https://blog.gongquiz.com/2021/04/07/%ed%8e%b8%ec%8b%ac%eb%9f%89-2-2mm%eb%a1%9c-%ea%b0%80%ea%b3%b5%eb%90%9c-%ec%84%a0%eb%b0%98-%ea%b0%80%ea%b3%b5%eb%ac%bc%ec%9d%84-%eb%8b%a4%ec%9d%b4%ec%96%bc-%ea%b2%8c%ec%9d%b4%ec%a7%80%eb%a1%9c/