• KIEAE Journal
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• v.12 no.3
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• pp.53-60
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• 2012

This research is an illustrative research to verify the thermo environmental change created after introduction of indoor pond through abridged model test and simulation analysis. Especially, temperature and comfort level are analyzed by adjusting factors like size of water space, distance length, and location. Summary of the research is as follows. First, the most effective size of water space is 7% of the indoor size, from southern side. Temperature reduction effect is about $1.6^{\circ}C$(5.5%), and for the comfort level, it is found that pmv index increases 8%. Second, based on the simulation of distance length with the sphere, it is more effective as it is close to the surface. If distance length is more than 0.5m, there is no effect on reduction of temperature and comfort level of indoor environment. Lastly, for the analysis by location of the introduced water space, simulation is undertaken by dividing the water space (14% of the indoor size) with front, side, rear and center types. Temperature reduction effect is found to be : front type ($-1.53^{\circ}C$), side type ($-0.82^{\circ}C$), rear type ($-0.44^{\circ}C$), center type ($-0.28^{\circ}C$), respectively. The indoor environment change data by introduction of water space, found in this research, is at initial phase, but it is deemed to be a basic data to refer when planning actual water space.

• Journal of Multimedia Information System
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• v.8 no.2
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• pp.101-110
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• 2021

In computer vision, single-image super resolution has been an area of research for a significant period. Traditional techniques involve interpolation-based methods such as Nearest-neighbor, Bilinear, and Bicubic for image restoration. Although implementations of convolutional neural networks have provided outstanding results in recent years, efficiency and single model multi-scalability have been its challenges. Furthermore, previous works haven't placed enough emphasis on real-number scalability. Interpolation-based techniques, however, have no limit in terms of scalability as they are able to upscale images to any desired size. In this paper, we propose a convolutional neural network possessing the advantages of the interpolation-based techniques, which is also efficient, deeming it suitable in practical implementations. It consists of convolutional layers applied on the low-resolution space, post-up-sampling along the end hidden layers, and additional layers on high-resolution space. Up-sampling is applied on a multiple channeled feature map via bicubic interpolation using a single model. Experiments on architectural structure, layer reduction, and real-number scale training are executed with results proving efficient amongst multi-scale learning (including scale multi-path-learning) based models.

• Journal of Environmental Science International
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• v.12 no.9
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• pp.977-986
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• 2003

In this study, the scenario for a numerical modeling of the fine grid scale air dispersion phenomena was proposed and an analysis of the special event which was occurred on September 3, 2002 was performed using by a coarse grid prognostic meteorological model, a fine grid diagnostic meteorological model and a fine grid air dispersion model. Based on the results, we found that the local circulations, like as land-sea breeze, should be seriously considered for evaluating the high PM10 concentration event and for making the reduction policy of the major air pollutant emissions in Ansan area.

• Journal of the Korean Data and Information Science Society
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• v.27 no.6
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• pp.1645-1651
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• 2016

A lot of data, particularly in the medical field, contain variables that have a measurement error such as blood pressure and body mass index. On the other hand, recently smoothing methods are often used to solve a complex scientific problem. In this paper, we study a Bayesian curve-fitting under functional measurement error model. Especially, we extend our previous model by incorporating covariates free of measurement error. In this paper, we consider penalized splines for non-linear pattern. We employ a hierarchical Bayesian framework based on Markov Chain Monte Carlo methodology for fitting the model and estimating parameters. For application we use the data from the fifth wave (2012) of the Korea National Health and Nutrition Examination Survey data, a national population-based data. To examine the convergence of MCMC sampling, potential scale reduction factors are used and we also confirm a model selection criteria to check the performance.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.47-57
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• 2010

Subgrid scale stabilization method is applied to Woo and Liu(2004)'s extended Boussinesq FEM numerical model to eliminate the 2dx wiggles. In order to optimize the computational efficiency, Hessian operator is introduced and the matrix of velocity vector is combined to one matrix for solving matrix equations. The mass lumping technique is also applied to the matrix equations of auxiliary variables. The newly developed code is applied to simulate Vincent and Briggs(1989)' wave transformation experiments and the results show that the numerical solution is almost wiggle-free and it matches very well with experimental data. Due to improvement of computational efficiency and wiggle reduction, it is plausible to apply this model to a realistic problem such as harbor oscillation problems.

