## 3 Results and Discussion
### Experimental Results  
Figure 9 provides the temperature profiles of the experimental results for the temperature distribution at the \(T_{\text{sp}}\), \(T_{\text{ref}}\), \(T_{1}\), \(T_{2}\), \(T_{3}\), \(T_{4}\), and \(T_{5}\) points, as well as the calculation of \(T_{\text{j}}\) for the ALFHS mounted to the CLRDL. Figure 10 provides the profile for the CUFHS mounted to the CLRDL. The temperature distributions in the steady-state are shown in Tables 1 and 2, respectively. The experimental results show that all downlink temperature distributions differed except for the \(T_{\text{sp}}\) distribution.  
The temperature of each specified point increased gradually; however, the temperature gradients were different. In the ALFHS and CUFHS, the \(T_{\text{sp}}\) changed faster in the steady-state at 91.7 \({}^{\circ}\)C. The \(T_{\text{j}}\) was calculated as being 121.7 \({}^{\circ}\)C. In both cases, the \(T_{\text{ref}}\) was lower than the \(T_{\text{sp}}\) because of the effect of thermal resistance (\(R_{\text{th, sp-ref}}\)). The \(T_{\text{a}}\) was the temperature in the enclosed test box, which varied over time at different points. The margin of error for the temperature between the numerical simulation and the experimental results was within 2%.  
The \(T_{\text{j}}\) of an LED lamp operating at any specified temperature ambience can be predicted quickly with the unique thermal resistance model by using the temperature that was measured at a reference point [28]. We can obtain the \(T_{\text{sp}}\) by measuring the \(T_{\text{ref}}\) temperature; \(T_{\text{j}}\) can then be calculated using Equation (2).  
The experimental results displayed in Tables 2 and 3 demonstrate that the CUFHS and ALFHS exhibited similar heat sink capability for CLRDL thermal reduction. In this study, the numerical simulation was performed first and was followed by the experimental validation for heat sinks. An industrialized test box and lighting structure design were produced and reliability predictions were conducted using an accelerated life testing.  
Figure 8: (**a1–a5**) show the simulation results using an isometric view (\(xy\) plane) for the temperature distribution at \(T_{1}\), \(T_{2}\), \(T_{\text{sp}}\), \(T_{3}\), \(T_{4}\), \(T_{5}\), and \(T_{\text{ref}}\) points of ALFHS; (**b1–b5**) are of the CUFHS; each of them are mounted to the CLRDL after INST.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Time (min.)** & \(T_{\text{SP}}\) & \(T_{\text{j}}\) & \(T_{\text{ref}}\) & \(T_{\text{1}}\) & \(T_{\text{2}}\) & \(T_{\text{3}}\) & \(T_{\text{4}}\) & \(T_{\text{5}}\) \\ \hline
120 & 91.7 & 121.7 & 83.6 & 65.1 & 48.5 & 37.8 & 39.1 & 71.7 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Temperature (\({}^{\circ}\)C) distribution of specified points for ALFHS mounted to the CLRDL after INST in the steady-state.  
Figure 9: Chart of specified points of \(T_{\text{sp}}\), \(T_{\text{j}}\)\(T_{\text{ref}}\), \(T_{\text{1}}\), \(T_{\text{2}}\), \(T_{\text{3}}\), \(T_{\text{4}}\), and \(T_{\text{5}}\) temperature distributions for the ALFHS mounted to the CLRDL after INST.  
Figure 10: Chart of specified points of \(T_{\text{sp}}\), \(T_{\text{j}}\), \(T_{\text{ref}}\), \(T_{1}\), \(T_{2}\), \(T_{3}\), \(T_{4}\), and \(T_{5}\) temperature distributions for the CUFHS mounted to the CLRDL after INST.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Time (min)** & \(T_{\text{sp}}\) & \(T_{\text{j}}\) & \(T_{\text{ref}}\) & \(T_{\text{1}}\) & \(T_{2}\) & \(T_{3}\) & \(T_{4}\) & \(T_{5}\) \\ \hline
120 & 91.7 & 121.7 & 81.4 & 56.1 & 47.4 & 40.2 & 38.1 & 62.1 \\ \hline \end{tabular}
\end{table}
Table 3: Temperature (\({}^{\circ}\)C) distribution of specified points for CUFHS mounted to CLRDL after INST in the steady-state.