1. Department of Mechanical Science and Engineering; Nagoya University; Nagoya 464-8603 Japan
2. Institute for Computational and Mathematical Engineering; Stanford University; Stanford CA 94305-4040 U.S.A.
3. Air and Missile Defense Department; Johns Hopkins University; Laurel MD 20723-6099 U.S.A.
4. Department of Mechanical Engineering; Stanford University; Stanford CA 94305-4040 U.S.A.