Wang Ki-chun, the judoka who won a silver medal in the 2008 Beijing Olympics, was caught using a mobile phone at an Army boot camp and put in brig for eight days.
He was kicked out of the camp without finishing the four-week training.
Athletes who have won a medal in the Olympics can substitute their mandatory military service for a month of military training plus 30 more months of sporting activity in their field.
But an Army officer said Wang brought his mobile phone with him and failed to turn in his personal belongings when he entered a boot camp on Dec. 10 and was caught using it. He was put in the brig on Dec. 31.
Eight other recruits who borrowed his mobile phone were also put either in the brig or in a disciplinary camp.
Wang was prematurely discharged from the camp on Jan. 7 for failing to complete the training. He will have to undergo the entire process all over again.