## 2 Literature Review
From the viewpoint of frequency of fatal accidents and probability of fatal accidents, after evaluating the degree of risk by work type, the risk ranking was presented [2]. [PERSON] et al. (2012) suggested a model integrating the qualitative risk evaluation and quantitative risk evaluation. The author evaluated the expert perception using the accident rate (number of accidents per 1000 workers). Using the criteria of accident rate, the expert perception of the aspect of risk assessment was investigated. Through the research, the degree of risk for a plaster worker was higher than other workers [16]. [PERSON] and [PERSON] (2018) presented the joint analysis which was combined with the proportional risk assessment technique and time series processes. Using this joint analysis, the construction risk was analyzed according to the time series method considering accident types in the construction sector. The most dangerous accident type was'slipping, falls, missteps' [31]. [PERSON] et al. (2019) carried out the quantitative analysis of nine sub-contractors using 8500 accident data in South Korea. As a result of the research, the accident data of sub-contractors was the most relevant to the type of work, and from the viewpoint of quantitative analysis,'reinforced concrete construction work' and 'earth work' had the most accidents [32]. [PERSON] et al. (2016) analyzed the exposure level of the total volatile organic compounds (TVOCs) at eight waterproofing and painting work sites. The results of the research showed that since the worker was exposed to amounts of TVOCs that were higher than the limits, the primer application task was the most dangerous task on the waterproofing work site, and the epoxy-resin application task was the most dangerous task on the painting work site [33]. As shown in Table 1, the results of the literature review are summarized considering frequency and probability aspects for work type and accident type. From the viewpoint of degree of risk in construction work, the limitations of previous research are summarized below. First, previous research mainly focused on the risk assessment considering the frequency aspect or the probability aspect for construction work type or accident type. Second, there are various construction work types such as building and civil infrastructure construction. However, the overall review of construction work had not considered identifying the differences between each work type. Third, previous research did not suggest risk assessment considering construction work type and accident type simultaneously from the viewpoint of frequency of fatal incidents and probability of fatal incidents. Furthermore, this study is related to the research conducted by [PERSON] and [PERSON] (2022) [2] and is similar, however, there are the following differences. First, unlike previous research, this study uses an integrated time series and estimation method to solve the uncertainty problem. The integrated time series and estimation method has the advantage of prediction which is applied to solve the uncertainty problem. Second, unlike previous research, this study evaluates the frequency of incidents and probability of fatal incidents not only regarding work types but also accident types. The construction risk is evaluated in a comprehensive manner. Referring to previous research, the following are considered to reduce the research gap. First, the fatal incident for work type and accident type is evaluated considering frequency and probability aspects. Second, in this study, all construction work types are categorized as building and civil construction site types regardless of the specific type of construction work. Therefore, this research aims to confirm the degree of risk of all construction work by analyzing the frequency of fatal incidents and probability of fatal incidents using the uncertainty method in South Korea, and accident types on each construction work are investigated further.