UA 3851 then AA 2612 at Houston
Seoul → Houston → Chicago
Timetable, Houston time
17:54UA 3851 from Seoul at the gate
17:27AA 2612 to Chicago leaves the gate
23 h 33 apart on the timetable, overnight
AA 2612 leaves 23 h 33 after UA 3851 arrives on the timetable: more than half a day, so not a connection we count.