My research interests center on flux compactifications, their mathematical structures, and their applications to string phenomenology and cosmology. A recent development in F-theory compactification opens a new window for GUT model building. In F-theory, four-dimensional physics in which we are interested is encoded by fluxes and singularities in Calabi-Yau geometries. My current research mainly focuses on F-theory model building. It is interesting to understand better the role of the fluxes as well as the relation between physics quantities and singularities in the F-theory framework.