The calculated distance (air line) between Uiju and Kangdong-ŭp is approximately 111 miles respectively 178 kilometers.
By car or train, the actual journey to Kangdong-ŭp is certainly longer, as only the direct route (as the crow flies) between Uiju and Kangdong-ŭp has been calculated here.
Air line (approximately)
178 kilometers
96 nautical miles