Han made his first South Korean team, as an eighteen-year-old junior, at the 2000 Summer Olympics in Sydney.

[2][3][4] When South Korea hosted the 2002 Asian Games in Busan, Han won a total of four medals, including two in the freestyle relays.

He also enjoyed his teammate Cho Sung-Mo by giving the Koreans a 2–3 finish in the 1500 m freestyle, earning him a bronze in 15:22.38.

Han rounded out the field to last place by two hundredths of a second (0.02) behind Hungary's Tamás Szűcs, outside his entry time of 1:52.28.

He also helped out his South Korean team, including three-time champion Park Tae-Hwan, to defend their medals from Busan in the 400 and 800 m freestyle relays.