어기어차 is a misspelled of 어기여차
어기여차
「감탄사」
여럿이 힘을 합할 때 일제히 내는 소리
It’s an interjection used when a number of people work together. It’s rarely used these days. It can be found in traditional folk songs’ lyrics like 뱃노래 (song of sailors).
The conception of the song Hanryang is a story of old days, so they used old words.