https://blog.gongquiz.com/2021/11/07/%ec%9d%b4%eb%ac%b8%ec%84%b8-%ea%b7%b8%eb%85%80%ec%9d%98-%ec%9b%83%ec%9d%8c%ec%86%8c%eb%a6%ac%eb%bf%90-1987%e5%b9%b4-%e3%83%9e/