• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.397-405
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• 2010

This study proposes visualization methods of the diurnal passenger flows on the Metropolitan Seoul Subway system (MSSs) and examines the passenger trip behaviors of major central business districts (CBDs). We mine the MSS passenger flow information from a single day T-card passenger trip transaction database. It is practically intractable to analyze such flows, involving huge, complex space-time data, by means of general statistical analysis. On the other hand, dynamic visualizations of the passenger flows make it possible to analyze intuitively and to grasp effectively characteristics of the passenger flows. We thus propose several methods to visualize the passenger flow information. In particular, we visualize dynamic passenger flows of each link on the subway network and analyze the time-space characteristics of passenger ridership for the three major CBDs. As the result, we can ascertain the strong association between CBD and subway line and clarify the distinction among three major CBDs in the diurnal patterns of subway passenger flow.

• Journal of Ocean Engineering and Technology
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• v.10 no.3
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• pp.83-88
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• 1996

두 인접한 원주 유동장을 입자 영상 속도계를 이용하여 연구하였다. 실험은 회류수조에서 행하였다. 흐름방향에 평행하게 배치하는 방법과 직교배열의 두가지 방법으로 원주를 배열하였다. 연구 결과는 다른 연구자의 결과와 일치함을 보여주었다. 본 연구를 통하여 입자 영상 속도계를 이용한 유동장 해석이 대단히 효과적임을 알 수 있었다.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.100-111
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• 1994

This study was carried out for understanding the characteristics of the spray around high speed vessels. Prismatic planing hull made of an acrylate board was used to the tests. The distribution of local spray velocity were estimated from the analysis of the spray visualization. A new test system for measuring the spray thickness is proposed, and was used to estimate the local spray thickness in the model. The pressure distributions on the bottom of the hull are measured and integrated to estimate the pressure drag of the model in the towing tests. Finally. the spray drag/lift component is separated from the total drag/lift on the prismatic hull. These test results show that the spray drag component on high speed vessels is relatively large and important in total drag.

• Journal of Korea Multimedia Society
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• v.8 no.10
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• pp.1322-1328
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• 2005

The circulation flows passing through the Ekman boundary layer on the rotating disk and transfer the angular momentum into the interior region of the container. Consequently, the circulation enhances the momentum transfer and the interior fluid is divided by a propagating shear front. This investigation focuses on computer vision and image processing technique for analysis of Non-Newtonian Fluids. To visualize marching velocity shear front for the transient flow, a particular shaped particles and light are used. To validate the proposed method, quantitative image are compared with the optical data acquired by a direct measurement of LDV (Laser Doppler Velocimetry).

• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.605-615
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• 2001

SMAC method, one of the numerical simulation techniques, is modified from the original MAC method for the time-dependent variation of fluid flows. The Navier-Stokes equations for incompressible time-dependent viscous flow is applied, and marker particles which present the visualization of fluid flaws are used. In this study, two-dimensional numerical simulations of the water column collapse are carried out by SMAC method, and the simulation results are compared with Martin and Moyce's experimental data and result of the MPS method. A good results are obtained. This numerical simulation could also be applied to the breaking phenomenon of hydraulic structures such as dam break.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.1025-1030
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• 2007

여러 학계와 산업계로부터 인체영상과 같은 정적인 볼륨 데이터뿐만 아니라, 유체 흐름과 같은 동적으로 움직이는 Time-Variant 볼륨 데이터에 대한 실시간 렌더링의 요구가 계속되고 있다. 일반적으로 Time-Variant 데이터는 그 크기가 정적 볼륨 데이터의 수배에서 수백 배에 이르러, 이를 실시간으로 가시화하는 데에 많은 어려움이 있어왔다. 한편, PC 그래픽스 하드웨어의 급격한 발전에 따라 슈퍼컴퓨터나 다수의 컴퓨터들을 이용한 병렬/분산 렌더링으로나 가능했던 Time-Variant 볼륨 데이터의 실시간 볼륨 렌더링을 한대의 일반 PC에서 수행하려는 시도가 계속되고 있다. GPU의 꼭지점 및 프래그먼트 쉐이더(vertex & fragment shader)는 수치 계산에 최적화된 벡터 연산과 사용자 프로그래밍 기능으로 빠른 볼륨 렌더링을 일반 PC에서도 가능하게 했다. 본 논문에서는 GPU를 이용해서 Time-Variant 볼륨 데이터를 빠르게 가시화하고, 이렇게 개발한 GPU 볼륨 렌더링 프로그램을 사용자가 사용하기 편리하도록 사용자 친화적인 유저 인터페이스를 설계하고 구현하였다. 특히, 시간에 따라 동적으로 변화해야 하는 전이함수를 최대한 편리하게 생성할 수 있도록 전이함수 에디터에 중점을 두었다.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.48-51
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• 2004

