https://www.syu.ac.kr/blog/2021%ed%95%99%eb%85%84%eb%8f%84-%ed%95%98%ea%b3%84-%ec%84%9c%ec%9a%b8%ec%8b%9c%ec%a0%95-%eb%8c%80%ed%95%99%ec%83%9d-%ec%9d%b8%ed%84%b4%ec%8b%ad-%ed%94%84%eb%a1%9c%ea%b7%b8%eb%9e%a8-%ec%8b%a0%ec%b2%ad/4-%ed%86%b5%ec%9e%a5-%ea%b3%84%ec%a2%8c-%ec%a0%95%eb%b3%b4%ec%84%9c%ec%8b%9d-%ec%82%ac%eb%b3%b8-%eb%b3%84%eb%8f%84-%ec%a0%9c%ec%b6%9c/