I've just found the actor of Dr Champ through asianwiki. His name is
Kim Hyeong Beom and I can't find him in MDL. Now I'm not sure they are the same actor... What do you think?
Maybe I'm confussed, or it's such a small role that it's not included in their filmography. I think that
Yum Dong Hun has also a supportive role in Empress Ki drama, is a minister.