• 1994-1995 Clinical Instructor, Department of Obstetrics & Gynecology, Asan Medical Center, Seoul, Korea • 1995-1997 Instructor-Lecturer, Department of Obstetrics & Gynecology, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea • 1997-2001 Assistant Professor, Department of Obstetrics & Gynecology, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea • 2000-2001 Research scholar in Center for Research on Reproduction and Women's Health, Department of Obstetrics & Gynecology, University of Pennsylvania Medical Center (Research using Bill and Melinda Gates Fund) • 2001-2006 Associate Professor, Department of Obstetrics & Gynecology, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea • 2006-2018 Professor, Department of Obstetrics & Gynecology, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea • 1997-2018 Director, Clinic for Reproductive Medicine and Infertility, Division of Reproductive Endocrinology and Infertility, Department of Obstetrics & Gynecology, Asan Medical Center, Seoul, Korea

 Regulation of ovarian folliculogenesis and its clinical application  Pathophysiology of PCOS  Regeneration of uterine endometrium.  USG-guided interventional treatment of benign ovarian cyst, hydrosalpinx and uterine fibroid