UA 3852 then BA 5769 at San Francisco
Seoul → San Francisco → Chicago O'Hare
Timetable, San Francisco time
08:46UA 3852 from Seoul at the gate
06:01BA 5769 to Chicago O'Hare leaves the gate
21 h 15 apart on the timetable, overnight
BA 5769 leaves 21 h 15 after UA 3852 arrives on the timetable: more than half a day, so not a connection we count.