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Rapid Surface Reconstruction from a Point Cloud Using the Least-Squares Projection
유동진 한국정밀공학회 2010 International Journal of Precision Engineering and Vol. No.
A new approach for the rapid and robust surface reconstruction from a point cloud is presented based on the distance field and the least-squares projection (LSP) algorithm. This novel approach works directly on the point cloud without any explicit or implicit surface reconstruction procedure. First, a coarse base polygonal model was created directly from the distance field for the given point cloud through the iso-surface extraction. After acquiring a rough base polygonal model, we obtain a quality polygonal model through the iterative refinement and leastsquares projection which projects current working polygonal model onto the point cloud in a least-squares sense. The main contribution of this work is the robust and fast surface reconstruction from randomly scattered 3D points only without any further information. We demonstrate the validity and efficiency of this new approach through a number of application examples.
New Paradigms in Cellular Material Design and Fabrication
유동진 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
This paper presents an effective method for designing three dimensional (3D) cellular materials containing complex internal cellular microstructures. The volumetric distance field (VDF) strategy is developed to eliminate voxelization and interpolation processes required in the conventional voxel based DF method. By introducing a hybrid method based on the VDF and triply periodic minimal surface (TPMS) cellular topology, we can design a variety of 3D cellular materials with intricate internal microstructures and arbitrarily-shaped external surfaces with unprecedented efficiency and accuracy. Experimental results show that the proposed design method has the capability to combine the perfectly interconnected channel networks based on the TPMS microstructures and the given object geometries in a consistent framework irrespective of the complexity of objects. In addition, in order to show the generality and versatility of the proposed method, a set of valuable applications are also illustrated through the innovative heat sink, heat exchanger, and enhanced lightweight cellular structure designs. Our findings suggest that the proposed design principles offered by TPMS-based cellular topology and VDF can be applied to create a wide range of advanced 3D cellular materials.
유동진,김광혁 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.9
Additive manufacturing (AM) method has been a promising technique to produce three-dimensional (3D) tissue engineering scaffolds comprised of complex pore morphologies. Multi-functional scaffolds fabricated through AM techniques can provide outstanding combinations of mechanical and biological properties including stiffness, strength, toughness, and fluidic permeability. Among the various scaffold design methods, the pore morphology based on triply periodic minimal surface (TPMS) has been of great interest to many researchers due to its easy and accurate controllability on design parameters such as pore size, pore shape, volume fraction, and inner channel interconnectivity. In this paper, we propose a new multi-morphology scaffold design algorithm for building a wide variety of complex hybrid scaffolds composed of multiple TPMS morphologies and arbitrarily-shaped transition boundaries within one scaffold using the volumetric distance field (VDF) and the beta growth function (BGF). Through a variety of design results, we demonstrate the potential to design highly complex and heterogeneous scaffolds with enhancements in stiffness, strength, and permeability. In the method, the resulting scaffold hybrid morphology can be easily and accurately controlled to systematically explore a multitude of transition pore morphologies thereby enabling the optimization of multi-functional properties such as a combination of a high mechanical stiffness together with a high biological diffusion rate.
유동진 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.10
New bispsoralen derivatives 5-10, 8-MOP-NHCO(CH2)nCONH-8-MOP (BPSBA-Cn, n = 0, 1, 2, 3, 4 and 5) in which 5 position of an 8-methoxypsoralen (8-MOP) is linked by various lengths of bisamide polymethylene chain to 5 position of the other 8-MOP, have been synthesized by the amidation of 5-amino-8-methoxypsoralen (12) with a,w -alkanoyl dichloride. Photophysical properties of their derivatives including p-p stacking interaction between the two aromatic moieties were investigated by UV absorption and fluorescence emission spectra. Efficient ring-ring stacking interactions have been observed in BPSBA-C4 (9) from the percent hypochromism (%H) of the models.