Tae-U

On May 13, 2014, under the stage name Do. Ka, he was introduced as a member of the upcoming boy group BTL. He debuted with the group on May 15 with the digital single "Beyond The Limit".

On November 24, 2015, Do. Ka was spotted as a member of the newly formed boy group Road Boyz under the stage name Ha Neul. It is presumed that he unofficially departed from BTL, as a reserve member, was later introduced.