Who gives a rat's ass what either Korea or Japan think about an English naming convention?  Last I checked neither nation is comprised of native English speakers and they don't get a vote in what native English-speaking nations decide to call this body of water, IN ENGLISH.  We can call it the "Sea of Jello" and there isn't a damned thing they can do about it, other than whine like babies.  Perhaps in commemoration of this foolishness we should call it the "Sea of Idiots" and have done with it.