加加林宇航员培训中心
On September 5, 2007, the Korean Ministry of Science and Technology chose Ko San over Yi So-Yeon based on performance in tests during training in Russia. However, on March 10, 2008, this decision was reversed, after the Russian Federal Space Agency asked for a replacement because Ko apparently violated security protocol for maintaining secret information twice at the Yuri Gagarin Cosmonaut Training Center.