도초음파

Search Result 34, Processing Time 0.035 seconds

Evaluation of Depth of Surface-breaking Slit by Nondestructive Self-calibrating Technique Using Laser Based Ultrasound (레이저 유도 초음파 및 자기보상 기법을 이용한 재료의 표면균열 깊이 비파괴 평가)

  • Lee, Jun-Hyeon;Choe, Sang-U;Ha, Sang-Bong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.26 no.4
    • /
    • pp.745-753
    • /
    • 2002
  • It is required to evaluate nondestructively the crack depth of surface-breaking cracks for the assurance of safety of structure. Optical generation of ultrasound produces well defined pulses with a repeatable frequency content, that are free of any mechanical resonances; they are broad band and are ideal for the measurement of attenuation and scattering over a wide frequency range. Self-calibrating surface signal transmission measurement is very sensitive and practical tool for surface-breaking crack depth. In this paper, the self-calibrating technique by laser-based ultrasound is used to evaluate the depth of surface-breaking crack of material. It is suggested that the relationship between the signal transmission and crack depth can be used as a practical model for predicting the surface-breaking crack depths from the signal transmission measured in structure.

Basic study on proliferation control of cancer cells using combined ultrasound and LED therapeutic module (초음파와 LED를 이용한 일체형암세포 증식억제 모듈의 기초연구)

  • Cho, Kyung-rae;Choe, Se-woon
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.22 no.8
    • /
    • pp.1107-1113
    • /
    • 2018
  • Ultrasonography and photodynamic therapy have been proposed as useful tools as a treatment for inducing necrosis of cells using reactive oxygen species. Apoptosis is an internal mechanism necessary for cells regardless of damage. Ultrasound has the effect of inducing the apoptosis of these cells, and the frequency of 1 MHz is the most applicable area for medical use. The laser which is generally used in photodynamic therapy has a heat reaction and the treatment is limited. However, as a small light emitting diode is developed, it shows possibility to minimize the equipment and reduce heat reaction. On the other hand, there are relatively few researches on direct effects of light compared with studies using photosensitizers, and the area is also limited. Therefore, in this paper, we have developed a cancer cell proliferation control module using ultrasonic and light emitting diodes, which have relatively few side effects, and quantitatively analyze the effect of the module to propose an optimal suppression technique.

A Study of Non-contacting Ultrasonic Technique for Evaluation of Fiber Reinforced Composite Materials (섬유강화 복합재료의 비접촉식 초음파 평가 기법 연구)

  • Choi Sang-Woo;Seo Kyeong-Cheol;Lee Joon-Hyun;Byun Joon-Hyun
    • Proceedings of the Korean Society For Composite Materials Conference
    • /
    • 2004.10a
    • /
    • pp.268-271
    • /
    • 2004
  • Non-contact technique should be developed for receiving ultrasonic wave for on-line monitoring of processing defects of fiber reinforced composites, since couplant must be applied on composite materials when conventional ultrasonic testing technique was used. Restriction of conventional ultrasonic testing technique was proven by transmitting and receiving ultrasonic wave on CFRP in various direction of wave propagation with various incident angle of ultrasonic beam. Air-coupled transducer and laser interferometer were applied for non-contacting reception of ultrasonic wave in fiber reinforced composite materials. Air-coupled transducer has optimal sensitivity and frequency band of 300kHz has homogeneous characteristics on direction of wave propagation.

  • PDF

Study of Acoustic Streaming at Resonance by Longitudinal Ultrasonic Vibration Using Particle Imaging Velocimetry (입자 영상 유속계를 이용한 초음파 수직진동에 의해 유도된 공진상태에서의 음향유동에 관한 연구)

  • 노병국;이동렬
    • The Journal of the Acoustical Society of Korea
    • /
    • v.23 no.5
    • /
    • pp.340-352
    • /
    • 2004
  • Acoustic streaming induced by the microscopic longitudinal ultrasonic vibration at 28.5 ㎑ is visualized between the quiescent glass plate and ultrasonic vibrator by particle imaging velocimetry(PIV) using laser. To investigate the augmentation of air flow velocity of acoustic streaming. the velocity variations of air streaming between the stationary plate and ultrasonic vibrator are measured in real-time. It is experimentally investigated that the magnitude of the acoustic streaming dependent upon the gap between the ultrasonic vibrator and stationary p1ate results in the variations of the average velocity fields as a outcome of the bulk air flow caused by the ultrasonic vibration. In addition. maximum acoustic streaming velocity exists at resonant gap. 18mm that is one of the resonant gaps (H=18, 24, 30, 36㎜) at which resonance occurs. The variation of the local maximum turbulent intensity with axial direction appear to reveal the value of 8%∼70% dependent upon the gap between the quiescent glass plate and ultrasonic vibrator. Shearstress is also maximized at the center region of the vibrator and the vorticity is also maximum and minimum in the neighborhood of the center of the vibrator at which the local maximum turbulent intensity and shear stress exist.

