USB3.0 SD / 마이크로 SD 카드 리더기

To confirm that Windows detects your USB device, complete the following:

Press the Windows key+R, type devmgmt.msc, and press Enter.
In Device Manager, under the appropriate heading, confirm that your expansion card is listed and that there isn't an exclamation mark next to it.  For example, a USB controller card would be under Universal Serial Bus controllers.
Your USB device is listed according to the name of the chipset. 

To confirm that the Mac OS detects your USB device, complete the following:

Click the Apple icon.
Click About This Mac.
Click More Info or System Report.
Under the appropriate heading, confirm that your USB device is listed and that there isn't an error. For example, a network card would be under Ethernet Cards.
You may need to refresh the System Information page after you plug in your device.  To do so, press Command + R with the System Information page open.

Your USB device is listed according to the name of the chipset.

If the USB device does not work after your computer has been in extended hibernation, it is likely that Windows has automatically turned off the USB Root hub to save power. 

The steps below outline how to configure the USB root hub to stay on during hibernation, to prevent this from happening.
 

Windows 10 / 8

On your keyboard, press the Windows key + X and select Control Panel.
Click Hardware and Sound, then click Power Options.
Click Change plan settings for the plan you want to change.
Click Change advanced power settings.
Click the plus sign (+) next to “USB settings” and “USB selective suspend setting” to expand the options and change the setting to Disabled.
Click OK to apply the setting.
Note: You may need to disconnect and re-connect your USB device after applying these settings to re-establish the connection.

Windows 7 / Vista

Click the Start button and select Control Panel.
Click Hardware and Sound, then click Power Options.
Click Change plan settings for the plan you want to change.
Click Change advanced power settings.
Click the plus sign (+) next to “USB settings” and “USB selective suspend setting” to expand the options and change the setting to Disabled.
Click OK to apply the setting.
Note: You may need to disconnect and re-connect your USB device after applying these settings to re-establish the connection.

Windows XP

On your desktop, right-click the My Computer icon and select Properties.
Click the Device Manager tab.
Expand Universal Serial Bus controllers by clicking the arrow to the left of it.
Right-click the first USB Root Hub device and select Properties.
Click the Power Management tab.
Clear the box next to Allow the computer to turn off this device to save power.
Click OK to apply the setting.
Repeat steps 4-7 for any remaining devices in the Universal Serial Bus Controllers section with “Root Hub” in the name.
Note: You may need to disconnect and re-connect your USB device after applying these settings to re-establish the connection.

This memory card reader can read or write both cards at the same time. However, it could not support direct transfer to data between cards. The suggested way is transfer from card to computer, then from the computer to the other card.

It is not a storage device. It links the various memory cards from your camera or other device which act as a storage device, to your computer thru a USB type C port.