Tatsuhiko KUGA†, Hideki KOBAYASI†, Hiroshi SAKAMAKI* and Tetuyuki TANIAI
College of Science and Technology, Nihon University, Funabashi Campus;Narashinodai, Funabashi-shi 274-8501 Japan † TOTO Ltd.; 304-701 Nishiyama Oroshicho, Toki-shi 509-5202 Japan