This is the 16024th most frequent Korean word.
북상하고서
"북상하고서" means "after moving northward."
북상하고서 is used here to describe an event (the typhoon moving northward) occurring before the subsequent action (causing damage).
태풍이 북상하고서 많은 지역에 피해를 입혔다.
After the typhoon moved northward, it caused damage to many areas.
북상하고서 is used to indicate the completion of the ascending northward action in relation to establishing the base afterward.
그들은 산을 북상하고서 새로운 기지를 세웠다.
After ascending northward in the mountain, they established a new base.
북상하고서 positions the northward movement as the event preceding stopping for repairs.