When I moved, I packed 20 kilos of essentials in a suitcase, and another suitcase of nice-to-haves. I managed to get the second suitcase checked in as well (sob story at check in), but was prepared to send it unaccompanied baggage if necessary (18-20 kgs to Korea may be 200 pounds-ish). The important bit is to prioritise what you really need, and if it all goes wrong the person taking you to the airport can take the second case home again. The heavier the second case, the less likely you will be able to check it in