i solved the issue. it was brave brower. it used memory even if it turned off. i am curious. it was not detected by monitoring program. OS is window 8.1
when computer turn on, it uses about 30% memory(2.5GB) normally. but recently it uses 50% memory ( 4GB). so i open resource monitor. avp.exe( PID : 1688 ) and avpui.exe ( PID : 22756 ) use about 20% memory. I think it is unusual. could somebody explain about it?