• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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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.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.646-651
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• 2003

Quantitative performance test on the conventional 2D-PIV and the hybrid angular 3D-PIV (Stereoscopic PIV) was carried out. LES Data sets on an impinging jet which are provided on the webpage(http://www.vsj.or.jp/piv) for the PIV Standard Project were used for the generation of virtual images. The generated virtual images were used for the 2D-PIV and 3D-PIV measurements. The measurement results showed that the results obtained by 2D-PIV on average values are closer to the LES data than those obtained by 3D-PIV, but the turbulent properties obtained by 2D-PIV are largely underestimated than those obtained by 3D-PIV.

• 한국가시화정보학회:학술대회논문집
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• 2001.12a
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• pp.108-122
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• 2001

In a continuing effect to study the mixmg enhancement by large-scale streamwise vortices in lobed mixing flows, an advanced PIV system named as dual-plane stereoscopic PIV system was used in the present study to conduct simultaneous vorticity (all three components) measurement of an air jet exhausted from a lobed nozzle. Unlike 'classical' 2-D PIV system or conventional 'single-plane' stereoscopic PIV system, the dual-plane stereoscopic PIV system used in the present study can obtain the flow velocity (all three components) fields at two spatially separated planes simultaneously. Therefore, it can provide the distributions of all the three components of vorticity vectors instantaneously and simultaneously. The evolution and interaction characteristics of the large-scale streamwise vortices and azimuthal Kelvin-Helmholtz vortices in the lobed jet mixing flow were revealed instantaneously and quantitatively from the measurement results of the dual-plane stereoscopic PIV system. The characteristics of the mixing process in the lobed jet mixing flow were analyzed based on the simultaneous measurement results of the steamwise vorticity and azimuthal Kelvin-Helmholtz vorticity distributions.

• Journal of the Korean Society of Visualization
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• v.3 no.1
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• pp.26-35
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• 2005

The combination of ultrasound echo images with digital particle image velocimetry (DPIV) method has resulted in a two-dimensional, two-component velocity field measurement technique appropriate for opaque flow conditions including blood flow in clinical applications. Advanced PIV processing algorithms including an iterative scheme and window of offsetting were used to increase spatial resolution. The optimum concentration of the ultrasound contrast agent used for seeding was explored. Velocity validation tests in fully developed laminar pipe flow and pulsatile flow showed good agreement with both optical PIV measurements and the known analytic solution. 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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• 2001.12a
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• pp.62-74
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• 2001

Present paper describes the principles of PIV measurement approaching from the analytical view, which enables to explain the general form of principles covering all the PIV measurement, and that gives theoretical basis for its higher measurement performances. The explanation of the measurement principles started from the definition of governing equation in differential form as same as the gradient method, and the integral along the particle path line was executed to show the principle of the correlation method with same basis. The integral processes clearly shows the analytical reason why the correlation peak gives the terminal point of path line, and how the effects of deformation and rotation of fluid appears in the correlation map. These results have no differences from our experiences and understandings of the conventional PIV measurement definition in final form. However, the analytical approach enable to understand those facts a priori, and it makes easy to achieve the innovative higher performances of measurement. Analytical explanation clearly shows the behavior of the residual errors caused by the fluid motion, and it enables to analyze the measurement uncertainty theoretically.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.733-737
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• 2001

Heat generated from the electronic parts in PDP is undesirable physical properties. To attain optimal arrangement of the electronic parts in PDP, thermal flows in PDP should be analyzed. PIV measurement has been made to quantify the characteristics of the inner flows and outer flows of an actual PDP. The quantity of heat flux from PDP has been estimated using the PIV results. Measurement system consists of Ar-ion laser, CCD camera and an image grabber installed on a host computer.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.5
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• pp.633-640
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• 2003

The present experimental study is focused on the application of multi-point simultaneous measurement by PIV(Particle Image Velocimetry) to guide vane region within diffuser pump. Various different kinds of rotational velocity were selected as experimental condition. Optimized cross correlation Identification to obtain velocity vectors is implemented with direct calculation of correlation coefficients. Fine optical setup concerned with PIV performance is arranged for the accurate PIV measurement of high-speed complex flow. Variable flow pattern are represented quantitatively at the stator region.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.11-18
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• 1998

The present experimental study is focused on the application of multi-point simultaneous measurement by PIV(Particle Image Velocimetry) to rotor-stator region within centrifugal turbine pump. Six different kinds of rpm(120, 500, 1000, 1500, 2000 and 2500) are selected as experimental condition. Optimized cross correlation identification to obtain velocity vectors is implemented by direct calculation of correlation coefficients. Fine optical setup deeply concerned with PIV performance is arranged for accurate PIV measurement of high-speed complex flow. The instantaneous and time-mean velocity distribution and velocity profile are represented quantitatively at the rotor and stator region.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.29-35
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• 2000

The present experimental study is focused on the application of multi-point simultaneous measurement by PIV(Particle Image Velocimetry) to guide vane region within diffuser pump. Various different kinds of rotational velocity were selected as experimental condition. Optimized cross correlation identification to obtain velocity vectors is implemented with direct calculation of correlation coefficients. Fine optical setup concerned with PIV performance is arranged for the accurate PIV measurement of high-speed complex flow. Variable flow pattern are represented quantitatively at the stator region.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.145-146
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• 2006

Recently, the next-generation advanced flow visualization techniques such as holographic PIV, dynamic PIV, echo-PIV, micro/nano-PIV, and X-ray PIV have been introduced. These advanced measurement techniques have a big potential as the core technology for analyzing outmost thermo-fluid flows in future. These would be indispensable in solving complicated thermo-fluid flow problems not only in the industrial fields such as automotive, space, electronics, aero- and hydro-dynamics, steel, and information engineering, but also in the research fields of medical science, bio-medical engineering, environmental and energy engineering etc. Especially, NT (Nano Technology) and BT (Bio Technology) strongly demand these advanced measurement techniques, because it is impossible for conventional measurement methods to observe most complicated nano- and bio-fluidic phenomena. In this presentation, the basic principle of these high-tech flow visualization techniques and their practical applications which cannot be resolved by conventional methods, such as blood flows in a micro-tube, in vivo analysis of micro-circulation, and flow around a living body will be introduced as a blue ocean strategy.