1. School of Chemical & Biological Engineering and NANO Systems Institute-National Core Research Center, Seoul National University, Kwanak-gu, Seoul 151-744, South Korea, Department of Chemical Engineering, Yonsei University, Seodaemun-gu, Seoul 120-749, South Korea, Department of Chemistry, Inha University, Inchon, South Korea, and Department of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea