1. Department of Internal Medicine, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, College of Medicine, Soonchunhyang University, Seoul, Korea.
3. Department of Internal Medicine, Konyang University College of Medicine, Daejeon, Korea.
4. Department of Internal Medicine, Wonkwang University, School of Medicine, Iksan, Korea.
5. Department of Medicine, Sungkyunkwan University, School of Medicine, Seoul, Korea.