Okay, the user wants me to translate "quarter-circle" into Korean. Let me think. The term "quarter-circle" refers to a quarter of a circle, which is 90 degrees. In Korean, "quarter" is "사분의 일" or "사분의 1", and "circle" is "원". So combining them, it would be "사분의 일 원" or "사분의 1 원". But I should check if there's a more standard term. Sometimes technical terms might have specific translations. Maybe "사분원" is a common term? Let me confirm. Yes, "사분원" is the standard term for a quarter-circle in Korean. So the correct translation is "사분원".