Pak managed only sixth at the 2009 Pyongyang Marathon but he was entered into the men's marathon at the 2009 World Championships in Athletics and came 43rd with a time of 2:21:12. He won his first international medal at the East Asian Games that year, taking the half marathon silver. He had a strong run at the 2010 Pyongyang race, running 2:14:09 – his fastest time since 2007. However, he had to settle for second place behind surprise winner Ivan Babaryka. He ran at the 2010 Asian Games and was eighth in the marathon. In his sole outing of 2011, he represented North Korea at the 2011 World Military Games, finishing fifth.