## 5 Conclusions  
In this paper, an optimal lens and heatsink design has been analyzed both through theoretical investigation and experiments to provide the appropriate light distribution characteristics required in seaport lighting application. Then, prototypes of seaport LED luminaires were fabricated using the optimized lens and heatsink. Finally, actual measurements results of LED and conventional HID seaport luminaires in a seaport installation were showed and discussed.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Commercial HID (Metal Halide) Luminaire** & **Fabricated LED Luminaire** \\ \hline \hline \end{tabular}
\end{table}
Table 7: Characteristics of LED and HID luminaires for seaport lighting application.  
In case of lens optimization, in order to develop a lens that provides a uniform light distribution, four types of lens were theoretically analyzed and their actual light distribution was measured. As a result, the type D lens showed an overall uniformity of 0.73, whereas the required overall uniformity is about 0.7. In optimization of heatsink, the thermal characteristics of a heatsink with various shapes and structures have been investigated. The temperature difference between type D with a hexagonal-shaped fin (best case) and type A with a vertical fin (worst case) was 7.1 K at the bottom of the heatsink, and these results are very similar to those of simulated cases.  
To verify the feasibility of the developed prototype LED seaport luminaire in seaport lighting application, the light distribution characteristics of the fabricated prototype LED seaport luminaire with conventional HID seaport luminaires were theoretically analyzed. Then, actual measurements using the testbed with a total of six sections with 56 measurements points were conducted. The LED seaport luminaire shows more uniformly distributed values such as an overall uniformity of 0.5 (in case of simulation: 0.72) and average illuminance of 80 lx (in case of simulation: 92 lx). Moreover, the LED luminaire has a higher luminous efficacy of 124 lm/W compared with that of the commercial HID (metal halide) luminaire of about 70 lm/W. The required characteristics of seaport lighting application were investigated, and the analyzed features of the LED and commercial HID (metal halide) luminaire were described in the discussion section. Summarizing the above simulated and measured results, it can be seen that LED luminaires with more uniform light distribution, higher luminous efficacy, and less power consumption are more suitable for port lighting than conventional HID (metal halide) luminaires.  
In this paper, the seaport with a horizontal layout was considered and analyzed. Thus, the seaport with a vertical layout, which has long single block perpendicular to the shore, may require different light distribution characteristics [31; 32]. However, a similar approach to the method used in this paper will be helpful in that case, also. In the future, additional research is needed to improve and to secure environmental resistance according to environmental conditions such as salt water.  
Conceptualization, J.K. ([PERSON]); formal analysis, J.K. ([PERSON]); investigation, J.K. ([PERSON]); resources, J.K. ([PERSON]); writing--original draft preparation, J.K. ([PERSON]) and J.K. ([PERSON]); writing--review and editing, J.K. ([PERSON]); supervision, [PERSON] All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Standardization of KS for public smart lighting and implementation of performance evaluation system of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20209810400020).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest.