• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.43-44
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• 2012

Deterioration factors such as CO₂ and chloride ions cause steel corrosion in RC structures. The diffusion of these factors depends on the water content in concrete. To examine the moisture condition of concrete, this research considers the availability of the steel effect ratio, which is calculated by Resistivity Estimation Model (REM). It is concluded that the steel effect ratio is expected to be available as a quantitative evaluation method in the assessment of concrete layer resistivity.

• Steel and Composite Structures
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• v.15 no.2
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• pp.221-245
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• 2013

This paper presents an analytical solution to the thermomechanical bending analysis of functionally graded sandwich plates by using a new hyperbolic shear deformation theory in which the stretching effect is included. The modulus of elasticity of plates is assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. The effects of functionally graded material (FGM) layer thickness, volume fraction index, layer thickness ratio, thickness ratio and aspect ratio on the deflections and stresses of functionally graded sandwich plates are investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.145-149
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• 1995

This study is to recognize the effect of silica-fume, fly-ash, and chemical proportion in mortar that have salt on the inside affect steel bar corrosion. water-binder ratio, 0.5, compounds, each of 10, 15, 20% by weight of cement, Nacl mixing weight, 0.5, 1.0, 2.0% by weight of binder, The speciment is sealed and cured for 28days, the corrosion area ratio and weight reduction ratio is measured after the accelerated corrosion test of 20 cycles. The conclusion shows that there is no suppression effect of steel bar corrosion of silica-fume, fly-ash, in case of having salt on the inside.

• Journal of environmental and Sanitary engineering
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• v.7 no.1
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• pp.45-56
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• 1992

The Anaerbic Anoxic/oxic process is one of the biological treatment methods to remove nitrogen and phosphorus effectively which are nutritional elements for eutrophication. Supernatant of primary sediment of Anaerobic digester is used as a carbon source instead of methanol methanol supply in usual A$_{2}$/O process. The efficiency of the following treatment processes are as follow : 1) Changing recycle ratio in the usual A$_{2}$/O process without the stage of Anaerobic digester. 2) Changing recycle ratio in the usual A$_{2}$/O process with the supernatant supply of the Anaerobic digester. In the result of comparison, changing recycle ratio is almost no effect in the removal of phosphorus, however the effect of removal in nitrogenous substance are remarkable, and the effect of Anaerobic digester is not as effective as expected because the BOD removed in the digester partly, the rate of phosphorus to the BOD exceed pertinent range.

• Journal of Ocean Engineering and Technology
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• v.11 no.1
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• pp.55-64
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• 1997

A wing operating in close proximity to the ground exhibits a reduction in induced drag, which increase the lift/drag ratio. The poert-augmented ram (RAR) phenomenon involves directiing the efflux from forward mounted propulsion ststem under the wings, with the efflux nearly stagnated under the wings. In the present paper, 3 dimentional PAR was numerically studied by solving the Navier-Stokes equations. Pressure distribution and velocity vectors are calculated around the wing surface and the ground. Through the numerical simulation, Cp values and lift/drag ratio are carefully reviewed by changing the height/chord; 0.05, 0.1, 0.3 and 0.8. The shape of model is NACA 0012 with a span/chord ratio of 3.0. According to the numerical results, the relationship between lift/drag and height/chord is fairly reasonable.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.2
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• pp.61-66
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• 2014

Temporal disappearance of weather phenomena effect is frequently observed in flight simulator when large volume of terrain data are processed. This problem was solved by employing culling scheme at static ratio in the existing scheme. However, since this approach causes the irregular rendering speed according to volume of data, it is necessary to develop a new culling scheme to maintain steady rendering speed by adjusting the culling ratio dynamically. In this paper, we propose a new culling scheme to make use of distance of the visibility to determine culling ratio depending on volume of terrain data. The experimental results show that rendering speed is preserved by the proposed scheme without affecting the visuality at rendering the scene and weather phenomena effect together.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.390-395
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• 2003

The effect of recirculated exhaust gas on exhaust emissions under four kinds of nozzle tip with the different fuel consumption rate are experimentally investigated by using an once-through boiler with FGR system. The purpose of this study is to develop the FGR control system for reducing NOx in a boiler. Intake and exhaust oxygen concentrations, and equivalence ratio are applied to discuss the effect of FGR rate on exhaust emissions at various fuel consumption rates. It is found that NOx emissions are decreased, while soot emissions are increased owing to the drop of intake and exhaust oxygen concentrations, and the rise of equivalence ratio as FGR rates are elevated.

• Journal of the Korean Society of Clothing and Textiles
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• v.5 no.2
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• pp.63-68
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• 1981

Succeding to Report I, to determine the effect of opening conditions and areas of clothes ($10\%,\;20\%,\;30\%,\;40\%$ of total area) on the warmth keeping properties, cooling method was employed by using Latin Square Design, The following results were obtained: 1) The warmth keeping ratio was varied with the opening conditions and the: order was downward, upward, horizontal and up & downward opening 2) The size of opening areas was in inverse proportion to the warmth keeping ratio, 3) In the horizontal opening, the thickness of air layers in clothes did not effect on the warmth keeping ratio.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.451-457
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• 2000

A series of consolidated undrained triaxial tests for compacted short fiber reinforced clay were performed to increase the field applications, e.g. retaining wall, waste landfill, soft ground etc. of soil admixtures mixed with short fiber. Kaolin clay and three types of fiber were selected. To acquire reliable length of fibers, an auto cutter was used and a helical mixer was also used to avoid floating of fibers during mixing soil and fibers. It is found that reinforcing effect by aspect ratio and mixing ratio of short fiber decreases as confining pressure is increased. Reinforcing effect has a maximum value at the aspect ratio of 120 and the fiber content of 0.6%∼1.2% and low confining pressure like 50kPa.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.617-620
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• 2006

The EVA polymer is used as a modifier in the repair mortar, which contains various admixtures and mineral admixtures. It has been reported that the effect of polymer in cement mortar by the cement-polymer ratio only, but effect of admixtures over the polymer mortar was unknown. In this study, the fresh and mechanical properties of polymer cement mortar influenced by the range of silica fume ratio were investigated. It was found that with increasing the ratio of silica fume, mechanical properties(compressive strength, flexural strength, adhesive strength) of repair mortar is improved and drying shrinkage is increased.