• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.90-93
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• 2009

The use of physics based deformation methods is continuously increasing in computer graphics area such as game and simulation. Many researchers have worked on this method. However, relatively few researchers have considered the development of the user interaction to the 3D objects. This research proposes a physics-based deformation technique using AR (Augmented Reality) environments to enhance user immersion and the effectiveness of the deformation. In the AR circumstances, the physics based deformation should be accomplished in realtime. In the proposed method, we combine RBF (Radial Basis Function) [1] and LSM (Lattice Shape Matching) [2, 3] and apply it to polygonal models for real-time user interaction. The dynamics of the LSM is also calculated to trace the movement of each lattice. Finally these algorithms are implemented in AR environments.

• Journal of the Korean Mathematical Society
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• v.36 no.3
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• pp.621-631
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• 1999

In this paper we briefly describe the geometry of the Cayley hyperbolic plane and we show that every uniform lattice in quaternionic space cannot be deformed in the Cayley hyperbolic 2-plane. We also describe the nongeometric bending deformation by developing the theory of the Cartan angular invariant for quaternionic hyperbolic space.

• Steel and Composite Structures
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• v.24 no.2
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• pp.249-264
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• 2017

In this paper free linear vibration of lattice composite conical shells will be investigated. Lattice composite conical shell consists of composite helical ribs and thin outer skin. A smeared method is employed to obtain the variable coefficients of stiffness of conical shell. The ribs are modeled as a beam and in addition to the axial loads, endure shear loads and bending moments. Therefore, theoretical formulations are based on first-order shear deformation theory of shell. For verification of the obtained results, comparison is made with those available in open literature. Also, using FEM software the 3D finite element model of composite lattice conical shell is built and analyzed. Comparing results of analytical and numerical analyses show a good agreement between them. Some special cases as variation of geometric parameters of lattice part, effect of the boundary conditions and influence of the circumferential wave numbers on the natural frequencies of the conical shell are studied. It is concluded, when mass and the geometrical ratio of the composite lattice conical shell do not change, increment the semi vertex angle of cone leads to increase the natural frequencies. Moreover for shell thicknesses greater than a specific value, the presence of the lattice structure has not significant effect on the natural frequencies. The obtained results have novelty and can be used for further and future researches.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.2
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• pp.113-118
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• 2006

A new last design approach based on the Limb line FFD (LFFD) and Scale factor FFD (SFFD) is presented in this paper. The proposed last design method utilizes the dynamic trimmed parametric patches for the measured foot 3D data and last 3D data. Furthermore, the proposed last data generation system utilizes cross sectional data extracted obtained from the measured 3D foot data. First, the last design rule of the LFFD is constructed on the FFD lattice based on foot last shape analysis. Secondly, SFFD is constructed on the LFFD new lattice based on scale factor deformation. The scale factor is constructed on the boundary edges of polygonized patch and the cross section last data boundary edge of the polygon object. Suppose the two boundary curves have been preprocessed so that they run in the same direction and they forms the SF(Scale Factor). In addition, the control points of FFD lattice are derived with cross. sectional data interpolation methods from a finite set of 3D foot data.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.9
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• pp.700-706
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• 2003

This paper presents a 3D last design system that provides the 3-dimensional last data based on the FFD(Free Form Deformation) method. The proposed system utilizes the control points for deformation factor to convert from the 3D point cloud foot data to the 3D point cloud last data. The deformation factor of the FFD is obtained from the conventional last design technique, and constructed on the FFD lattice based on the bottom view and lateral view of the measured 3D point cloud foot data. In addition, the control points of FFD lattice is decided on the anatomical points of foot. The deformed 3D last obtained from the proposed FFD is saved as a 3D dxf foot data. The experimental results demonstrate that the proposed system have the descent 3D last data based on the openGL window.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.103-110
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• 2011

A two-dimensional immiscible droplet deformation phenomena on moving wall in a channel has been investigated by using lattice Boltzmann method involving two-phase model. The dependence of the deformation of the droplet with different sizes on the contact angle and the velocity of bottom wall has studied. When the bottom wall starts to move, the deformation of the droplet occurs. For the largest bottom wall velocity, eventually, the deformation of the droplet is classified into the three patterns according to the contact angle.

• Structural Engineering and Mechanics
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• v.21 no.6
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• pp.677-698
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• 2005

In engineering practice, tubular connections are usually assumed pinned or rigid. Recent research showed that tubular joints may exhibit non-rigid behavior under axial or bending loads. This paper is concerned with establishing a new classification for tubular joints and investigating the effect of joint rigidity on the global behavior of CHS (Circular Hollow Section) lattice girders. Parametric formulae for predicting tubular joint rigidities are proposed, which are based on the finite element analyses through systematic variation of the main geometric parameters. Comparison with test results proves the reliability of these formulae. By considering the deformation patterns of respective parts of Vierendeel lattice girders, the boundary between rigid and semirigid tubular connections is built in terms of joint bending rigidity. In order to include characteristics of joint rigidity in the global structural analysis, a type of semirigid element which can effectively reflect the interaction of two braces in K joints is introduced and validated. The numerical example of a Warren lattice girder with different joint models shows the great effect of tubular joint rigidities on the internal forces, deformation and secondary stresses.

• Archives of Metallurgy and Materials
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• v.67 no.4
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• pp.1525-1529
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• 2022

Co-Cr-Mo based sheet I-WP lattice was fabricated via laser powder bed fusion. The effect of microstructure and the I-WP shape on compressive mechanical response was investigated. Results of compression test showed that yield strength of the sheet I-WP was 176.3 MPa and that of bulk Co-Cr-Mo (reference material) was 810.4 MPa. By applying Gibson-Ashby analytical model, the yield strength of the lattice was reversely estimated from that of the bulk specimen. The calculated strength of the lattice obtained was 150.7 MPa. The shape of deformed lattice showed collective failure mode, and its microstructure showed that strain-induced martensitic transformation occurred in the overall lattice. The deformation behavior of additively manufactured sheet I-WP lattice was also discussed.

• Journal of Korean Association for Spatial Structures
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• v.19 no.2
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• pp.51-61
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• 2019

The objective of this study is to analysis the seismic response of 200m spanned honeycomb lattice domes under horizontal and up-down ground motion of El Centro earthquake. For the analysis of seismic response of the honeycomb lattice domes by rise/span ratio, the time history analysis is used for the estimation of the dynamic response. The low rise lattice dome is less deformed and less stressed than the high rise lattice dome for the earthquake ground motion. The 3-dimensional earthquake response is not significantly different the dynamic response of one directional ground motion. The earthquake response of domes with LRB isolation system is significantly reduced for the asymmetric vertical deformation and the horizontal and vertical accelerations.

• Structural Engineering and Mechanics
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• v.37 no.6
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• pp.617-632
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• 2011

A concept of crash energy absorbing (CEA) lattice structure for an inflatable morphing vehicle body (Lee et al. 2008) has been investigated as a method of providing rigidity and energy absorption capability during a vehicular collision (Lee et al. 2007). A modified analytical model for the CEA lattice structure design is described in this paper. The modification of the analytic model was made with a stiffness approach for the elastic region and updated plastic limit analysis with a pure plastic bending deformation concept and amended elongation factors for the plastic region. The proposed CEA structure is composed of a morphing lattice structure with movable thin-walled members for morphing purposes, members that will be locked in designated positions either before or during the crash. What will be described here is how to model the CEA structure analytically based on the energy absorbed by the CEA structure.