Chemical Mechanical Polishing(CMP) is popularly used in production of semiconductor because of large area polishing ability probability of improvement for more integrated circuit. However, present CMP processing causes some non-uniformity errors which can be critical for highly integrated circuit. Previous studies predict that flow-field of slurry during CMP can create non-uniformity, but no quantitative measurement has conducted. In this study, using PIV, slurry velocity flow-field during CMP is measured by changing the ratio of RPM of pad and carrier with tuned PIV system adequate for small room in CMP machine and Cabot's non-groove pad Epad-A100. The result show that velocity of slurry is majorly determined by pad-rpm and the ratio of between carrier and pad rpm make some changes in streamlines.

• The Journal of the Acoustical Society of Korea
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• v.17 no.2
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• pp.71-78
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• 1998

와(vortex) 박리는 고형물체가 유동내에서의 유체의 흐름을 방해할 때 발생하는 전 형적인 주기적 진동 현상이다. 본 연구에서는 삼각주형 실린더가 유동내에 유발하는 와 발 리 특성을 가시화 기법, 와에 의해 변조된 초음파의 파워 스펙트럼 및 유동관에서의 진동측 정 등을 통해 연구하였다. 가시화 관찰과 유동측정 실험 결과, 발생 와는 발생체 전면으로부 터 3d와 5d 사이에서 가장 안정성이 유지됨을 발견하였다. 넓은 레이놀즈 수(104≤Re≤106) 의 유동영역에서 액체와 기체원형유동의 측정 실험결과로부터 스트로우할(Strouhal) 수가 와발생체 폭(d)과 형상비(d/D)의 증가함수이며, 삼각주 단면의 높이에 반비례함을 알 수 있 었다. 또한 실험 결과로부터 실린더의 기하학적 치수로 삼각주형 실린더의 스트로우할 수를 예측할 수 있는 경험식을 제시하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1511-1520
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• 2004

A flow visualization of the two-dimensional rigid fling-clap motions of the flat-plate wing are performed to gain knowledge of butterfly mechanisms that might be employed by butterflies during flight. In this numerical visualization, the time-dependent Navier-Stokes equations are solved for cyclic fling and clap types of wing motion. The separation vortex pair that is developed in the fling phase of the cyclic fling and clap motion is observed to be stronger than those of the fling followed by clap and pause motion(1st cycle motion). This stronger separation vortex pair in the fling phase is attributable to the separation vortex pair of the outside space developed in the clap phase as it moves into the opening in the following fling phase. Accordingly, higher lift and power expenditure coefficients in the fling after clap phase is caused by the stronger separation vortex pair.

• Journal of the Korean Society of Visualization
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• v.13 no.1
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• pp.30-34
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• 2015

This study concerns flow and heat transfer characteristics of FC-72 condensing flow in a micro-channel. A computational model of condensing flow with a hydraulic diameter of 1 mm is constructed using the FLUENT computational fluid dynamics code. The computed void fraction contour plots are presented for different mass velocities. The smooth-annular, wavy-annular, transition and slug flows are observed with the model, which are quite similar to those observed in a micro-channel experiment. The computed two-phase condensing heat transfer coefficient is compared with previous empirical correlation for two-phase condensation heat transfer in micro-channels.