Development of software for computing forming information using a component based approach

ABSTRACTIn shipbuilding industry, the manufacturing technology has advanced at an unprecedented pace for the last decade. As a result, many automatic systems for cutting, welding, etc. have been developed and employed in the manufacturing process and accordingly the productivity has been increased drastically. Despite such improvement in the manufacturing technology, however, development of an automatic system for fabricating a curved hull plate remains at the beginning stage since hardware and software for the automation of the curved hull fabrication process should be developed differently depending on the dimensions of plates, forming methods and manufacturing processes of each shipyard. To deal with this problem, it is necessary to create a “plug-in” framework, which can adopt various kinds of hardware and software to construct a full automatic fabrication system. In this paper, a framework for automatic fabrication of curved hull plates is proposed, which consists of four components and related software. In particular the software module for computing fabrication information is developed by using the ooCBD development methodology, which can interface with other hardware and software with minimum effort. Examples of the proposed framework applied to medium and large shipyards are presented

Investigation of Enhanced Polygon Wall Boundary Model in PNU-MPS Method

With regard to demonstration of fluid flow, there are two descriptions which are Eulerian description and Lagrangian description. In the field of CFD (Computational Fluid Dynamics), a number of studies relevant to grid method based on Eulerian description have been conducted generally. However, when the grid method is employed to simulate flow field, it is inevitable to give consideration to convection term which generates severe numerical diffusion and fluctuation. To obtain the accuracy of solution, a different type of method based on Lagrangian description is come to the fore. Numerical approaches following Lagrangian description have been called meshfree or particle method. Even though particle method does not accompany convection term and fully satisfies conservation of mass, its studies have not been carried out extensively because it is difficult to implement the boundary conditions correctly due to insufficient number of particles in the vicinity of boundary. It affects directly the stability of flow field and accuracy in computation. In MPS (Moving Particle Semi-implicit) method [1], fixed-type of dummy particles are placed inside wall boundary. By placing extra particles as the wall, it seems to be not easy to satisfy the boundary condition for sharp-edged or extremely thin body configuration. In this study, the enhanced polygon wall boundary model, which was suggested originally by Mitsume et al. [2], is employed to the PNU-MPS (Pusan-National-University-modified MPS) method [3] to improve and stabilize the analysis of fluid flow with arbitrary-shaped body including sharp-edged body configuration without any additional particles. The developed simulation method, called as PNU-MPS-POLY, is adopted to the Couette flow and the lid-driven cavity flow with various corner angles. The present simulation results are validated through comparison with the analytic solutions, the experiments [4], and other simulation results [5,6]

Effects on Growth and Osteogenic Differentiation of Mesenchymal Stem Cells by the Zinc-Added Sol-Gel Bioactive Glass Granules

Responses of mesenchymal stem cells (MSCs) cultured with zinc-added (2 and 5%) bioactive glass granules were evaluated in terms of cell growth and osteogenic differentiation. MSCs were cultured with different quantities (3, 10 and 30) of glass granules for up to 21 days in the osteogenic medium. Cell growth was stimulated by a small quantity of glasses, particularly those that contained zinc. Osteogenic differentiation, as assessed by alkaline phosphatase activity (ALP) activity, was significantly enhanced by the glasses, particularly with large quantities of glass and for prolonged culturing. Expression of bone-sialo protein (BSP) was significantly up-regulated around the bioactive glass granules. Moreover, the zinc addition significantly altered the ALP and BSP depending on the culture time and glass quantity. Cellular mineralization was improved in all glass samples, and particularly in the 2% zinc-glass. Taken together, the zinc addition to bioactive glass induced the MSCs growth and their osteogenic differentiation, at least to the level of zinc-free glass, and with even higher level observed depending on the quantity and culture time. These findings indicate that the zinc addition to bioactive glass may be useful in development of biomaterials for the stimulation of adult stem cell in bone tissue engineering