https://blog.gongquiz.com/2021/02/24/%ed%83%84%ec%84%b1%ed%8c%8c-%ec%86%8d%eb%8f%84%ea%b0%80-v1-v2%ec%9d%b8-%eb%91%90-%eb%a7%a4%ec%a7%88%ec%9d%b4-%ec%9d%b4%eb%a3%a8%eb%8a%94-%ea%b2%bd%ea%b3%84%eb%a9%b4%ec%97%90-%ed%83%84%ec%84%b1/