1. Australian Nuclear Science and Technology Organisation, PMB 1, Menai (Sydney), NSW, 2234, Australia
2. Ocean and Ice Engineering Department, National Maritime Research Institute, 181-0004, Tokyo-to, Mitaka-shi, Shinkawa 6-38-1, Japan
3. National Maritime Research Institute, 6-38-1, Shinkawa, Mitaka, Tokyo 181-004, Japan