Papers by Author: Seung Hyun Yoo

Abstract: The existence of a crack in a structure produces changes in modal parameters of it such as natural frequencies, damping, displacement and strain mode shapes. This paper is focused on characterization of crack detection methods using strain mode shapes. To characterize crack detection methods, we changed sensing grids from corner grid to cross grid and geometry of the specimens from rectangular to triangular plate. Rest of conditions was fixed. For crack detection criteria, COMAC, ECOMAC, ADSM and new method have been used and the results are compared with each other. The COMAC, ECOMAC and ADSM showed limited capacity of crack detection on plates but the new method gave good results in 90% of all cases.

Abstract: Investigation of the bone mineral density (BMD), microstructural and mechanical properties in the Otsuka Long Evans Tokushima Fatty (OLETF) and Otsuka Long Evans Tokushima Fatty (LETO) rats were performed. The BMD and microstructural analyses were carried out using PIXI-mus and non-invasive highresolution micro-computed tomography (micro-CT) system. The mechanical properties analyses were determined by finite element analysis based on micro-images. The BMD was significantly larger in LETO rat than in OLETF rat. The microstructural and mechanical properties were deteriorated and decreased in OLETF rat. The results showed that bone strength is decreased in OLETF in spite of high body weight.