1. Graduate Student, Dept. of Environmental Engineering, Yonsei Univ., Wonju 220-710, South Korea.
2. Associate Professor, Dept. of Environmental Biotechnology, City for Scientific Research and Technology Applications, New Borg El Arab City, Alexandria 21934, Egypt.
3. Associate Professor, Dept. of Geography and Environmental Engineering, U.S. Military Academy, West Point, NY 10996.
4. Dept. of Civil and Environmental Engineering, Pennsylvania State Univ., University Park, PA 16802.
5. Bioenergy Research Center, Korea Institute of Energy Research, Daejeon 305-343, South Korea.
6. Associate Professor, Dept. of Environmental Engineering, Yonsei Univ., Wonju 220-710, South Korea (corresponding author).