1 Department of Environmental Engineering (YIEST), Yonsei University, 234 Maeji, Heungup, Wonju, 220-710, South Korea; Trojan Technologies, 3020 Gore Rd., London, Ontario, N5V 4T7, Canada; Department of Chemical and Biochemical Engineering, University of Western Ontario, London, Ontario, N6A 5B9, Canada.
2 Department of Environmental Engineering (YIEST), Yonsei University, 234 Maeji, Heungup, Wonju, 220-710, South Korea.
3 Electronic Materials and Device Research Center, Korea Electronics Technology Institute, Seongnam, 463-816, South Korea.
4 Department of Environmental Engineering (YIEST), Yonsei University, 234 Maeji, Heungup, Wonju, 220-710, South Korea. Electronic address: jwk@yonsei.ac.kr.