The calculated distance (air line) between Yŏnggwang-ŭp and Kaesŏng is approximately 150 miles respectively 241 kilometers.
By car or train, the actual journey to Kaesŏng is certainly longer, as only the direct route (as the crow flies) between Yŏnggwang-ŭp and Kaesŏng has been calculated here.
Air line (approximately)
241 kilometers
130 nautical miles