First, I don't know the expression but I can feel what that means like kinda :) Korean ppl are good at making new onomatopoeias and mimetic words. In other words, they often express their feelings and how it looks like in their own ways without using expressions from dictionary Speaking of common expressions on dictionary 모락모락 김이 나다 it's steaming 모락모락 expresses how the steam comes up 새록새록 기억이 떠오르다 I can recall the memories 새록새록 expresses how the memories are coming up in your mind Like this, it's a bit difficult to explain this kind of expression as only korean uses in this way :) Back to the main question, 도록도록 sounds like poping sounds for me. I don't mean I'm correct. I'm just guessing. When air is stucked in your eyes it makes poping sounds when it comes out of the eyes. I hope it is helpful for you :) TMI, Languages are changing so I hope you spend time to explore new words like slangs from time to time. If there is a language that makes new words at the fastest pace around the world could be Korean language of others. This is just my opinion haha :) bye

글 쓴 사람이 만든 단어 같아요. 눈이 많이 쌓였을 때 그 위를 걸으면 '뽀드득 거린다' 또는 '뽀드득 소리가 난다'라고 표현하는데, '뽀드득' 대신에 만들어 사용한 용어인 거 같습니다. 한국어에 '도록도록'이라는 표현은 없어요. I think the writer made the word to express the sound when we walk on snow. We normally say '뽀드득.' It looks like '도록도록' is used instead of saying '뽀드득.' There isn't the expression '도록도록' in Korean. So I guess the writer coined the onomatopoeia.