• 한국추진공학회지
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• 제6권1호
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• pp.55-62
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• 2002

미세수적과 레이저 평면광을 사용하여 새로운 유동의 가시화 방법을 제안하였다. 미세수적은 약 5 내지 $10\mu\textrm{m}$ 크기로 가정용 초음파 가습기를 사용하여 생성시켰다. 조명은 3 W의 알곤 이온 레이저와 원통형 렌즈를 사용하여 레이저 평면광을 특정 와류장 단면에 형성시켰다. 이와 같은 새로운 유동의 가시화 방법을 측정부의 크기가 $0.9 m(W){\times}$0.9 m(H){\times}2.1 m(L)$$인 공군사관학교의 소형 풍동을 통하여 적용하였다. 가시화 결과를 통하여 미세수적을 이용한 새로운 가시화 방법이 풍동실험에 적용하기에 비교적 용이하며, 안전한 방법임을 보였다. 아울러 이 방법은 일반적으로 풍동실험에 적용되고 있는 스모크 가시화의 단점들을 보완함은 물론, 좀 더 높은 유동속도에서도 적용할 수 있었다.

• 한국가시화정보학회지
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• 제3권2호
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• pp.3-13
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• 2005

The optical patterantor provides the high resolution and quantitative information of the spray. Fuel distribution and Sauter Mean Diameter (SMD) can be measured from fluorescence and Mie-scat-tering images. To correct the attenuation of the laser beam and signal in dense spray region, the method to find the geometric mean of the signal intensities obtained from two cameras was evaluated and verified in a solid-cone spray. In high pressure environment, the increased number density of the droplets cause multiple scattering. The optical patternation technique using a laser beam instead of a laser sheet was applied to minimize the multiple scattering problem. The pattern of a coaxial spray was changed from hollow-cone to solid-cone shape, and the spray angle was reduced as the ambient pressure increased from 0.1 to 4.0 MPa.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 추계학술대회 논문집
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• pp.86-89
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• 2004

One most feasible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been successfully achieved so far due to various limitations in the light illumination and fluorescence signal detection. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having five(5) microns thickness by use of a micro focus laser line generator. The laser sheet beam illuminates an exact plane of concentration measurement field to increase the signal to noise ratio and considerably reduce the depth uncertainty. Nile Blue A was used as fluorescent dye for the present LIF measurement. The enhancement of the fluorescent intensity signals was performed by a solvent mixture of water $(95\%)$ and ethanol (EtOH)/methanol (MeOH) $(5\%)$ mixture. To reduce the rms errors resulted from the CCD electronic noise and other sources, an expansion of grid size was attempted from $1\times1$ to 3(3 or 5(5 pixel data windows and the pertinent signal-to-noise level has been noticeably increased accordingly.

• 한국가시화정보학회지
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• 제3권1호
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• pp.63-70
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• 2005

Optical Line Patternator(OLP) has been applied to get a distribution of the spray at high ambient pressure. OLP is a combined technique of extinction measurement and image processing. The attenuated intensity of laser beam after traversing spray region was measured by using a photo-detector, and the line image of Mie-scattering was captured simultaneously in the path of each laser beam by using a CCD camera. The distribution of extinction coefficient in the spray is obtained by processing these data with the algebraic reconstruction technique. From the distribution of extinction coefficient, the surface distribution of spray can be reconstructed. OLP does not use laser sheet but use laser beam so that the noise effect of multiple scattering, caused by increasing number density of droplet in high pressure environment, is reduced drastically. OLP is expected as a suitable method which can investigate the characteristics of relatively large spray under the high pressure environment such as liquid rocket engine.

