1. Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Korea.
2. Department of Internal Medicine, Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea.
3. Department of Internal Medicine, Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, University of Ulsan College of Medicine, Gangneung Asan Hospital, Gangneung, Korea.