1. Public Healthcare Center, Seoul National University Hospital, Seoul, Korea.
2. Department of Medicine, College of Medicine, Seoul National University, Seoul, Korea.
3. Laboratory of Emergency Medical Services, Seoul National University Hospital Biomedical Research Institute, Seoul, Korea.
4. Department of Public Health Sciences, Seoul National University Graduate School of Public Health, Seoul, Korea.
5. Department of Emergency Medicine, Seoul National University Hospital, Seoul, Korea.
6. Department of Emergency Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.