• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.91-91
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• 2011

The quality of the surface layer in concrete structures plays an important role in the durability of the concrete. The concrete factory products are made as they improve the appearance of the surface and compressive strength in need. A common criterion to judge the quality of concrete products frequently seen in our daily life appears to be "beauty" in terms of consistent shaping. However, as for most concrete curb in such areas where a large amount of anti-freezing agents(NaCl) and ice and snow melting agents(CaCl2) are spread over roads to ensure road safety during the winter season, since deterioration advances from the surface, scaling is seen on the surface concrete due to deterioration which combined freezing damage and salt damage. Especially, In cold northern districts, the spreading amount of deicing salts increases by regulation of studded tire use, and the scaling of the concrete products, the various parts of concrete structures for roads is increasing in recent years. In this study, L-shape concrete curb were targeted, the permeable form method with the commercial permeable sheet was applied to it and the improvements of the quality were examined. By the permeable form method, surface layers got strengthened, which prevented permeation of the deterioration factor from the outside, and the scaling resistance of the upper surface where the permeable sheet was applied improved exceedingly. It will be expected by applying the permeable form method to various concrete products that frost resistance improves and scaling damage decreases.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.2
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• pp.47-57
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• 2023

The increase of impermeable area ratio is causing hydrologic cycle problems in urban areas and groundwater depletion in rural areas, permeable pavements are getting attention to expand permeable areas. The performance of the permeable concrete block pavement, which is part of the permeable pavement, is greatly affected by the porosity. In addition, the permeability coefficient is a major factor when designing permeable concrete block pavement. Existing porosity and permeability test methods have problems such as uneconomical or poor field applicability. The object of this study was to develop a methodology for evaluating porosity and permeability coefficient using a surface image of a permeable concrete block. Specimens are manufactured with various porosity ranges and porosity and permeability tests are performed. After surface image preprocessing, normalization and binarization methods were compared. Through this, the method with the highest correlation with the lab test result was determined. From the results, the PDR (pore determined ratio) was obtained. Simple linear regression analysis is performed with PDR and lab test results. The results showed a high correlation of R² more than 0.8, and the errors were also low.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.691-699
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• 2010

In recent years, increases in impervious areas with rapid urbanization and land use changes are causing numerous hydrologic cycle and environmental problems. Impermeable pavement have a various defect such as collection rainwater, decreasing of sliding resistance, and etc. In this study, the hydrologic cycle effect of permeable pavement were analyzed by the experiment and the numerical simulation. The numerical model used was a modified SWMM especially for considering the hydrologic cycle effect of permeable pavement. The parameters of modified SWMM were revised by the experimental results. Also, the effects of runoff quantity reduction are reviewed when permeable pavement is applied to Incheon Cheongna watershed. The hydrologic cycle analysis of Incheon Cheongna watershed, continuous simulations of urban runoff were performed. The analysis results of permeable pavement setup effect on runoff are follows: the surface runoff after permeable pavement setup decreases to 74.35% of the precipitation whereas the surface runoff before permeable pavement setup amounts to 81.38% of the precipitation; the infiltration after permeable pavement setup increases to 15.13% of the precipitation whereas the infiltration before permeable pavement setup amounts to 8.32% of the precipitation.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.259-262
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• 1998

The Anterior surface and posterior surface of rigid gas permeable(RGP) contact lenses has been studied by scanning electron microscopy. Results point out that the ultrastructure of contact lenses surface was some different on the anterior and posterior surface of RGP. The Quantitative study of surface roughness suggest that the anterior surface was more smooth than the posterior surface. These results suggest that the materials characters appeared the contact lens surface. The morphology of the anterior and posterior surface have different, Maybe, these result have a manufacture processing of the contact lenses. But some surface appeared a foreign body particles.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.419-426
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• 2012

Fresh concrete has 10~20% extra water in it. As those water remain entrapped air in the concrete, life span of structures is reduced. For that reason, if extra water is eliminated, it will be useful to improve the durability of the structures. Though there were many reports about permeable formwork, the study on the properties of permeable liner itself has been insufficient. In addition, making holes on the form causes lowering of workability. Therefore, this study reviewed the properties of woven and non-woven permeable liner and formwork which has no holes on the form. For the woven and non-woven permeable liner, they showed great application with W/C decrease, lowering roughness, increased compressive strength of surface area and slight loss of cement paste, when the were applied to concrete. In addition, they showed different performance according to the density of woven liner or thickness of non-woven liner. Furthermore, when using the draining non-woven permeable liner which has drainage path inside, concrete surface showed required performance with high workability, without drilling the holes on the form.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.181-192
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• 2009

