Huge quantities of aged highway bridges in Japan are required to be maintained in sound condition under a severe budget constraint. Then, it is important to clarify the feature of degradation of highway bridges based on inspection data of target structures. However, it is thought that the feature of degradation of highway bridges are subjected to the strong influence of design specifications applied to them. In this paper, history of design specifications used for construction of highway bridges in Japan until now was investigated from a viewpoint of durability. As a result, it became clear that degradation prediction could be possible by referring design specifications for each highway bridges.

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 The purpose of this study is investigate evacuation measures against tsunami. Reduction of casualty by establishment of shelter were evaluated in every point of the region by the simulator. Based on the result, in the tsunami inundation zone, effective locations were found to be located inland rather than near the coast. Shelter on the coast, increases casualty by leading evacuees to hazardous area. On the other hand, shelter in the inland has a function as a guidance that indicates the direction to safe area. In conclusion, in the target area, it was found that the evacuation guidance is more effective than establishment of shelter.

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 Recently, in the Japanese field of natural disaster risk management, the term “resilience” is frequently used relating to city's recovery from natural disaster damage. The concept of resilience in the field of natural disaster risk management has been developed under the influence of the studies on vulnerability to natural disaster and resilience of ecological/socio-ecological system.
 This paper reviews the researches of vulnerability and resilience in the field of natural disaster risk management and ecological/socio-ecological system in order to identify and analyze the relation between vulnerability and resilience and the development of these concepts. Based on the review, the concepts of urban system resilience are classified into two definitions: resilience as stability and one as adaptable regenerative ability. Also, the prospect of future research is suggested to establish the framework of urban system resilience to natural disasters.

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 The present paper demonstrates that the bifurcation analysis method proposed by Akamatsu et al.¹⁵⁾ is readily applicable to the retail location model due to Harris & Wilson (1978)¹⁾. Employing 4-zone example, we analytically predict when and in which zone the agglomeration of retailers emerge. Our analysis also suggests that “spatial period doubling cascade” previously observed in some new economic geography models, proved in Ikeda et al.¹⁴⁾ and Akamatsu et al.¹⁵⁾, exists in Harris & Wilson model.

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