• Title, Summary, Keyword: n-dimensional volume

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Flood Impact Pressure Analysis of Vertical Wall Structures using PLIC-VOF Method with Lagrangian Advection Algorithm

  • Phan, Hoang-Nam;Lee, Jee-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.6
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    • pp.675-682
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    • 2010
  • The flood impact pressure acting on a vertical wall resulting from a dam-breaking problem is simulated using a navier-Stokes(N-S) solver. The N-S solver uses Eulerian Finite Volume Method(FVM) along with Volume Of Fluid(VOF) method for 2-D incompressible free surface flows. A Split Lagrangian Advection(SLA) scheme for VOF method is implemented in this paper. The SLA scheme is developed based on an algorithm of Piecewise Linear Interface Calculation(PLIC). The coupling between the continuity and momentum equations is affected by using a well-known Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm. Several two-dimensional numerical simulations of the dam-breaking problem are presented to validate the accuracy and demonstrate the capability of the present algorithm. The significance of the time step and grid resolution are also discussed. The computational results are compared with experimental data and with computations by other numerical methods. The results showed a favorable agreement of water impact pressure as well as the global fluid motion.

Wear Analysis of the Ti-N Coated Punch in Piercing According to the Volume of Production (생산수량에 따른 Ti-N 코팅 펀치의 마멸해석)

  • 황상홍;고대철;김병민
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.3
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    • pp.149-157
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    • 2000
  • Tool wear in the shearing process such as blanking, piercing and trimming is very important, because it has great effects on the dimensional accuracy, working efficiency and economy. Most of tools in the shearing process have the coated layer at surface fur good wear and corrosion resistance. When the surface of tool is teated, the wear Phenomena of coated surface layer and inner layer may be different. This paper describes a computer modelling technique by the finite element method in order to investigate the wear mechanism and to predict the wear profile of Ti-N coated tool in piercing process according to the volume of Production. Wear coefficients of the coated layer and inner layer are obtained through Pin-on-Disk wear test, respectively. To verify the effectiveness of the suggested technique, the technique is applied to wear analysis in piercing recess of piston pin and simulation results are compared with experimental ones.

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Historical review and it's application on the volume of lattice polyhedron - Focused on sequence chapter - (격자다면체 부피에 대한 역사적 고찰 및 그 응용 - 수열 단원에의 응용 -)

  • Kim, Hyang-Sook;Ha, Hyoung-Soo
    • Journal for History of Mathematics
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    • v.23 no.2
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    • pp.101-121
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    • 2010
  • This article includes an introduction, a history of Pick's theorem on lattice polyhedron and its proof, Reeve's theorem on 3-dimensional lattice polyhedrons extended from the Pick's theorem and Ehrhart polynomial generalized as an n-dimensional lattice polyhedron, and then shows the relationship between the volume of 3-dimensional polyhedron and the number of its lattice points by means of Reeve's theorem. It is aimed to apply the relationship to the visualization of sums in sequences.

DEVELOPMENT OF AN ORTHOGONAL DOUBLE-IMAGE PROCESSING ALGORITHM TO MEASURE BUBBLE VOLUME IN A TWO-PHASE FLOW

  • Kim, Seong-Jin;Park, Goon-Cherl
    • Nuclear Engineering and Technology
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    • v.39 no.4
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    • pp.313-326
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    • 2007
  • In this paper, an algorithm to reconstruct two orthogonal images into a three-dimensional image is developed in order to measure the bubble size and volume in a two-phase boiling flow. The central-active contour model originally proposed by P. $Szczypi\'{n}ski$ and P. Strumillo is modified to reduce the dependence on the initial reference point and to increase the contour stability. The modified model is then applied to the algorithm to extract the object boundary. This improved central contour model could be applied to obscure objects using a variable threshold value. The extracted boundaries from each image are merged into a three-dimensional image through the developed algorithm. It is shown that the object reconstructed using the developed algorithm is very similar or identical to the real object. Various values such as volume and surface area are calculated for the reconstructed images and the developed algorithm is qualitatively verified using real images from rubber clay experiments and quantitatively verified by simulation using imaginary images. Finally, the developed algorithm is applied to measure the size and volume of vapor bubbles condensing in a subcooled boiling flow.

Measurement Method of the Masseter Muscle Volume Using 3D Computed Tomography (3D CT를 이용한 교근의 부피측정)

  • Baek, Jung Hwan;Choi, Jong Woo;Yoo, Sun Kuk;Kim, Yong Oock;Park, Beyoung Yun
    • Archives of Plastic Surgery
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    • v.32 no.5
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    • pp.589-592
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    • 2005
  • Since G.N. Hounsfield's clinical use of computed tomography in 1971, digital imaging technique using computers has shown an eye opening progress. Progress has made 3-dimensional understanding of not only facial bones but muscles and other connective tissues possible through 3-dimensional reconstruction of preexisting tomographical images. Also, quantitative analysis of density, distance, volume has become possible, allowing objective analysis of preoperative and postoperative states through imaging. The authors measured the masseter muscle volume of 20 normal individuals and 8 female patients through 3-D reconstructive CT imaging and made a statistical analysis of the measurements. The method used in our study may be applied to the diagnosis of disease causing the change of the facial volume and presurgical design as a useful tool to provide objective information on the evaluation of surgery outcome.

