1 Department of Internal Medicine, The Catholic University of Korea College of Medicine, 56, Dongsu-ro, Bupyung-gu, Incheon 403-720, Korea.
2 Department of Internal Medicine, The Catholic University of Korea College of Medicine, 56, Dongsu-ro, Bupyung-gu, Incheon 403-720, Korea mjkim@catholic.ac.kr.