• Structural Engineering and Mechanics
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• v.71 no.6
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• pp.683-697
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• 2019

The reinforced concrete (RC) structures usually suffer large residual displacements under strong motions. The large residual displacements may substantially reduce the anti-seismic capacity of structures during the aftershock and increase the difficulty and cost of structural repair after an earthquake. To reduce the adverse residual displacement, several self-centering energy dissipation braces (SCEBs) have been proposed to be installed to the RC structures. To investigate the seismic responses of the RC structures with SCEBs under the earthquake excitation, an extended Bouc-Wen model with degradation and self-centering effects is developed in this study. The extended model realized by MATLAB/Simulink program is able to capture the hysteretic characteristics of the RC structures with SCEBs, such as the energy dissipation and the degradation, especially the self-centering effect. The predicted hysteretic behavior of the RC structures with SCEBs based on the extended model, which used the unscented Kalman filter (UKF) for parameter identification, is compared with the experimental results. Comparison results show that the predicted hysteretic curves can be in good agreement with the experimental results. The nonlinear dynamic analyses using the extended model are then carried out to explore the seismic performance of the RC structures with SCEBs. The analysis results demonstrate that the SCEB can effectively reduce the residual displacements of the RC structures, but slightly increase the acceleration.

• Journal of Environmental Science International
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• v.24 no.3
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• pp.303-316
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• 2015

The relationship between urban spatial structures and GHG-AP integrated emissions was investigated by statistically analyzing those from 25 administrative districts of Seoul. Urban spatial structures, of which data were obtained from Seoul statistics yearbook, were classified into five categories of city development, residence, environment, traffic and economy. They were further classified into 10 components of local area, population, number of households, residential area, forest area, park area, registered vehicles, road area, number of businesses and total local taxes. GHG-AP integrated emissions were estimated based on IPCC(intergovernmental panel on climate change) 2006 guidelines, guideline for government greenhouse inventories, EPA AP-42(compilation of air pollutant emission factors) and preliminary studies. The result of statistical analysis indicated that GHG-AP integrated emissions were significantly correlated with urban spatial structures. The correlation analysis results showed that registered vehicles for GHG (r=0.803, p<0.01), forest area for AP (r=0.996, p<0.01), and park area for AP (r=0.889, p<0.01) were highly significant. From the factor analysis, three groups such as city and traffic categories, economy category and environment category were identified to be the governing factors controlling GHG-AP emissions. The multiple regression analysis also represented that the most influencing factors on GHG-AP emissions were categories of traffic and environment. 25 administrative districts of Seoul were clustered into six groups, of which each has similar characteristics of urban spatial structures and GHG-AP integrated emissions.

• Earthquakes and Structures
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• v.16 no.1
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• pp.97-107
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• 2019

The frame structures investigated in this paper is composed of Concrete encased columns with L-shaped steel section and steel beams. The seismic behavior of this structural system is studied through experimental and numerical studies. A 2-bay, 3-story and 1/3 scaled frame specimen is tested under constant axial loading and cyclic lateral loading applied on the column top. The load-displacement hysteretic loops, ductility, energy dissipation, stiffness and strength degradation are investigated. A typical failure mode is observed in the test, and the experimental results show that this type of framed structure exhibit a high strength with good ductility and energy dissipation capacity. Furthermore, finite element analysis software Perform-3D was conducted to simulate the behavior of the frame. The calculating results agreed with the test ones well. Further analysis is conducted to investigate the effects of parameters including concrete strength, column axial compressive force and steel ratio on the seismic performance indexes, such as the elastic stiffness, the maximum strength, the ductility coefficient, the strength and stiffness degradation, and the equivalent viscous damping ratio. It can be concluded that with the axial compression ratio increasing, the load carrying capacity and ductility decreased. The load carrying capacity and ductility increased when increasing the steel ratio. Increasing the concrete grade can improve the ultimate bearing capacity of the structure, but the ductility of structure decreases slightly.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.251-261
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• 2007

This study is to investigate the damage assessment of adjacent structures due to tunneling in urban environment. Model tests were carried out with two-story masonry building structures in various shapes and locations. The damage level of adjacent structures were very differently estimated in accordance with the shape ratio (L/h) of structures, construction stages, and various locations. The results of model tests were plotted on the damage level graphs in order to predict the direction of damage levels for the different types of structures (i.e. stiffness of structures, L/h). The progressive crack development mechanism at various construction stages was revealed through model tests and crack size indicated more conservative side of damage level on the damage level graph.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.485-492
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• 2000

