https://qooah.com/2011/07/06/%e3%80%8a3g-watchdog%e3%80%8b3g-%e7%9c%8b%e9%96%80%e7%8b%97%e9%98%b2%e6%ad%a2%e4%b8%8a%e7%b6%b2%e6%b5%81%e9%87%8f%e8%b6%85%e9%a1%8d/