https://blog.gongquiz.com/2021/11/08/%ec%95%a0%ed%94%8c%ec%9b%8c%ec%b9%984-gps%eb%8f%84-%ec%b6%a9%eb%b6%84%ed%96%88%eb%8d%98-%ec%b2%ab%eb%b2%88%ec%a7%b8-%ec%9d%b4%ec%9c%a0-%ec%95%84%ec%9d%b4%ed%8f%b0-%ec%97%86%ec%9d%b4-%ec%9d%8c-2/