• Journal of the Korean housing association
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• 제24권3호
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• pp.45-53
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• 2013

It is important to secure green spaces to solve the urban heat island phenomenon, which is among problems resulted by high-density developments in metropolitan areas. However, it is hard to secure such green spaces in established urban areas so Green Rooftop development approaches have recently been highlighted and introduced as a solution to the situation. The present study conducts a simulation on residential areas in urbanized regions to quantitatively evaluate the effects of green rooftop developments through a comparison of changes in the air temperatures before and after relevant development projects. According to the evaluation results, when the green roof top development is conducted in the available areas, the temperature is reduced by 0.14 degree. The extension of green project to the entire building showed the reduction of the temperature by 0.29 degree. Based on these results, it can be concluded that the green rooftop development is a practically solution for reducing the air temperature of urbanized areas.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제53권4호
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• pp.413-416
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• 2008

The cultivation of green manure crop is considered as a good management practice by increasing soil organic matter and fertility levels. This experiment was conducted to improve the soil environment under rice-based cropping system at paddy soil (fine loamy, mixed, nonacid, mesic, family of Aeric Fluventic Haplaquepts) in National Institute of Crop Science (NICS), Korea in 2006 to 2007. The variation of soil temperature in green manure plots was lower than without green manure (control) during spring season (April to May). The temperature variation of no tillage plot (broadcast before rice harvest) was the lowest among treatments. After green manure cropping, the soil bulk density and porosity ratio were improved at the top soil. The production of green manure was the highest athairy vetch and barley mixture plot by partial tillage. However, mixture treatment had no improvement on soil organic matter. After rice cropping with green manure application, soil quality was improved such as soil physical properties except mixture treatment. Therefore, we suggest that soil quality should be improved by green manure cultivation under rice-based cropping system.

• Transactions of the Korean hydrogen and new energy society
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• 제32권6호
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• pp.565-572
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• 2021

Hydrogen is currently produced from natural gas reforming or industrial process of by-product over than 90%. Additionally, there are green hydrogens based on renewable energy generation, but the import of green hydrogen from other countries is being considered due to the output variability depending on the weather and climate. Due to low density of hydrogen, it is difficult to storage and import hydrogen of large capacity. For improving low density issue of hydrogen, the gaseous hydrogen is liquefied and stored in cryogenic tank. Density of hydrogen increase from 0.081 kg/m³ to 71 kg/m3 when gaseous hydrogen transfer to liquid hydrogen. Density of liquid hydrogen is higher about 800 times than gaseous. However, since density and boiling point of liquid hydrogen is too lower than liquefied natural gas approximately 1/6 and 90 K, to store liquid hydrogen for long-term is very difficult too. To overcome this weakness, this paper introduces storage method of hydrogen based on liquid/solid (slush) and facilities for producing slush hydrogen to improve low density issue of hydrogen. Slush hydrogen is higher density and heat capacity than liquid hydrogen, can be expected to improve these issues.

• Journal of the Korean Ceramic Society
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• 제26권3호
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• pp.347-360
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• 1989

Spinel, mullite, forsterite and cordierite composition powders were synthesized from Mg(NO3)2.6H2O, Al(NO3)3.9H2O and SiCl4-ethanol solution by spray pyrolysis method and the sinterability of these powders were investigated. The bulk density of spinel and mullite specimens sintered at 1,$700^{\circ}C$ for 1hr was 3.56g/㎤(99.5% relative density) and 3.16g/㎤(99.7% relative density), respectively. (Green compacts were made from powders prepared at 1,00$0^{\circ}C$). The bulk density of forsterite and cordierite specimens sintered at 1,480 and 1,40$0^{\circ}C$ for 2hrs were 3.217 and 2.155g/㎤, respectively. (Green compacts were made from powders prepared at 1,00$0^{\circ}C$). The constituent compositions of spinel and mullite specimens sintered at 1,$700^{\circ}C$ for 1hr were 27.5wt% MgO and 70.5wt% Al2O3, respectively. Vickers microhardness and fracture toughness of spinel sintered at the above condition were 13.7GPa and 2.6MN.m3/2, respectively, and room temperature bending strength, 425MPa, was nearly maintained even at the elevated temperature. In the case ofmullite specimens, those values were 13.5GPa, 2.2MN/m3/2 and 430MPa, respectively.

