## 5 Conclusions  
In this study, we conducted a performance comparison experiment on four interface devices (a 2D mouse, 2D & 3D mice, a VR controller, a Kinect sensor and bend-sensing data glove) that were able to control Kmodstudio, a mining industry software, in a VR environment. We analyzed the total working time, the number of device clicks, and click accuracy for a total of ten experimenters after they completed operations predefined in Kmodstudio.  
We then conducted a survey to evaluate the ease of learning, ease of use, immersion and fatigue for each device. Our findings show that the 2D mouse achieved the best performance in its working time, click accuracy, ease of learning and ease of use, while the Kinect sensor and the bend-sensing data glove received the highest score for immersion and fatigue.  
The 2D mouse has many restrictions on overall body movements because the users control it while sitting on a chair. Therefore, given that the goal of implementing a VR environment is to maximize immersion that enables us to perceive the virtual world as if it were real, a 2D mouse that limits body movements is not suitable. The Kinect sensor and the bend-sensing data glove, which could maximize immersion with relatively no restrictions on body movements, showed excellent performance in working time and click accuracy. Thus, it is considered to be a suitable user interface device to control mining industry software in a VR environment.  
Currently, 3D user interface devices such as the Kinect sensor and bend-sensing data glove cannot completely replace traditional 2D user interface devices such as keyboards and mice. Although 3D user interface devices are effective in providing a high level of immersion in a VR environment, some operations still require character inputs using keyboards, or precise control using 2D mice to control mining industry software. Nevertheless, as VR technology rapidly advances and various HMD devices are commercialized, it is expected that the market demand for the development and utilization of user interface devices for controlling mining industry software will be even greater.  
Although several previous studies have been performed in the development of user interface devices that can enhance user immersion and effectively control software in a VR environment [22; 23; 24; 25; 26; 27; 28; 29], they did not quantitatively compare the performances of the various user interface devices that are able to control mining industry software. Therefore, our research findings are expected to be a useful reference material for the future development of user interface devices in the mining industry. In future work, the workload with user interface devices needs to be evaluated using standard tests such as NASA-TLX [31].  
Y.C. conceived and designed the experiments; H.K. performed the experiments; H.K. and Y.C. analyzed the data; Y.C. contributed reagents/materials/analysis tools; H.K. and Y.C. wrote the paper.  
This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1D1A1A09083947).  
The authors declare no conflict of interest.