1. Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
2. Panasonic Science Research Alliance Laboratories, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
3. Research Center for Sustainable Energy and Environmental Engineering, Faculty of Engineering, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan
4. Technology Division, Panasonic Holdings Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi, Osaka 570-8501, Japan