• Journal of Environmental Impact Assessment
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• 제32권6호
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• pp.437-449
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• 2023

This study measured PM₁₀ concentrations and wind speeds in buffer green spaces and neighborhood parks located along the road, and compared them with roadside measurementresults to understand the effect of mitigating PM₁₀ concentrations by type of green space and the influence of wind speeds on it. As a result of the analysis, the effect of mitigating PM₁₀ concentration was different depending on the type of roadside green space, and an increase in wind speed had a significant effect on reducing PM₁₀ concentration. In buffer green areas with high planting density, wind speed was low and PM₁₀ stagnated inside, resulting in the highest concentration. On the other hand, green areas in neighborhood parks with relatively low planting density had high wind speeds and the lowest PM₁₀ concentration. The non-green area within the neighborhood park recorded the highest wind speed, which was advantageous for the spread of PM₁₀, but the concentration was higherthan that of the green area. Therefore, in orderto reduce PM₁₀ concentration in roadside green space, it is necessary to create green space with good ventilation, and the combined effect of green space and wind speed seems to be more advantageous in reducing PM₁₀ concentration. Green spaces capture and remove PM inside, contributing to reducing the concentration of PM outside. In order to manage PM in the entire city and on roads, it is necessary to increase planting density and leaf area in roadside green spaces, such as buffer green spaces, so that PM can be removed within the green spaces. However, in green spaces such as neighborhood parks that are actively used by city residents, in orderto minimize damage to users due to PM, it is desirable to create green spaces with a structure that allows PM to spread to the outside rather than stagnate inside.

• Korean Journal of Soil Science and Fertilizer
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• 제43권1호
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• pp.105-112
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• 2010

Applications of plant residues and green manures generally improve the properties of soil under conventional farming system. Therefore, we investigated the improvement of selected soil physical properties, bulk density, porosity, and water content, soil penetration resistance, and soil microbial biomass carbon (SMBC) content as affected by different management practices: 1) conventional tillage without rice straw or green manure crop treatment (TNT, check plot), 2) no-tillage amended with rice straw (NTRS), 3) no-tillage amended with rye (NTR), 4) no-tillage amended with Chinese milk vetch (NTCMV), 5) no-tillage without rice straw or green manure crop treatment (NTNT), The values of bulk density, porosity, and water content ranged from 1.22 to 1.37 Mg $m^3$, from 48.3 to 54.0%, and from 35.0 to 40.2%, respectively. The management practices might positively influence the changes in the selected soil properties, especially in the second experimental year. The soil penetration resistance and SMBC content were also improved after applying rice straw and green manure crops as comparing with TNT. Therefore, applications of the rice straw and green manure crop management practices under no-tillage system positively influenced soil physical properties and soil microbial activities in paddy field.

• Journal of the Korean Society of Tobacco Science
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• 제16권2호
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• pp.113-121
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• 1994

The green peach aphid was relatively the majority(36.9-72.3% ) among all alate aphids collected from tobacco plants. Density of glatae was relatively lower on varieties Tl 1112 and Br 21 than on Va 115 or Y S A among seven varieties tested. However, no considerable difference was observed in general biology of nymphs produced by alatae on the tobacco varieties. About 55% of alate green peach aphid collected from tobacco fields produced progency, and over 80% of the nymphs became adults on cut tobacco leaves in petri dish. Adult longevity of both alate and apteral green peach aphid was shorter, and numbers of nymphs produced by both types were lower in summer than in autumn. Apterae produced more nymphs than alatae, but the longevity of apterae was shorter.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.387-390
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• 2006

The protective layer of AC-PDP was fabricated by laminating an MgO green sheet. The MgO green sheet was made by coating MgO solution composed of solvent, dispersant, binder, and MgO nano-powder. The MgO solution was coated by the die casting method on the base film. We fabricated three kinds of MgO green sheets of which thicknesses were 20, 28, and $40\;{\mu}m$, respectively. The MgO nano-powder showed lower CL intensity and ${\gamma}i$ than the e-beam MgO. The MgO green sheet applied panels showed low luminance and current density. The efficiency was almost same as the conventional e-beam MgO panel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제19권12호
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• pp.1112-1117
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• 2006

The properties of LTCC green tape with addition of binder were investigated in order to understand an effects of binder on multilayer processing. A green sheet form was fabricated through tape casting method with the MLS-22 powder. The lamination density increased with increasing amount of binder and lamination pressure. With increasing amount of binder, the elongation of ceramic sheets increased but the tensile stress and air-permeability decreased. The addition of excessive binder is caused defects in the green sheet during via hole punching. The optimum condition of the via hole without defects was observed from amount of the binder 10 wt%.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.731-732
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• 2006

Recently warm compaction techniques are focused on and commercialization of one high-density compaction process in the P/M industry. Another development is a new SEGLESS using a developed lubricant that reduces ejection force at room temperature compaction. It is possible to achieve high-density by reducing lubricant amount. In this paper we confirmed that green density was $7.35g/cm^3$ at 686MPa of compaction pressure when the new SEGLESS was applied to relatively lower temperature warm compaction process, such as $80^{\circ}C$.