Finite Element Simulation of Laser-Generated Ultrasound and Interaction with Surface Breaking Cracks (유한요소법을 이용한 레이저 유도 초음파와 표면 균열과의 상호작용 모델링)

  • Jeong, Hyun-Jo;Park, Moon-Cheol
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.24 no.3
    • /
    • pp.259-267
    • /
    • 2004
  • A finite element method is used to simulate interaction of laser-based ultrasounds with surface breaking tracks in elastic media. The laser line source focused on the surface of semi-infinite medium is modeled as a shear dipole in 2-D plane strain finite elements. The shear dipole-finite clement model is found to give correct directivity patterns for generated longitudinal and shear waves. The interaction of surface waves with surface breaking cracks (2-D machined slot) is considered in two ways. Both the source and receiver are fixed with respect to the cracks in the first case, while the source is moving in another case. It is shown that the crack depth tested in the range of 0.3-5.0mm $({\lambda}_R/d=0.21{\sim}3.45)$ can be measured using the corner reflected waves produced by the fixed laser source. The moving laser source is found to cause a large amplitude change of reflected waves near crack, and the crack whose depth is one order lower than the wavelength ran be detected from this change.

Study on Application of Ultrasonic Propagation Imager for Non-destructive Evaluation of Composite Lattice Structure (복합재 격자 구조 비파괴평가를 위한 초음파전파 영상화 시스템 활용 연구)

  • Park, Jae-Yoon;Shin, Hye-Jin;Lee, Jung-Ryul
    • Composites Research
    • /
    • v.30 no.6
    • /
    • pp.356-364
    • /
    • 2017
  • Composite lattice structures are tried to be used in various fields because of its benefit in physical properties. With increase of demand of the composite lattice structure, nondestructive testing technology is also required to certificate the quality of the manufactured structures. Recently, research on the development of the composite lattice structure in Republic of Korea was started and accordingly, fast and accurate non-destructive evaluation technology was needed to finalize the manufacturing process. This paper studied non-destructive testing methods for composite lattice structure using laser ultrasonic propagation imaging systems. Pulse-echo ultrasonic propagation imaging system was able to inspect a rib structure wrapped with a skin structure. To reduce the time of inspection, a band divider, which can get signal in different frequency bands at once, was developed. Its performance was proved in an aluminum sandwich panel. In addition, to increase a quality of results, curvature compensating algorithm was developed. On the other hand, guided wave ultrasonic propagation imaging system was applied to inspect delamination in a rib structure. To increase an area of inspection, multi-source ultrasonic wave propagation image was applied, and defects were successfully highlighted with variable time window amplitude mapping algorithm. These imply that ultrasonic propagation imaging systems provides fast and accurate non-destructive testing results for composite lattice structure in a stage of the manufacturing process.

Manufacture of an Acousto-Optical Spectrometer for Radio Astronomical Observations (우주전파관측용 음향광학 전파분광기의 제작)

  • 임인성;최재현;오승엽
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.8 no.1
    • /
    • pp.1-12
    • /
    • 1997
  • The acousto-optical spectrometer as a new type backend of the receiver system for radio astronomical observations is manufactured for radio signal analysis. We studied on the effect of Acousto-Optic and Acousto-Optic devices and designed the optics system. We manufactured the optical mount and the CCD detector for deflected beam and interface card. This acousto-optical spectrometer consisted of a laser, optics, acousto-optic deflector, CCD detector and Interface card. This system use He-Ne laser as a light source and use optics to get parallel beam and to focus the deflected beam. Acousto-optic deflector converts IF signal to ultrasonic wave and deflect the laser beam according to the Bragg deflection. The ultra wide band acousto-optic deflector has 1 GHz bandwidth and a total of 2,048 channel Charge Coupled Device for signal detection. In this study, we discuss the theoretical description on the effect of Acousto-optics, the design of the optics, manufacture of optical mount, CCD detector, interface card and we presented the results of experiment. As a result of measurement, we have 1,000 channels bandwidth from CCD channels.

  • PDF