KE 852 then ZH 634 at Incheon
Beijing Capital → Seoul → Shenzhen
Timetable, Seoul time
21:55KE 852 from Beijing Capital at the gate
14:55ZH 634 to Shenzhen leaves the gate
17 h apart on the timetable, overnight
ZH 634 leaves 17 h after KE 852 arrives on the timetable: more than half a day, so not a connection we count.