Yu Sun boks first international success was winning the Youth Asia Cup in 1987 with the North Korean team. In 1989 she won among adults in an individual of the Asian Cup, a year later it reached with the women's team at the Asian Championship in the final.
Three times she was nominated for the World Championships, namely 1989, 1991 and 1993. They belonged in 1991 the total Korean ladies team, the world champion. In 1993 she took with the North Korean team silver and mixed with Il Sung Li bronze. In the same year she was third in the Asian TOP8 ranked games.
In 1992 she qualified for participation in the Olympic Games, where she reached the quarter-finals in the individual and doubles with Li Bun Hui after the semi-final defeat against the Chinese Chen Zihe / Gao Jun won the bronze medal.
In the ITTF World Ranking Yu Sun -bok end of 1992 and the end of 1993 was passed at number nine.
Results from the ITTF database