• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.156-161
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• 1998

This describes a numerical method for predicting the incompressible unsteady laminar three-dimensional flows of fluid behaviour with free-surface. The elliptic differential equations governing the flows have been linearized by means of finite-difference approximations, and the resulting equations have been solved via a fully-implicit iterative method. The free-surface is defined by the motion of a set of marker particles and interface behaviour was investigated by way of a 'Lagrangian' technique. Using the GALA concept of Spalding, the conventional mass continuity equation is modified to form a volumetric or bulk-continuity equation. The use of this bulk-continuity relation allows the hydrodynamic variables to be computed over the entire flow domain including both liquid and gas regions. Thus, the free-surface boundary conditions are imposed implicitly and the problem formulation is greatly simplified. The numerical procedure is validated by comparing the predicted results of a periodic standing waves problems with analytic solutions or experimental results from the literature. The results show that this numerical method produces accurate and physically realistic predictions of three-dimensional free-surface flows.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.242.1-242.1
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• 2014

The electron cyclotron resonance plasma source with a belt-type magnet assembly (BMA) is designed for effective plasma confinements. For characterizing the plasma source, the plasma parameters are measured by Langmuir probe. However, the plasma parameters and the motion of charged particles near the ECR zone are not easy to diagnostics, because of the high plasma density and temperature. Thus, as an alternative method, the electromagnetic simulation of the plasma source has been performed by using three-dimensional particle-in-cell and Monte Carlo collisional (PIC-MCC) simulation codes. For considering the limitation of simulation resources and time, the periodic boundary condition is applied and the coulomb collision is neglected. In this paper, we present the results of 3D PIC simulations of ECR plasmas with BMA and we compare them with the experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.686-692
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• 2012

Solid free-form fabrication (SFF) technology was developed to fabricate three-dimensional (3D) scaffolds for tissue engineering (TE) applications. In this study, we developed a polymer deposition system (PDS) and created 3D microstructures using a bioresorbable polycaprolactone (PCL) polymer. Fabrication of 3D scaffolds by PDS requires a combination of several devices, including a heating system, dispenser, and motion controller. The system can process a polymer with extremely high precision by using a 200 ${\mu}m$ nozzle. Based on scanning electron microscope (SEM) images, both the line width and the piled line height were fine and uniform. Several 3D micro-structures, including the ANU pattern (a pattern named after Andong National University), $45^{\circ}$ pattern square, frame, cylindrical, triangular, cross-shaped, and hexagon, have been fabricated using the polymer deposition system.

• Structural Engineering and Mechanics
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• v.12 no.4
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• pp.409-428
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• 2001

The characteristics of dynamic wheel loads of heavy vehicles running on bridge and rigid surface are investigated by using three-dimensional analytical model. The simulated dynamic wheel loads of vehicles are compared with the experimental results carried out by Road-Vehicles Research Institute of Netherlands Organization for Applied Scientific Research (TNO) to verify the validity of the analytical model. Also another comparison of the analytical result with the experimental one for Umeda Entrance Bridge of Hanshin Expressway in Osaka, Japan, is presented in this study. The agreement between the analytical and experimental results is satisfactory and encouraging the use of the analytical model in practice. Parametric study shows that the dynamic increment factor (DIF) of the bridge and RMS values of dynamic wheel loads are fluctuated according to vehicle speeds and vehicle types as well as roadway roughness conditions. Moreover, there exist strong dominant frequency resemblance between bounce motion of vehicle and bridge response as well as those relations between RMS values of dynamic wheel loads and dynamic increment factor (DIF) of bridges.

