• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.582-584
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• 2003

본 논문은 수중에서 유동하는 입자의 움직임을 추적하고 유체의 흐름에 따라 분산되는 입자의 분산정도 그리고 입자의 침강패턴을 분석하기 위한 계산형 3차원 시스템을 제안한다. 이러한 계산형 시스템은 물과 같은 공간에서 움직이는 입자들을 고려하고 있는데, 물의 흐름을 위해 운동량방정식과 연속방정식을 일반화하여 흐름을 제어하고 있다. 또한 물이라는 공간 특성을 고려하여, 입자간에 작용하는 부력, 침강력등의 물리적인 힘을 적용시키고 있다. 이렇게 제안된 시스템을 통해 다양한 외부적 요인에 따라 움직임을 달리하는 유동 입자들은 실제 울에서와 같이 유사하게 가시화되도록 한다. 이렇게 가시화된 유동 입자의 움직임을 추적하여 입자들의 침전패턴까지도 미1리 예측해 낼 수 있게 된다.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.53-65
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• 1995

입자화상 처리기법은 유체역학 분야의 정량적 유동가시화에 있어서 중요한 역할을 하고 있다. 회전 유동의 측면 사진을 찍을 때, 측정부의 볼록면 때문에 그 영상에서 광학적 변형이 일어나게 된다. 이러한 변형은 측정부의 형상은 물론 회전유동의 방향에 의해서도 큰 영향을 받는다. 정확한 유동장을 얻기 위해서 이러한 변형이 적절한 방법에 의하여 교정된다. 교정한 실험 데이터를 수치해석 결과와 비교해 보면 정량적으로 잘 맞는 것을 알 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1732-1739
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• 2004

In this paper, we proposed a visualization system with ANN algorithm that traits the motion of particles that move colliding in the water, where we got a great deal of variable information and predicts the distribution of particles according to the flowing of water and the pattern of their precipitation. We adopted ART2 to detect sensitively the collision between particles in this visualzation. Various particles and their mutual collision influencing the force such as buoyancy force, gravitational force, and the pattern of precipitation are considered in this system. Flowing particles whose motion is changed with the environment can be visualized in the system presented here as they are in real water.

• Journal of the Korean Society of Visualization
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• v.20 no.2
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• pp.63-69
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• 2022

In this study, we numerically simulate the condensational growth of micron-sized particles traveling through a pipe filled with humidified air. Using the finite volume method and Lagrangian particle tracking technique, the mixture of particle-laden flow with moist air in a T-juction pipe is simulated. The condensational growth of particles is calculated by considering the mass transfer of vapor in the air onto the particle surface. The results indicate that the growth rate of the particles increases as the relative humidity of air is higher. Furthermore, the placement of a porous media with low permeability in the pipe could enhance the degree of condensational growth.

• Journal of the Korean Society of Visualization
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• v.4 no.2
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• pp.3-5
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• 2006

Recently, the next-generation advanced flow visualization techniques such as holographic PIV, aynni.c PIV, echo-PIV, micro/nano-PIV, and X-ray PIV have been introduced. These advanced mea-surement techniques have a big potential as the core technology for analyzing outmost thermo-fluid flows in future. They would be indispensable in solving complicated thermo-fluid flow problems not only in 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 technology 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 the nano- and bio-fluidic flow phenomena. In this article, 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 are introduced as a blue ocean strategy.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.45-46
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• 2001

PIV(Particle Image Velocimetry : 입자영상유속계)는 유동장에 분포된 추종입자의 위치를 영상처리에 의해 자동추적 함으로써 속도벡터를 전유동영역에 걸쳐 동시에 구할 수 있는 계측기법이다. 따라서, CFD와 같이 정량적 및 정성적으로 수치해석된 결과와 바로 비교 검토가 가능한 유일한 실험기법으로 인식되고 있다. 본 실험에서는 CFD에 의한 모형의 유체유동 특성을 분석하고 이를 회류수조에서 PIV를 이용해 모형 전개판 주위의 유체흐름을 분석하여 각 전개판 모형의 유체유동 특성을 파악하였다. (중략)

• Journal of the Korean Society of Visualization
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• v.19 no.1
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• pp.36-42
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• 2021

This study measured the velocity of magnetic particles inside the power generation using external heat sources. Single Plane Illumination Microscopy (SPIM) was used to measure magnetic particles that are simultaneously affected by bubbly flow and magnetic field. It has the advantage of reducing errors due to particle superposition by illuminating the thin light sheet. The hydraulic diameter of the power generation is 3mm. Its surface is covered with a coil with a diameter of 0.3 mm. The average diameter of a magnetic particle is 200nm. The excitation and emission wavelengths are 530 and 650nm, respectively. In order to find out the flow characteristics, a total of four velocity fields were calculated in wide and narrow gap air bubbles, between the wall and the air bubble and just below the air bubble. Magnetic particles showed up to 8.59% velocity reduction in the wide gap between air bubbles due to external magnetic field.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.68-72
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• 2006

Vertical fence has the coherent flow structure in front of the fence. In the present study, the wake change due to the flow separator in front of the vertical fence was experimentally investigated. Quantitative method was applied to study the separated shear flow field. The results show the flow separator changes the downstream shear flow and alters the curvature of separated shear layer As the freestream velocity increased, the reattachment length also increased.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.118-131
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• 1991

The effects of free surface on vortex shedding phenomena around a bluff body were studied by both numerical simulation and flow visualization experiments. A vortex method, which approximates the vorticity field as the sum of discrete vortices; was used for the numerical simulation. Flow visualization experiments were performed in the KRISO cavitation tunnel. Hydrogen bubble was used as illumination material. Free surface elevation was also measured during experiments. The hydrodynamic drag and lift were predicted by numerical simulation. The predicted period of vortex shedding was compared with the results of experiments.

• The Journal of the Acoustical Society of Korea
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• v.23 no.5
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• pp.340-352
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• 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.