• Structural Engineering and Mechanics
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• v.53 no.1
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• pp.89-104
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• 2015

In current bridge management systems (BMSs), load and speed restrictions are applied on unhealthy bridges to keep the structure safe and serviceable for as long as possible. But the question is, whether applying these restrictions will always decrease the internal forces in critical components of the bridge and enhance the safety of the unhealthy bridges. To find the answer, this paper for the first time in literature, looks into the design aspects through studying the changes in demand by capacity ratios of the critical components of a bridge under the train loads. For this purpose, a structural model of a simply supported bridge, whose dynamic behaviour is similar to a group of real railway bridges, is developed. Demand by capacity ratios of the critical components of the bridge are calculated, to identify their sensitivity to increase of speed and magnitude of live load. The outcomes of this study are very significant as they show that, on the contrary to what is expected, by applying restriction on speed, the demand by capacity ratio of components may increase and make the bridge unsafe for carrying live load. Suggestions are made to solve the problem.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1324-1327
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• 2009

Social infrastructure is the basis of public welfare and should be recognized and managed as important assets. Bridge is one of the most important infrastructures to be managed systematically because the impact of the failure is critical. It is essential to monitor the performance of bridges in order to manage them as an asset. But current analytical methods such as predictive modeling and structural analysis are very complicated and difficult to use in practice. To apply these methods, structural and material condition data collection should be performed in each element of bridge. But it is difficult to collect these detailed data in large numbers and various kinds of bridges. Therefore, it is necessary to collect data of major measurement items and predict the life of bridges roughly with advanced information technologies. When certain measurement items reach predefined limits in the monitoring bridges, precise performance measurement will be done by detailed site measurement. This paper describes the selection of major measurement items that can represent the tendency of bridge life and introduces automated bridge data collection test-bed using wireless sensor network technology. The following will be major parts of this paper: 1) Examining the features of conventional bridge management system and data collection method 2) Mileage concept as a bridge life indicator and measuring method of the indicator 3) Test-bed of automated and real-time based bridge life indicator monitoring system using wireless sensor network

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.5
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• pp.215-226
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• 2017

In this paper, an experimental study was carried out for vibration control of cable bridges with structurally flexible characteristics. For the experiment on vibration control, a model bridge was constructed by reducing the Seohae Grand Bridge and the shear type MR damper was designed using the wind load response measured at Seohae Grand Bridge. The shear type MR damper was installed in the vertical direction at the middle span of the model bridge, and dynamic modeling was performed using the power model. The tests of the vibration control were carried out by non-control, passive on/off control and Lyapunov control method on model bridge with scaled wind load response. The performance of the vibration control was evaluated by calculating absolute maximum displacement, RMS displacement, absolute maximum acceleration, RMS acceleration, and size of applied power using the response (displacement, acceleration, etc.) from the model bridge. As a result, the power model was effective in simulating the nonlinear behavior of the MR damper, and the Lyapunov control method using the MR damper was able to control the vibration of the structure and reduce the size of the power supply.

• Korea Science and Art Forum
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• v.20
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• pp.421-428
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• 2015

Electronic/hybrid car and electroplating rectifier should have switching devices such as SCR, MOSFET, IGBT. And those switching devices should be operated by gate driver. In this paper, we propose high power gate driver that contains H-Bridge using 4 BJTs. H-Bridge and transformer generate isolate power. And gate control signal is transferred to isolated one by photo coupler and operate real switching device. We designed H-Bridge and 555-Timer by PSpice simulation and manufactured real product. Finally we succeed to operate 27V 50,000A electroplating rectifier using proposed gate driver.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.113-118
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• 2001

