- St. Vincent Hospital Intern
- Resident at Gangnam St. Mary’s Hospital
- Clinical instructor at St. Vincent's Hospital
- Full-time lecturer and assistant professor at St. Vincent's Hospital
- Director of Neonatal Department, International St. Mary's Hospital, Catholic Kwandong University
- Director, Department of Pediatrics, Catholic Kwandong University International St. Mary's Hospital
- Professor at Catholic Kwandong University International St. Mary's Hospital
