1. National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan
2. Ricoh Company, LTD. 5-10 Yokarakami, Kumanodo, Takadate, Natori, Miyagi 981-1241, Japan
3. Graduate School of System Design, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan