The calculated distance (air line) between Hwangju-ŭp and Hongwŏn is approximately 149 miles respectively 240 kilometers.
By car or train, the actual journey to Hongwŏn is certainly longer, as only the direct route (as the crow flies) between Hwangju-ŭp and Hongwŏn has been calculated here.
Air line (approximately)
240 kilometers
130 nautical miles