On the RCMP website, they specifically say that mailed-in applications should take about 8 weeks, but can take 120 days or more, and that you shouldn't contact them asking where it is until after those 120 days are up.
Also, a heads-up to any other Canadians out there -- even though your city/provincial police department may be in charge of administering national-level criminal record checks in your region, and even though they consult the same national database that the RCMP does, unless you specifically have a CRC from the RCMP (as in, it says RCMP on the paper), immigration will not accept it. Even if the Korean consulate back home stamps it. Maybe you'll get lucky and be able to argue it through / get someone at immigration who doesn't care, but the official policy is to reject anything that is not specifically issued by the RCMP.