1. Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Emergency Medicine, Samsung Medical Center, Seoul, Korea.
3. Department of Pediatrics, Samsung Medical Center, Seoul, Korea.
4. Department of Emergency Medicine, Seoul National University Hospital, Seoul, Korea.
5. Department of Emergency Medicine, Ajou University School of Medicine, Suwon, Korea.