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Lee H.H.,Dongyang University | Chun Y.S.,Land and Housing Institute
Advanced Materials Research | Year: 2014

To improve the seismic performance of existing residential buildings, strengthening methods for T-shaped walls are evaluated through the performance tests. Almost damaged three specimens are strengthened by aramid fiber sheet and additional reinforcement. Cyclic lateral loads are applied to the top of the specimen with constant axial load. From these, strengthened wall by aramid fiber sheet and additional reinforcement shows the almost 100% strength and deformation capacity recovery comparing the undamaged wall. For the convenience of wall strengthening method in a residential state, using of aramid fiber sheet is recommended from this performance test results. © (2014) Trans Tech Publications, Switzerland.

Lee J.-S.,The Seoul Institute | Nam J.,University of Seoul | Lee S.-S.,Land and Housing Institute
International Journal of Sustainable Transportation | Year: 2014

This study examines the impacts of the built environment measures based on two geographic scales, i.e., traffic analysis zone and one quarter-mile buffer on individual mode choice in the Houston metropolitan area. It is confirmed that they have significant impacts on mode choice in varying degrees. The models including the buffer-based measures are more reasonable than those with conventional zone-based variables for both home-based work and other trips. Finally, the elasticity estimates suggest the built environments are undervalued in the conventional transportation practices. Both land use and transport pricing measures should be considered complementary to control the demand for driving. © 2014 Copyright Taylor and Francis Group, LLC.

Zi G.,Korea University | Moon D.Y.,Kyungsung University | Lee S.-J.,Korea University | Jang S.Y.,Korea Railroad Research Institute | And 3 more authors.
Engineering Failure Analysis | Year: 2012

We investigated a conical crack formed near a fastening bolt of a concrete railway sleeper in a slab track system. The crack initiated from the bottom of the sleeper and penetrated the sleeper completely forming a conical shape. To study the reason for this and to examine the failure mechanism, we used a three dimensional finite element method and a series of experimental programs. The result of the numerical simulation was verified with the experimental data. From this study, we concluded that the conical crack was caused by the volume expansion of the freezing water leaking into the plastic insert of the fastener hole. The effect of location of the frozen insert holes, initial fastening force and compressive strength of concrete on the freezing force was also studied in this study. © 2012 Elsevier Ltd.

Chun Y.S.,Land and Housing Institute | Chang K.K.,Korea University
Magazine of Concrete Research | Year: 2016

Special reinforced concrete coupling beams in high-seismic-risk regions require specific diagonal bundled reinforcement details that must be strictly followed to ensure proper structural performance. However, when these details are applied to coupled shear wall structures, the coupling beams' width must match the width of the walls, resulting in a complicated rebar layout and difficulty in on-site installation. Especially when applied with special shear wall structures, the joint between the coupling beam and the shear wall results in extremely complex reinforcement details that are almost impossible to install on site. With a view to overcoming such problems, this paper evaluates and reports on seismic resistance performance tests performed on coupling beams with a single diagonal reinforcement bar together with headed bars (DHB) reinforcement details, as a proposed alternative solution. Test results show that the test specimen HB75, in which the headed bars substituted for 75% of the capacity of the diagonal reinforcing bundled bars, had superior ductility and energy dissipation capability, as well as lower strength and stiffness degradation compared to other test specimens. Thus, this research indicates that the headed bars can be a practical alternative to hoops of diagonal bundled bars for confining concrete in coupling beams.

Cho S.,Land and Housing Institute
A/Z ITU Journal of the Faculty of Architecture | Year: 2011

After World War II, Seoul and Tokyo had experienced similar urban problems as part of their rapid urbanization and had been developed western planning systems to modernize their urban structures. Seoul and Tokyo had very similar planning schemes for redevelopment, which consisted of legal urban redevelopment projects and subsidies under the Urban Redevelopment Law. The differences in their government operations system and application of development tools caused differences in their urban structures. This article describes each government's efforts and legal systems to illustrate the spatial transform of central areas in Seoul and Tokyo using documentary research and GIS data. This article is intended to address implications on the downtown redevelopment policies of Seoul and Tokyo. And to conclude, 2 Asian mega cities have lost many traditional urban structures under legal redevelopment project until 1990s. Fortunately their planning schemes are changing by making them aware of how redevelopment projects should make conserve traditional urban structures.

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