## 3 Materials and Methods
### Analysis Method  
This study identified areas expected to face damage due to collapse in collapse hazard zones, such as flooding zones, and quantified assessment benefits. To this end, this study set up damage hazard zones by criteria for steep collapse hazard zones designated by Japan's Ministry of Land, Infrastructure, Transport and Tourism (quoted from the Criteria for Damage Hazard Zones of Collapse Hazard Zones, National Disaster Prevention Institute). The criteria for steep collapse hazard zones refer to the scope of damage feared towards residential housing and public facilities adjacent to steep sloping sides with gradients above 30\({}^{\circ}\) and length above 5 m. This is a method to identify damage hazard zones due to collapse based on the benefit/cost analysis manual for landslide disasters by the Ministry of Land, Infrastructure, Transport and Tourism of Japan. Generally, the gradient of a steep slope is about twice its height (limited to approximately 50 m) from the bottom of the steep slope. When the limit exceeds 50 m, the height is limited to 50 m [10] (Figure 2). These criteria are based on the existing literature, such as the Study on the Applicability of an Early Warning System using Rainfall Data in Korea of the Natural Disaster Management Institute [11]. \begin{table}
\begin{tabular}{c c c c c} \hline
**Si-Do** & **Si-Gu** & **Project Site** & **Site Area (ha)** & **Project Period** \\ \hline Jeonnam & Yeosu & Odongdo & 2.5 & 2011–2013 \\ Gyeongsangbuk & Sacheon & Mangsan park & 2.47 & 2008–2011 \\ Gyeongsangbuk & Gimcheon & Moam & 2.35 & 2012–2013 \\ Jeonbuk & Gunsan & Wolmyeong & 2.0 & 2010–2011 \\ Jeonbuk & Gunsan & Sinheung & 0.8 & 2010–2013 \\ Jeonbuk & Gunsan & Seonyang & 0.7 & 2010–2011 \\ Gangwon & Sokcho & Dongmyumg & 0.7 & 2007–2011 \\ Gangwon & Chuncheon & Soyang & 0.6 & 2010–2011 \\ Jeonnam & Gwangyang & Myeongiu & 0.3 & 2011–2012 \\ Gyeongsangbuk & Yecheon & Beakieon & 0.05 & 2010–2011 \\ \hline \end{tabular}
\end{table} 
Table 4: Project sites for benefit/cost analysis (NEMA, 2012). Figure 1: Location map of analysis areas. 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))). This study investigated both domestic and foreign criteria for identifying collapse hazard areas, all of which proved suitable for Korea. Since collapse hazard zones features vary by zone, benefit items could also vary across areas. This study classified collapse hazard zones into the following categories: major (human loss and material loss); middle (private facilities and public facilities); minor (buildings, farming facilities, livestock facilities, other facilities, roads and bridges, national park facilities, farming facilities, school facilities, forestry facilities, railway facilities, military facilities, cultural facilities, and other facilities); and detailed items (houses, pensions, containers, collective rooming facilities, buried factories, farmlands swept away, greenhouses, damaged cattle sheds, damaged vehicles, tunnel collapse, roads swept away, walls and fences damaged, damage to forests, damaged cultural assets, and damaged electric power, gas, and city water). Benefits should be quantified according to the damage relief effects of a selected program. This study used the natural disaster recovery guidelines (2010) method to quantify each benefit item. Natural disaster recovery guidelines (2010) set the amount of support funds (unit price) to be shouldered by the government and autonomous bodies in case of natural disasters. Support funds are directed to the area affected by a disaster based on these guidelines, which assess the amount of damage as presented in the Disaster Yearbook (Table 5).