The calculated distance (air line) between Pyeongtaek and Gapyeong is approximately 62 miles respectively 100 kilometers.
By car or train, the actual journey to Gapyeong is certainly longer, as only the direct route (as the crow flies) between Pyeongtaek and Gapyeong has been calculated here.
Air line (approximately)
100 kilometers
54 nautical miles