[1] He finished sixth in the 55-kg division at the 2004 Asian Wrestling Championships in Almaty, Kazakhstan, and later represented his nation North Korea at the Summer Olympics a few months later.

O qualified as a lone wrestler for the North Korean squad in the men's featherweight class (55 kg) at the 2004 Summer Olympics in Athens, by receiving a wildcard invitation from the International Federation of Associated Wrestling (FILA).

[2] He lost his opening match 3–4 to the host nation's Amiran Kardanov, much to the delight of the home crowd inside Ano Liossa Olympic Hall.

Despite a single defeat, O rallied his stretch to edge Armenia's Martin Berberyan off the mat (5–2), and then awarded a free pass to score another triumph, when his other opponent Harun Doğan did not show up on the final bout because of sustained injuries.

[3] This biographical article relating to a North Korean sport wrestler or wrestling coach is a stub.