He returned to Korea in 1979, to establish a child and adolescent psychiatry service as well as training program. He founded and became the president of several professional organizations including Korean Academy of Child and Adolescent Psychiatry, Korean Society of Child Abuse and Neglect, and Korean Association of Persons of Autism. He provided an excellent model of how to establish child psychiatry in a developing country from scratch. He also founded the Asian Society of Child and Adolescent Psychiatry and Allied Professions (ASCAPAP) in 1996, and has contributed significantly in developing child psychiatry service in Asian countries. He has been also very active in the International Association of Child and Adolescent Psychiatry and Allied Professions (IACAPAP) as an Executive Committee member and currently a Vice President of the Association representing the Asian region. He was instrumental in working on the World Psychiatric Association’s Presidential Programme on Global Child Mental Health.
His major clinical and research interests have been social/cultural changes and child mental health, “reactive” developmental, emotional, and behavioral disorders in rapidly changing societies, and development of Attachment Promotion Therapy. He is also known for his work on internet addiction of children and adolescents in Asian countries.