STABLE MINIMAL HYPERSURFACES IN A CRITICAL POINT EQUATION

  • HWang, Seung-Su
    • Communications of the Korean Mathematical Society
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    • v.20 no.4
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    • pp.775-779
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    • 2005
  • On a compact n-dimensional manifold $M^n$, a critical point of the total scalar curvature functional, restricted to the space of metrics with constant scalar curvature of volume 1, satifies the critical point equation (CPE), given by $Z_g\;=\;s_g^{1\ast}(f)$. It has been conjectured that a solution (g, f) of CPE is Einstein. The purpose of the present paper is to prove that every compact stable minimal hypersurface is in a certain hypersurface of $M^n$ under an assumption that Ker($s_g^{1\ast}{\neq}0$).

Material distribution optimization of 2D heterogeneous cylinder under thermo-mechanical loading

  • Asgari, Masoud
    • Structural Engineering and Mechanics
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    • v.53 no.4
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    • pp.703-723
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    • 2015
  • In this paper optimization of volume fraction distribution in a thick hollow cylinder with finite length made of two-dimensional functionally graded material (2D-FGM) and subjected to steady state thermal and mechanical loadings is considered. The finite element method with graded material properties within each element (graded finite elements) is used to model the structure. Volume fractions of constituent materials on a finite number of design points are taken as design variables and the volume fractions at any arbitrary point in the cylinder are obtained via cubic spline interpolation functions. The objective function selected as having the normalized effective stress equal to one at all points that leads to a uniform stress distribution in the structure. Genetic Algorithm jointed with interior penalty-function method for implementing constraints is effectively employed to find the global solution of the optimization problem. Obtained results indicates that by using the uniform distribution of normalized effective stress as objective function, considerably more efficient usage of materials can be achieved compared with the power law volume fraction distribution. Also considering uniform distribution of safety factor as design criteria instead of minimizing peak effective stress affects remarkably the optimum volume fractions.

Development of a Three Dimensional Mesh Generation Program for CFD Simulations (CFD 해석을 위한 3차원 격자생성 프로그램의 개발)

  • Chang J.;Kim S.-R.;Hur N.
    • 한국전산유체공학회:학술대회논문집
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    • pp.157-163
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    • 2001
  • In the present study a mesh generation program is developed for three dimensional flow analyses with complex geometry. By the present program one can define vertices using various coordinate systems and cells for finite volume approach. Rendered display of the generated mesh can be also available in both orthographic and perspective projection modes. Through perspective projection mode, one can check the quality of generated mesh by moving around inside the mesh like a virtual reality. The examples of the program execution is given in the paper.

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TOTAL SCALAR CURVATURE AND EXISTENCE OF STABLE MINIMAL SURFACES

  • Hwang, Seung-Su
    • Honam Mathematical Journal
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    • v.30 no.4
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    • pp.677-683
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    • 2008
  • On a compact n-dimensional manifold M, it has been conjectured that a critical point metric of the total scalar curvature, restricted to the space of metrics with constant scalar curvature of volume 1, should be Einstein. The purpose of the present paper is to prove that a 3-dimensional manifold (M,g) is isometric to a standard sphere if ker $s^*_g{{\neq}}0$ and there is a lower Ricci curvature bound. We also study the structure of a compact oriented stable minimal surface in M.

Efficient approach for determining four-dimensional computed tomography-based internal target volume in stereotactic radiotherapy of lung cancer

  • Yeo, Seung-Gu;Kim, Eun Seog
    • Radiation Oncology Journal
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    • v.31 no.4
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    • pp.247-251
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    • 2013
  • Purpose: This study aimed to investigate efficient approaches for determining internal target volume (ITV) from four-dimensional computed tomography (4D CT) images used in stereotactic body radiotherapy (SBRT) for patients with early-stage non-small cell lung cancer (NSCLC). Materials and Methods: 4D CT images were analyzed for 15 patients who received SBRT for stage I NSCLC. Three different ITVs were determined as follows: combining clinical target volume (CTV) from all 10 respiratory phases ($ITV_{10Phases}$); combining CTV from four respiratory phases, including two extreme phases (0% and 50%) plus two intermediate phases (20% and 70%) ($ITV_{4Phases}$); and combining CTV from two extreme phases ($ITV_{2Phases}$). The matching index (MI) of $ITV_{4Phases}$ and $ITV_{2Phases}$ was defined as the ratio of $ITV_{4Phases}$ and $ITV_{2Phases}$, respectively, to the $ITV_{10Phases}$. The tumor motion index (TMI) was defined as the ratio of $ITV_{10Phases}$ to $CTV_{mean}$, which was the mean of 10 CTVs delineated on 10 respiratory phases. Results: The ITVs were significantly different in the order of $ITV_{10Phases}$, $ITV_{4Phases}$, and $ITV_{2Phases}$ (all p < 0.05). The MI of $ITV_{4Phases}$ was significantly higher than that of $ITV_{2Phases}$ (p < 0.001). The MI of $ITV_{4Phases}$ was inversely related to TMI (r = -0.569, p = 0.034). In a subgroup with low TMI (n = 7), $ITV_{4Phases}$ was not statistically different from $ITV_{10Phases}$ (p = 0.192) and its MI was significantly higher than that of $ITV_{2Phases}$ (p = 0.016). Conclusion: The $ITV_{4Phases}$ may be an efficient approach alternative to optimal $ITV_{10Phases}$ in SBRT for early-stage NSCLC with less tumor motion.