UA 2409 then K4 538 at O'Hare
Los Angeles → Chicago → Seoul
Timetable, Chicago time
05:58UA 2409 from Los Angeles at the gate
01:45K4 538 to Seoul leaves the gate
19 h 47 apart on the timetable, overnight
K4 538 leaves 19 h 47 after UA 2409 arrives on the timetable: more than half a day, so not a connection we count.