North Korean radar and anti-aircraft batteries along the DMZ would probably locate and take out a number of the drones. I think such an idea would actually work better if executed by activist groups in China if they are able to not get cracked down on by the Chinese authorities:
A researcher has called on the United States to consider using drones to send USB sticks with information that can effectively win the hearts of North Koreans and provide them with information about the outside world.
Senior Researcher Kim Yon-ho at the U.S.-Korea Institute at Johns Hopkins School of Advanced International Studies made the call in his recent contribution to Foreign Policy on Saturday.
Kim said that there are limitations to the conventional methods of smuggling high-tech data into North Korea, claiming that delivering USBs with drones is a high-tech alternative to traditional smuggling tactics.
The researcher said that due to the flourishing black market and technological developments, the means of access to outside media has advanced beyond televisions, radios, and DVDs into more interactive forms such as PCs, tablets and USB drives.
Kim said that USB drives are considered effective means of accessing information about the outside world, as they are smuggled through balloons and easily made available on the black market. [KBS World Radio]
You can read the whole Foreign Policy article at this link. The article pretty much makes the case that I have been making for year to execute a coordinated information warfare strategy within North Korea which should be part of a larger strategy to undermine the legitimacy of the Kim regime.