• 한국해양학회지
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• v.29 no.2
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• pp.95-106
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• 1994

Tidal and wind-driven currents in Chinhae Bay are investigated using a three-dimensional numerical model developed by Kim et al. (1993). The simulations indicate that the flow patterns in the bay are predominated by the bathymetry, wind and river inflow, and the effects of wind on the flow pattern in the inner bay are much stronger than those in the entrance channel. Computed tidal currents coincide with the field measurements. The horizontal and vertical velocities of tidal and residual currents are strong in the entrance channel of the bay, whereas the velocities are relatively weak in the western and northern parts of the bay. Computed velocity fields show the expected phase difference between the velocities in the surface and those in the bottom layer, and these characteristics are more remarkable during the spring tide than the neap tide. The surface currents in the bay depend strongly on the wind and river inflow, and such phenomena are more remarkable during the neap tide than the spring tide.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.6
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• pp.425-434
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• 2019

It is important to ensure the seismic safety of pile-bent bridges constructed in areas with thick soft ground consisting of various soil layers against seismic motion in these layers. In this study, several synthetic seismic waves that are compatible with the seismic design spectrum for rock sites were generated, and the ground acceleration history of each soil layer was obtained based on ground analyses. Using these acceleration histories, each soil layer was modeled using equivalent linear springs, and multi-support excitation analyses were performed using the input motion obtained at each soil layer. Due to the nonlinear behavior of the soft soil layers, the intensity of the input ground motion was not amplified, which resulted in the elastic behavior of the bridge. In addition, inputting the acceleration history obtained from a particular layer simultaneously into all the ground springs reduced the response. Therefore, the seismic performance of this type of bridge might be overestimated if multi-excitation analysis is not performed.

• Computers and Concrete
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• v.18 no.5
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• pp.1053-1063
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• 2016

As concrete is most usable material in construction industry it's been required to improve its quality. Nowadays, nanotechnology offers the possibility of great advances in construction. For the first time, the nonlinear buckling of straight concrete columns armed with single-walled carbon nanotubes (SWCNTs) resting on foundation is investigated in the present study. The column is modelled with Euler-Bernoulli beam theory. The characteristics of the equivalent composite being determined using the Mori-Tanaka model. The foundation around the column is simulated with spring and shear layer. Employing nonlinear strains-displacements, energy methods and Hamilton's principal, the governing equations are derived. Differential quadrature method (DQM) is used in order to obtain the buckling load of structure. The influences of volume percent of SWCNTs, geometrical parameters, elastic foundation and boundary conditions on the buckling of column are investigated. Numerical results indicate that reinforcing the concrete column with SWCNTs, the structure becomes stiffer and the buckling load increases with respect to concrete column armed with steel.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.458-467
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• 2012

In this study, the linear viscoelastic response of a rectangular laminated plate is investigated. The viscoelastic properties, expressed by two basic spring-dashpot models, that is Kelvin and Maxwell models, is assumed in the range to investigate the influence of viscoelastic coefficients to mechanical behavior. In the present study, viscoelastic responses are performed for two popular equivalent single-layered theories, such as the first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT). Compliance and relaxation modulus of time-dependent viscoelastic behavior are approximately determined by Prony series. The constitutive equation for linear viscoelastic material as the Boltzmann superposition integral equation is simplified by the convolution theorem of Laplace transformation to avoid direct time integration as well as to improve both accuracy and computational efficiency. The viscoelastic responses of composite laminates in the real time domain are obtained by applying the inverse Laplace transformation. The numerical results of viscoelastic phenomena such as creep, cyclic creep and recovery creep are presented.

• Atmosphere
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• v.14 no.4
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• pp.3-18
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• 2004

Neglecting the vertical transport from the surface, most of the previous studies on the long-range transport of pollutants have only considered the horizontal transport caused by the free atmosphere wind. I used a three dimensional numerical model, MM5 (The fifth generation Penn State Univ./NCAR Mesoscale Model) for the simulation of vertical transport of pollutants and investigated the mechanism of the vertical transport of atmospheric pollutants between planetary boundary layer(PBL) and free atmosphere by fronts. From the three dimensional simulation of MM5, the amount of pollutants transport from PBL to free atmosphere is 48% within 18 hour after the development of front, 55% within 24 hour, and 53% within 30 hour. The ratios of the vertically transported pollutant for different seasons are 62%, 60%, 54%, and 43% for spring, summer, fall, and winter, respectively. The most active areas for the vertical transport are the center of low pressure and the warm sector located east side of cold front, in which the strong upward motion slanted northward occurs. The horizontal advection of pollutants at the upper level is stronger than at the lower level simply because of the stronger wind speed. The simulation results shows the well known plum shape distribution of pollutants. The high concentration area is located in the center and north of the low pressure system, while the second highest concentration area is in the warm sector. It is shown that the most important mechanism for the vertical transport is vertical advection, while the vertical diffusion process plays an important role in the redistribution of pollutants in the PBL.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.1
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• pp.31-42
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• 2000

