Stephan Haggard posted some interesting information on Chinese investment in the DPRK. See his posts here and here.
In this graph, Dr. Haggard breaks down the Chinese investment data by year and industry:
It is worth noting that the graph only sums the number of registered projects, not the value of the investments. Based on satellite imagery and trade data, I think we can make a strong case that the mining sector would be the area receiving the largest infusion of Chinese investment inflows.
Dr. Haggard also shows that most Chinese investment flows into the DPRK originate from the provinces along its border:
In a second post, Dr. Haggard offers a graph of cumulative direct investment from China:
