Leopard tips: The disk SDStorage is in use and could not be ejected

I met the problem on Leopard again. Today when I tried to ejected my SD card reader, I saw the error message

The disk SDStorage is in use and could not be ejected. 
Try quitting applications and try again.

( SDstorage is my SD card label. )

I had no idea which application was using the card reader. After quitting most of my applications, the error popped whenever I tried to eject the disk. Then I found how to eject it by force, here is how:

1. Launch Terminal ( Applications -> Utilities -> Terminal )
2. Type the command :

	hdiutil eject -force /Volumes/SDStorage

replace the "SDStorage" with the disk label of yours.
3. press Enter to run the command. You disk should be ejected now.

Do remember don't disconnect the disk unless the ejection is done. Some days ago, I met this same error. Back then, I did not know how to eject the device by this command, so I just disconnect the SD card reader. I thought it was a big deal, but I was wrong, the SD card was damaged eternally. Luckily, there was anything important on that card. So, for the safety of the disk and the data, if you even can not eject the disk by the above command, I recommend you to shutdown the mac before taking the disk out.