Papers by Author: Yoo Shin Kim

Abstract: An experimental and numerical study of polymer electrolyte membrane fuel cell (PEMFC) is presented and compared with the experimental data to investigate the effects of pressure gradient, flow rate, humidification and supplied oxidant type for the practical application. The membrane and electrolyte assembly (MEA) materials are implemented by double-tied catalyst layers. A single-phase two-dimensional steady-state model is is implemented for the numerical analysis. Testing condition is fixed at 60sccm and 70°C in anode and cathode, respectively. It is found that the performance of PEMFC depend highly on the conditions as gas pressure, temperature, thickness, supplied oxidant type (Oxygen/Air) as well as humidification. The results show that the humidification effect enhances the performance more than 20% and the pure oxygen gas as fuel improves current density more than 25% compared to ambient air suppliance as oxidant.

Abstract: A shape design optimization of the boom system in high ladder vehicle modeled by 3-dimensional finite elements is carried out. The structural analysis is performed using 3-D FEA (Finite Element Analysis) giving the results of displacements, stresses and natural frequencies. The section height and width of the boom is controlled by the FEA result data. The subproblem approximation method is implemented for the optimal shape based on displacement and principal stress. In the meantime, Lanzcos algorithm method is implemented in order to find the natural frequency of the system. The optimal models obtained by three different optimization processes are compared with the initial model and evaluated for economic conditions respectively. It is found that the different shape optimization processes give the different shape optimization results, which suggest their unique optimal shapes under their necessary design condition.