• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.208-213
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• 2010

This paper deal with an analysis of the ground surface potential profiles using a hemispherical scaled-model. Because it is very difficult to draw valid conclusions concerning a general grounding problem from actual field data, scale model tests can be used to determine the ground surface potential profile around the grounding electrodes according to the configuration of grounding electrodes. In this work, a hemispherical vessel with a diameter of 1,100 [mm] was employed to simulate uniform soil and CDEGS program was employed to compare the measured and simulated results. As a result, the ground surface potential around the grounding electrode was significantly raised and the ground surface potential at the just upper point of ground electrode particularly was higher than other points. The ground surface potential of counterpoise was higher than other grounding electrodes such as mesh and grounding rods and the ground surface potential strongly depends on the frequency responses of grounding electrodes. Also the results measured with the small-sized model were in reasonably agreement with the data obtained from simulation.

• Geomechanics and Engineering
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• v.8 no.6
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• pp.769-781
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• 2015

The skin friction of a pile foundation is important and essential for its design and analysis. More attention has been given to the softening behaviour of skin friction of a pile. In this study, to investigate the load-transfer mechanism in such a case, an analytical solution using a nonlinear softening model was derived. Subsequently, a load test on the pile was performed to verify the newly developed analytical solution. The comparison between the analytical solution and test results showed a good agreement in terms of the axial force of the pile and the stress-strain relationship of the pile-soil interface. The softening behaviour of the skin friction can be simulated well when the pile is subjected to large loads; however, such behaviour is generally ignored by most existing analytical solutions. Finally, the effects of the initial shear modulus and the ratio of the residual skin friction to peak skin friction on the load-settlement curve of a pile were investigated by a parametric analysis.

• Water for future
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• v.29 no.6
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• pp.237-247
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• 1996

In this study two rainfall-runoff models, the NWS-PC model and the Storage Function Model (SFM), were compared to see their applicability in the flood forecasting at the river system. The SFM has been adopted in the flood-forecasting and warning system for the major rivers in Korea since 1974, and the NWS-PC model, a physically based model, has been developed to simulate soil moisture changing as well as the surface and subsurface flow at the watershed and in the river streams. Case studies were carried out using flood event data observed at the Mihochun watershed in Geum-river basin during 1985 to 1995. Simulated results from both models were compared with the observed data with respect to the RMS errors and relative errors for peak flow discharges and total runoff volumes to show the advantages and disadvantages of both models and to suggest the way to improve their performances.

• Geotechnical Engineering
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• v.14 no.2
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• pp.79-92
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• 1998

Parametric studies based on laboratory pilot tests were performed to investigate the relationships between electrical resistivity and properties of contaminated soils. Three kinds of sandy soils sampled and leachate from an industrial waste landfill were mired to model the contaminated soils. Electrical resistivity of soils was measured by using a simulated resistivity cone penetrometer probe. In the experiments. the electrical resistivity was observed by changing the water content, void ratio, unit weight, degree of saturation, and concentration of the leachate. The test results show that the electrical resistivity of soils depends largely on the water content and the electrical property of pore water rather than unit weight and types of soils.

• Journal of Korean Society on Water Environment
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• v.25 no.3
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• pp.375-385
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• 2009

The estimation of delivery ratio is a essential part of Korean Total Maximum Daily Loads (TMDL) procedure which needs a number of observed stream flow and pollutants data. If observed data were not sufficient, researchers have to find other alternatives. One of them is to make indirect data by using watershed models, such as Soil and Water Assessment Tool (SWAT) and Hydrological Simulation Program - FORTRAN (HSPF) and so on. In this study, indirect daily data was made by using SWAT model. To build the Byongseong-SWAT model accurately, crop cultures are reflected by handling the MGT.file in SWAT model. Especially, mass of manure and schedule of crop culture are inputted through investigating domestic research papers as well as fieldwork. After calibrating SWAT model in comparison with the 22-years flow and pollutants observed outlet data, the delivery ratio of Byongseong watershed is calculated by using daily simulated data during 2004-2007. Empirical equations for delivery ratio through multi-regression analysis are developed by using meteorological and physical factors such as flow, watershed area, stream length, catchment slope, curve number (CN) and subbasin's pollutant discharge loads.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.196-203
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• 2000

