UA 806 then TP 4392 at San Francisco
Seoul → San Francisco → Boston
Timetable, San Francisco time
06:30UA 806 from Seoul at the gatealso OZ 6620
22:10TP 4392 to Boston leaves the gate
15 h 40 apart on the timetable
TP 4392 leaves 15 h 40 after UA 806 arrives on the timetable: more than half a day, so not a connection we count.