1. Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
2. Marketing & Planning Department, Magnesia Division, Ube Material Industries, Ltd., 1985, Kogushi, Ube, Yamaguchi 755-8510, Japan
3. Graduate School of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan