https://blog.gongquiz.com/2021/05/26/terzaghi-%ec%95%95%eb%b0%80-%ec%9d%b4%eb%a1%a0%ec%8b%9d%ec%9d%98-%ea%b0%80%ec%a0%95-%ec%a4%91-%ec%98%b3%ec%a7%80-%ec%95%8a%ec%9d%80-%ea%b2%83%ec%9d%80-%ec%9d%91%ec%9a%a9%ec%a7%80%ec%a7%88%ea%b8%b0/