https://www.syu.ac.kr/blog/%eb%b3%b4%eb%8f%84%ec%9e%90%eb%a3%8c-%ec%82%bc%ec%9c%a1%eb%8c%80-%ea%b5%90%ec%9c%a1%ea%b5%ad%ec%a0%9c%ed%99%94%ec%97%ad%eb%9f%89-%ec%9d%b8%ec%a6%9d%eb%8c%80%ed%95%99-%ec%84%a0%ec%a0%95-2/%ea%b5%ad%ec%a0%9c%ed%99%94-%ea%b8%80%eb%a1%9c%eb%b2%8c-%ec%99%b8%ea%b5%ad%ec%9d%b8-%ec%9c%a0%ed%95%99%ec%83%9d-%ec%9d%b4%eb%af%b8%ec%a7%80/