Yun qualified for the 2008 Summer Olympics in Beijing, where she competed as a lone female athlete in the women"s modern pentathlon. In the end, Yun finished the event with cross-country running in thirty-third place, for a total score of 4,872 points.
She also won a gold medal for the women"s individual event at the 2006 Asian Modern Pentathlon Championships in Kaohsiung, Taiwan. During the competition, Yun struggled in the early segments, with poor scores in pistol shooting and a one-touch épée fencing, but managed to attain twenty-fourth-place finishes in freestyle swimming and show jumping.
