First Author:   Nguyen Duc Tiep Graduate School of Economics, Kyoto University ductiep@hic.mbox.media.kyoto-u.ac.jp   Coop Yoshida 205, 24-5 Yoshida Nakaadachi-cho, Sakyo-ku, Kyoto-shi Kyoto, 606-8306, Japan   +81-90-1967-1369(Phone) +81-90-1967-1369(Fax)