• Geomechanics and Engineering
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• v.17 no.1
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• pp.81-95
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• 2019

Due to the importance of soil reinforcement using geotextiles in geotechnical engineering, study and investigation into long-term performance, design life and survivability of geotextiles, especially due to installation damage are necessary and will affect their economy. During installation, spreading and compaction of backfill materials, geotextiles may encounter severe stresses which can be higher than they will experience in-service. This paper aims to investigate the installation damage of geotextiles, in order to obtain a good approach to the estimation of the material's strength reduction factor. A series of full-scale tests were conducted to simulate the installation process. The study includes four deliberately poorly-graded backfill materials, two kinds of subgrades with different CBR values, three nonwoven needle-punched geotextiles of classes 1, 2 and 3 (according to AASHTO M288-08) and two different relative densities for the backfill materials. Also, to determine how well or how poorly the geotextiles tolerated the imposed construction stresses, grab tensile tests and visual inspections were carried out on geotextile specimens (before and after installation). Visual inspections of the geotextiles revealed sedimentation of fine-grained particles in all specimens and local stretching of geotextiles by larger soil particles which exerted some damage. A regression model is proposed to reliably predict the installation damage reduction factor. The results, obtained by grab tensile tests and via the proposed models, indicated that the strength reduction factor due to installation damage was reduced as the median grain size and relative density of the backfill decreases, stress transferred to the geotextiles' level decreases and as the as-received grab tensile strength of geotextile and the subgrades' CBR value increase.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.303-314
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• 2009

The present paper shows the results of numerical and experimental modal analyses of Francis runners, which were executed in air and in still water. In its first part this paper is focused on the numerical prediction of the model parameters by means of FEM and the validation of the FEM method. Influences of different geometries on modal parameters and frequency reduction ratio (FRR), which is the ratio of the natural frequencies in water and the corresponding natural frequencies in air, are investigated for two different runners, one prototype and one model runner. The results of the analyses indicate very good agreement between experiment and simulation. Particularly the frequency reduction ratios derived from simulation are found to agree very well with the values derived from experiment. In order to identify sensitivity of the structural properties several parameters such as material properties, different model scale and different hub geometries are numerically investigated. In its second part, a harmonic response analysis is shown for a Francis runner by applying the time dependent pressure distribution resulting from an unsteady CFD simulation to the mechanical structure. Thus, the data gained by modern CFD simulation are being fully utilized for the structural design based on life time analysis. With this new approach a more precise prediction of turbine loading and its effect on turbine life cycle is possible allowing better turbine designs to be developed.

• Computers and Concrete
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• v.9 no.4
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• pp.245-255
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• 2012

The damping effect of a Concrete-filled Rectangular Steel Tube (CRST) frame structure is studied in this paper. Viscous dampers are employed to insure the function of the building especially subjected to earthquakes, for some of the main vertical elements of the building are not continuous. The shaking table test of a 1:15 scale model was conducted under different earthquake excitations to recognize the seismic behavior of this building. And the vibration damping effect was also investigated by the shaking table test and the simulation analysis. The nonlinear time-history analysis of the shaking table test model was carried out by the finite element analysis program CANNY. The simulation model was constructed in accordance with the tested one and was analyzed under the same loading condition and the simulation effect was then validated by the tested results. Further more, the simulation analysis of the prototype structure was carried out by the same procedure. Both the simulated and tested results indicate that there are no obvious weak stories on the damping equipped structure, and the dampers can provide the probability of an irregular CRST frame structure to meet the requirements of the design code on energy dissipation and deformation limitation.

• Korea Trade Review
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• v.47 no.5
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• pp.147-160
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• 2022

This study aim to use the GTAP model to analyze the impact of RCEP Fermentation in the Korean manufacturing industry by quantifying the RCEP tariff commitment table. The research results show RCEP has boosted output in all sub-manufactures except wood and printed matter due to increased export volumes. Wood products, on the other hand, are more reliant on imports due to lower production due to lower domestic sales or overall exports. After RCEP came into effect, the import and export scale of Korea's manufacturing industry expanded effectively. Among them, the positive impact on the intensive low-tech manufacturing industries such as clothing and leather products, wood products and printing products, and food, beverage and tobacco products is greater than the positive impact on the technology-intensive medium and high-tech and high-tech manufacturing industries. And found that the growth rate of Korea's manufacturing trade is basically proportional to the tax reduction rate of RCEP. Finally, in order to promote the development of the manufacturing industry, some suggestions are put forward that need the government's policy support and strengthen the regional cooperation with RCEP member countries.

• Structural Engineering and Mechanics
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• v.73 no.6
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• pp.685-698
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• 2020

The dynamic stability of a functionally graded polymer microbeam reinforced by graphene oxides subjected to a periodic axial force is investigated. The microbeam is assumed to rest on an elastic substrate and is subjected to various immovable boundary restraints. The weight fraction of graphene oxides nanofillers is graded across the beam thickness. The effective Young's modulus of the functionally graded graphene oxides reinforced composite (FG-GORC) was determined using modified Halpin-Tsai model, with the mixture rule used to evaluate the effective Poisson's ratio and the mass density. An improved third order shear deformation theory (TSDT) is used in conjunction with the Chebyshev polynomial-based Ritz method to derive the Mathieu-Hill equations for dynamic stability of the FG-GORC microbeam, in which the scale effect is taken into account based on modified couple stress theory. Then, the Mathieu-Hill equation was solved using Bolotin's method to predict the principle unstable regions of the FG-GORC microbeams. The numerical results show the effects of the small scale, the graphene oxides nanofillers as well as the elastic substrate on the dynamic stability behaviors of the FG-GORC microbeams.