Flight Changi Airport departs from Singapore Changi Airport at 23:00 and arrives at Seoul Gimpo International Airport at 06:20.
The flighttime is about 6h 20m. The distance travelled ("as the bird flies"): 2961 Km. So the average speed is roughly 468 Km.
There is an 1 hour time difference between Singapore and Seoul
The best day to arrive at Singapore is Sunday and it would be best to avoid Wednesday, as prices are on average 141.88% higher than on Sunday. (Average prices, based on 400574 datapoints.)
We have a lot more statistics for flights OZ 752 and between Singapore and Seoul.