났던

In a sentence

• 어제는 하늘에 무지개가 났던 날이에요.

  Yesterday was the day when a rainbow appeared in the sky.

  The word '났던' is used here to indicate a past occurrence (the rainbow appearing) being described in the sentence.

• 그는 어릴 때 꿈이 있었는데 지금 기억나는 건 내가 말했던 목표였다.

  When he was young, he had a dream, but now what I remember is the goal I had mentioned.

  The word '났던' illustrates a momentary past event (having mentioned the goal).

• 작년에 도전 상을 받았던 기억이 정말 자랑스럽다.

  I am really proud of the memory of having received the challenge award last year.

  '났던' conveys the act of having received the award as a past completed action.