줄은 몰랐다

didn't know that …

→ 줄
phrase Rare #20,765
didn't know that … Attach it to a preceding clause to say you didn’t know something was the case or would happen. 은 adds emphasis.
KO: 네가 여기 살 줄은 몰랐다.
EN: I didn’t know you lived here.

금화 야 내도 저렇게 살 줄은 몰랐다

I never thought you’d end up living like that, Geumhwa.

— Svaha: The Sixth Finger (2019)

그런 여인이 있을 줄은 몰랐다

I never knew there was such a woman.

— 가구야공주 이야기 (2013)

크리스가 그런 일을 하고 있는 줄은 몰랐다.

I didn't know Chris was doing that.

그렇긴 하지만 타이어가 터질 줄은 몰랐다?

That may be true, but I didn't expect the tire to blow out.

— 필사의 추적 (1981)

미국인을 찾고 있다 오늘 당신이 여기 서 만날 예정 이었던 남자 미국인 인 줄은 몰랐다

I'm looking for an American—the man you were supposed to meet here today. I didn't know he was American.

— 학살기관 (2017)