UA 3852 then BA 5599 at San Francisco
Seoul → San Francisco → Dallas-Fort Worth
Timetable, San Francisco time
08:46UA 3852 from Seoul at the gate
06:38BA 5599 to Dallas-Fort Worth leaves the gate
21 h 52 apart on the timetable, overnight
BA 5599 leaves 21 h 52 after UA 3852 arrives on the timetable: more than half a day, so not a connection we count.