$knowndrives = @("A:","B:")
$knowndrvice = "\.CompanyAuthorizedDevices.txt"

$outstr = ""
$usbdrives = (Get-WmiObject CIM_LogicalDisk | Where-Object DriveType -eq 2).DeviceID
if ($usbdrives.Length -eq 0) {
  $outstr = $outstr + (Get-Date -Format "yyyy/MM/dd HH:mm") + ", Information, No USB removable device found.`n"
} else { 
  foreach ($usbdrive in $usbdrives){
    if ( -not ($knowndrives.ToUpper() -contains ($usbdrive).ToUpper())){
      $outstr = $outstr + (Get-Date -Format "yyyy/MM/dd HH:mm") + ", Warinig, USB removable device found. (" + $usbdrive + ")`n"
      if (Test-Path $usbdrive$knowndrvice) {
        $outstr = $outstr + (Get-Date -Format "yyyy/MM/dd HH:mm") + ", Information, The device is authorized by the company. (" + $usbdrive + ")`n"
      } else {
        mountvol $usbdrive /d
        if ($LASTEXITCODE -eq 0) {
          $outstr = $outstr + (Get-Date -Format "yyyy/MM/dd HH:mm") + ", Information, Successfully unmounted. (" + $usbdrive + ")`n"
        } else {
          $outstr = $outstr + (Get-Date -Format "yyyy/MM/dd HH:mm") + ", Error, Unmounting failure. (" + $usbdrive + ")`n"
        }
      }
    }
  }
}
$outstr