1. Department of Internal Medicine, School of Medicine, Ewha Womans University, Seoul, Korea.
2. Department of Internal Medicine, College of Medicine, Hanyang University, Seoul, Korea.
3. Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
4. Department of Internal Medicine, School of Medicine, Chonnam University, Gwangju, Korea.
5. Department of Internal Medicine, School of Medicine, Yonsei University, Seoul, Korea.
6. Department of Internal Medicine, School of Medicine, Seoul National University, Seongnam, Korea.
7. Department of Internal Medicine, School of Medicine Kyung Hee University, Seoul, Korea.