Interdisciplinary Program in Bioinformatics, Seoul National University, Gwanak-Gu, Seoul, 151-747, Republic of Korea.|Department of Computer Science and Engineering.|Department of Applied Biology and chemistry, Seoul National University, Gwanak-Gu, Seoul, 151-744, Republic of Korea.|Department of Computer Science and Engineering.|Department of Computer Science and Engineering.|Interdisciplinary Program in Bioinformatics, Seoul National University, Gwanak-Gu, Seoul, 151-747, Republic of Korea.