Yoon Jong-shin
In February 2016, Ken contributed to the "Moorim School OST" with the song "When I See You" (). On May 24, it was announced that Ken would be collaborating with Mystic Entertainment's Yoon Jong-shin on his monthly collaboration project, Melody Monthly. The project which has included artists like Seventeen's vocal unit and Epik High's Tablo, the single "Over Sleep" was released on May 30, 2016. On December 22, 2016, Ken contributed to "The Legend of the Blue Sea" soundtrack with the song "Fool" ().