https://blog.gongquiz.com/2021/05/03/%eb%8b%a4%ec%9d%8c-%ec%a7%84%eb%a6%ac%ed%91%9c%ec%97%90-%ed%95%b4%eb%8b%b9%ed%95%98%eb%8a%94-gate%eb%8a%94-%ec%96%b4%eb%8a%90-%ea%b2%83%ec%9d%b8%ea%b0%80-%ec%a0%95%eb%b3%b4%ec%b2%98%eb%a6%ac/