The calculated distance (air line) between Seongnam-si and Hongch’ŏn is approximately 45 miles respectively 72 kilometers.
By car or train, the actual journey to Hongch’ŏn is certainly longer, as only the direct route (as the crow flies) between Seongnam-si and Hongch’ŏn has been calculated here.
Air line (approximately)
72 kilometers
39 nautical miles