• Title/Summary/Keyword: 2-dimensional visualization

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Development of Stereoscopic Micro-PTV Method (Stereoscopic micro-PTV기법의 개발)

  • Yu, Cheong-Hwan;Kim, Hyoung-Bum
    • 한국가시화정보학회:학술대회논문집
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    • 2007.11a
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    • pp.109-113
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    • 2007
  • Micro-PIV is a well-known method for measurement of two- dimensional, two-component velocity in the microfluidic devices. Lots of the micro fluidic devices generate three-dimensional flow and 3D measurement of velocity is helpful to understand the physics of micro flow phenomena. In this study, we developed new micro 3D measurement method by applying 2-frame PTV in stereoscopic micro system. In this study, we did the validation study of SMPTV by using the simulated flow model to verify the accuracy and the feasibility of measurement and compared with SMPIV method. The results showed that SMPTV provides better spatial resolution and measurement accuracy than SMPIV method.

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Three-dimensional Laminar Flow Past a Rotating Cylinder (회전하는 원형 실린더 주위의 층류 유동장에 관한 수치적 연구)

  • Lee, Yong-Suk;Yoon, Hyun-Sik;Doo, Jeong-Hoon;Ha, Man-Yeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.11
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    • pp.827-833
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    • 2009
  • The present study numerically investigates three-dimensional laminar flow past a rotating circular cylinder placed in a uniform stream. For the purpose of a careful analysis of the modification of flow by the effect of the rotation on the flow, numerical simulations are performed at a various range of rotational coefficients ($0{\leq}{\alpha}{\leq}2.5$) at one Reynolds number of 300. As ${\alpha}$ increases, flow becomes stabilized and finally a steady state beyond the critical rotational coefficient. The 3D (three dimensional) wake mode of the stationary cylinder defined at this Reynolds number has been disorganized according to ${\alpha}$, which were observed by the visualization of 3D vortical structures. The variation of the Strouhal number is very weak when the wake pattern is changed according to the rotational coefficient. As ${\alpha}$ increases, the lift increases, whereas the drag decreases.

Three-dimensional Laminar Flow past a Rotating Cylinder (회전하는 원형 실린더 주위의 층류 유동장에 관한 수치적 연구)

  • Lee, Yong-Suk;Doo, Jeong-Hoon;Ha, Man-Yeong;Yoon, Hyun-Sik
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2733-2737
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    • 2008
  • The present study numerically investigates three-dimensional laminar flow past a rotating circular cylinder placed in a uniform stream. For the purpose of a careful analysis of the modification of flow by the effect of the rotation on the flow, numerical simulations are performed at a various range of rotational speeds($0{\leq}{\alpha}{\leq}2.5$) at one Reynolds number of 300. As $\alpha$ increases, flow becomes stabilized and finally a steady state beyond the critical rotational speed. The 3D (three dimensional) wake mode of the stationary cylinder defined at this Reynolds number has been disorganized according to $\alpha$, which were observed by the visualization of 3D vortical structures. The variation of the Strouhal number is significant when the wake pattern is changed according to the rotational speed. As $\alpha$ increases, the lift increases, whereas the drag decreases.

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Flow Visualization and Unstructured Grid Computation of Flow over a High-Speed Projectile (고속탄자 유동의 가시화 실험 및 비정렬격자 계산)

  • 이상길;최서원;강준구;임홍규;백영호;김두연;강호철
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.2
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    • pp.12-20
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    • 1998
  • Exter ballistics of a typical high-speed projectile is studied through a flow-visualization experiment and an unstructured grid Navier-Srokes computation. Experiment produced a schlieren photograph that adequately shows the characteristic features of this complex flow, namely two kinds of oblique cone shocks and turbulent wake developing into the downstream. A hybrid scheme of finite volume-element method is used to simulate the compressible Reynolds-Averaged Navier-Stok- es solution on unstructured grids. Osher's approximate Riemann solver is used to discretize the cinvection term. Higher-order spatial accuracy is obtained by MUSCL extension and van Albada ty- pe flux limiter is used to stabilize the numerical oscillation near the solution discontinuity. Accurate Gakerkin method is used to discretize the viscous term. Explict fourth-order Runge-Kutta method is used for the time-stepping, which simplifies the application of MUSCL extension. A two-layer k-$\varepsilon$ turbulence model is used to simulate the turbulent wakes accurately. Axisymmetric folw and two-dimensional flow with an angle of attack have been computed. Grid-dependency is also checked by carrying out the computation with doubled meshes. 2-D calculation shows that effect of angle of attack on the flow field is negligible. Axi-symmetric results of the computation agrees well with the flow visualization. Primary oblique shock is represented within 2-3 meshes in numerical results, and the varicose mode of the vortex shedding is clearly captured in the turbulent wake region.

