• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.47-50
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• 2003

The wind flow and pollutant dispersion over a two-dimensional sinusoidal hilly obstacle with slope (the ratio of height to half width) of 0.7 have been investigated experimentally and numerically. Flow over a single sinusoidal hill model was visualized in a subsonic wind tunnel. The mean velocity profiles, turbulence statistics, and pollutant concentration distribution were measured at the Reynolds number based on the obstacle height (H=40mm) oft $2.6\times10^4$. Experimental results for flow over a flat ground were agreed with the theoretical and numerical results. When a pollutant source is located behind the hilly terrain, the pollutant dispersion appeared even in the upstream region due to recirculation flow.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.59-62
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• 2002

A study of three-dimensional unsteady incompressible flow past elliptic disk with aspect ratio 3 is presented. Numerical visualization using the vortex filament method was performed at Reynolds number of 20,000 on the basis of the minor diameter, the random walk method was used to calculate viscous diffusion effect. We suggest 3 stages about the wake development according to its structures, stability and motions and described the characteristics of each stages. The structure of the elliptic wake is more complicate and unstable than the wake behind a circular disk.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 PARALLEL CFD 2006
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• pp.209-210
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• 2006

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.47-52
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• 2001

Micro-injection molding and microfluidic devices with the help of MEMS technologies including the LIGA process are expected to play important roles in. micro-system industries, in particular the bioapplication industry, in the near future. Understanding fluid flows in micro-channels is important since micro-channels are typical geometry in various microfluidic devices and mold inserts for micro-injection molding. In the present study, both experimental and numerical studies have been carried out to understand the detailed flow phenomena in micro-channel filling process. Three sets of micro-channels of different thickness were fabricated and a flow visualization system was also developed to observe the filling flow into the micro-channels. Experimental flow observations were extensively made to find the effects of channel width and thickness, and effects of surface tension and volume flow rate and so on. And a numerical analysis system has been developed to simulate the filling flow into micro-channels with the surface tension effect taken into account. Discussed are the flow visualization experimental observations along with the predictability of the numerical analysis system.

• 한국수자원학회논문집
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• 제34권6호
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• pp.605-615
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• 2001

수치시뮬레이션 기법 중 하나인 SMAC법은 시간의 변화에 따른 유동의 현상을 해석하기 위해 MAC법을 수정 한 기법이다. 비압축 점성 흐름을 풀기 위해 Navier-Stokes 방정식을 사용하였으며, 유동을 가시화하기 위해 마커입자가 사용되었다. 본 연구에서는 SMAC법을 사용한 2차원 물기등 붕괴현상의 수치시뮬레이션을 수행하였으며, 시뮬레이션 결과는 Martin과 Moyce의 실험 결과 및 MPS법의 계산결과와 비교하였고, 좋은 결과가 얻어졌다. 또한, 이 수치시뮬이션은 댐 붕괴와 같은 수공구조물의 붕괴현상에 적용할 수 있겠다.

• 한국가시화정보학회지
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• 제18권2호
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• pp.51-58
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• 2020

Research on shock structures of supersonic jet through visualization experiments in low-pressure environment have not been actively conducted. Therefore, in this study, shock waves and supersonic jets were analyzed and compared by numerical analysis and Schlieren technique at low-pressure. Schlieren technique is commonly used to visualize the shock waves generated by density gradient as interferometric methods. Pressure ratio of entrance and ambient was set around 4 to observe moderate under-expanded jet. For validation of experimental and numerical results, the shock structure and frequency were compared. In the case of ST and C nozzle, the results were shown that the difference of shock cell distance was within 10%. The Mach number gradually decreased due to energy reduction, and the error rate was within 7%. D nozzle was not fitted to be observing the shock structure. Because the interface between rarefaction fan and supersonic jet was ambiguous and oscillating phemenoma occurred at end of jet, the supersonic jet in low ambient pressure was observed and analyzed.

• 대한설비공학회지:설비저널
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• 제17권4호
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• pp.382-394
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• 1988

Dynamic characteristics of thermally-forced stratification process in a square enclosure with a linear temperature profile at the side walls have been investigated through flow visualization experiment and numerical analysis. The experiment was performed on air with the Rayleigh numbers of order $10^5$. A particle tracer method is used for the flow visualization and to obtain a sudden linear temperature profile at the side walls copper blocks which already have a linear temperature profile are come into contact with the thin copper plates of the test section. Immediately a meridional circulation is developed and heat transfer takes place from the wall to the interior region by circulation of fluid and finally a thermal stratification is achieved. In the numerical study, QUICK scheme for convective terms, SIMPLE algorithm for pressure correction, and the implicit method for the time marching are adopted for the integration of conservation equations. Comparison of flow visualization and numerical results shows that the developing flow patterns are very similar in dynamic nature even though there is a time lag due to the inevitable time delay in setting up a linear temperature profile. For high Rayleigh numbers, the oscillatory motion is likely to take place and stratified region is extended. However, initial temperature adjustment process is much slower than that for low Rayleigh numbers.

• 한국수소및신에너지학회논문집
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• 제29권2호
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• pp.155-162
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• 2018

In this paper, the reliability of the numerical analysis using the two phase flow on the behavior of the hydrogen bubbles in the alkali electrolysis stacks was investigated by comparing the results obtained from numerical analysis and flow visualization experiments. As the results, through comparison with results gotten to visualization experiments, it is possible to approximate analysis for the flow of hydrogen bubbles in the stacks by numerical analysis using the two-phase flow. Also, the flow of hydrogen bubbles around the electrodes could be similarly analyzed by numerical analysis using the two-phase flow.

• 디지털융복합연구
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• 제7권1호
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• pp.57-71
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• 2009

The visualization of business reports has received greater attention from information system scholars. Tables, graph and charts are often used to represent vast amount of complex numerical data and spreadsheet visuals become a de facto standard in business. This study suggests the use of individual's cognitive differences on business report visualization instead of providing "one visual fits all type of reports." It is argued that reports with data augmented by appropriate visuals will affect the efficiency and effectiveness of an individual's learning outcomes and subsequently his or her decision making processes. It is argued here that report visualization can augment the usefulness of contents and enhance many desirable features of reports as specified in those proposed models.

• 대한기계학회논문집B
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• 제23권3호
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• pp.408-418
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• 1999

Incompressible flow inside a circular cylinder Including periodically oscillating free surface waves was studied primarily by using a numerical method. We developed a finite difference scheme based on the MAC method applicable to three-dimensional free-surface flows, and applied it to the present flow model to study tho flow characteristics as well as the fluid stirring. To verify the validity of our scheme, we performed a simple experiment for flow visualization. We found that the numerical results show a reasonable agreement with the observed flow patterns.