The calculated distance (air line) between Gwangmyeong and Gyeongsan-si is approximately 154 miles respectively 248 kilometers.
By car or train, the actual journey to Gyeongsan-si is certainly longer, as only the direct route (as the crow flies) between Gwangmyeong and Gyeongsan-si has been calculated here.
Air line (approximately)
248 kilometers
134 nautical miles