## 2 Literature Review  
Because drivers obtain 90% of road information through vision [4], securing driver visibility is important for safe driving. However, adverse weather such as rain and fog have a serious effect on driver visibility [5]. During rain, photons of light that hit water droplets may be absorbed or scattered. The scattered light forms a luminous veil, reducing the luminance contrast visible through the rain. As a result, the direct effect of light in the atmosphere reduces visibility [6], and reduced visibility has a serious effect on driver safety [7]. The reason why visibility is impaired during fog is because the light from road lighting is absorbed and scattered by the fog in the atmosphere. Because of this, some of the light is lost or reflected back towards road users in the form of a veil of fog that obscures details of the road ahead [8]. This decrease in visibility due to fog results in a decrease in the driver's visual and operating abilities, threatening safe driving [9; 10]. According to Korea's 2022 traffic accident statistics, the fatality rate from traffic accidents on a clear day is 1.3 people/100 cases, the fatality rate during rain is 2.0 people/100 cases, and the fatality rate during fog is 6.3 people/100 cases [11]. The fatality rate during rain was found to be 53.8% higher than on a clear day, and during fog, the fatality rate was 384.6% higher than on a clear day. In the case of traffic accident fatality rate by time zone, the fatality rate from 06:00 to 18:00, corresponding to daytime, is 1.3 people/100 cases, and the fatality rate from 18:00 to 06:00, corresponding to nighttime, is 2.4 people/100 cases. It was analyzed that the traffic accident fatality rate at night was 85.8% higher than during the daytime [11]. In the United States, the National Highway Traffic Safety Administration (NHTSA) provides normal and rain fatality rate statistics between the lighted section and the non-lighted section. According to 2020 statistics, the fatality rate was 0.52/100 for the section with lights in rain while 1.01/100 for the section without lights, indicating that the fatality rate of the non-lighted section in rainfall is 48.6% higher than that of the lighted section [12]. In other words, the severity of traffic accidents is very high at night and in adverse weather, and road lighting is considered a measure that can reduce the fatality rate of traffic accidents during adverse weather at night. Road lighting has great potential to improve traffic safety and, most importantly, reduce the severity of road accidents [13]. However, most studies related to road lighting are conducted under normal weather conditions. [PERSON] et al. [14] investigated the effect of adjusting the level of road lighting on night driving performance. The level of road lighting was adjusted to four levels using 14 subjects, and the recognition distance and reaction time for moving targets and walking pedestrians were investigated. As a result, it was verified that the brighter the road lighting, the longer the recognition distance to the target and the shorter the reaction time. [PERSON] et al. [15] investigated the preference between 3000 K and 4000 K road lighting from the driver's perspective through a survey, and, as a result, 3000 K road lighting was evaluated as preferable. [PERSON] et al. [16] investigated the interaction between road lighting and car headlights in terms of target detection distance and presented results showing that target recognition distance changes according to changes in road lighting intensity. [PERSON] et al. [17] conducted a dark adaptation study using LEDs with different color temperatures in the process of finding the performance of designated road lighting, and the results suggested that the dark adaptation time increases as the color temperature increases.