Flight Incheon International Airport departs from Seoul Incheon International Airport at 10:20 and arrives at Xiamen Gaoqi International Airport at 12:30.
The flighttime is about 3h 10m. The distance travelled ("as the bird flies"): 1197 Km. So the average speed is roughly 378 Km.
There is an 1 hour time difference between Seoul and Xiamen