https://blog.faceutil.com/2017/03/29/%eb%af%b8%ea%b5%ad%eb%b0%95%ec%82%ac%ec%9c%a0%ed%95%99%ea%b0%80%ea%b8%b0-10-sop-statement-of-purpose-personal-history-statement-%ec%9e%91%ec%84%b1%ed%95%98%ea%b8%b0-%e2%85%b2/