https://www.syu.ac.kr/blog/%ea%b1%b4%ec%84%a4%ea%b7%bc%eb%a1%9c%ec%9e%90-%ea%b3%a0%ec%9a%a9up-%ec%84%9c%ed%8f%ac%ed%84%b0%ec%a6%88-%eb%aa%a8%ec%a7%91/02-%ea%b1%b4%ec%84%a4%ea%b7%bc%eb%a1%9c%ec%9e%90-%ea%b3%a0%ec%9a%a9up-%ec%84%9c%ed%8f%ac%ed%84%b0%ec%a6%88-%ec%a7%80%ec%9b%90%ec%84%9c_%ec%9e%90%ea%b8%b0%ec%86%8c%ea%b0%9c%ec%84%9c%ec%84%9c%ec%8b%9d/