The calculated distance (air line) between Hŭngnam and Hwangju-ŭp is approximately 128 miles respectively 206 kilometers.
By car or train, the actual journey to Hwangju-ŭp is certainly longer, as only the direct route (as the crow flies) between Hŭngnam and Hwangju-ŭp has been calculated here.
Air line (approximately)
206 kilometers
111 nautical miles