1. Department of Pediatrics, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Statistics, Graduate School of Chung-Ang University, Seoul, Korea.
3. Department of Pediatrics, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Pediatrics, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Korea.
5. Department of Biostatistics, Soonchunhyang University Seoul Hospital, Seoul, Korea.
6. Department of Applied Statistics, Chung-Ang University, Seoul, Korea.
7. Department of Pediatrics, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Korea.
8. Department of Pediatrics, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.