In this study, the hydrological properties of permeable pavement were analyzed by the experiment and the numerical simulation. The numerical model used was a modified SWMM especially for considering the hydrological response of permeable pavement. The parameters of modified SWMM were revised by the experimental results, and then the practicability was evaluated through the comparison of the experimental and numerical simulation results. In the experiments, three different rainfall intensities such as 65 mm/hr, 90 mm/hr, 95 mm/hr were supplied for 4 hrs, and the hydraulic properties including surface outflow, subsurface outflow, ground water level, soil water contents were measured for 10 hrs. The results showed rainfall intensity effected directly on surface outflow volume and subsurface outflow volume was more effected by ground water level than rainfall intensity. The ground water level and the soil water contents were under estimated as compared with the experimental data except the portion of occurring direct runoff. The surface and subsurface outflow discharge were simulated very well in comparison with the experimental data. Consequently, the modified SWMM could be used very effectively to evaluate the hydrological property of permeable pavement.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.376-384
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• 2018

The aerodynamic far-field noise was computed by an acoustic analogy code using the permeable surface for the UH-1H rotor blade in hover. The permeable surface surrounding the blade was constructed to include the thickness noise, the loading noise, and the flow noise generated from the shock waves and the tip vortices. The computation was performed with compressible three-dimensional Euler's equations and Navier-Stokes equations. The high speed impulsive noise was predicted and validated according to the permeable surface locations. It is confirmed that the noise source caused by shock waves generated on the blade surface is a dominant factor in the far-field noise prediction.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.207-208
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• 2022

Since 1960, the green area has decreased due to rapid urbanization and the artificial surface has increased, and the repair and water function of the previous surface has decreased due to the decrease in rainwater absorption capacity. In addition, the risk of carbon dioxide and fine dust is emerging due to the use of fossil fuels due to urbanization. As a result, permeable blocks, an eco-friendly product, are in the spotlight. Therefore, this study was conducted to examine the strength properties of the permeable block using a hydroball. As a result of the experiment, the flexural strength and compressive strength tended to decrease as the hydroball replacement rate increased. It is judged that the hydroball absorbs a large amount of moisture during the mixing process and lacks moisture required for curing, resulting in a decrease in strength. According to KS F 4419, since the hydroball replacement rate is satisfied up to 20%, further research is needed to analyze the adsorption performance of air pollutants in the future and evaluate their utilization as a permeable block in the future.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3116-3121
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• 2007

In this paper, the inverse shape design is introduced using the permeable wall boundary condition. Inverse shape design defines the blade shape for the prescribed Mach numbers or pressure distribution on its surface. It calculates the normal mass flux from the difference between the calculated and prescribed pressure at the surface. A new geometry can be achieved after applying the quasi one-dimensional continuity equation from the leading edge to the trailing edge. For validation of this method, two test cases are studied. The first test case of inverse shape design illustrates the cosine bump with a strong shock. After seven geometry modifications, the shock-free bump geometry can be obtained. The second example concerns the redesign of a transonic turbine cascade. The initial isentropic Mach distribution has a peak on the upper surface. The target isentropic Mach number distribution was imposed smoothly. The peak of Mach distribution has disappeared at the final geometry. This proposed inverse design method has proven to be an efficient and robust tool in turbomachinery design fields.

• Journal of the Korean Geosynthetics Society
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• v.18 no.1
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• pp.79-89
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• 2019

The field measurement and laboratory experiment were conducted to investigate the effect of reducing the surface temperature of the functional aspect of the heat island phenomenon of the permeable block which is made the recycled synthetic resin rather than the existing concrete permeable block. Field measurement was taken for 3 days in consideration of dry condition and wet condition and laboratory experiment was divided into dry condition, rainfall simulating condition, and wetting condition. The variations of temperature and the evaporation rate of water moisture content after experiment were confirmed. As a result of field measurement, it is confirmed that the surface temperature decreases due to the difference in albedo of the pore block surface rather than the cooling effect due to the latent heat of vaporization. The evaporation of moisture in a dry state where drought persisted or a certain level of moisture was not maintained in the surface layer. As a result of laboratory experiment, resin permeable block gives higher surface temperature when it is dry condition than concrete permeable block, but the evaporation of water in the pore is kept constant by capillary force in rainfall simulation condition, and higher temperature reduction rate. As a result of measuring the evaporation rate after laboratory experiment, it is confirmed that the effect of reducing temperature is increased as the evaporation rate of water is higher. Based on these results, correlation formula for evaporation rate and temperature reduction rate is derived.