group Wanna One Ha Sung-woon attended Music Bank' rearsal held at the public hall of KBS New Building in Yeouido, Seoul on the morning of the 7th.
About Music Bank
Music Bank is a South Korean music program which airs every Friday at 17:00 KST on KBS2. As of 2015, the show is also broadcast in more than a hundred countries through KBS World.
 Wikipedia