紫色戀愛(자색연애)

It is better to use the term '한자(Chinese characters)' than '고대국어'. The 고대국어 means 한국어 before the Joseon Dynasty, and then Korea was in the era of discord beyween the colloquial and the literary. cause borrowed 한자 from Chinese, I think it would be better to use '한자' I have bad English, sorry. thanks

I mean the old Korean languge that used the 한자 as a writing system

What do you mean by "고대 국어"?