1. Department of Preventive Medicine, Korea University, College of Medicine, Seoul, Korea.
2. Ewha Medical Research Institute, Ewha Womans University, School of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Korea University, College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Konkuk University, School of Medicine, Chungju, Korea.
5. Ministry of Education, Science and Technology, Seoul, Korea.
6. Seoul Metropolitan office of Education, Seoul, Korea.