1. Department of Environmental Engineering, University of Seoul, 90 Junnondong, Dongdaemungu, Seoul, 130-743, Korea, (E-mail: ishan@uos.ac.kr; jwshin@uos.ac.kr)
2. Water Environment and Remediation Center, Korea Institute of Science and Technology PO Box 131, Cheongryang, Seoul, 130-650, Korea, (E-mail: animaplus@hanmail.net)