https://blog.gongquiz.com/2022/11/19/plc%ea%b8%b0%eb%b3%b8-%eb%aa%a8%eb%93%88ccu%ec%9d%98-%ea%b5%ac%ec%84%b1%ec%9d%b4-%ec%95%84%eb%8b%8c-%ea%b2%83%ec%9d%80-%ea%b8%b0%ea%b3%84%ec%a0%95%eb%b9%84%ec%82%b0%ec%97%85%ea%b8%b0%ec%82%ac-20/