• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.33-40
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• 2012

This paper proposes a method to implement biological early warning systems(BEWS). This system generates periodically data event using a monitoring daemon and it extracts the feature parameters from this data sets. The feature parameters are derived with 6 variables, x/y coordinates, distance, absolute distance, angle, and fractal dimension. Specially by using the fractal dimension theory, the proposed algorithm define the input features represent the organism characteristics in non-toxic or toxic environment. And to find a moderate algorithm for learning the extracted feature data, the system uses an extended learning algorithm(UChoo) popularly used in machine learning. And this algorithm includes a learning method with the extended data expression to overcome the BEWS environment which the feature sets added periodically by a monitoring daemon. In this algorithm, decision tree classifier define class distribution information using the weight parameter in the extended data expression. Experimental results show that the proposed BEWS is available for environmental toxicity detection.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.1-12
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• 1994

This paper deals with the time-dependent analysis of reinforced and prestressed concrete beams. Based on the age-adjusted effective modulus method, the structural behavior in accordance with time is analyzed using the force equilibrium and strain compatibility condition within a typical section. Unlike most of presented approaches adopting some assumptions, such as non-cracking of concrete and consideration of steel effect as a transformed concrete area only, more accurate results can be obtained at all loading conditions since all materials are considered together so as to be maintained their given properties and the cracking effect is included at the same time. Several parameter studies are conducted with the objective to identify the significance of various effects on the time-dependent response of concrete members, i.e., stress re-distribution of each material and occurrance of long-term deflection, etc. Moreover, the obtained results can be used at design and/or construction stage for the purpose of more accurate prediction of structural response with time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.287-295
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• 2013

This paper developed advanced gravity model for higher estimation accuracy, that deals with residuals. Previously studied paper using gravity model's residual, residual calculated that observed O-D value minus derived O-D value from gravity model, and this residual added to the target year's estimated value from gravity model. In this paper, residuals calculated on gravity model parameter estimation process, and this residual is revealed the same value that observed O-D value devided by derived O-D value from gravity model. And case study resulted that developed new gravity model that applied accordance rate of observed O-D value and derived O-D value from gravity model has higher estimation accuracy than other gravity models as basic gravity model and residual plused gravity model.

• Korean Journal of Ichthyology
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• v.32 no.2
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• pp.55-62
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• 2020

The Relative weight index is an index for evaluating nutritional condition of fish by calculating a ratio of observed weight to standard weight. The purpose of this study is estimating standard Length-Weight relationships (standard LWRs) to calculate standard weight for application of relative weight index and analyze frequency distribution of relative weight index of 10 freshwater fish in the South Korea. The standard LWRs for each species was calculated by the Length-Weight data sets from 798 times of captures at 141 sites. The correlation of determination (r²) for all species was over 0.9 and values of parameter b were within the expected range according to Froese (2006). We calculated in increments of 10 from 10 to 90 percentile of relative weight index for each species, and it could be used as a standard for quantitative assessment of nutritional condition of freshwater fish.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.4
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• pp.245-256
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• 2016

In the companion paper (I - Database and Site Response Analyses), site-specific response analyses were performed at more than 300 domestic sites. In this study, a new site classification system and design response spectra are proposed using results of the site-specific response analyses. Depth to bedrock (H) and average shear wave velocity of soil above the bedrock ($V_{S,Soil}$) were adopted as parameters to classify the sites into sub-categories because these two factors mostly affect site amplification, especially for shallow bedrock region. The 20 m of depth to bedrock was selected as the initial parameter for site classification based on the trend of site coefficients obtained from the site-specific response analyses. The sites having less than 20 m of depth to bedrock (H1 sites) are sub-divided into two site classes using 260 m/s of $V_{S,Soil}$ while the sites having greater than 20 m of depth to bedrock (H2 sites) are sub-divided into two site classes at $V_{S,Soil}$ equal to 180 m/s. The integration interval of 0.4 ~ 1.5 sec period range was adopted to calculate the long-period site coefficients ($F_v$) for reflecting the amplification characteristics of Korean geological condition. In addition, the frequency distribution of depth to bedrock reported for Korean sites was also considered in calculating the site coefficients for H2 sites to incorporate sites having greater than 30 m of depth to bedrock. The relationships between the site coefficients and rock shaking intensity were proposed and then subsequently compared with the site coefficients of similar site classes suggested in other codes.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.2
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• pp.125-135
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• 2005

Generation and transport of nonpoint source pollution, especially sediment-associated pollutants, are profoundly influenced by hydrologic features of runoff. In order to identify pollutant export rates, hence, clear knowledge of rainfall-runoff relationship is a pre-requisition. In this study, performance of AnnAGNPS model was assessed based on the ability of the model to predict rainfall-runoff relationship. Three catchments, each under different nearly single land use, were simulated. From the results, it was found that the model was likely to produce better predictions for larger catchments than smaller catchments. Because of using the daily time scale, the model could not account for short durations less than 24 hours, especially high intensity events with multiple peak flow that significantly contribute to the generation and transport of pollutants. Since CN information for regional areas has not been built up, a careful selection of CN is needed to achieve accurate prediction of runoff volume. Storm distribution also found to be considered as an important calibration parameter for the hydrologic simulation.

