I expected/thought... (but): 줄 알았다
A/V/N + 줄 알았다 can used to show that your expectations were defied — ‘I expected/thought X, but’. It is the opposite of 줄 몰랐다:
한국친구가 모든 외국인이 햄버거를 먹는 줄 알았어요. My Korean friend thought that all foreigners eat hamburgers (but they don’t).
저는 모든 한국인이 K-팝을 듣는 줄 알았어요. I thought all Koreans listened to K-Pop (but they don’t).
긴 영화 있는 줄 알았어요. I thought it would be a long movie (but it wasn’t).
The outcome can be made explicit with 줄 알았는데:
오늘은 비가 올 줄 알았는데 맑은 하늘이에요. I expected it to rain today but the skies are clear.
톰 크루즈가 키가 큰 줄 알았는데 정말 작아요. I thought Tom Cruise was tall but he’s really short.
서울에 빨리 갈 줄 알았는데 3시간 이상 걸렸어요. I thought going to Seoul would be fast but it took more than 3 hours.