Use 에 for destinations and existence
With movement verbs such as 가다 (to go) and 오다 (to come), 에 marks the destination. With 있다 and 없다, 에 commonly marks where something or someone exists.
Use 에서 for the place of an action
When someone eats, studies, works, exercises, or does another action in a place, 에서 normally marks that action location.
One place, two different meanings
‘학교에 가요’ focuses on school as the destination. ‘학교에서 공부해요’ focuses on school as the setting of the action. Looking at the verb is often the fastest way to choose.
에 also marks time
When a specific time answers ‘when?’, 에 commonly follows it. Relative time words such as 오늘, 내일, and 어제 usually appear without 에, so learn the whole time expression rather than attaching 에 automatically.
내일 normally does not need 에 here.
에서 can also mean a starting point
With movement, 에서 can mark where a trip or movement starts. This is different from its action-location use, but the shared idea is that the event begins or takes place at that location. 까지 often marks the endpoint.
부산 is the destination, so use 에.