International migration and multiculturalism in Asia and South Korea

노트 : Paper prepared for presentation at the International Joint Symposium on “Sociopolitical Transformation in Globalizing Asia: Integration or Conflict?”, Waseda University, February 20-22, 2008

Understanding the Korean diaspora from comparative

노트 : Transformation & Prospect toward Multiethnic, Multiracial & Multicultural Society: Enhancing Intercultural Communication Session 2 “Diaspora 1

Two-Dimensional Materials for Organic Reaction Vessels and Proton Exchange Membranes

Department of Energy Engineering (Energy Engineering)Two-dimensional (2D) materials are promising candidates for use in membrane applications owing to their high chemical stability, thermal stability, and outstanding mechanical strength. Especially, the graphene sandwich structure has been studied extensively as a container for well-defined 2D confined spaces. Many researchers have attempted to understand chemical reactions in confined spaces because unexpected reactions can occur owing to the nanoconfinement effect and high van der Waals (vdW) pressure. To understand chemical reactions in confined spaces, creating a well-defined 2D confined space is very important. Also, it was demonstrated that hexagonal boron nitride (h-BN) showed the highest proton conductivity than other 2D materials, and so interesting of h-BN for proton exchange membrane (PEM) has been increased. Since h-BN showed high chemical and thermal stability than conventional polymer PEM, it is important to explore application of h-BN for PEM. This paper discussed our approaches to understand organic chemical reaction in confined space of graphene sandwich and apply h-BN for proton exchange membrane. The first part of my thesis pertains to the use of graphene sandwich nanoreactors for carrying out organic chemical reactions. Studies have observed phase transitions or hydrolysis of inorganic materials in the graphene sandwich structure, but organic chemical reactions in this structure have not been reported to date. To understand reactions in confined spaces, it is important to study organic chemical reactions in the graphene sandwich structure. I synthesized three monomers, namely dopamine, o-phenylendiamine (oPD), and 3,4-ethylene-dioxythiophene (EDOT) in a graphene sandwich. These monomers were 2D polymerized in a 2D confined space with polycrystallinity. In addition, 2D polycrystalline polydopamine exhibited reduced sheet resistance and increased bending stability and Young???s modulus. The second part pertains to the use of hexagonal boron nitride (h-BN) for fabricating proton exchange membranes. A fuel cell with a large-area single-oriented AA???-stacked trilayer h-BN were fabricated. The fuel cell with the AA???-stacked trilayer h-BN exhibited high power density of 0.66 W cm-1 and an open circuit voltage (OCV) of 0.958 V. The OCV degradation rate of h-BN (10% for single-layer BN and 5% for AA-stacked trilayer h-BN) was low compared to that of Nafion (56%) in stability tests conducted under harsh condition because the h-BN blocked gas crossover and reduced generation of reactive radicals. Furthermore, I tried to fabricate new fuel cell structure for trilayer h-BN with AA???-stacking by Pt deposition in third part. To reduce costs of Pt and oxygen resistance in cathode reaction, deposition of Pt nanoparticles on trilayer h-BN with AA???-stacking were studied. By atomic layer deposition, uniform high density of Pt nanoparticles was prepared, successfully. Uniform Pt nanoparticles were used cathodes of new fuel cell based on trilayer h-BN with AA???-stacking.clos

Hodge ideals and spectrum of isolated hypersurface singularities

We introduce Hodge ideal spectrum for isolated hypersurface singularities to see the difference between the Hodge ideals and the microlocal $V$-filtration modulo the Jacobian ideal. Via the Tjurina subspectrum, we can compare the Hodge ideal spectrum with the Steenbrink spectrum which can be defined by the microlocal $V$-filtration. As a consequence of a formula of Mustata and Popa, these two spectra coincide in the weighted homogeneous case. We prove sufficient conditions for their coincidence and non-coincidence in some non-weighted-homogeneous cases where the defining function is semi-weighted-homogeneous or with non-degenerate Newton boundary in most cases. We also show that the convenience condition can be avoided in a formula of Zhang for the non-degenerate case, and present an example where the Hodge ideals are not weakly decreasing even modulo the Jacobian ideal.Comment: 29 page

Monet of the orient

This dress is inspired by painter Claude Monet woks, especially soft pastel tone of Water Lilly in colors. The purpose of the dress is to express oriental beauty coming from Korean traditional costume ‘Hanbok’ that has balloon lines with pastel tone of color. It could be worn for evening wear