In this study, the evaluation method of diffusion characteristics of Suspended Soli&SS) and the generation limit(source and thick) are investigated, which is significantly affecting on marine examined by construction works such as dredging and reclamation. Dispersion characteristics of SS is examined by hydraulic tests and numerical works in consideration with the Pusan Port. Hydraulic model test was performed in 2-D wave flume to find the limit wave conditon of re-suspension of solid as well as the time dependent characteristics of settlement The results obtainded in the study are as follows; 1) The quantituative evaluation af SS is the basic parameter of marine environmental impact assessment in related with the port development The SS increases as the water content of sea bed solid increases and the density decreases. 2) The sea bed solid in Sinsundai area, Pusan Port has the water content range of 83~157% 3) The ratio of suspension velocity against settlement velocity is about 0.25 and SS concentration converges as the wave heigh. 4) The SS increases 2 time when time step increases 3 time(10 sec to 30 sec) in numerical simulation It means that the effect of the time step should be checked in detail to stable. The diffusion The diffusion coefficient are Affiected senstively in the dispersion process while sea ved friction coefficinet have not strong relation in the simulated area

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.2
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• pp.119-129
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• 1999

It may be said that ancient wild Chinese garden had been founded during Qin dynasty and completed through Han, Sui and Tang dynasties. At first used as hunting areas for kings, the ancient resort forests began to take forms of garden. They dug a pond in the garden and made a simulated mountains with the soil that came from the excavations for the pond and suc pavilions has Gyong, Ru, Gak etc. were built around the pond. The ponds were different in size from those in Korea, being of the lake-like size. they made three island in the pond, which were the islands of Taoist hermits with supernatural powers, called Bong-lae, Young-ju and Band-jang respectively. the traditional of making those islands began in the Qin era and were completed in the Han era, being descended to posterity as a traditional garden structure of 'three islands in one pond' garden style. Such style was brought to Korea and first appeared as Kung-Nam-Ji in Back-jae kingdom and then brought to Japan, becoming the tradition of constructing ponds from early Heian era. Those lake-like huge Chinese ponds constituted the core of ancient garden where various feasts took place. Such ponds were also placed at the center of the gardens and played the roles of feasting garden ponds. Through the above-mentioned studies of the ancient Chines garden, the origin of them and the influence of the ancient Chinese ponded garden upon those of Korea and Japan were investigated.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.4
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• pp.103-110
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• 1996

Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by slag is an attractive solution if the P sorption capacity of the slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with dust and cake waste products (slag) from BHP steel industry in Australia as adsorbing media indicated that they had higher sorption capacity of P than that of a sandy loam soil from North Sydney, Australia. P transport in the dust and cake columns exhibited characteristics S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical non-equilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted proportionally to the adsorbent's sorption capacity.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.35-41
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• 2000

Residual stress is defined as a minimum stress with a large displacement of specimens and the residual stress after peak shear stress appears with displacement volume but there is no provision to select the residual stress. In the previous study, residual stress was recorded when the change of shear load is small in the condition of the strain more than 15%. But, in this study, hyperbolic function((No Abstract.see full/text), b=experimental constant) of soil test is adapted to joint of rock and the propriety is investigated. In a landslide and landsliding of artificial slope, wedge failure of tunnel with a large displacement, tests are simulated from peak stress to residual stress for safety analysis. But now. direct shear stress and triaxial compressive tests are usually performed to find out characteristics of shear stress about joint. Although these tests get a small displacement, that data of peak stress and residual stress are used for safety analysis. In this study, we tried to determine failure criteria for joints of rock using ring shear test machine. The residual stress following shear behavior was determined by the result of ring shear test and direct shear test. In conclusion, after comparing the results of the two test, we found that cohesion(c) and internal friction angle(ø) of ring shear test are 30% and 22% respectively of those of the direct shear test.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.1
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• pp.83-94
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• 1994

The first part of this study dealt with the determination of soil parameters for Lade's double work-hardening model using the raw data obtained from cubical and cylinderal triaxial tests At present, it should be investigated which test can simulated satisfactorily the behavior of soft clayey foundation. In this regard, plate bearing test on the 2-dimentional model foundation(218cm long, 40cm wide, 19&m high) was performed, and finite element analysis carried out to abtain the behavior of the foundation. Settlement, lateral displacement, displacement vector and mode of failure were measured and these values were compared with numerical values in order to validate the numerical program developed by authors. The FEM technique was based on Christain-Boehmer's method, in which the displacement is obtained at each nodal point while stress and pore water pressure at each element.In this research, Biot's equation, which explains was elahorately the phisical meaning of consolidation, was selected, as a governing equation, coupled with Lade's double surface work-hardening constitutive model.