• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.468-470
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• 2007

This paper is to present an approach for generating coarse resolution (MODIS data) fraction images of forested region in Korea peninsula using forest type area fraction derived from high resolution data (ASTER data) in regional forest area. A 15-m spatial resolution multi-spectral ASTER image was acquired under clear sky conditions on September 22, 2003 over the forested area near Seoul, Korea and was used to select each end-member that represent a pure reflectance of component of forest such as different forest, bare soil and water. The area fraction of selected each end-member and a 500-m spatial resolution MODIS reflectance product covering study area was applied to a linear mixture inversion model for calculating the fraction image of forest component across the South Korea. We found that the area fraction values of each end-member observed from high resolution image data could be used to separate forest cover in low resolution image data.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.2
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• pp.60-72
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• 1992

This study aims at predicting the behavior of saturated soft clayey foundation subjected to earth structure loads such as tidal dike, embankment etc. by using Biot's consolidation equation coupled with elasto-viscoplastic constitutive model. To validate the computer program developed b author, a case study was performed for the site of Kwang-yang steel works improved by sand drain, where since the beginning of the works, field measurements(settlement, lateral displacement and excess pore water pressure) had been accurately achieved. Comparisons between numerical results and observation values were carried out. The main results obtained are summarized as follows : 1. Settlement and lateral displacement between numerical and observation values show satisfactory accordance. 2. As for the exess pre water pressure, numerical results appear to be larger than observation values, which may be due to the existence of sand seams which were not found during soil investigation. 3. Useful data available for failure prediction of soft foundation can be secured by examining lateral displacement, settlement, exess pore water pressure and stress paths.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1262-1266
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• 2004

The current combining of computer and geographic information technology. The result of such research oil determinate objective factors of hydrologic-topographical parameters through joining hydrology and GIS(Geographic Information System). In this study, we wish to offer the base data to determinate hydrologic-topographical parameters request of runoff model analysis in this basin. First, we computed the CN(curve number) by using GIS, and then classify the digital map of soil group and landuse on the Sulma river basin. Second, we used Avenue Script to calculate the height of efficient GIS work before using the Clark model to work out flood runoff flow.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.4
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• pp.405-413
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• 2010

The vibration characteristics of fully and partially embedded piles with flexibly supported end carrying an eccentric tip mass are investigated. The pile model is based on the Bernoulli-Euler theory and the soil is idealized as a Winkler model for mathematical simplicity. The governing differential equations for the free vibrations of such members are solved numerically using the corresponding boundary conditions. The lowest three natural frequencies and corresponding mode shapes are calculated over a wide range of non-dimensional system parameters: the rotational spring parameter, the relative stiffness, the embedded ratio, the mass ratio, the dimensionless mass moment of inertia, and the tip mass eccentricity.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.412-419
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• 2002

This paper presents a parametric study on the behavior of integral abutment PSC beam bridge. An integral abutment bridge is a simple span or multiple span continuous deck type bridge having the deck integral with the abutment wall. The rational structural model and design load combinations accounting for each construction stage are proposed. It can be used for defining the effect of earth pressure and temperature change in the design process including for determining maximum flexural responses. The bending moment at each response location due to the design load combination is investigated according to the change of flexural rigidity of piles and abutment height. The flexural responses of proposed model are computed for the cases of applying the Rankine passive earth pressure and the earth pressure based on the soil-structure interaction respectively, and the results are discussed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.454-461
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• 2001

Dynamic responses of a multi-span simply supported bridge are examined under seismic excitations considering damage of bearings. An idealized mechanical model which can consider components such as pounding, friction at the supports, abutment-soil interaction, rotational and translational motions of foundations, and the nonlinear pier motions, is developed to analyze the effects due to damage of bearings. It is assumed that the bearing's response after failure can be expressed with a sliding model with a friction coefficient between the superstructure and the pier top. It is found that the global seismic behaviors are significantly influenced by the damage of bearings and the damage of bearings may lead to unseating failure at unpredicted supports. Therefore, It can be concluded that detailed seismic response analyses of bridge systems considering damage of bearings is required for the purpose of the seismic safety evaluation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.78-83
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• 2007

The paper focuses on the establishment of optimized bucket path planning and trajectory control designated for force-reflecting backhoe reacting to excavation environment, such as potential obstacles and ground characteristics. The developed path planning method can be used for precise bucket control, and more importantly for obstacle avoidance which is directly related to safety issues. The platform of this research was based on conventional papers regarding the kinematic model of excavator. Jacobian matrix was constructed to find optimal joint angles and rotation angles of bucket from position and orientation data of excavator. By applying Newton-Raphson method optimal joint angles and bucket orientation were derived simultaneously in the way of minimizing positional errors of excavator. The model presented in this paper was intended to function as a cornerstone to build complete and advanced path planning of excavator by implementing soil mechanics and further study of excavator dynamics together.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42
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• pp.38-49
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• 2000

Two application rates (9 and 18 t/ha) of poultry litter and a recommended rate of commercial fertilizer were studied to determine their effects on nutrient (N and P) losses in surface and subsurface runoff and loadings in soil layers from conventionally-tilled com by the treatments. The model predicted higher sediment losses than observed data from all treatments. The overpredicted sediment losses resulted in overprediction of organic-N and sediment-P losses in surface runoff. Simulated soluble-P losses in surface runoff were close to observed data, while NO3-N losses in surface runoff were underpredicted from all treatments. Observed NO3-N concentrations in leachate at 1.0-m depth from commercial fertilizer treatment were fairly well predicted. But the concentratins were overpredicted from poultry litter treatments due to high simulation of organic-N mineralization simulated by the model.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.1
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• pp.39-53
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• 1994

To investigate the behaviour of the embankment on very soft foundation reinforced geotex- files,the laboratory model test in order to analyze the elementary effects of geotextile reinfor- cement and the finite element program analyzing the stresses and deformations characteristics was carried out. A two-dimensional nonlinear finite element program called GEOTEXT(a modification of ISBILD) for the static analysis of embankment on very soft foundation reinforced geotextiles has been developed. Both linear and nonlinear hyperbolic stress-strain soil models are inclu- ded, and incremental and stage construction can be simulated. However, the program GEO- TEXT is not developed herein as an adaptable design tool for practicing engineer. It was found that the geotextile reinforcement significantly reduced the shear stresses in the foundation and decreased the vertical differential settlements at the top of the embank- ment. This influence was more pronounced as the tensile strength of the geotextile was increased.

• Environmental Analysis Health and Toxicology
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• v.21 no.3 s.54
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• pp.239-244
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• 2006

Caenorhabditis elegans(C. elegans) is a free-living soil nematode that commonly used as a biological model and recently, much work has been done using C. elegans as a toxicity model. To evaluate the acute toxicity of phenols to C. elegans, worms were subsequently exposed to nine different xenobiotics. This study described lethal toxicity, reproductive toxicity and movement inhibition using 2-propylphenol, 4-propylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-phenylphenol, 4-phenylphenol, nonylphenol and 4-dodecylphenol to C. elegans for 24 hr or 72 hr. We found that phenols used in this study were very toxic to C. elegans. The order of lethal toxicity, reproductive toxicity and movement inhibition is as follows. 4-propylphenol > 2-phenylphenol > 2-tert-butylphenol > 2-propylphenol > nonylphenol > B-tert-butylphenol > 4-dodefylphenol > 4-tert-butylphenol > 4-phenylphenol.