KE 852 then KE 643 at Incheon
Beijing Capital → Seoul → Singapore
Timetable, Seoul time
21:55KE 852 from Beijing Capital at the gate
14:35KE 643 to Singapore leaves the gate
16 h 40 apart on the timetable, overnight
KE 643 leaves 16 h 40 after KE 852 arrives on the timetable: more than half a day, so not a connection we count.