Kim Hyo-jung, known professionally as Hyolyn, is a South Korean singer and songwriter under BridÊ’, a production company she founded herself. She is a former member of the girl group Sistar and its sub-unit Sistar19. Kim Hyo-jung, known professionally as Hyolyn, is a South Korean singer and songwriter under BridÊ’, a production company she founded herself. She is a former member of the girl group Sistar and its sub-unit Sistar19.