Career
He bats and throws right-handed. Ko played college baseball at Kyungsung University in Busan. He was drafted by the Doosan Bears in the 3rd round (20th overall) of the 2008 of Korea Baseball Organization Draft.
In the set-up role, Ko drew the attention of the league when he posted a 1.95 European Research Area and earned 16 holds in 2009.
He enjoyed another great season as a setup man in 2010, when he earned 22 holds which was runner-up in the KBO league. In 2011, Ko earned 14 holds but his European Research Area rose to 4.44.
In 2012, he finished the season with a 8.62 European Research Area losing all ability to control his pitches. Ko was sent down to the second-tier team of the Bears in the middle of the 2012 season and traded to the North Carolina Dinos after the season.
