• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.11a
• /
• pp.204-211
• /
• 2001

For the treatment of high compressibility number in the Reynolds equation, a new class of exponential high-order shape functions has been recently introduced in the literatures. In this paper a FE lubrication analysis method of high speed gas mechanical face seals is developed, implementing these shape functions. Their validity and usefulness are presented using 1-D gas bearing models. And a validation of developed 2-D analysis code is shown with a gas flat and spiral groove face seal models.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2013.10a
• /
• pp.149-150
• /
• 2013

Recently, various types of perforated breakwaters are being constructed for protecting offshore storm waves. In general, perforated breakwaters have wave chambers with perforated walls at seaside. Purposes of the wave chambers are to reduce wave reflections and maximum wave forces acting on the breakwater. Impact wave forces due to wave breaking can attack to the perforated wall directly, so the effects have to be considered in the design of the perforated wall carefully. Using resonance channels for wave energy dissipation, a new concept perforated breakwater is proposed, which is free from impact loads. Numerical simulation was made for wave reflection characteristics of the breakwater with respect to major design parameters. Numerical analysis was carried out using the Galerkin's FE model based on the linear potential theory considering energy dissipation on the perforated plate. Variations of wave reflection was investigated according to perforated ratios of perforated plate.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.3
• /
• pp.589-597
• /
• 2015

Wave energy harvesting system using OWC(Oscillating Water Column) and MB (Movable Body) attached at the caisson breakwater was studied. This system was suggested to maximize wave energy extraction using resonant phenomena of oscillating water column and buoy in wave channel (Park et al., 2014). Not only incident waves but also reflected waves from the breakwater can be used as sources of exciting force for harvesting wave energy efficiently. Using Galerkin finite model based on the linear wave theory (Park, 1991), the performance of the system was evaluated for various damping ratios of power take off system. Numerical results show that the proposed system is excellent in efficiency compared with that of conventional system and the performance of the system is governed by the resonance of oscillating water column in the wave channel. In addition, the additional efforts to minimize viscous damping was found to be necessary because viscous damping occurring in the channel and around the moving buoy is significant in generation efficiency.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.10
• /
• pp.1427-1435
• /
• 2010

A mixed finite element model was developed using the classical plate theory to analyze the nonlinear bending of a plate. The appropriate weight functions for the constraints integrated over the domain were determined by the Lagrange multiplier method by using the principle of minimum virtual energy; which provides the constitutive relations between force-like variables and strains. All of detail terms of element wise coefficient matrices and associate tangent matrices to be used in the Newton iterative method are presented. Then, the linear solutions of the current model and those of the traditional displacement model under the SS (simple support) boundary conditions were compared with the existing analytical solution. The post-processed images of the nonlinear results of the force-like variables are presented to show the continuity of the solutions at the joint of the element boundaries. Finally, the converged nonlinear finite element solutions of the current model are compared with those of existing traditional displacement model.