• The Journal of Engineering Geology
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• v.29 no.4
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• pp.509-529
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• 2019

This study performs to evaluate the role of filter material at alluvial well for intake of riverbank filtration and the applicability and improvement effect of dual filter well. To achieve this objective, dual filter intake well and single filter intake well were installed with different filter conditions at riverbank free surface aquifer in soil layer then we evaluated filter material condition, permeability, optimum yield and well efficiency according to yield in drawdown test. As a results, we assumed forming dual filter layer minimizes sudden speed changes at boundary between aquifer and filter layer by cushioning of groundwater flow. This suppresses warm current then intake groundwater efficiently, therefore it seems decreasing peripheral groundwater level changes in spite of higher intake water amount than single filter intake well. Furthermore, we confirmed by test, installing dual filter improves permeability, optimum yield and well efficiency. The result will be used by combining with former study to set up standard of design/construction of dual filter intake well at alluvial aquifer layer. Furthermore, we expect this result will be used to prove application effect of dual filter intake well compared to single filter one and radial collector well which are mainly applied on riverbank filtration.

• Journal of Animal Science and Technology
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• v.44 no.2
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• pp.261-270
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• 2002

This study was executed to elucidate the degree of satisfaction with working environment and the factors affecting it for workers who are engaged in the composting plants with livestock manure in the Han-river watershed. As an evaluation on site, we applied the self-administered questionaire including general characteristics, working conditions, degree of satisfaction with working environment, and degree of satisfaction with working condition. Simultaneously, we analysed the exposure levels of odor (ammonia, hydrogen sulfide, and odor intensity) in the boundary area of plants. As a result of the study, health condition, odor, work load, dust, and smoking were proved to be the main factors affecting the degree of satisfaction with working environment for workers who are employed in the composting plants with livestock manure in the Han-river watershed. Of them, it was investigated that health condition, odor, and work load accounted for 61.3% of the total degree of satisfaction with working environment and health condition(p$<$0.01), odor(p$<$0.05), work load(p$<$0.05), and dust(p$<$0.05) were statistically significant. It was concluded that the degree of satisfaction with working environment was high for the workers who had good health status and low for the workers who had the relatively considerable work load and were often exposed to odor and dust. Therefore, to increase the degree of satisfaction with working environment for workers who are engaged in the composting plants with livestock manure, the measures that can reduce the exposure levels of odor and dust emitting from the composting plant with livestock manure should be improved.

• 한국해양학회지
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• v.26 no.1
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• pp.13-23
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• 1991

For the purpose of examining the depositional sedimentary environments in the Han River estuary and around the Kyunggi Bay posterior to the Han river's developments, a hydrological and sedimen-tological survey was carried out. According to the hydrological and sedimentological conditions, the studied area can be divided into 3 depositional sedimentary environments: Fluvial, Estuarine and coastal-Bay. Posterior to the Han river's developments, however, the alterations of hydrodynamic condition in the Han river have caused a substantial change of the sedimentary environments in the lower Han river and its estuary. That is, the contents of total suspended sediment anterior to the Developments decreased from 37mg/l (in the lower Han River) and 500-1750 mg/l (at the Kanghwa Bridge) to 18 mg/l and 208-1142 mg/l posterior to the developments. these changes seem to have caused the siltation near the sin-gok Underwater Dam. Thus the characters of the boundary condition between the fluvial and the estuarine environments have rapidly changed. It is considered that these changes result mainly from the construction of the two underwater dams for the maintenance of the water level of the Han river. As the estuary is a transition zone between land and sea, these changes in the Han River estuary might affect the sedimentary environments around the Kyunggi Bay. In order to verify the effects of these changes, it is necessary that a detailed survey be carried out around the Han River estuary including the Imjin and Yesong River estuaries.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.621-632
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• 2007

The purpose of this study was the estimation and formulation of orthotropic flexural rigidities considering the deformed shape for a plate stiffened with rectangular ribs. Analytical results of methods modifying the flexural rigidity of the x-direction, the y-direction or both directions were compared at the center, the x-directional quarter point and the y-directional quarter point of stiffened plates loaded at the center. The composite method modifying the flexural rigidity of both directions improves the accuracy compared with the other methods. Moreover, the ratio of modified coefficients for each directional rigidity can be expressed as a function corresponding to each dimension of stiffened plates. The application of modified coefficient functions to various types of stiffened plates with different boundary conditions, aspect ratios and rib arrangement shows that the increment of the error ratio is small compared with examples of this study and the application of proposed functions shows more accurate results than previous methods modifying the flexural rigidity. Therefore, by using the modified coefficient functions proposed in this study, the orthotropic plate analysis of plates stiffened with rectangular ribs can easily achieve more accurate displacement results.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.343-359
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• 2017

Many researches and policies have been carried out for saving energy in buildings. However, there are a few studies of thermal characteristics of wood-based materials that have been widely used as structural materials and finishing materials in buildings. In this study, thermal bridging areas were found to investigate thermal performance of residential building using non wood-based materials and wood-based materials. And heat transfer analysis of 16 case studies according to composition of structural materials and finishing materials was conducted. Also in this experiment, Physibel Trisco was used as the heat transfer analysis simulation tool, which conforms to the calculation method of ISO 10211. Analytical modeling was also carried out according to the ISO 10211, and the boundary temperature conditions were set at room temperature $20^{\circ}C$ and outdoor temperature $-11.3^{\circ}C$ (Seoul standard) according to the energy saving design standard in South Korea. Applied structures are classified according to the cases of concrete structure with non wood-based finishing materials, concrete structure with wood-based finishing materials and wood structure. Analyzed building elements were divided into a wall, a roof, an interlayer floor and a bottom floor. As a result, it can be confirmed that the thermal bridge of the concrete structure and wood structure were caused by the geometrical and material causes. In addition, the structural thermal bridge was caused in the discontinuity of the insulation in the concrete structure. Also it was confirmed that the linear heat transfer coefficient of the wall decreases when the wood-based materials are applied to the concrete structure.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.126-139
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• 1994

