The calculated distance (air line) between Wŏnsan and Hwangju-ŭp is approximately 96 miles respectively 154 kilometers.
By car or train, the actual journey to Hwangju-ŭp is certainly longer, as only the direct route (as the crow flies) between Wŏnsan and Hwangju-ŭp has been calculated here.
Air line (approximately)
154 kilometers
83 nautical miles