• 한국화재소방학회논문지
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• 제15권1호
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• pp.41-46
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• 2001

수평 평판과 충돌하는 제트에 의해 생성되는 연기유동을 관찰하기 위해 질소가스네 kerosene 연기입자를 띄워 유동장을 가시화하였다. 광원으로는 아르곤-이온 레이져 평면광이 사용되었다. Kerosene smoke의 산란 광에 의한 수직평면 상(image)과 수평평면 상을 고속 CCD 카메라와 비디오 카메라로 녹화하였으며, 얻어진 영상으로부터 연기선단의 순간속도 및 평균속도를 측정하였다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 추계학술대회 논문집
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• pp.108-111
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• 2004

Laser induced incandescence and laser induced fluorescence techniques have been investigated to measure the concentrations of soot and PAH, respectively. The Nd:YAG and dye lasers were used to form a sheet beam, and its wavelength were modulated to obtain a optimized signals of soot and PAH. Results showed that the relative size groups of soot and PAH can be measured by using our laser techniques.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.65-74
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• 2004

Measurement of concentration distributions of suspended particles in a micro-channel is out of the most crucial necessities in the area of Lab-on-a-chip to be used for various bio-chemical applications. One most feasible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been successfully achieved so far due to various limitations in the light illumination and fluorescence signal detection. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having five(5) microns thickness by use of a micro focus laser line generator. The laser sheet beam illuminates an exact plane of concentration measurement field to increase the signal to noise ratio and considerably reduce the depth uncertainty. Nile Blue A was used as fluorescent dye for the present LIF measurement. The enhancement of the fluorescent intensity signals was performed by a solvent mixture of water $(95\%)$ and ethanol (EtOH)/methanol (MeOH) $(5\%)$ mixture. To reduce the rms errors resulted from the CCD electronic noise and other sources, an expansion of grid size was attempted from $1\times1\;to\;3\times3\;or\;5\times5$ pixel data windows and the pertinent signal-to-noise level has been noticeably increased accordingly.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.17-22
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• 2001

The flow induced by a circular jet vertically impinging under a horizontal plate is investigated by visualization technique, using kerosene smoke in nitrogen gas to visualize the flow in the vortex as well as under the plate. The light source was the sheet beam of Ar-Ion laser. The vertical and 3-dimensional images of vortices were recorded by the digital video camera.

• 한국가시화정보학회지
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• 제6권1호
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• pp.27-33
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• 2008

Air flow inside an automotive HVAC module has been investigated using a high-resolution PIV technique with varying the temperature operation mode. The PIV system consists of a 2-head Nd:YAG laser (125 mJ), a high-resolution CCD camera (2K$\times$2K), optics and a synchronizer. A real automotive HVAC module was used directly under real operating condition. Some casing parts of the HVAC module were replaced with transparent windows for capturing clear flow images with laser light sheet beam illumination. Time-averaged velocity fields were obtained for two different temperature control modes. Flow characteristics of the air-conditioned air flow inside the automotive HVAC system for the two temperature baffle conditions were evaluated.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.1-13
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• 2004

A scanning stereo-PIV system was developed to measure the three-dimensional distribution of three-component velocity in a turbulent round jet. A laser light beam produced by a high repetition rate YLF pulse laser was expanded vertically by a cylindrical lens to form a laser light sheet. The light sheet is scanned in a direction normal to the sheet by a flat mirror mounted on an optical scanner, which is controlled by a programmable scanner controller. Two high-speed mega-pixel resolution C-MOS cameras captured the particle images illuminated by the light sheet, and stereoscopic PIV method was adopted to acquire the 3D-3C-velocity distribution of turbulent round jet in an octagonal tank filled with water. The jet Reynolds number was set at Re=1000 and the streamwise location of the measurement was fixed at approximately x = 40D. Time evolution of three-dimensional vortical structure, which is identified by vorticity, is visualized. It revealed that the existence of a group of hairpin-like vortex structures was quite evident around the rim of the shear layer of the jet. Turbulence statistics shows good agreement with the previous data, and divergence of a filtered (unfiltered) velocity vector field was $7\%\;(22\%)$ of root-me an-squared vorticity value.