1. Department of Materials Science and Technology, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka, Niigata 940-2188, Japan
2. Research Fellow of the Japan Society for the Promotion of Science (DC), Tokyo 102-0083, Japan
3. National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan