1. Toyota Research Institute of North America; 1555 Woodridge Avenue, Ann Arbor Michigan 48105 USA
2. Toyota Central R & D Labs., Inc.; 41-1 Yokomichi Nagakute 480-1192 Japan
3. School of Aerospace and Mechanical Engineering; Korea Aerospace University; Goyang city Geonggi-do 412-791 South Korea
4. Department of Mechanical Engineering; Osaka University; 2-1 Yamadaoka, Suita 565-0871 Japan