민찬이

In a sentence

• 민찬이는 책을 열심히 읽고 있어요.

  Minchan is reading a book diligently.

  In this sentence, '민찬이' is used as the subject of the sentence, referring to a person named Minchan. The suffix '-이' is attached to indicate the subject form.

• 우리 학교에 민찬이라는 친구가 있어요.

  There is a friend named Minchan in our school.

  '민찬이' is used as part of introducing a person ('민찬' followed by '이라는', indicating 'named Minchan')

• 민찬이한테 물어봐주세요.

  Please ask Minchan about this.

  Here, '민찬이' is used with the '한테' particle, indicating that the action of asking is directed towards Minchan.