On special guided trips, arranged for tourists and permitted by Pyongyang, Patrick Chovanec, a professor at Tsinghua University's School of Economics and Management in Beijing, has twice visited North Korea. On each trip, he and his fellow travelers were accompanied by official guides, only permitted in certain areas, and asked to delete "objectionable" photos from their digital cameras. Yet the visits afforded Chovanec a rare glimpse inside the Hermit Kingdom.