1. Department of Chemistry, Yonsei University, 50 Yonsero, Seodaemun-Gu, Seoul 120-749, Republic of Korea
2. Department of Microbiology, College of Medicine, Yonsei University, Seoul 120-752, Republic of Korea
3. Department of Chemistry, Kangwon National University, Chuncheon 200-701, Republic of Korea
4. Department of Laboratory Medicine and Research Institute of Bacterial Resistance, College of Medicine, Yonsei University, 211 Eonjuro, Gangnam-Gu, Seoul 135-720, Republic of Korea