Flight Changi Airport departs from Singapore Changi Airport at 23:00 and arrives at Seoul Incheon International Airport at 06:20.
The flighttime is about 6h 20m. The distance travelled ("as the bird flies"): 2923 Km. So the average speed is roughly 462 Km.
There is an 1 hour time difference between Singapore and Seoul
The best day to arrive at Singapore is Monday and it would be best to avoid Thursday, as prices are on average 298.59% higher than on Monday. (Average prices, based on 432711 datapoints.)
We have a lot more statistics for flights QF 752 and between Singapore and Seoul.