1. Department of Computer Science, Sogang University, 1 Sinsu-dong, Mapo-gu, Seoul, 121-742, Korea
2. Diquest Research Center, Diquest Inc., 7F, Sindo B/D, 1604-22, Seocho-dong, Seocho-gu, Seoul, 137-070, Korea
3. Department of Computer Science and Program of Integrated Biotechnology, Sogang University, 1 Sinsu-dong, Mapo-gu, Seoul, 121-742, Korea