• Structural Engineering and Mechanics
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• v.73 no.2
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• pp.191-207
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• 2020

This study aims at investigating the size-dependent free vibration of porous nanoplates when exposed to hygrothermal environment and rested on Kerr foundation. Based on the modified power-law model, material properties of porous functionally graded (FG) nanoplates are supposed to change continuously along the thickness direction. The generalized nonlocal strain gradient elasticity theory incorporating three scale factors (i.e. lower- and higher-order nonlocal parameters, strain gradient length scale parameter), is employed to expand the assumption of second shear deformation theory (SSDT) for considering the small size effect on plates. The governing equations are obtained based on Hamilton's principle and then the equations are solved using an analytical method. The elastic Kerr foundation, as a highly effected foundation type, is adopted to capture the foundation effects. Three different patterns of porosity (namely, even, uneven and logarithmic-uneven porosities) are also considered to fill some gaps of porosity impact. A comparative study is given by using various structural models to show the effect of material composition, porosity distribution, temperature and moisture differences, size dependency and elastic Kerr foundation on the size-dependent free vibration of porous nanoplates. Results show a significant change in higher-order frequencies due to small scale parameters, which could be due to the size effect mechanisms. Furthermore, Porosities inside of the material properties often present a stiffness softening effect on the vibration frequency of FG nanoplates.

• Steel and Composite Structures
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• v.35 no.5
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• pp.671-685
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• 2020

This manuscript presents impacts of gradation of material functions and axial load functions on critical buckling loads and mode shapes of functionally graded (FG) thin and thick beams by using higher order shear deformation theory, for the first time. Volume fractions of metal and ceramic materials are assumed to be distributed through a beam thickness by both sigmoid law and symmetric power functions. Ceramic-metal-ceramic (CMC) and metal-ceramic-metal (MCM) symmetric distributions are proposed relative to mid-plane of the beam structure. The axial compressive load is depicted by constant, linear, and parabolic continuous functions through the axial direction. The equilibrium governing equations are derived by using Hamilton's principles. Numerical differential quadrature method (DQM) is developed to discretize the spatial domain and covert the governing variable coefficients differential equations and boundary conditions to system of algebraic equations. Algebraic equations are formed as a generalized matrix eigenvalue problem, that will be solved to get eigenvalues (buckling loads) and eigenvectors (mode shapes). The proposed model is verified with respectable published work. Numerical results depict influences of gradation function, gradation parameter, axial load function, slenderness ratio and boundary conditions on critical buckling loads and mode-shapes of FG beam structure. It is found that gradation types have different effects on the critical buckling. The proposed model can be effective in analysis and design of structure beam element subject to distributed axial compressive load, such as, spacecraft, nuclear structure, and naval structure.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.174-179
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• 2017

Soil parameters are required inputs to crop models, which estimate crop yield under a given environment condition. The Korean Soil Information System (KSIS), which provides detailed soil profile record of 390 soil series in the HTML (HyperText Markup Language) format, would be useful to prepare soil input files. Korean Soil Information System Processing Tool (KSISPT) was developed to aid generation of soil input data based on the KSIS database. Java was used to implement the tool that consists of a set of modules for parsing the HTML document of the KSIS, storing data required for preparing soil input file, calculating additional soil parameter, and writing soil input file to a local disk. Using the automated soil data preparation tool, about 940 soil input data were created for the DSSAT model and the ORYZA 2000 model, respectively. In combination with soil series distribution map at 30m resolution, spatial analysis of crop yield could be projected under climate change, which would help the development of adaptation strategies.

• Earthquakes and Structures
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• v.12 no.3
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• pp.333-347
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• 2017

Masonry infill walls are unavoidable parts of any building to create a separation between internal space and external environment. In general, there are some prevalent openings in the infill wall due to functional needs, architectural considerations or aesthetic concerns. In current design practice, the strength and stiffness contribution of infill walls is not considered. However, the presence of infill walls may decisively influence the seismic response of structures subjected to earthquake loads and cause a different behavior from that predicted for a bare frame. Furthermore, partial openings in the masonry infill wall are significant parameter affecting the seismic behavior of infilled frames thereby decreasing the lateral stiffness and strength. The possible effects of openings in the infill wall on seismic behavior of RC frames is analytically studied by means of pushover analysis of several bare, partially and fully infilled frames having different bay and story numbers. The stiffness loss due to partial opening is introduced by the stiffness reduction factors which are developed from finite element analysis of frames considering frame-infill interaction. Pushover curves of frames are plotted and the maximum base shear forces, the yield displacement, the yield base shear force coefficient, the displacement demand, interstory drift ratios and the distribution of story shear forces are determined. The comparison of parameters both in terms of seismic demand and capacity indicates that partial openings decisively influences the nonlinear behavior of RC frames and cause a different behavior from that predicted for a bare frame or fully infilled frame.