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An Efficient Visualization Method of Two-Dimensional Vector Fields (2차원 벡터 필드의 효율적인 가시화 방법)

  • Jung, Il-Hong
    • Journal of Korea Multimedia Society
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    • v.12 no.11
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    • pp.1623-1628
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    • 2009
  • This paper presents the development of certain highly efficient and accurate method for computing tangent curves for two-dimensional vector fields. Unlike convention methods, such as Runge-Kutta, for computing tangent curves which produce only approximations, the method developed herein produces exact values on the tangent curves based on piecewise linear variation over a triangle in 2D. This new method assumes that the vector field is piecewise linearly defined over a triangle in 2D. It is also required to decompose the rectangular cell into two triangular cells. The critical points can be easily found by solving a simple linear system for each triangle. This method is to find exit points by producing a sequence of points on the curve with the computation of each subsequent point based on the previous. Because points on the tangent curves are calculated by the explicit solution for each triangle, this new method provides correct topologies in visualizing 2D vector fields.

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Biplots of Multivariate Data Guided by Linear and/or Logistic Regression

  • Huh, Myung-Hoe;Lee, Yonggoo
    • Communications for Statistical Applications and Methods
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    • v.20 no.2
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    • pp.129-136
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    • 2013
  • Linear regression is the most basic statistical model for exploring the relationship between a numerical response variable and several explanatory variables. Logistic regression secures the role of linear regression for the dichotomous response variable. In this paper, we propose a biplot-type display of the multivariate data guided by the linear regression and/or the logistic regression. The figures show the directional flow of the response variable as well as the interrelationship of explanatory variables.

Visualization of the Water Column Collapse by using SMAC Method (SMAC법을 이용한 물기등 붕괴의 가시화)

  • Kim, Nam-Hyeong;Kim, Nam-Guk
    • 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.

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Representing variables in the latent space (분석변수들의 잠재공간 표현)

  • Huh, Myung-Hoe
    • The Korean Journal of Applied Statistics
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    • v.30 no.4
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    • pp.555-566
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    • 2017
  • For multivariate datasets with large number of variables, classical dimensional reduction methods such as principal component analysis may not be effective for data visualization. The underlying reason is that the dimensionality of the space of variables is often larger than two or three, while the visualization to the human eye is most effective with two or three dimensions. This paper proposes a working procedure which first partitions the variables into several "latent" clusters, explores individual data subsets, and finally integrates findings. We use R pakacage "ClustOfVar" for partitioning variables around latent dimensions and the principal component biplot method to visualize within-cluster patterns. Additionally, we use the technique for embedding supplementary variables to figure out the relationships between within-cluster variables and outside variables.

Stereoscopic micro-PIV measurements of jet flow (미세제트 유동의 Stereoscopic micro-PIV측정)

  • Yu, Cheong-Hwan;Kim, Hyoung-Bum
    • Journal of the Korean Society of Visualization
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    • v.5 no.1
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    • pp.43-48
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    • 2007
  • Micro-PIV(particle image velocimetry) has been widely used to measure the velocity of micro flow. Although this micro-PIV method can give accurate 2D instantaneous velocity information of mea-surement plane, it cannot resolve the out of plane component of velocity vectors. Lots of the micro fluidic devices generate three-dimensional flow and 3D measurement of velocity is useful to understand the physics of micro flow phenomena. In this study, we constructed stereoscopic micro-PIV(SMPIV) system and applied this method to the impinging micro jet flow. The results show that this method can produce accu-rate 3D reconstruction of micro jet flow.

Numerical Visualization of the Shock Wave System Discharged from the Exits of Two-Parallel Ducts (두 평행한 관 출구로부터 방출되는 충격파시스템의 수치해석적 가시화)

  • Jung Sung Jae;Kweon Yong Hun;Kim Heuy Dong;Kang Chang Soo
    • 한국가시화정보학회:학술대회논문집
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    • 2004.11a
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    • pp.72-75
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    • 2004
  • The present study describes a computational work to investigate detailed behaviors of the twin shock waves discharged from the exits of two-parallel ducts. In computations, the Yee-Roe-Davis's TVD scheme was used to solve the unsteady, three-dimensional, inviscid, compressible, Euler equations. The distance between two ducts is varied and the Mach number of the incident shock wave is changed below 2.0. The results obtained show that on the symmetric axis between two-parallel ducts, the maximum pressure achieved by the merge of twin shock waves and its location strongly depend upon the distance between two-parallel ducts and the Mach number of the incident shock wave. It is also found that the twin shock waves discharged from the exits of two-parallel ducts leads to the complicated flow fields, such as Mach stem, spherical waves, and vertical structures.

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