https://blog.gongquiz.com/2022/11/13/60hz-6%ea%b7%b9%ec%9d%b8-%ea%b5%90%eb%a5%98-%eb%b0%9c%ec%a0%84%ea%b8%b0%ec%9d%98-%ed%9a%8c%ec%a0%84%ec%88%98%eb%8a%94-%eb%aa%87-rpm%ec%9d%b8%ea%b0%80-%ea%b3%b5%ec%a1%b0%eb%83%89%eb%8f%99/