When to use protest in Korean
Korean: 항의[ hang-ui ]

When to use it
항의 means saying or showing strongly that you think something is wrong or unfair. People use it when they complain to a person, a store, a school, or an office, or when they join a public protest. It is often used with 하다: to protest or complain.
Example sentences
학생들이 급식에 항의했어요.
The students protested about the school lunch.
저는 계산이 틀려서 항의했어요.
I complained because the bill was wrong.
엄마가 시끄러운 음악에 항의했어요.
Mom complained about the loud music.
승객들이 긴 지연에 항의했어요.
The passengers protested the long delay.
그는 불공평한 규칙에 항의했어요.
He protested the unfair rule.
손님이 차가운 커피에 항의했어요.
The customer complained about the cold coffee.