I wrote an entry about (으)니까 that will be very helpful before reading this. It is my opinion that once you learn (으)니까, understanding this grammar becomes much easier.
I’ll cover the theory of the grammar in the first section and then go through some sample sentences in the second section.
The pattern can be broken down into two parts: 다(가) and 보니까.
다(가) conveys the same meaning as the 다가 grammar and here the 가 is usually dropped but the meaning stays the same. In the case of a verb it means the action is occurring, and then something else happens before the action is finished. This action can be a short term action like eating, or walking. Or it can be a long term action such as studying Korean, or watching a TV series. When it is an adjective, it means a certain state was in existence, and then something happens so that the existence of the state is changed.
보니까 expresses the meaning of “to become aware of” or “be made aware of” or “seeing that”. I talk about this translation in detail in the link above and encourage you to check it out.
When you combine them together you are doing some action, or there is a state in existence, and during the action or state, you “become aware of something”, or “now see that”. In other words that is commonly used to translate this grammar into English – ‘Realise’.
- During study, I found out it was not difficult. 공부하다 보니까 어렵지 않았어요.
- While I was eating, I found out it was not my order. 먹다가 보니까 제가 시킨 게 아니었어요
- It was very weird at first, but more I use it, I found out that it is pretty. 처음에는 이상했는데 자꾸 보다 보니까 예쁜 것 같아요
- Seeing that I do not have money, I cannot buy good stuff to my kids. 돈이 없다 보니까 아이들한테 좋은 물건을 사 줄 수 없어요
- Seeing that I am hungry, I just ended up eating whatever. 배가 고프다 보니 아무거나 먹게 됐어요
Some other grammar structure that may have a similar feel but isn’t quite the same:
Why it is not the same as 면서. The English translation may be similar – while I was studying I realised that it isn’t hard. But 면서 implies a stronger focus on simultaneous events. 다 보니까 is not about simultaneous events.
Why it is not the same as 했는데. 했는데 means you are saying you were studying as background information, and then using that as a basis to say that it isn’t difficulty. To get the meaning close to the original sentence you would have to change the ending to 어렵지 않더라고요.