## 3 Materials and Methods
### Analysis Method
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Contents** & & **Unit** & **Unit Cost (KRW)** \\ \hline \multirow{4}{*}{A. Death, missing, injury} & \multirow{4}{*}{Relief fund} & Death, Missing (Householder) & Person & 10,000,000 \\  & & Death, Missing (Family member) & Person & 5,000,000 \\  & & Injury (Householder) & Person & 5,000,000 \\  & & Injury (Family member) & Person & 2,500,000 \\ \hline B. Relief of victims & Relief of victims & Relief money & Person/day & 6000 \\ \hline C. Housing & \multirow{2}{*}{Housing damage} & Whole damage/Loss & House & 30,000,000 \\  & recovery & Half damage & House & 15,000,000 \\ \hline D. Agricultural & Agricultural land & Agricultural land missing & m\({}^{2}\) & 2087 \\ land recovery & Missing or burying & Agricultural land buried & m\({}^{2}\) & 840 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Application contents of natural disaster recovery guideline. Figure 2: Sectional view of criteria of steep collapse hazard zones [10]. Source: Ministry of Land, Infrastructure and Transport Infrastructure Development Institute, Japan. ([[http://www.mlit.go.jp/sogoseisaku/inter/keizai/gijyutu/pdf/sediment_e.pdf](http://www.mlit.go.jp/sogoseisaku/inter/keizai/gijyutu/pdf/sediment_e.pdf)]([http://www.mlit.go.jp/sogoseisaku/inter/keizai/gijyutu/pdf/sediment_e.pdf](http://www.mlit.go.jp/sogoseisaku/inter/keizai/gijyutu/pdf/sediment_e.pdf))). Benefit/cost analysis is a method for comprehensively evaluating all the long-term costs and benefits from social and national perspectives. It is widely used for evaluating the economic impact of public programs, such as disaster prevention programs, despite the difficulties in assessing their true costs and benefits. Several indexes have been used for such analyses, such as B/C, NPV, and IRR--all of which can be used as complementary criteria in evaluating investment projects depending on the purpose of the application and traits of the investment project. This study proposes to analyze the investment effects using the B/C ratio, which is currently used to analyze the economic impact of the natural disaster hazard zone management guidelines introduced by the National Emergency Management Agency [12]. The B/C ratio could be expressed as follows:  
\[\frac{B}{C}=\sum_{t=0}^{n}\frac{B_{t}}{(1+r)^{t}}/\sum_{t^{\prime}=0}^{n^{ \prime}}\frac{C_{t^{\prime}}}{(1+r)^{t^{\prime}}} \tag{1}\]  
where \(B\) is total benefit, \(C\) total cost, \(r\) discount rate, \(B_{t}\) benefits generated \(t\) years after the investment, \(C_{t}\) incurred costs, \(n\) period of benefit analysis, \(n^{\prime}\) period of cost analysis, \(t\) the year in which t benefits were analyzed, and \(t^{\prime}\) the year when the project was implemented. Each element and assessment method for carrying out the benefit/cost analysis can be presented as follows [10]. Cost: The costs of analyzing costs and benefits are not assessed separately since the analysis is conducted for projects that are completed, so the cost refers to the total cost of the project (Table 6). Also there are real project costs in the all of the 10 project zones. Costs are calculated as construction costs and compensation expenses (land, building, business, etc. ). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Project Site** & **Cost (USD Million)** & **Project Site** & **Cost (USD Million)** \\ \hline Odongdo & 16.0 & Seonyang & 6.5 \\ Mangan Park & 3.7 & Dongmyumg & 5.0 \\ Moam & 8.0 & Soyang & 3.3 \\ Wolmyeong & 5.0 & Myeongiu & 1.2 \\ Sinheung & 15.0 & Beakieon & 2.6 \\ \hline \hline \end{tabular} Source: Natural Disaster Management Institute. Korea, 2011 ([[http://www.ndmi.go.kr/research/research/view.jsp](http://www.ndmi.go.kr/research/research/view.jsp)]([http://www.ndmi.go.kr/research/research/view.jsp](http://www.ndmi.go.kr/research/research/view.jsp))).  
\end{table} 
Table 6: Cost of project sites.