• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.323-326
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• 2003

This paper presents a new algorithm that can refine hexahedral elements while maintaining the appropriate connectivity. In the algorithm, at first the regions of mesh to be refined are defined and, then, the zero-thickness element layers inserted into the interfaces between the regions. All the meshes in the regions, in which the zero-thickness layers are inserted, are to be regularized in order to improve the shape of the slender elements on the interfaces. This algorithm is applied to the analysis of plastic deformation process. The results show that the refined mesh gives smaller relative errors than the original mesh.

• Transactions of Materials Processing
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• v.12 no.4
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• pp.334-339
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• 2003

This paper presents a new algorithm that enables the refinement of hexahedral elements while maintaining the appropriate connectivity. In the algorithm, at first the regions of mesh to be refined are defined and, then, the zero-thickness element layers are inserted into the interfaces between the regions. All the meshes in the regions, in which the zero-thickness layers are inserted, are to be regularized in order to improve the shape of the slender elements on the interfaces. This algorithm is applied to the analysis of plastic deformation process. The results show that the refined mesh gives smaller relative errors than the original mesh.

• Journal of computational fluids engineering
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• v.19 no.2
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• pp.99-107
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• 2014

The aim of the present study is to investigate the flow interference between two adjacent undulating fish-like body, and its effect on the undulating propulsion. For this purpose, unsteady two dimensional incompressible flow calculations were conducted using an unstructured mesh flow solver, coupled with an overset mesh technique. To deal with mesh deformation due to fish locomotion, spring analogy is utilized. The fish body used in the simulation is constructed from the NACA0012 airfoil. The study indicates that the propulsion of undulating fish is proportional to frequency and wavelength of the midline oscillation when there is no adjacent fish. It also reveals that average thrust was increased when the vortex shedding from the tail was conserved well and pressure difference between upper and lower sides of the fish was magnified due to flow interference. From this study, which relative position and phase difference of locomotion between two fishes can generate maximum thrust was known among six different cases.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.5-13
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• 2016

In this study, Coupled Eulerian-Lagrangian (CEL) analysis, which is one of the large deformation analyses, was incorporated to investigate excavation damage zone (EDZ) under TBM advancement. Considering the quasi-static condition, the dynamic analysis was performed to simulate the real TBM advancement and subsequently a case study on mesh and TBM excavation rate was carried out for satisfying a balance of accuracy and economic computational time. Based on this, a series of parametric studies were performed for different rock types and tunnel diameters. From the numerical analysis results, it is found that EDZ was taken to range within 0.4D(D=tunnel diameter) for most rocks. It is also found that the EDZ tends to increase as the tunnel diameter increases.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.68-74
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• 2011

Recently, thanks to the advanced computational power and numerical methods, it is made possible to analyze the flow around moving bodies using computational fluid dynamics techniques. In those simulations, moving mesh techniques should be able to represent both the body motion and boundary deformation, which are frequently encountered in fluid-structure interaction and/or six degree-of-freedom problems. In the present study, the staggered loosely coupling algorithm was used for fluid-structure interaction and the Laplacian operator based technique was used for moving mesh. For the verification of the developed computational method, the flow around a two-dimensional cylinder was simulated and analyzed.

• ETRI Journal
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• v.30 no.1
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• pp.152-154
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• 2008

We present a simple and efficient technique for a plausible elastic deformation of three-dimensional objects. An elastic sweep surface is constructed by interpolating key cross sections with positions, orientations, and boundary shapes determined by physical simulation of simple mass-spring systems. The deformable parts of an object are approximated by the elastic sweep surfaces, and the vertices of the deformable parts are bound to nearby sweep surfaces. As an external force is applied, the corresponding parts of an object change their shapes elastically. We demonstrate the effectiveness of our technique and show its real-time performance on mesh objects.

