https://blog.gongquiz.com/2021/02/23/%eb%8d%b0%ec%9d%b4%ed%84%b0-%ea%b0%9c%ec%b2%b4entity%ec%9d%98-%ec%84%b1%ec%a7%88-%eb%b6%84%eb%a5%98-%ec%8b%9d%eb%b3%84-%ec%88%98%eb%9f%89-%ec%83%81%ed%83%9c-%ed%8a%b9%ec%84%b1-%eb%93%b1/