Here’s why it's so difficult to translate Korean mimetic words to English.

Words

훨훨 - mimetic word used to describe flight ( Interjection )

쑥쑥 - mimetic word used to describe growth ( Interjection )

터벅터벅 - mimetic word used to describe walking ploddingly ( Interjection )

무럭무럭 - mimetic word used to describe healthy growth ( Interjection )

주렁주렁 - mimetic word used to describe hanging in clusters ( Interjection )

Phrases

새가 훨훨 날았어요 - The bird flew flap flap ( Informal polite )

키가 쑥쑥 커요 - Growing tall ( Informal polite )

쟤 무슨 안 좋은 일 있나 봐~ 왜 이렇게 터벅터벅 걷냐? - Something bad's going on with him/her. Why is he/she walking so ploddingly? ( Informal casual )

야 터벅터벅 걷지 마! 자신감 있게 걸어야지! - Hey! Don't walk ploddingly. Walk with confidence! ( Informal casual )