I was unaware that: 줄 몰랐다

A/V/N + 줄 몰랐다 shows that you were previously unaware of something, but now you know. It is the opposite of 줄 알았다:

I was unaware that it had V-ed: ㄴ 줄 몰랐다

그가 아파트에서 이사간 줄 몰랐어요.

I didn’t know he moved out of the apartment. 

그 사람이 졸업한 줄 몰랐어요.

I didn’t know he’d already graduated.

I was unaware that it Vs: 는 줄 몰랐다

저는 라마단 동안에 해가 뜰 때부터 해가 질 때가지 무슬림들이 물도 못 마시는 줄 몰랐어요.

I was unaware that during Ramadan, Muslims can’t even drink water from sunrise to sunset.

그 사람은 딸기에 알레르기가 있는 줄 몰랐어요.

I was unaware that he’s allergic to strawberries.

I was unaware that it’s N: 인 줄 몰랐다

중국어는 성조 언어인 줄 몰랐어요.

I didn’t know that Chinese was a tonal language.

많은 유럽 도시에서 전차가 인기가 있는 대중교통 수단인 줄 몰랐어요.

I was unaware that trams were a popular means of public transportation in many European cities.

그 여자가 채식주의자인 줄 몰랐어요.

I didn’t know she was a vegetarian. 

I was unaware that it’s A: ㄴ 줄 몰랐다

한국 음식이 그 정도로 매운 줄 몰랐어요.

I didn’t know Korean food was that spicy.

이 책이 그만큼 흥미로운 줄 몰랐어요.

I didn’t know this book was that interesting.

언어를 배우기가 그 정도로 어려운 줄 몰랐어요.

I didn’t know it was that difficult to learn a language. 

I was unaware that it would be (in the future): ㄹ 줄 몰랐다

출근했을 때 길이 막힐 줄 몰랐어요.  

I didn’t know there would be a traffic jam when I left work. 

유학하기 위해 미국에 갈 줄 몰랐어요.

I was unaware that my friend would go to America to study abroad. 

저의 말이 그를 화나게 할 줄 몰랐어요.

I was unaware that what I said would upset him.