Iโm always really happy when Yoon Do Hyun/YB is part of the OST, itโs even gotten to the point where itโs an instant reason to add a drama to my watchlist 
Heโs got some beautiful ballads, but I like his rocksound better. Some of my favorites are:
My secret dreams - Arang and the magistrate
Silence - Taxi
๋น๋ฐ์ ์ฉ - Stranger
What the Ggang - Again my life