Kim Sung Hyun , formerly known as Yoo Jeong Woo, is a South Korean actor. He made his acting debut in 2017 with a role in "Love After School" (방과후 연애), under the stage name Yoo Jeong Woo. He is currently managed by EL Park (이엘파크) and has decided to use his birth name. (Source: MyDramaList)