## 3 Development of Decision-Making Factors to Determine the EMP Protection Level  
Recently, a study was conducted on the differentiation of EMP protection levels to reduce the construction costs and times of EMP protection facilities in the South Korean military and to implement efficient protection measures [21]. As a result of conducting a Delphi analysis with 21 EMP protection experts from the military and private sector, it was confirmed that a vulnerability analysis for EMP attacks should be performed first to differentiate EMP protection levels. Along with this, the damage recovery time for an EMP attack was derived as an essential factor of the EMP protection vulnerability analysis. In other words, it was confirmed that EMP protection measures and protection  
Figure 1: Classification of EMPs. levels could be applied discriminately, according to the time required for recovery. Table 1 summarizes the research results conducted by [PERSON] et al. (2018). As shown in Table 1, a variety of factors were derived such as the missions of troops, terrain conditions, threat factors, and available troops. Using the decision-making factors mentioned in Table 1, the importance of EMP protection facilities was selected based on their levels. It was important to select an appropriate protection level for the characteristics of each echelon using EMP protection facilities. The selection criteria of the importance levels are shown in Table 2.  
By evaluating the EMP resistance of electronic devices based on the protection importance levels mentioned in Table 2, we selected 30 V/m for the minimum electric field strength showing simple malfunctions ([PERSON], 1984) and 1 kV/m for the minimum level showing hardware damage ([PERSON], 1984). Based on these experimental results and expert advice, it was confirmed that the shielding standards could be established by subdividing the EMP differentiation standards of the military into Levels 1, 2, and 3 as shown in Table 3. \begin{table}
\begin{tabular}{c l} \hline \hline
**Factor** & **Description** \\ \hline Time & Recovery time of damaged equipment should be considered. \\  & The replacement time of the damaged equipment should be considered. \\  & The price of the equipment affected by the EMP should be reflected. \\ \hline Energy & The tolerance of the equipment attacked by the EMP should be considered. \\  & Type of damage (loss, recovery cost, etc.) due to the EMP attack should be considered. \\  & The allowable damage level due to the EMP attack should be considered. \\ \hline Mission & The impact on emergency activity (military, civil defense, etc.) due to equipment failure by EMP attack should be considered. \\ \hline  & Construction costs of EMP protection should be considered. \\  & The possibility of recovering the damaged equipment should be considered. \\  & The ease of recovery of the damaged equipment should be considered. \\  & The possibility of replacing the damaged equipment should be considered. \\  & The ease of replacement of the damaged equipment should be considered. \\ \hline Terrain & The environmental condition (underground, geological, etc.) where the equipment attacked by the EMP is located must be considered. \\  & The characteristics of the EMP protection facility (concrete, underground, etc.) should be considered. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Decision-making factors to determine EMP protection level.