First Author:   Kazuo Mino Graduate School of Economics mino@econ.osaka-u.ac.jp   Graduate School of Economics, Osaka University, 1-7 Machikaneyama Toyonaka, 650-0043, Japan   81-6-6850-5232(Phone) 81-6-6850-5232(Fax) http://www2.econ.osaka-u.ac.jp/~mino/index2.html Second Author: Seiya Fujisaki Graduate School of Economics ege010fs@mail2.econ.osaka-u.ac.jp   Graduate School of Economics, Osaka University, 1-7 Machikaneyama Toyonaka, 650-0043, Japan