## 4 Experiment and Simulation
### Lighting System Simulation
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Outdoor** & & & \multicolumn{4}{c}{_Skin Type II (Unit: J/m\({}^{2}\))_} & \multicolumn{4}{c}{_Skin Type III (Unit: J/m\({}^{2}\))_} \\ \cline{3-10}
**Time (EUD)** & **Factors** & & **CASE 1** & **CASE 2** & **CASE 3** & **CASE 4** & **CASE 1** & **CASE 2** & **CASE 3** & **CASE 4** \\ \cline{2-10}
**(J/m\({}^{2}\))** & _RVUID_ & **51** & **61** & **77** & **156** & **68** & **82** & **103** & **208** \\ \hline \hline \multirow{4}{*}{30 Min (157.38)} & \multicolumn{4}{c}{95.90} & \multicolumn{4}{c}{152.38} \\ \cline{2-10}  & \(t_{r}\) (s) & 0 & 0 & 0 & 12,474 & 0 & 0 & 1482 & 23,248 \\ \cline{1-1}  & \(V\!UID_{in}\) & 0.0 & 0.0 & 0.0 & 60.28 & 0.0 & 0.0 & 7.16 & 112.34 \\ \cline{1-1}  & _Total EUD_ & 157.38 & 157.38 & 187.38 & 188.68 & 157.38 & 157.38 & 161.10 & 215.70 \\ \cline{1-1}  & \multicolumn{1}{c}{Met _RVA_} & O & O & O & O + 1 & O & O & O + 1 & O + 1 \\ \hline \hline \multirow{4}{*}{20 Min (91.40)} & \multicolumn{4}{c}{57.52} & \multicolumn{4}{c}{91.40} \\ \cline{2-10}  & \(t_{r}\) (s) & 0 & 816 & 4093 & 20,417 & 2174 & 5057 & 9426 & 31,192 \\ \cline{1-1}  & \multicolumn{1}{c}{_VULID_in} & 0.0 & 3.95 & 19.78 & 98.66 & 10.50 & 24.44 & 45.55 & 150.72 \\ \cline{1-1}  & \multicolumn{1}{c}{_Total EUD_} & 91.40 & 93.45 & 101.67 & 142.62 & 96.85 & 104.09 & 115.05 & 169.66 \\ \cline{1-1}  & \multicolumn{1}{c}{Met _RVA_} & O & O + 1 & O + 1 & O + 1 & O + 1 & O + 1 & O + 1 & O + 1 \\ \hline \hline \multirow{4}{*}{10 Min (44.58)} & \multicolumn{4}{c}{28.06} & \multicolumn{4}{c}{44.58} \\ \cline{2-10}  & \(t_{r}\) (s) & 4752 & 6915 & 10,191 & 26,516 & 8272 & 11,155 & 15,524 & 37,290 \\ \cline{1-1}  & \multicolumn{1}{c}{_VULID_in} & 22.96 & 33.41 & 49.25 & 128.13 & 39.97 & 53.90 & 75.01 & 180.19 \\ \cline{1-1}  & \multicolumn{1}{c}{_Total EUD_} & 56.50 & 61.93 & 70.15 & 111.11 & 65.33 & 72.57 & 83.53 & 138.14 \\ \cline{1-1}  & \multicolumn{1}{c}{Met _RVA_} & O + 1 & O + 1 & O + 1 & O + 1 & O + 1 & O + 1 & O + 1 & O + 1 \\ \hline \hline \multirow{4}{*}{0 Min (0)} & \multicolumn{4}{c}{0} & \multicolumn{4}{c}{0} & \multicolumn{4}{c}{0} \\ \cline{2-10}  & \(t_{r}\) (s) & 10,559 & 12,721 & 15,998 & 32,322 & 14,078 & 16,962 & 21,331 & 43,096 \\ \cline{1-1}  & \multicolumn{1}{c}{_VULID_in} & 51.02 & 61.47 & 77.30 & 156.18 & 68.03 & 81.96 & 103.07 & 208.25 \\ \cline{1-1}  & \multicolumn{1}{c}{_Total EUD_} & 26.49 & 31.92 & 40.14 & 81.09 & 35.32 & 42.56 & 53.52 & 108.12 \\ \cline{1-1}  & \multicolumn{1}{c}{Met _RVA_} & I & I & I & I & I & I & I \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of UV exposure amount according to the duration of outdoor activities of the user. In Table 3, the Met _RVA_ entry was marked with 'O' or 'I' or 'O + I' when _RVA_ could be met in outdoor, indoor, or both. When outdoor activities are carried out for 30 min, all outdoor activities are found to meet the _RVULD_ of those aged 40, although outdoor activities are not enough for users aged 60 and over, whereas the dose requirement of adults aged 41 to 59 depends on the skin type. When outdoor activities are performed for 20 min, skin type 2 is satisfied with outdoor activity until age 21, and for other ages, indoor UVB LED lighting appears to be supplemented. To achieve the daily amount of vitamin D synthesis, after 30 min of outdoor activity, users 60 years or older with skin type II or III can use the indoor UVB LED lighting for 3 h, 27 min, and 54 s (12,474 s) or 6 h, 27 min, and 28 s (23,248 s). In addition, users who are not carrying out outdoor activities and who have skin type II can meet their daily vitamin D synthesis amount by exposure to UVB LED general lighting for at least 2 h 55 min, and 59 s (10,559 s) and up to 8 h, 58 min, and 42 s (32,322 s) of the total amount. Meanwhile, users with skin type III are able to meet the daily amount of vitamin D synthesis when exposed for at least 3 h, 54 min, and 38 s (14,078 s) and up to 11 h, 58 min, and 16 s (43,096 s).