At the 2004 Summer Olympics in Athens, Ku qualified for the second time as a member and captain of the South Korean squad in the women's volleyball tournament after receiving an automatic berth from the Asian Championships. Unable to improve a fair performance from Sydney, she and the rest of the South Korean team were defeated in the quarterfinal match against Russia with a unanimous set score of 0–3 (17–25, 15–25, 22–25). Ku was also appointed as the flag bearer for Korea, along with former basketball coach Kim Sung-Ho, under a joint march in the opening ceremony.