The dry deposition velocities and fluxes of air pollutants such as SO2(g), O3(g), HNO3(g), sub-micron particulates, NO3(s), and SO42-(s) were estimated according to local meteorological elements in the atmospheric boundary layer. The model used for these calculations was the multiple layer resistance model developed by Hicks et al.1). The meteorological data were recorded on an hourly basis from July, 1990 to June, 1991 at the Austin Cary forest site, near Gainesville FL. Weekly integrated samples of ambient dry deposition species were collected at the site using triple-fiter packs. For the study period, the annual average dry deposition velocities at this site were estimated as 0.87$\pm$0.07 cm/s for SO2(g), 0.65$\pm$0.11 cm/s for O3(g), 1.20$\pm$0.14cm/s for HNO3(g), 0.0045$\pm$0.0006 cm/s for sub-micron particulates, and 0.089$\pm$0.014 cm/s for NO3-(s) and SO42-(s). The trends observed in the daily mean deposition velocities were largely seasonal, indicated by larger deposition velocities for the summer season and smaller deposition velocities for the winter season. The monthly and weekly averaged values for the deposition velocities did not show large differences over the year yet did show a tendency of increased deposition velocities in the summer and decreased values in the winter. The annual mean concentrations of the air pollutants obtained by the triple filter pack every 7 days were 3.63$\pm$1.92 $\mu\textrm{g}$/m3 for SO42-, 2.00$\pm$1.22 $\mu\textrm{g}$/m-3 for SO2, 1.30$\pm$0.59 $\mu\textrm{g}$/m-3 for HNO3, and 0.704$\pm$0.419 $\mu\textrm{g}$/m3 for NO3-, respectively. The air pollutant with the largest deposition flux was SO2 followed by HNO3, SO42-(S), and NO3-(S) in order of their magnitude. The sulfur dioxide and NO3- deposition fluxes were higher in the winter than in the summer, and the nitric acid and sulfate deposition fluxes were high during the spring and summer.

• Journal of the Korean earth science society
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• v.42 no.6
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• pp.605-622
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• 2021

Seasonal forecasting has numerous socioeconomic benefits because it can be used for disaster mitigation. Therefore, it is necessary to diagnose and improve the seasonal forecast model. Moreover, the model performance is partly related to the ocean model. This study evaluated the hindcast performance in the upper ocean of the Global Seasonal Forecasting System version 5-Global Couple Configuration 2 (GloSea5-GC2) using a multivariable integrated evaluation method. The normalized potential temperature, salinity, zonal and meridional currents, and sea surface height anomalies were evaluated. Model performance was affected by the target month and was found to be better in the Pacific than in the Atlantic. An increase in lead time led to a decrease in overall model performance, along with decreases in interannual variability, pattern similarity, and root mean square vector deviation. Improving the performance for ocean currents is a more critical than enhancing the performance for other evaluated variables. The tropical Pacific showed the best accuracy in the surface layer, but a spring predictability barrier was present. At the depth of 301 m, the north Pacific and tropical Atlantic exhibited the best and worst accuracies, respectively. These findings provide fundamental evidence for the ocean forecasting performance of GloSea5.

• Journal of the Korea Convergence Society
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• v.10 no.3
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• pp.395-400
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• 2019

The Web environment of the frontend domain is increasingly competitive to preempt the new standard of presentation layer. N-Screen, a service that enables users to seamlessly use one content in various devices in Korea, is competing for market preemption by recognizing it as a core service of the future. In the cloud computing, N-screen is a typical service type. However, most of the frontend research required for groupware in enterprise environments has been limited to responsive web design for the web and native apps for mobile. Gradually, the need for MVC design patterns is increasingly widening in enterprise environments to overcome the cultural differences of companies and to support one source multi-use strategy supporting multiple devices and development productivity. Therefore, in this study, we will analyze and design JPetStore with hybrid application design based on Spring MVC, e-government standard framework environment of next generation web standard, and provide reference model of frontend hybrid apps design in future enterprise environment.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1542-1549
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• 2011

The Transitional zone between bridge abutment and earthwork is one of the representative vulnerable zones in railway where differential settlements may take place due to the different supportive stiffness. Although transitional zones are managed with stricter standards than those of the other earthwork zones either in the design and construction stages, it is very difficult to prevent differential settlement perfectly. A three-dimensional numerical analyses were performed by applying train moving load in this study. The analytical model including abutments and earthwork zones was constituted with rail, sleepers, track concrete layer (TCL), hydraulic stabilized base (HSB), reinforced road bed, and road bed using railway and road base structure. The clamp connecting the rail and sleeper were also modeled as the element with spring coefficient. The train wheel is modeled in the actual size and moved on the rail with 300 km/hr speed. The deformation characteristics at each point of the rail and the ground were considered in detail when moving the train wheel. The analysis results were compared with those from the two-dimensional analysis without considering moving load. The research results show that displacement and stress were greater in the three-dimensional analysis than in other analyses, and the three-dimensional analysis with moving load should be performed to evaluate railway performance.

• Structural Engineering and Mechanics
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• v.73 no.2
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• pp.209-223
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• 2020

This paper investigates the buckling behavior of carbon nanotube-reinforced composite plates supported by Kerr foundation model. In this foundation elastic of Kerr consisting of two spring layers interconnected by a shearing layer. The plates are reinforced by single-walled carbon nanotubes with four types of distributions of uniaxially aligned reinforcement material. The analytical equations are derived and the exact solutions for buckling analyses of such type's plates are obtained. The mathematical models provided, and the present solutions are numerically validated by comparison with some available results in the literature. Effect of various reinforced plates parameters such as aspect ratios, volume fraction, types of reinforcement, parameters constant factors of Kerr foundation and plate thickness on the buckling analyses of carbon nanotube-reinforced composite plates are studied and discussed.