https://purengom.com/2008/01/26/%ec%98%a4%eb%9e%9c%eb%a7%8c%ec%97%90-psp%eb%a5%bc-%ea%ba%bc%eb%82%b4%eb%b3%b4%ea%b3%a0-psp%ec%99%80-ds%ec%9d%98-%ec%b0%a8%ec%9d%b4%ec%97%90-%eb%8c%80%ed%95%b4%ec%84%9c-%ec%83%9d%ea%b0%81%ed%95%98/