1. Department of Pediatrics, Childhood Asthma Atopy Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Pediatrics, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
3. Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
4. Department of Pediatrics, Hallym University Secred Heart Hospital, Seoul, Korea.
5. Department of Pediatrics, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.
6. Department of Pediatrics, Severance Children's Hospital, College of Medicine, Yonsei University, Seoul, Korea.
7. Department of Pediatrics, CHA University School of Medicine, Seoul, Korea.
8. Department of Pediatrics, Gangnam Severance Hospital, College of Medicine, Yonsei University, Seoul, Korea.
9. Graduate School of Public Health, Seoul National University, Seoul, Korea.