She started out doing middle- and long-distance track as a teenager and broke the South Korean indoor record for the 3000 metres at the 2005 Asian Indoor Games, taking the silver medal behind India's O. P. Jaisha. She established herself nationally in 2006 at the age of seventeen by winning the 5000 metres national title and placing second over 1500 metres. She ran in both the 3000 m and 5000 m at the 2008 World Junior Championships in Athletics and finished 15th and tenth, respectively. She also made her debut over the half marathon that year, winning a race in Incheon in March setting a best of 73:14 at the Kagawa Marugame Half Marathon in Japan.