Midfielder who joined Mainz 05 in 2014 after spending three years with VfL Wolfsburg. He became a member of the South Korean national team in 2008.
He debuted professionally for Jeju United in 2007.
He scored his first international goal on January 9, 2010 in a friendly against Zambia.
He was born in Nonsan, South Chungcheong, South Korea.
He and Park Ji-Sung became teammates on the South Korean national team.