https://www.syu.ac.kr/blog/%ec%84%9c%ec%9a%b8%eb%b6%81%eb%b6%80%ea%b3%a0%ec%9a%a9%ec%84%bc%ed%84%b0-%ea%b5%ac%ec%9d%b8%ec%a0%95%eb%b3%b4-%eb%b0%8f-%ec%b1%84%ec%9a%a9%eb%b0%95%eb%9e%8c%ed%9a%8c-%eb%93%b1-%ed%99%8d%eb%b3%b4/%ea%b5%ac%ec%9d%b8%ec%a0%95%eb%b3%b4%ec%84%9c%ec%9a%b8%eb%b6%81%eb%b6%80%ea%b3%a0%ec%9a%a9%ec%84%bc%ed%84%b0-2020-3-26-pdf_page_1/