## 4 Results
### Field Test at the Samdo Mine  
The developed system was installed on four vehicles, and field experiments were performed along the path from the office to the mine edit (Figure 8). The developed digital device was attached to the front of the vehicle, and a smartphone was installed inside the vehicle so that it could be checked by the driver. The experiment was conducted using a diesel truck and three sedans (Figure 9), and four vehicles moved back and forth along the route from the office to the mine edit. The movements of other vehicles could be checked in real time on each smartphone screen. The vibration, distance from the surface, gas concentration, and dust concentration measured for each vehicle are shown in Figure 10. Although the positions of the four vehicles slightly differed at a particular time, the sensor values showed a similar trend because they moved in succession while maintaining a close distance. The vibration, distance from the surface, and dust concentration changed significantly almost simultaneously, because the dust was generally generated in high-vibration areas. The gas concentration was high in the middle and at the end of the graphs. Because the experiment was conducted by having the test vehicles move back and forth from the office to the mine edit, the area of high gas concentration in the middle of the graph corresponded to the vicinity of the mine edit. The Samdo mine is a limestone mine; therefore, gas emission is not a significant problem. However, the high gas concentration was attributed to the numerous vehicles parked around the mine edit and office.  
Figure 8: Route from the office to the mine edit for the application of the developed system, (**a**) a photo of the mineral processing facility and water facility, and (**b**) a photo of the mine edit.  
Figure 7: Data logging results of vibration, distance from the surface, gas concentration, and dust concentration.  
Figure 10: Data logging result graphs of the experimental results of four vehicles.  
Figure 9: Photos of vehicles and installed digital devices used in the experiment.  
From the graphs, the changes in the values acquired through various sensors in each vehicle can be continuously checked; however, similarly determining the spatial distribution of the data is challenging. Because the data obtained in this study included location information through GPS, all the data of the four vehicles were averaged for the adjacent data using ArcGIS Pro and were subsequently visualized (Figure 11). The points indicating high vibration or a short distance from the surface are distributed in Sections A and B. Section A comprised the mineral processing facility and car wash facility (Figure 8a) for vehicles leaving the mine, and high vibration values were also observed around the mine edit (Figure 8b), corresponding to Section B. In Section A, the road surface was rough, and the road was narrow because of the car wash equipment on the side; therefore, vehicles should be driven with care. In Section B, vehicles shook significantly owing to a sudden change in the slope. Vehicles could move more stably if road conditions in these areas are improved. The dust concentration was generally low near the office; however, it was high near Sections A and B. This was because many vehicles and equipment were concentrated around the mine edit and mineral processing facility, and the dust washed from the car wash equipment accumulated on the top of the road, causing a dust wind when vehicles passed by. The gas concentration was relatively distributed and was high in the vicinity of the office and mine edit. This is because vehicle exhaust gas is the leading cause of the high gas concentration, and vehicles are mainly concentrated around the office and mine edit. In addition, as the vehicle continued to move, a high gas concentration was distributed over the entire route.