1. Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
2. Department of Internal Medicine, College of Medicine, Korea University, Seoul, Korea.
3. Department of Internal Medicine, Eulji University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Inje University College of Medicine, Busan, Korea.
5. Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea.
6. Department of Internal Medicine, Konyang University College of Medicine, Daejeon, Korea.