Singer IU revealed the prudent side of singer Yoon Sang.

IU came out on MBC’s “Come to Play” and said “I usually call him ‘dad’. He also sends me a lot of text messages on how I did on variety shows. However, there is one thing bad about this. He gets sad and mad at me if I don’t text him back.”
IU said “One day, I met him at a radio show and he asked me ‘why do you ignore texts from your dad?’” and got mad at me. Yoon Sang said embarrassingly, “I have this personality where everything has to be done quickly and efficiently or I get mad. So whenever a reply is late, I get nervous, mad, and sad at the same time.”
Also on the show was jazz pianist Kim Gwang Min, and guitarist Lee Byung Woo.

Source : Askactor