The simple modifier (으) ㄴ has two major functions in relation to the type of verb to which it is attached. First, when attached to a descriptive verb or adjective and then placed before a noun, it becomes noun that is equal to adjective. Here are some examples:
- 큰 학교 (Keun Hakkyo) – Large school
- 적은 눈물 (Cheokeun Nunmul) – Few tears
- 좋은 사람 (CheounSaram) – Good Man
The second use is that when it is attached to processive verb right before a noun it takes a past meaning. Something like [someone] did or has done as shown on samples below:
- 앉은 사람 (Anjeun saram) – The person who sat or who has sat. This is lifted from statement –> 사람이 앉었어요 (Sarami anjeosseoyo)
- 걸은 여자 (Keoreun yoja) – The lady who walked –> 여자가 걸었어요 (Yojaga keoreoseoyo).
Since this form for processive verbs takes a past tense meaning, therefore, this modifier can neither be attached to past base nor future base. As such you would hear or see 썼은 편지 (Sseosseun pyonji) written letter or 써겠은 편지 (Sseokesseun pyonji) letter that we/I will write.