1. Senior Researcher, Korea Institute of Water and Environment, KOWACO, 462-1, Jeonmin-dong, Yuseong-gu, Daejeon, 305-730, Korea.
2. Professor, Division of Environmental and Resource Engineering, Hokkaido Univ., North 13, West 8, Kitaku, Sapporo, Hokkaido, 060-8628, Japan.