## 1 Introduction and Literature Review
The entrances and exits to underground mines are called shafts, and the placement of only one communication device in one shaft limits reliable communication in the event of various incidents in a multi-shaft underground mine. The following were included in this study for improvement the reliable performance of underground mine communication systems:  
* Checking the availability of a three-shaft underground mine communication system;
* Options for improving maintenance;
* Suggesting the overall approach to keep the resource system ready and calculating the results using system dynamic modeling. Markov analysis is used to calculate the reliability of production systems that can be maintained, and the quality of maintenance can be improved, which we have used to calculate. In this study, the communication system of the Oyu Tolgoi underground mine was taken as an example, and the reliability of the communication system of the mine was analyzed separately for each part of the communication system (in the example of the site link) and also for the overall communication system. Repairable and non-repairable parts on Komatsu dump trucks for open pit copper mining were analyzed and it was revealed that the wheels are as the most important parts of the dump trucks. According to the analysis, results were introduced, showing results on using reliability-centered maintenance, such as reducing the downtime of heavy equipment,increasing productivity, and reducing operating costs, pre-saving important necessary parts and optimally planning the interval between preventive maintenance [11]. Therefore, the installation of a communication device in each shaft is a key factor in influencing the system's reliability, since the studies conducted on communication systems, including underground mine communication systems, are very rare, and we have considered the studies made on the examples of other systems other than the communication system. To prolong the life of power systems and reduce the cost of maintenance, data were collected using environmental monitoring technology. Based on that information, various causes of damage to power system components are analyzed. Although a repair strategy is proposed in the paper by [PERSON] based on the results of the system's dynamic design to prevent major failures, shortcomings were noted, such as the model being too general and not modeled for each power system detail [12]. The authors introduced how the system dynamics were used in the study methodology by simulating the reliability of the actual system [13]. There are not many works that have analyzed the reliability of a system using system dynamics modeling. A mixed model of Markov system dynamics is used as an example of resource system maintenance. Based on results assessment of other studies in this field, it was found that most of the studies considered exponential distribution a single-standby system. The methodological variables used in these works contain many differential equations. These differential equations are difficult to calculate. Therefore, this study uses system dynamics modeling to analyze the reliability of standby systems [14]. In this paper [15], Markovian processes are modeled using exponential distributions and calculated analytically. The model in this study was described as from \(P_{t}[1,0]\) to \(P_{t}[0,1]\), from \(P_{t}[1,0]\) to \(P_{t}[1,1]\), and from \(P_{t}[0,1]\) to \(P_{t}[1,1]\). The model was taken without transition between processes, and it was different from our case. However, principally it is not very different from our model. Then, in their paper, [16] proposed a hybrid approach called the Markov system dynamics (MSD) approach, which combines the Markov model with system dynamics simulation for time-dependent availability analysis. A difference from our model was the addition of a reduced state to the model described in this work. In the next part of this paper, the direction of the study is determined, the methodology is developed, and the results are discussed.