I am truly glad to have cast you as Newgrounds' own Nene, I REALLY am. I caught this just by chance in my Audio feed, and not only are your expressions impeccable in both languages... your English is impeccable!
I only know a tiny, tiiiiiny bit of Korean so it didn't get me through all of this demo but I presumed that a lot of it had to do with the flow of what it was you were saying at any given point in time, e.g. the student chiding her classmate for dozing off in class. Amazing vocal clarity, at any rate -- and I'm looking forward to having you on board the project when the script is done!