Best-estimate thermal-hydraulic codes, CATHARE2 V1.2 and RELAP5/MOD3, hate been assessed against the BETHSY 6.2 tc six-inch cold leg break loss-of-coolant accident (LOCA) test. Main objective is to analyze the overall capabilities of the two codes on physical phenomena of concern during the small break LOCA i.e. two-phase critical flow, depressurization, core water level de-pression, loop seal clearing, liquid holdup, etc. The calculation results show that the too codes predict well both in the occurrences and trends of major two-phase flow phenomena observed. Especially, the CATHARE2 calculations show better agreements with the experimental data. However, the two codes, in common, show some deviations in the predictions of loop seal clearing, collapsed core water level after the loop seal clearing, and accumulator injection behaviors. The discrepancies found from the comprision with the experimental data are larger in the RELAP5 results than in the CATHARE2. To analyze the deviations of the two code predictions in detail, several sensitivity calculations have been performed. In addition to the change of two-phase discharge coefficients for the break junction, fine nodalization and some corrections of the interphase drag term are made. For CATHARE2, the change of interphase drag force improves the mass distribution in the primary side. And the prediction of SG pressure is improved by the modification of boundary conditions. For RELAP5, any single input change doesn't improve the whole result and it is found that the interphase drag model has still large uncertainties.

• Journal of the Korean earth science society
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• v.21 no.3
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• pp.315-322
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• 2000

In this study, the data used for the models were a set of 56 geologic estimates of long-term fault slip rates. The hest models were those in which mantle drag was convergent on the Transverse Ranges in the San Andreas fault system, and faults had a low friction (${\mu}$= 0.3). It is clearly important to decide whether these cases of low strength are local anomalies or whether they are representative. Furthermore, it would be helpful to determine fault strength in as many tectonic settings as possible. Analysis of data was considered by unsuspected sources of pore pressure, or even to question the relevance of the friction law. To contribute to the solution of this problem, three attempts were tried to apply finite element method that would permit computational experiments with different hypothesized fault rheologies. The computed model has an assumed rheology and plate tectonic boundary conditions, and produces predictions of present surface velocity, strain rate, and stress. The results of model will be acceptably close to reality in its predictions of mean fault slip rates, stress directions and geodetic data. This study suggests some implications of the thermoelastic characteristics to interpret the relationship with very low strength of San Andreas fault system.

• Composites Research
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• v.18 no.1
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• pp.45-54
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• 2005

The delamination in the filament-wound composite flywheel rotor often lowers the performance of the flywheel energy storage system. A conventional ring type hub usually causes tensile stresses on the inner surface of the composite rotor, resulting in lowering the maximum rotational speed of the rotor. In this work, the stress and strain distributions within a hybrid composite rotor were derived from the two-dimensional governing equation with the specified boundary conditions, and an optimum pressure at the inner surface of the rotor was proposed to minimize the strength ratio and maximize the storage energy. A split type hub was introduced to apply the calculated optimum pressure at the inner surface, and a spin test was performed up to 40,000 rpm to demonstrate the performance of the split type hub with radial and circumferential strains measured using a wireless telemetry system. From the analysis and the test, it was found that the split type hub successfully generates a compressive pressure on the inner surface of the rotor, which can enhance the performance of the composite rotor by lowering the strength ratio within the rotor.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.617-625
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• 2016

The objective of this study was to evaluate the groundwater drawdown and streamflow depletion due to each groundwater pumping from 110 wells located near stream using the Hunt's analytical solution (1999). The calculated results revealed that the streamflow depletion rate divided by the pumping rate for each well location mostly exceeded about 80% of pumping rate on average for 5 years. The results also showed that the stream boundary condition has made the influence distance shorter and the drawdown distribution skewed except for the streambed hydraulic conductivity and the stream bed factor (SBF) lower than $1.0{\times}10^{-9}m/s$ and 1.0, respectively. It was found that the groundwater pumping has significant impacts on the stream depletion showing above 80 % of stream depletion rate when the streambed hydraulic conductivity is higher than $1.0{\times}10^{-7}m/s$ and the stream depletion factor(SDF) is lower than 100. However, for other conditions, the SDF is not sufficient to be used as a criterion for determining whether the pumping has great impacts on stream depletion or not. Furthermore, the variation of the streambed hydraulic conductance has little change in stream depletion rate for the condition that the stream width is greater than 400 m.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1427-1435
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• 2010

A mixed finite element model was developed using the classical plate theory to analyze the nonlinear bending of a plate. The appropriate weight functions for the constraints integrated over the domain were determined by the Lagrange multiplier method by using the principle of minimum virtual energy; which provides the constitutive relations between force-like variables and strains. All of detail terms of element wise coefficient matrices and associate tangent matrices to be used in the Newton iterative method are presented. Then, the linear solutions of the current model and those of the traditional displacement model under the SS (simple support) boundary conditions were compared with the existing analytical solution. The post-processed images of the nonlinear results of the force-like variables are presented to show the continuity of the solutions at the joint of the element boundaries. Finally, the converged nonlinear finite element solutions of the current model are compared with those of existing traditional displacement model.