Well, it appears that the two have worked together for Yoon Gun’s digital single “Don’t Say No,” which will be released on February 13, 2011 at 12am. (On Korean music websites such as Melon, Soribada, Bugs, and Naver Music) The song “Don’t Say No” is written and produced by Yoon Gun. The song contains acoustics, piano, and a string orchestra as background music. The genre is “Unplugged Pop”: and the lyrics are about confessing one’s love. Cr: soompi Gosh.. Accoustics+piano+string orchestra+confession!!! Plus Seohyun sang it! And Yoon Gun's voice is great too.. I bet I will fallin' in love with this song <3