• Proceedings of the KSR Conference
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• 2006.11b
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• pp.322-327
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• 2006

Banwol bridge with steel plate girder and Pyongtaek bridge with PSC bos girder have been operated maintenance measuring system by the Seoul-Chonan of Kyongbu express railway. By analyzing the theoretical and experimental values of design load for these two bridge, the establishment of reference maintenance for measuring items was deduced from research. Two materials, steel and concrete plates, were considered as the upper structure. Actual measurement data for the behavior under speed, structural analysis results, and the presented references were analyzed and used to set up the reference establishment. The measuring items are stress(strain), displacement, dynamic acceleration, expansion movement, and dynamic frequency. The maintenance reference was established by comparing analytical and measuring values of the five items with respect to structural state class.

• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.79-85
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• 2003

In this study, the behavior characteristics of specimen strengthened with CFRP plate were analyzed according to the change of temperature. CFRP plate itself has a good resistance at the high temperature, but epoxy used as a adhesive is lost its bonding strength at the relatively low temperature. Therefore, this study carries out experiment on the beams slot-bonded with CFRP plates in order to maintain the successful bonding strength of epoxy at high temperature. It is presented that the range of glass transition temperature is 60-8$0^{\circ}C$ and RC beams slot-bonded with CFRP plate shows more increasing resistance and failure load than that of interface bonded at the high temperature.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.255-258
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• 2005

Recently, demands for the reduction of noise generated by transformers have been increasing. Almost all the noise generated by a transformer is a result of magnetostrictive vibration in the core. The noise radiates into the atmosphere from the tank through the insulation oil. One method of reduction such a noise is to build a free-standing enclosure of concrete and steel plates around the transformer. However, this method has some disadvantages, for example, a large area is needed for equipment installation. In this paper, the vibration and noise effects which is transferred from reinforce channel to insulation panel generated by transformer have been identified for the several kinds of insulation panel shape and damping sheet experimentally.

• Nuclear Engineering and Technology
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• v.45 no.4
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• pp.553-564
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• 2013

This study evaluates the local damage of a turbine in an auxiliary building of a nuclear power plant due to an external impact by using the LS-DYNA finite element program. The wall of the auxiliary building is SC structure and the material of the SC wall plate is high manganese steel, which has superior ductility and energy absorbance compared to the ordinary steel used for other SC wall plates. The effects of the material of the wall, collision speed, and angle on the magnitude of the local damage were evaluated by local collision analysis. The analysis revealed that the SC wall made of manganese steel had significantly less damage than the SC wall made of ordinary steel. In conclusion, an SC wall made of manganese steel can have higher effective resistance than an SC wall made of ordinary steel against the local collision of an airplane engine or against a turbine impact.

• Structural Engineering and Mechanics
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• v.69 no.3
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• pp.283-291
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• 2019

Accurately determining the natural frequencies and mode shapes of a structural floor is an essential step to assess the floor's human-induced vibration serviceability. In the theoretical analysis, the prestressed concrete floor can be idealized as a multi-span continuous anisotropic plate. This paper presents a new analytical approach to determine the natural frequencies and mode shapes of a multi-span continuous orthotropic plate. The suggested approach is based on the combined modal and perturbation method, which differs from other approaches as it decomposes the admissible functions defining the mode shapes by considering the intermodal coupling. The implementation of this technique is simple, requiring no tedious mathematical calculations. The perturbation solution is validated with the numerical results.

• Computers and Concrete
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• v.27 no.3
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• pp.269-282
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• 2021

A dynamic analytical solution for a simply supported, rectangular functionally graded plate with a porous middle layer under time-dependent load based on a refined third-order shear deformation theory with a cubic variation of in-plane displacements according to the thickness and linear/quadratic transverse displacement is presented. The solution achieved in the trigonometric series form and rests on the Green's function method. Two porosity types and their influence on material properties, and mechanical behavior are considered. The network of pores is assumed to be empty or filled with low-pressure air, and the material properties are calculated using the power-law distribution idealization. Numerical calculations have been carried out to demonstrate the accuracy of the kinematic model for the dynamic problem, the effect of porosity, thickness of porous layers, power-law index, and type of loading on the dynamic response of an imperfect functionally graded material plate.