• Archives of Craniofacial Surgery
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• v.19 no.4
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• pp.264-269
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• 2018

Background: Orbital resorbable mesh plates are adequate to use for isolated floor and medial wall fractures with an intact bony buttress, but are not recommended to use for large orbital wall fractures that need load bearing support. The author previously reported an orbital wall restoring surgery that restored the orbital floor to its prior position through the transnasal approach and maintained temporary extraorbital support with a balloon in the maxillary sinus. Extraorbital support could reduce the load applied on the orbital implants in orbital wall restoring surgery and the use of resorbable implants was considered appropriate for the author's orbital wall restoring technique. Methods: A retrospective review was conducted of 31 patients with pure unilateral orbital floor fractures between May 2014 and May 2018. The patients underwent transnasal restoration of the orbital floor through insertion of a resorbable mesh plate and maintenance of temporary balloon support. The surgical results were evaluated by the Hertel scale and a comparison of preoperative and postoperative orbital volume ratio (OVR) values. Results: The OVR decreased significantly, by an average of 6.01% (p<0.05) and the preoperative and postoperative Hertel scale measurements decreased by an average of 0.34 mm with statistical significance (p<0.05). No complications such as buckling or sagging of the implant occurred among the 31 patients. Conclusion: The use of resorbable mesh plate in orbital floor restoration surgery is an effective and safe technique that can reduce implant deformation or complications deriving from the residual permanent implant.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.247-250
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• 2007

Flexible media such as the paper, the film, etc. are thin, light and very flexible. They behave in geometrically nonlinear. Any of small force makes large deformation. So we must including aerodynamic effect when its behavior is predicted. Thus, it becomes fully coupled fluid-structure interaction(FSI) problem. In FSI problems, where the fluid mesh near the structure undergoes large deformations and becomes unacceptably distorted, which drive the time step to a very small value for explicit calculations, the arbitrary Lagrangian-Eulerian(ALE) methods or rezoning are used to create a new undistorted mesh for the fluid domain, which allows the calculations to continue. In this paper, FE sheet model considering geometric nonlinearity is formulated to simulate the behavior of the flexible media. Aerodynamic force to the media by surrounding air is calculated by solving the incompressible Navier-Stokes equations. Q2Q1(Taylor-Hood) element which means biquadratic for velocity and bilinear for pressure is used for fluid domain. Q2Q1 element satisfies LBB condition and any stabilization technique is not needed. In this paper, cantilevered sheet in the viscous incompressible Navier-Stokes flow is simulated to check the mesh motion and numerical integration scheme, and then falling paper in the air is simulated and the effects of some representative parameters are investigated.

• Journal of Korea Game Society
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• v.8 no.2
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• pp.47-55
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• 2008

This paper introduces that SSFE(Skeleton System for Facial Expression) to deform facial expressions by rigging of skeletons does same functions with 14 facial muscles based on anatomy. A three dimensional animation tool (MAYA 8.5) is utilized for making the SSFE that presents deformation of mesh models implementing facial expressions around eyes, nose and mouse. The SSFE has a good reusability within diverse human mesh models. The reusability of SSFE can be understood as OSMU(One Source Multi Use) of three dimensional animation production method. It can be a good alternative technique for reducing production budget of animations. It can also be used for three dimensional animation industries such as virtual reality and game.

• Computers and Concrete
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• v.31 no.2
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• pp.151-161
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• 2023

This paper presents an investigation of variables that cause spurious cracking in numerical modeling of concrete fracture. Spurious cracks appear due to the approximate nature of numerical modeling. They overestimate the dissipated energy, leading to divergent results with mesh refinement. This paper is limited to quasi-static loading regime, homogeneous models, cracking as the only nonlinear mode of deformation and cracking only due to tensile loading. Under these conditions, some variables that can be related to spurious cracking are: mesh alignment, ductility, crack band width, structure size, mesh refinement and load increment size. Case studies illustrate the effect of each variable and convergence analyses demonstrate that, after all, load-increment size is the most important variable. Theoretically, a sufficiently small load increment is able to eliminate or at least alleviate the detrimental influence of the other variables. Such load-increment size might be prohibitively small, rendering the simulation unfeasible. Hence, this paper proposes two alternatives. First, it is proposed an algorithm that automatically find such small load increment size automatically, which not necessarily avoid large computations. Then, it is proposed a double simulation technique, in which the crack is forced to propagate through the localization zone.