• 순환기질환의공학회:학술대회논문집
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• 순환기질환의공학회 2006년도 제6회 학술대회
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• pp.55-56
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• 2006

• 순환기질환의공학회:학술대회논문집
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• 순환기질환의공학회 2003년도 제3회 학술대회
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• pp.14-15
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• 2003

• 대한기계학회논문집B
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• 제28권12호
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• pp.1567-1572
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• 2004

Although accurate measurement of velocity profiles, multiple velocity vectors, and shear stress in arteries is important, there is still no easy method to obtain such information in vivo. This study shows the utility of combining ultrasound contrast imaging with particle image velocimetry (PIV) for non-invasive measurement of velocity vectors. The steady flow analytical solution and optical PIV measurements (for pulsatile flow) were used for comparison. When compared to the analytical solution, both echo PIV and optical PIV resolved the steady velocity profile well. Error in shear rate as measured by echo PIV (8%) was comparable to the error of optical PIV (6.5%). In pulsatile flow, echo PIV velocity profiles agreed well with optical PIV profiles. Echo PIV followed the general profile of pulsatile shear stress across the artery but underestimated wall shear at certain time points. These studies indicate that echo PIV is a promising technique for the non-invasive measurement of velocity profiles and shear stress.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2006년도 추계학술대회 논문집
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• pp.131-134
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• 2006

Whole flow fields of a room air conditioner (RAC) have been visualized by a Particle Image Velocimetry (PIV) technique to analyze the flow structure by various inlet and outlet angles, and to control an eccentric vortex which affects an efficiency and noise of the RAC. A test model with 5 stages of a cross flow fan has been manufactured and a transparent acryl has been installed at the side of the test model for the PIV experiment. The inlet and outlet flows and the flow inside the cross flow fan have been analyzed by varying the inlet grill angles and outlet blade angles. The movement of the eccentric vortex has been investigated experimentally by developing the measurement technique for the inner flow field of the cross flow fan, and the relationship between the control of the eccentric vortex and the inlet and outlet angles has been confirmed in this study.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.154-154
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• 2021

Since the development of Bubble Image Velocimetry (BIV) technique as the complementary technique of Particle Image Velocimetry (PIV), the application of digital imaging technique in the field of hydraulic and coastal engineering increased rapidly. BIV works very well in multi-phase flow (air-water) flows where the PIV technique doesn't. However, the velocity field obtained from BIV technique often resulted in a velocity vector on the outside of the flow (false velocity) since the Field of View (FOV) usually not only cover the air-water flow but also the area outside the flow. In this study, a simple technique of post processing velocity field was developed. This technique works based on the average of the pixel value in the interrogation area. An image of multi-phase flow of wave overtopping was obtained through physical experiment using BIV technique. The velocity calculation was performed based on the similar method in PIV. A velocity masking technique developed in this study then applied to remove the false velocity vector. Result from non-masking, manually removed and auto removed false velocity vector were presented. The masking technique show a similar result as manually removed velocity vector. This method could apply in a large number of velocity field which is could increase the velocity map post-processing time.

• 대한기계학회논문집B
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• 제31권2호
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• pp.181-187
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• 2007

Conventional PIV method uses two optical axis configuration during the image grabbing process. That is, the illumination plane and the recording plane must be parallel. This configuration is very natural to grab the whole field without the image distortion. In the real problem, it is often to meet the situation when this configuration is hard to be fulfilled. In the present study, the new PIV method which uses only single optical axis to grab the particle images is developed. This new PIV method becomes possible by utilizing the scanning method similar to the echo PIV technique. One particle image of the scanning PIV consists of scanned several line images and by repeating this scanning process, two particle images were grabbed and processed to produce the velocity vectors. An optimization study was performed to find parameters which minimize the measurement errors. The effects of particle diameter, beam overlap ratio and particle number density were investigated.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.114-115
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• 2007

As a carrier of malaria and sneak of blood, mosquitoes are regarded as an unpleasant insect. However, there are novel phenomena that happen inside a mosquito. Among them, we focused on the blood sucking function of a female mosquito. The main objective of this study was to investigate the mosquito's pumping mechanism in order to resolve the problem encountered when we inject or transport biologic fluids into a micro-chip. To analyze the pumping mechanism, we visualized the blood sucking process inside a female mosquito. Flow characteristics of blood flow in a proboscis were investigated experimentally using a micro-PIV velocity field measurement technique. The anatomical variation of head, thorax, abdomen which work as pumps and valves, was visualized using the syncrotron X-ray micro-imaging technique.

• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.515-525
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• 2000

A new acoustic field visualization technique is introduced in this study. Small particles of which density is small enough to follow up the air used for the noise field visualization. In order to quantify the noise, PIV(Particle Imaging Velocimetry) has been constructed. When the driving frequency is in the vicinity of the resonance frequency of the simplified 2-dimensional muffler system, an acoustic streaming is shown and of which velocity distribution is obtained through PIV technique. It is experimentally proved that the present technique is able to visualize and quantify the acoustic fields.

• 한국지반신소재학회논문집
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• 제17권3호
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• pp.33-46
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• 2018

본 논문에서는 대심도 굴착시 흙막이 벽체에 대한 실내 모형실험 결과를 다루었다. 지반의 지하수위와 벽체의 강성등의 영향인자가 흙막이 벽체 및 지반 거동에 미치는 영향에 대한 정성적 고찰을 위하여 기존 CIP 벽체와 CS-H벽체의 휨강성에 따른 상사법칙을 적용하여 제작 및 사용하여 모형실험을 수행하였으며, 실제 현장을 모사하여 버팀보 설치 및 굴착을 진행하였다. 또한 벽체, 지반 거동 분석을 위하여 PIV 분석을 수행하였으며, 벽체변위, 지반침하 및 지반 수평변위를 분석하여 지하수위가 높아질수록 벽체 강성이 작아질수록 변위가 커지는 것을 확인하였다.

• 대한기계학회논문집B
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• 제30권11호
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• pp.1027-1034
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• 2006

In order to investigate flow characteristics of chicken blood in a micro tube of 100$\mu$m in diameter, in-vitro experiments were carried out using a micro-PIV technique. The micro-PIV system consists of a microscope, 2-head Nd:YAG laser, 12 bit cooled CCD camera and a delay generator. Chicken blood with 40% hematocrit was supplied into a micro tube using a syringe pump. The blood flow shows clearly the cell free layer near the tube wall and its thickness is increased with increasing the flow speed. The hemorheological characteristics of chicken blood, including shear rate and shear stress were estimated from the PIV velocity field data obtained. Since the aggregation index of chicken blood is less than 50% of human blood, non-Newtonian flow characteristics of chicken blood are smaller than those of human blood. As the flow rate increases, the degree of flatness in the velocity profile at the center region is decreased and the parabola-shaped shear stress distribution becomes to have a linear profile. Under the same flow rate, chicken blood shows higher shear stress, compared with human blood.