1. Department of Pediatrics, Hallym University Kangnam Sacred Heart Hospital Hallym University College of Medicine Seoul South Korea
2. Department of Pediatrics, Kyung Hee University Medical Center Kyung Hee University College of Medicine Seoul South Korea
3. Department of Pediatrics, CHA Bundang Medical Center CHA University School of Medicine Seongnam South Korea
4. Department of Pediatrics, CHA Ilsan Medical Center CHA University Goyang South Korea
5. Department of Pediatrics, Chonnam National University Hospital Chonnam National University Medical School Gwangju South Korea
6. Department of Information and Statistics Korea National Open University Seoul South Korea