Current design practice for the prediction of tunnelling-induced ground movements depends on empirical methods, which are based on many assumptions and simplification of the modeling. Some discrepancies between the predictions and the measurements of ground movements regarding adjacent structures are inevitable. In order to investigate tunnel-induced ground movements affect on the settlement of existing structures as well as existing structures affect tunnel-induced ground movement, 2-D elasto-plastic finite element analysis are performed. The following influencing factors such as load of the structures, the width of structures, its bending and axial stiffness, its position relative to the tunnel are considered in the numerical analysis.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.50-51
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• 2017

The Urban-type building is an building that it relaxed the construction standard and subsidiary facility standard. The most of the urban-type buildings are pilotis, the main case of representing these building's fire risk is the Uijeongbu fire this study investigated to piloti urban type housing risk on the basis of Uijeongbu fire, and we checked structural problem that unable to escape from the rooftop inside the piloti. also, there was confirmed limit to the evacuation of the occupants because the smoke was rapidly transferred to the top layer through inside the electric duct. and when we analyzed smoke flow use of Fire simulation, it was confirmed Available Safety Egress Time that is four minutes of CO.

• Journal of East-Asian Urban History
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• v.3 no.1
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• pp.7-20
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• 2021

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.5
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• pp.436-443
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• 2011

Recognition of structures in urban environments is a fundamental ability for unmanned ground vehicles. In this paper we propose the geometrical featured voxel which has not only 3-D coordinates but also the type of geometrical properties of point cloud. Instead of dealing with a huge amount of point cloud collected by range sensors in urban, the proposed voxel can efficiently represent and save 3-D urban structures without loss of geometrical properties. We also provide an urban structure classification algorithm by using the proposed voxel and machine learning techniques. The proposed method enables to recognize urban environments around unmanned ground vehicles quickly. In order to evaluate an ability of the proposed map representation and the urban structure classification algorithm, our vehicle equipped with the sensor system collected range data and pose data in campus and experimental results have been shown in this paper.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.1
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• pp.205-212
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• 2002

The deterioration rate of concrete structures in urban area is accelerated due to rapid urbanization and environmental pollution. Repair materials and methods newly introduced in Korea should be investigated whether they are appropriate for the urban environment in Korea. The creek concrete structures are exposed in severe environmental condition than others. Based on these background in mind, the study is focused on evaluation of performance on repair materials used to rehabilitate creek concrete structures. To evaluate the performance of repair materials, four kinds of repair materials were selected based on polymer emulsion. This experimental study was conducted on fundamental performance such as setting time, compressive strength, bending strength, bonding strength, thermal expansion coefficient, and durability performance such as chloride diffusion, carbonation, chemical attack, and steel corrosion rate. On the basis of this study, the optimal repair material which is proper to the environment condition can be selected and service life of creek concrete structures can be extended. As a result, the life cycle cost can be reduced and the waste of material resources will be cut down.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.2
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• pp.76-88
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• 2017

The urban park plays important roles in protecting the urban landscape and improving citizens' health, recreation, and the emotional life. Above and beyond these roles, the urban park is expected to rearrange urban spatial structures as a kind of urban system. The purpose of this paper is to identify empirically to change urban spatial structures by construction of the urban park. This study regards gentrification around the urban park as a process to change urban spatial structures. The gentrification means the regeneration and upgrading of deteriorated urban property by the middle class or commercial developers. The site of case analysis is the Seoul Forestry Park in Sungdong-gu, Seoul. The Seoul Forestry Park is regarded as a representative urban park of Seoul, and caused gentrification around park after the 2005 opening. This study operationally defines the gentrification index and the accessibility index from an urban park and offers an empirical analysis of relation among the urban park, the gentrification and urban spatial structure in a statistic district which is the minimum unit of Korean statistic data in 2000, 2005, and 2010, using Difference-in-Difference method and linear probability model. The results of this empirical study show that the Seoul Forestry Park changes urban spatial structures by gentrification. It reverses a trend of migration of gentrifiers before and after construction of the Seoul Forestry Park. It suggests urban park construction as an alternative method for urban regeneration by inducing the middle class into the inner city of Seoul.