• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.527-534
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• 2003

This paper presents the LRB-based hybrid base isolation systems employing additional active/semiactive control devices for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. In this study, ideal hydraulic actuators (HAs) and ideal magnetorheological dampers (MRDs) are considered as additional active and semiactive control devices, respectively. Numerical simulation results show that all the hybrid base isolation systems are effective in reducing the structural responses of the benchmark cable-stayed bridge under the historical earthquakes considered. The simulation results also demonstrate that the hybrid base isolation system employing semiactive MRBs is robust to the stiffness uncertainty of the structure, while the hybrid system with active HAs is not. Therefore, the LRB-based hybrid base isolation system employing MRDs could be more appropriate in real applications for full-scale civil infrastructures.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.513-518
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• 2001

This research has been performed to estimate the hunting motion hysteresis of railway passenger cars. An old and a new car with almost same structure are chosen as analysis models. To solve effectively a set of simultaneous equations of motion strongly coupled with creep relations, shooting algorithm in which the nonlinear relations are regarded as a two-point boundary value problem is adopted. The bifurcation theory is applied to the dynamic analysis to distinguish differences between linear and nonlinear critical speeds by variation of parameters. It is found that there are some factors and their operation area to make nonlinear critical speed respond to them more sensitivity than linear critical speed. Full-scale roller rig tests are carried out for the validation of the numerical results. Finally, it is concluded that the wear of wheel profile and the stiffness discontinuities of wheelset suspension caused by deterioration have to be considered in the analysis to predict hysteresis of critical speed precisely.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.1
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• pp.24-32
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• 2010

The first full-scale u-City operation has started in Dongtan u-City. As local cities take over and operates the u-City, unexpected issues arise such as securing the budget of operating costs and self-providing the costs with business models utilizing the u-City assets. The paper presents a strategy for solving these issues. The strategy provides a foundation(infrastructure) for long-term operation models which may reduce the long-term operation costs. In order to establish the economic operating framework of u-City, suggested are some cost-reduction models based on the operating costs structure. For each model, a base framework with comparative analysis of operating costs is provided. With these models, each u-City may select a relevant model according to the characteristics of it. We hope that the framework provides the foundation for efficient and sustainable u-City operations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.205-210
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• 2004

The pulse detonation engine (PDE) has recently expected as a new aerospace propulsion system. The PDE system has high thermal efficiency because of its constant-volume combustion and its simple tube structure. We measured thrust of single-tube pulse detonation rocket (PDR) by two methods using the PDR-Engineering Model (full scale model) for ground testing. The first involved measuring the displacement of the PDR-EM by laser displacement meter, and the second involved measuring the time-averaged thrust by combining a load cell and a spring-damper system. From these two measurements, we obtained 130.1 N of time-averaged thrust, which corresponds to 321.2 sec of effective specific impulse (ISP). As well, we measured the heat flux in the wall of PDE tubes. The heat flux was approximately 400 ㎾/$m^2$. We constructed the PDR-Flight Mode] (PDR-FM). In the vertical flight test in a laboratory, the PDR-FM was flying and keeping its altitude almost constant during 0.3 sec.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.73-78
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• 1990

Large panel building systems are composed of vertical wall panels which support horizontal roof and floor panels to form a box like structure. The simplecity of the connections, which makes precast concrete economically viable, causes a lack of continuity in stiffness, strength and ductility. This precast concrete large panel systems typically have weak connection regions. Three types of 2-story full-scale precast concrete subassemblages were tested under reversed cyclic loading. The seismic resistance capacity and failure mode of each system are compared in connection with the characteristics of joint connection details.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.421-424
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• 2004

Model updating is a very active research field, in which significant efforts has been invested in recent years. Model updating methodologies are invariably successful when used on noise-free simulated data, but tend to be unpredictable when presented with real experimental data that are-unavoidably-corrupted with uncorrelated noise content. In this paper, Reanalysis using frequency response functions for correlating and updating dynamic systems is presented. A transformation matrix is obtained from the relationship between the complex and the normal frequency response functions of a structure. The transformation matrix is employed to calculate the modified damping matrix of the system. The modified mass and stiffness matrices are identified from the normal frequency response functions by using the least squares method. Full scale pseudo dynamic pier test is employed to illustrate the applicability of the proposed method. The result indicate that the damping matrix of correlated finite element model can be identified accurately by the proposed method. In addition, the robustness of the new approach uniformly distributed measurement noise is also addressed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.321-324
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• 2006

An experimental study on the bond strength of wall-slab joint in SC(steel plate-concrete) structure was performed. Six-full scale specimens were tested. Specimens were constructed with key variables, such as, development length, location of the bar and quantity of the shear bar. The experimental results, show that as the development length and quantity of the shear bar increase, the bond strength increases. As the bars is located on the inside the stud bolt, the bond performance was highly increased compared to the bars located out of plane of the stud bolts.

• Wind and Structures
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• v.16 no.5
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• pp.477-490
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• 2013

This paper presents results of calculations performed according to our own semi-empirical mathematical model of critical vortex excitation. All calculations are carried out using own computer program, which allows the simulation of both the across-wind action caused by vortices and the lateral response of analysed structures. Vortex excitation simulations were performed in real time taking into account wind-structure interaction. Several structures of circular cross-sections were modelled using a FEM program and calculated under the action of critical vortex excitation. Six steel chimneys, six concrete chimneys and two concrete towers were considered. The method of selection and estimation of the experimental parameters describing the model are also presented. Finally, the results concerning maximum lateral top displacements of the structures are compared with available full-scale data for steel and concrete chimneys.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.37-40
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• 2008

The study is an experimental test on full-scale flat plate slab-column interior connection. The punching shear on the flat plate slab-column connection can bring about the reason of the brittle punching shear failure which may result of collapsing the whole structure. From the development of residential flat plate system, the shear reinforcement is developed for preventing the punching shear. For making sure of the punching shear capacity, developed for shear reinforcement in slab-column connection, the structural test is performed. The dimension of the slabs was 2620*2725*180mm with square column (600*800mm). The slabs were tested up to failure monotonic vertical shear forces. The presences of S/S bar and wire mesh substantially increased the punching shear capacity and the ductility of the slab-column connections.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.138-144
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• 2004

Occupant protection in the side impact of a vehicle becomes one of the most important issues today. So, to reduce development time and cost, it needs test equipment which conducts an accurate simulation of the side impact crash. This paper describes a new test method for side impact, which utilizes a standard 12inch-HYGE-type sled facility. If a side impact sled test can simulate vehicle intrusion very well, it will contribute to develop full-scale side impact crash performance. The newly developed sled test method enables simulation for dummy motion, injury, door velocity, trim crack, and vehicle structure to be accurate. Ant also this sled test method can be applied to the development of side air-bag.