The calculated distance (air line) between Gyeongju and Gyeongsan-si is approximately 27 miles respectively 43 kilometers.
By car or train, the actual journey to Gyeongsan-si is certainly longer, as only the direct route (as the crow flies) between Gyeongju and Gyeongsan-si has been calculated here.
Air line (approximately)
43 kilometers
23 nautical miles