https://blog.gongquiz.com/2021/04/21/cnc%ec%84%a0%eb%b0%98%ec%97%90%ec%84%9c-2%eb%b2%88-%ea%b3%b5%ea%b5%ac%eb%a5%bc-%ea%b3%b5%ea%b5%ac%eb%b3%b4%ec%a0%95offset-4%eb%b2%88%ec%9d%98-%eb%b3%b4%ec%a0%95%eb%9f%89%ec%9c%bc%eb%a1%9c-%eb%b3%b4/