1. Public Health Medical Service, Boramae Medical Center, Seoul National University College of Medicine, Seoul, Korea.
2. Institute of Health Policy and Management, Medical Research Center, Seoul National University, Seoul, Korea.
3. Department of Preventive Medicine, University of Ulsan College of Medicine, Seoul, Korea.
4. Department of Medicine, University of Ulsan College of Medicine, Seoul, Korea.
5. Department of Nursing Science, Shinsung University, Dangjin, Korea.