Korean Air doesn't do any free or pay with miles upgrade at check in for anything. Only full fare purchase to the next class up.
UNLESS...they are oversold. You can often ask them if the flight is oversold as they will put economy passengers in business seats (with economy food). Status helps, but is not always required. I've done this from GMP-KIX (no status) and ICN-MNL (DL Silver/Sky Team Elite...but my two friends with me had no status).