Chun fought for the inaugural IBFsuper flyweight title in 1983, winning with a 5th-round TKO over Ken Kasugai in Osaka, Japan. He became the youngest Korean boxer to win a world title, at 19 years and 10 months old, and this record remains unbroken today. He defended the belt five times before losing it to future 3-time IBF super flyweight champion Ellyas Pical in Jakarta, Indonesia in 1985. After two more losses against lackluster competition, Chun retired in 1990.
