First Author:   Kazuhiro Yamamoto Graduate School of Economics, Osaka University yamamoto@econ.osaka-u.ac.jp   Graduate School of Economics, Osaka University, 1-7, Machikaneyama Toyonaka, 560-0043, Japan   +81-6-6850-5250(Phone) +81-6-6850-5250(Fax) Second Author: Ken Tabata Kobe City University of Foreign Studies tabataken@inst.kobe-cufs.ac.jp   Kobe City University of Foreign Studies, 9-1, Gakuenhigashimachi, Nishi-Ku Kobe, 651-2187, Japan