UA 2389 then K4 538 at O'Hare
New York LaGuardia → Chicago → Seoul
Timetable, Chicago time
07:51UA 2389 from New York LaGuardia at the gate
01:45K4 538 to Seoul leaves the gate
17 h 54 apart on the timetable, overnight
K4 538 leaves 17 h 54 after UA 2389 arrives on the timetable: more than half a day, so not a connection we count.