[Korean grammar] 만에 Expressing Time and Sequential Behavior

가: 대학교에 입학한 지 얼마 만에 졸업하셨어요?
How long did it take you to graduate after entering university?
나: 대학을 다니다가 아파서 5년을 쉬었기 때문에 입학한 지 5년 만에 졸업을 했어요.
I took a year off due to illness, so I graduated five years after en roiling.

가: 서울에서 KTX를 타니까 3시간 만에 부산에 도착하더라고요.
I took the KTX from Seoul and arrived in Busan in three hours.
나: KTX가 정말 빠르네요!
The KTX is really fast!

This expression is used to indicate that something occurred a certain amount of time after a previous event occurred. Accordingly, the preceding clause normally includes the phrase -(으)ㄴ 지 which indicates that the action described in the clause has been completed in a certain amount of time. A number denoting an amount of time is used in front of -만에.
• 집을 짓기 시작한 지 3년 만에 다 지었어요.
The house was finished (being built) three years after it was started.

• 아이가 잠이 든 지 30분 만에 다시 깼어요.
The child woke up again 30 minutes after falling asleep.

• 얼마 만에 한국에 다시 오셨어요?
How long has it been since you last came to Korea?

The expressions 동안 and 후에 are used in ways similar to 만에. Their differences are as follows.