how are you guessing/know this information just from the tracking number?
Educated guess based on the time it left. However, more poking around turned up that there's a UPS Cargo plane going from Incheon to Louisville (via Anchorage? doesn't say) right now that left at 1:20 PM, exactly the departure time that we got on our tracking info.
http://www.airport.kr/airport/flightinfo/IhCargoDepStatusList.iia?gubun=E
It was scheduled to leave at 12:50 and left at 1:20. The times match up, but I don't see this one on the flightaware.com list for UPS.