• Computers and Concrete
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• v.34 no.3
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• pp.347-353
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• 2024

This paper investigates the second-grade fluid between two parallel plates. Fluid is produced due to stretching. Convective heat and mass transfer features are elaborated with thermal and solutal stratification. Thermal radiation and chemical reactions are also assumed in heat and mass transport processes partial differential. Formulated non-linear partial differential equations are transformed into non-linear ordinary differential equations by utilizing the suitable transformation. Convergent series solutions are computed via Homotopy Analysis Method (HAM). Effects of Hartman number, temperature field, velocity distribution and Prandtl number are sketched and analyzed through graphs. It is noticed that velocity field first decreases and after some distance it shows increasing behavior by the increment.

• Journal of Korean Society of Steel Construction
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• v.16 no.6 s.73
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• pp.725-736
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• 2004

A new type of girder, called steel-confined prestressed concrete girder (SCP girder), has been developed, which maximizes the structural advantages of concrete, steel, and PS tendon, and improves on the shortcomings of steel plate girder, PSC I-girder, and preflex girder bridge for use in the construction of middle- or long-span bridges. To verify the propriety of design, structural safety, and applicability of this girder, a static load test was carried out (Kim et al.., 2002). Since the main damage typically sustained by steel bridges results from the fatigue caused by the repetition of traffic loads, fatigue safety must therefore be guaranteed in applying the SCP girder in the construction of real bridges. In this study, a fatigue test was carried out to investigate fatigue behavior and provide basic data for fatigue design. Based on the fatigue test, the fatigue safety of the girder was estimated. For the fatigue test, 10-m specimens were designed for a standard-design truckload (DB-24). A static load test was also performed before the fatigue test to analyze the structural behavior of the specimens. After the fatigue test, outer steel plates were removed to observe the condition of the concrete in the girder.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.87-94
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• 2017

In the nuclear power plant, the steel or polymer liner plates are adopted to prohibit the inner concrete surface from contacting with gas or liquid materials. If there is an accident, the plate may be damaged, and, in this case, concrete shall have the final responsibility to safety requirements. In this paper, an experimental research was carried out to investigate the effects of construction joint and wet and loading conditions on the permeability of concrete. The test results showed that, under a construction joint in the wet condition, leakage of gas pressure has been started from $1kg/cm^2$. However, when there are no construction joints, it is initiated from $2kg/cm^2$. In addition, under the air dried and unloading condition, regardless of with or without the presence of the construction joint, since the gas passage that exist in concrete is constant, leakage has a constant tendency to increase. Finally, under the loading condition, as described in Reference 1, since leakage is inversely proportional to the thickness of the wall, and, considering the wall thickness of the actual plant, it is found that there will not be no problem in the sealing of the gas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.126-136
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• 2018

A steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine inhomogeneous two materials. The steel plate is assembled by welding an existing composite beam. In this study, new steel-plate concrete composite beam, called a SPC Beam, was developed to reduce the shear connector and improve the workability. The SPC Beam was composed of folding steel plates and concrete, without a shear connector. The folding steel plate was assembled using high strength bolt instead of welding. To improve the workability in field construction, a hat-shaped Cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode. The flexural strength of the specimen for positive moment and negative moment was calculated using the plastic stress distribution method. The test results showed that the flexural strength of the new SPC Beam had 80% of the strength of a complete composite beam. In addition, increasing the composite ratio was possible through clearance controls of the cap. In this study, the performance of the SPC Beam was verified through additional experiments and analyses with the cross-sectional shape and cap as variables, because the representative shape in the positive negative moment region is targeted.