Career
He was born in Junten (Suncheon), Japanese of Korea and received higher education in Japan. Like the gold medalist Sohn Kee-chung, Nam Sung-yong used the Japanese pronunciation of his name, Nan Shōryū as of Korea was then a part of the Japanese Empire. After the Olympics, Nam Sung-yong worked at the Korean Sporting Association with Sohn Kee-chung.