The two-girder composite bridge has the girder space of more than 5m, for special case, over than 15m. Therefor, the design and construction of this bridge system require new approaches. To ensure the structural safety, the deck depth should be increased. Therefore, the economically designed deck system is necessary for th two-girder bridge. This study is the first step to develop the deck system for two-girder bridges. In this study, a literatute survey is performed to develop a new deck system for two-girder type of bridges. By considering the characteristics of two-girder bridge system, a cast-in-place PSC deck is proposed for the two-girder bridges. To examine structural behavior and safety of the proposed PSC deck, three real scale partition deck(3m$\times$5m) are tested under the static loading. In the test, the failure mode and behavior of each specimen, and ultimate load carrying capacity of the two-girder-bridge deck are identified.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.519-524
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• 2002

The long span PSC deck of composite girder bridge should be needed in order to improve the endurance and to simplify the structure of the steel bridge. However, there have been few domestic research activities about long-span PSC decks for the steel bridges with a small number of girders. In this study, a literature survey is performed to develop a new deck system for the steel bridge with a small number of girders. By considering the characteristics of a small number of girders bridge system, a cast-in-place long span PSC deck is proposed for a small number of girders bridges. To examine structural behavior and safety of the proposed PSC deck, the real scale partial models of the deck(12m$\times$3.2m) are tested under the static loading. In the test, the failure mode and behavior of each specimen, and ultimate load carrying capacity of the proposed PSC deck are identified.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.525-530
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• 2002

This study is peformed to propose the slab deck for the composite bridge with two girders. Considering the characteristics of the long span and the construction conditions in korea, a cast-in-place PSC deck was proposed for that bridge. To examine structural behaviors and safety of the proposed PSC deck, two real scale partitions of deck(12m$\times$3.2m) were tested under the fatigue loading. In the test, the failure mode and behaviors of each specimen, and the ultimate load carrying capacity of the two-girder-bridge deck were identified. Generally, the failure of concrete bridge deck is caused by the local punching shear stress resulting from the moving wheel load. Even though its ultimate flexural capacity is sufficiently larger than the demand, it could be failed by the punching shear fatigue. Therefore, the fatigue safety of the proposed PSC deck should be checked.

• Earthquakes and Structures
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• v.14 no.4
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• pp.297-303
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• 2018

Seismic behavior of Osmanli and Senyuva stone bridges was addressed in this study. A combination of FEM and DEM was employed for getting closer to the real behavior of the bridge. One of the unique features of this combinational method is simulation close to reality. Modal numerical analysis was also used to verify the modeling. At the end of earthquake, a part of two lateral walls of Osmanli bridge was broken. The growth of arch cracks also increased during the earthquake. A part of right-hand wall of Senyuva Bridge was destructed during the earthquake. The left-hand side of the bridge wall was damaged during the earthquake but was not destructed.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.3
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• pp.135-143
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• 2016

In this paper, a design concept of post-tensioned precast bridge piers was proposed to improve seismic behavior of the bridge pier. Mild reinforcing bars are placed continuously along the height of the column. Prestressing tendons are also provided to obtain re-centering capability for seismic events. Arrangement of the axial steels to prevent buckling of rebars at plastic hinge region was suggested and enhanced seismic performance was verified by experiments. Moment-curvature analyses were performed to evaluate the effect of effective prestress on seismic behavior after verifying the calculation method by cyclic tests of the precast columns. A real bridge pier was designed to investigate the seismic performance according to different level of effective prestress. Level of effective prestress showed obvious effect on crushing displacement but negligible effect on lateral displacement at fracture of tendons and reinforcements.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.261-268
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• 2006

This study represents results of fragility curve development for 3-span continuous bridge. To research the response of bridge under earthquake excitation, Monte Carlo simulation is performed to study nonlinear dynamic analysis. Because of limited number of real time histories from the Korean peninsula, a set of 150 synthetic time histories were generated. Fragility corves in this study are represented by lognormal distribution functions with two parameters and developed as a function of PGA. Five damage states were defined to express the condition of damage based on the actual experimental damage data of bridge column. As a result of this research, the value of damage probability corresponding to each damage state were determined. This approach may be used in constructing the fragility curves for all of bridge structure and, by extension, in constructing the seismic hazard map.