• Journal of Ocean Engineering and Technology
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• v.20 no.3 s.70
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• pp.24-36
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• 2006

This paper investigates wave loads of ships that suffer sinkage due to flood in a compartment caused by damage on the side of the hull. By analyzing ships with various sizesof damage opening, the influence of opening size on ship response is investigated. The motion of the damaged ship is analyzed by using the boundary element method, based on three-dimensional potential theory, considering hydrodynamic pressure in the flooded compartments. The shear forces, bending moments and torsional moments are calculated by the direct integration of the three dimensional hydrodynamic pressure on the outer and inner hulls. A RORO passenger ship with length of 174.8 m is considered in the numerical example, and results for wave loads are discussed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.99-106
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• 1999

In this study a base-isolated liquid storage tank subjected to seismic ground motion is numerically simulated on frequency , domain considering three-dimensional liquid-structure-soil interaction. A hybrid formulation which combines the versatility of finite elements for tank structure and the efficiency of boundary elements for liquid and soil region is adopted for efficient modeling. The base-isolation system using the effective stiffness and damping ratio is also included in this formulation. in order to demonstrate the accuracy and validity of the developed solution the numerical results were compared with the reference solutions in each interaction problem. The effects of the liquid filling ratio and the stiffness of base-isolation system on the behavior of the liquid storage tanks are analyzed.

• Journal of Information Processing Systems
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• v.15 no.2
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• pp.399-409
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• 2019

Three-dimensional (3D) human pose reconstruction from single-view image is a difficult and challenging topic. Existing approaches mostly process frame-by-frame independently while inter-frames are highly correlated in a sequence. In contrast, we introduce a novel spatial-temporal 3D human pose reconstruction framework that leverages both intra and inter-frame relationships in consecutive 2D pose sequences. Orthogonal matching pursuit (OMP) algorithm, pre-trained pose-angle limits and temporal models have been implemented. Several quantitative comparisons between our proposed framework and recent works have been studied on CMU motion capture dataset and Vietnamese traditional dance sequences. Our framework outperforms others by 10% lower of Euclidean reconstruction error and more robust against Gaussian noise. Additionally, it is also important to mention that our reconstructed 3D pose sequences are more natural and smoother than others.

• Journal of the Korean Institute of Intelligent Systems
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• v.5 no.3
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• pp.117-127
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• 1995

In this paper, we suggest a motion analysis method using ART-I1 competitive learning neural network and fuzzy reasoning by matching the same objects through the consecutive image sequence. we use the size and mean intensity of the region obtained from image segmentation for the region matching by the region and use a ART-I1 competitive learning neural network wh~ch has a learning ability to reflect the topology of the input patterns in order to select characteristic points to describe the shape of a region. Motion vectors for each regions are obtained by matching selected characteristic points. However, the two dimensional image, the projection of the the three dimensional real world, produces fuzziness in motion analysis due to its incompleteness by nature and the error from image segmentation used for extracting information about objects. Therefore, the belief degrees for each regions are calculated using fuzzy reasoning to l-nanipulate uncertainty in motion estimation.

• Journal of Broadcast Engineering
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• v.2 no.2
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• pp.125-135
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• 1997

This paper is concerned with realistic mainpulation of content in video sequences. Manipulation of content in video sequences is one of the content-based functionalities for MPEG-4 Visual standard. We present an approach to synthesizing video sequences by using the intermediate outputs of three-dimensional (3D) motion and depth analysis. For concreteness, we focus on video showing 3D motion of an observer relative to a scene containing planar runways (or roads). We first present a simple runway (or road) model. Then, we describe a method of identifying the runway (or road) boundary in the image using the Point of Heading Direction (PHD) which is defined as the image of, the ray along which a camera moves. The 3D motion of the camera is obtained from one of the existing 3D analysis methods. Then, a video sequence containing a runway is manipulated by (i) coloring the scene part above a vanishing line, say blue, to show sky, (ii) filling in the occluded scene parts, and (iii) overlaying the identified runway edges and placing yellow disks in them, simulating lights. Experimental results for a real video sequence are presented.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.177-184
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• 2002

Large amplitude sloshing can occur in contained fluid region due to the seismic ground motion. Also, The pressure by large amplitude sloshing damages the connections between the wall and roof of a fluid container and causes outflow of contained fluid. Therefore, to predict the dynamic behavior accurately, three dimensional analysis with the nonlinear boundary condition must be performed. In this study, the numerical solution procedure is developed using the boundary element method with the Lagrangian particle approach. In order to demonstrate the accuracy and validity of the developed method, the fluid motion for a free oscillation with small amplitude and a forced vibration are analyzed. And the numerical results are compared with the linear theory results and the previous studies with the nonlinear boundary condition.