Daejin University is a private university in Pocheon City, Gyeonggi province of South Korea. About 200 instructors are employed. The current president is Chung, Tae Soo, who has served since the university's founding.The university operates Daejin University China Campus, a study abroad program based at the campuses of two universities in the People's Republic of China: Soochow University in Suzhou, and Harbin Normal University in Harbin. Wikipedia.
Yoo D.J.,Daejin University
Biomaterials | Year: 2011
An effective method for the 3D porous scaffold design of human tissue is presented based on a hybrid method of distance field and triply periodic minimal surface (TPMS). By the creative application of traditional distance field algorithm into the Boolean operations of the anatomical model and TPMS-based unit cell library, an almost defects free porous scaffolds having the complicated micro-structure and high quality external surface faithful to a specific anatomic model can be easily obtained without the difficult and time-consuming trimming and re-meshing processes. After generating the distance fields for the given tissue model and required internal micro-structure, a series of simple modifications in distance fields enable us to obtain a complex porous scaffold. Experimental results show that the proposed scaffold design method has the potential to combine the perfectly interconnected pore networks based on the TPMS unit cell libraries and the given external geometry in a consistent framework irrespective of the complexity of the models. © 2011 Elsevier Ltd.
Hwang S.J.,Daejin University
Journal of Alloys and Compounds | Year: 2011
Nanocrystalline (nc) Cu with Al2O3 dispersoid (∼4 vol.%) was successfully synthesized by simple cryo-milling at 210 K with a mixture of Cu2O, Al, and Cu elemental powders. The milled powder was consolidated by hot pressing (HP) at 1123 K and 50 MPa for 2 h. TEM (Transmission Electron Microscopy) work revealed that both of the milled powder and the hot pressed (HPed) materials were comprised with a mixture of the nc-Cu and homogeneous distribution of Al2O3 dispersoids. The compressive and micro Vickers hardness tests were performed on the HPed materials (nanocrystalline Cu with 4 vol.% of Al2O3 dispersoid) at room temperature to characterize the mechanical properties of the materials. The compressive yield strength of the materials was as high as 863 MPa; the micro Vickers hardness 2600 MPa. The results of the mechanical tests apparently show that the relationship between the yield strength and the micro hardness of the HPed materials is in well agreement with Tabor's rule, H v = 3σy in MPa. The grain size of the nc-Cu was estimated by XRD using Scherrer's formula and TEM observation; the Al 2O3 dispersoid size was measured from element mapping by STEM-EDS (Scanning Transmission Electron Microscopy-Energy Dispersive Spectroscopy) works. An attempt was made to quantify the possible strengthening effects of the nc-Cu materials with Al2O3 dispersoid. Two strengthening mechanisms were proposed for high hardness and yield strength of the materials, i.e., grain size and dispersion hardening effects. © 2010 Elsevier B.V. All rights reserved.
Kim S.K.,Daejin University
Experimental & molecular medicine | Year: 2013
New colchicine analogs have been synthesized with the aim of developing stronger potential anticancer activities. Among the analogs, CT20126 has been previously reported to show immunosuppressive activities. Here, we report that CT20126 also shows potential anticancer effects via an unusual mechanism: the modulation of microtubule integrity and cell cycle arrest at the G2/M phase before apoptosis. When we treated COS-7 cells with CT20126 (5 μM), the normal thread-like microtubules were disrupted into tubulin dimers within 10 min and thereafter repolymerized into short, thick filaments. In contrast, cells treated with the same concentration of colchicine exhibited microtubule depolymerization after 20 min and never underwent repolymerization. Furthermore, optical density (OD) analysis (350 nm) with purified tubulin showed that CT20126 had a higher repolymerizing activity than that of Taxol, a potent microtubule-polymerizing agent. These results suggest that the effects of CT20126 on microtubule integrity differ from those of colchicine: the analog first destabilizes microtubules and then stabilizes the disrupted tubulins into short, thick polymers. Furthermore, CT20126 induced a greater level of apoptotic activity in Jurkat T cells than colchicine (assessed by G2/M arrest, caspase-3 activation and cell sorting). At 20 nM, CT20126 induced 47% apoptosis among Jurkat T cells, whereas colchicine induced only 33% apoptosis. Our results suggest that the colchicine analog CT20126 can potently induce apoptosis by disrupting microtubule integrity in a manner that differs from that of colchicine or Taxol.
Yoo D.,Daejin University
Materials Science and Engineering C | Year: 2013
This paper presented an effective method for the three-dimensional (3D) hierarchical porous scaffold design for tissue engineering. To achieve such a hierarchical porous structure with accurately controlled internal pore architectures, the recursive intersection Boolean operation (RIBO) was proposed in order to satisfy computational efficiency and biological function requirements of a porous scaffold. After generating the distance field (DF) for the given anatomic model and required pore architectures, the recursive DF modifications enable us to design hierarchical porous scaffolds with complex combinations of pore morphologies. A variety of experimental results showed that the proposed hierarchical porous scaffold design method has the potential benefits for accurately controlling both the porosity and the pore architecture gradients while preserving the advantages of triply periodic minimal surface pore geometries. © 2013 Elsevier B.V. All Rights Reserved.
Yoo D.-J.,Daejin University
International Journal of Precision Engineering and Manufacturing | Year: 2012
Recently, a paradigm shift is taking place in tissue engineering scaffold design from homogeneous porous scaffolds to functionally graded scaffolds that have heterogeneous internal structures with controlled porosity levels and architectures. This paper presents a new heterogeneous modeling methodology for designing tissue engineering scaffolds with precisely controlled porosity and internal architectures using triply periodic minimal surfaces. The internal architectures and porosity at the spatial locations of the scaffolds are determined based on a given distribution of architectures and porosity levels specified at a few selected points on the model. After generating the hexahedral elements for a 3D anatomical shape using the distance field algorithm, the unit cell libraries composed of triply periodic minimal surfaces are mapped into the subdivided hexahedral elements using the shape function widely used in the finite element method. By simply allocating parameter values related to the porosity and architecture type to the corner nodes in each hexahedral element, we can easily and precisely control the pore size, porosity, and architecture type at each region of the scaffold while preserving perfectly interconnected pore networks across the entire scaffold. © KSPE and Springer 2012.