First saw a photo of YEH with Kim Dong Yoon on soompi. (I find him really cute when I first saw the photo)
More photos of them together.
They were the MCs for Show Music Tank ( I think it was in yr 2004)
He is also a player in the soccer team which KJK is in.
I think he's either the goalkeeper/ forward of the team.
website for their soccer team
He was featured in KJK's Walking In One Spot MV(uploaded on Youtube by junjinluver)
Kim Dong Yoon in Wonder Girls MV- Irony (uploaded by mrshyukjae)
More photos of him...
He's actually quite buffed up. Saw on KJK's chinese website that he's quite closed to KJK and often goes to gym with KJK...
With MC Mong
(photo credits: KDY's CY, JYP official site)
He's cute right?
Hopefully he'll be more well-known in future.
His profile page at JYP site.