Career
His primary area of research is on the Manchu language. Seong served as a professor at Myongji University from March 1968 to May 1982. The translation of the Tale of the Nisan Shaman into Korean he made while there (Seong 1974) would prove to be an important reference for its later translation into English.
In 1982, Seong moved to Seoul National University, where he held various positions including professor from September 1982 to February 1999, dean of the College of Humanities from September 1995 to August 1997, and head of the Altaic Society of of Korea from March 1997 to February 2002.
In 2004, he was awarded the 26th Oe Sol Prize, established in honour of Choe Hyeon-bae by the Oe Sol Foundation.