• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.27-42
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• 2018

This study analyzed the utility of ammonium chloride ($NH_4Cl$) as a nitrogen source for methanotroph communities. When cultured in nitrate mineral salt (NMS) medium, the methanotroph community we identified four families, seven genera, and 16 type I and type II species of methanotrophs. Among species in the Methylobacter genus, Methylobacter marinus could be actively cultured in NMS medium without NaCl addition. Following the addition of 25 mM $NH_4Cl$, the numbers of the type I genera Methylomonas, Methylococcus, and Methylobacter were increased, whereas the numbers of the type II genera Methylocystis and Methylosinus were decreased after 5 days. In methanotroph communities, certain concentrations of $NH_4Cl$ affected methane consumption and growth of methanotrophs at the community level. $NH_4Cl$ caused a considerable decrease in the methane consumption rate and the expression of soluble methane monooxygenases (sMMOs) but did not inhibit the growth of Methylomonas methanica expressing sMMO. These results could be attributed to competitive antagonism of MMOs due to their direct involvement in ammonia oxidation.

• Korean Institute of Interior Design Journal
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• v.20 no.1
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• pp.199-207
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• 2011

After the development of printing technology since the 15th century and the rise of citizen consciousness in the 18th century, the library has taken a public concept. And after the 20th century, its role as a public library for the public was stressed, and as its spatial composition became miniaturized and specialized, its function changed from stacking and reading to various kinds including culture and service and is getting more complex beside the function of a library. Thereupon, this study aims to figure out the limitations of public libraries' opening years shown in advanced researches and understand the current status of spatial composition by complexation with the subjects of five public libraries opened after the end of December, 2006 in order to examine their tendencies of complexation and the characteristics of spatial composition by the complexation of public libraries. As a result, the present public libraries have at leaser more than two spaces with complex functions. According to the result of analysis on the types, locational relations between spaces showed the mixed type the most. In the types of building allocation, the building integrated type had a higher percentage than the separated type. About the types of entrance, the one common door type was fewer than the two separate door type. In the analysis on the types of the interior line of flow, the common type was similar to the dispersed type, and it is thought to be resulted from spatial composition rather than the preplanned line of flow.

• Journal of Environmental Science International
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• v.14 no.8
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• pp.719-722
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• 2005

This study is to find the effective way to green perpendicular wall spaces as soon as possible and to get basic data for activating the perpendicular greening on high story building through the experiment of container-type planting ground in which lightened artificial soil mixed with rock wool was put. Comparative studies of the sizes of containers and soil were carried out but separate management was not performed. Four plants(Euonymus fortunei var. radicans, Lonicera japonica, Parthenocissus quinquefolia, Parthenocissus tricuspidata) which have the capability to cover and screen perpendicular spaces were used in the experiment. In result, a container must be equipped with over 15cm depth soil mixed with less than $30\%$ of rock wool.

• ETRI Journal
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• v.30 no.4
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• pp.535-545
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• 2008

This paper introduces a systematic top-down and bottom-up design methodology to assist the designer in the implementation of continuous-time (CT) cascade sigma-delta (${\Sigma}{\Delta}$) modulators. The salient features of this methodology are (a) flexible behavioral modeling for optimum accuracy-efficiency trade-offs at different stages of the top-down synthesis process, (b) direct synthesis in the continuous-time domain for minimum circuit complexity and sensitivity, (c) mixed knowledge-based and optimization-based architectural exploration and specification transmission for enhanced circuit performance, and (d) use of Pareto-optimal fronts of building blocks to reduce re-design iterations. The applicability of this methodology will be illustrated via the design of a 12-bit 20 MHz CT ${\Sigma}{\Delta}$ modulator in a 1.2 V 130 nm CMOS technology.

• Ecology and Resilient Infrastructure
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• v.11 no.1
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• pp.11-22
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• 2024

A fishway is an artificial waterway or device used to resolve difficulties in the movement of fish in a river. Most existing fishways are made of concrete and emit toxic substances, which has a negative impact on the river environment. Accordingly, there is a need to develop fishway construction technology that is eco-friendly and can increase movement efficiency. The technology presented in this study is an integrated porous structure that combines the aggregate with a biopolymer material extracted from castor oil, a non-toxic material. It is a fishway construction technology using eco-friendly materials that can allow vegetation to grow on the surface. In this study, an eco-friendly fishway mixed with biopolymer and aggregate was built on a real scale and the fish movement efficiency was tested and analyzed. As a result of the experiment, a total of 201 fish of 14 species were released with tags inserted, and the detection rate of released fish was confirmed to be 82.6% on average. A total of 40 fish of 6 species were transported upstream through the fishway, and the average passage rate was confirmed to be 21.7%. As a result of checking the circadian migration pattern, it was found that all fish mainly migrate during the day. It was confirmed that there was no significant functional difference between a fishway using biopolymer and a concrete fishway. It is believed that a fishway using biopolymer can be used as a replacement for a concrete fishway.

• Journal of the Korean Society of Safety
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• v.6 no.4
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• pp.53-57
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• 1991

Engineers of building construction have made efforts to produce more convinient building of good quality through the development of technology and raw materials nowadaye. This study is conducted to recognize problems of exterior tiles through experiments on quality of tiles according to sizes, and to find out and Iecommend most suitaff sizes of tiles. The sizes which are used widely in Construction field are selected as,45$\times$45mm, 57$\times$87mm, 60$\times$108mm, 60$\times$187mm, 96$\times$200mm. Ready mixed compound are used as mortar and Compressed attachment method are used.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.185-186
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• 2023

Recently, a lot of nano-scale material technology development and research have been conducted in construction fields to improve the compressive strength and durability of cement-based Composites. There are some studies that have confirmed the properties and application effects of cement-based complex using each nanomaterial, but development and research using both materials are relatively limited. This study sought to confirm the effect of multi-wall carbon nanotubes (MWCNT) and nanosilica, which are representative construction nanomaterials, on the compressive strength, voids, and microstructure formation of cement. The purpose was to produce a cement composite by changing the mixing rate of the two nanomaterials, and to find the optimal mixing amount considering its mechanical and rheological properties.

• Journal of the Korea Institute of Building Construction
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• v.21 no.5
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• pp.459-468
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• 2021

Blocking electromagnetic waves on the exterior walls of buildings effectively reduces the intensity of electromagnetic fields in buildings, which leads to attenuation of electromagnetic disturbances, so there is a great interest in developing technologies. In this study, SiC by-products and graphite generated in the semiconductor field were selected and mixed into mortar after pretreatment such as pulverization to evaluate their physical properties and electromagnetic wave shielding performance. Considering the economic efficiency of each shielding material, only 10% volume of the outermost side of the experiment was mixed with each shielding material to evaluate the shielding performance. The shielding performance was predicted when the experiment was manufactured by mixing the shielding material with the entire volume of the experiment using the shielding effect evaluation formula. The results of the experiment showed that the shielding performance was up to 20 dB when SiC grains were mixed with shielding materials, the shielding performance was up to 18 dB when graphite powder was mixed with shielding materials, and the shielding performance was up to 28 dB when SiC powder was mixed with shielding materials, and the shielding performance was close to 30 dB, which is known to have a shielding rate of 99.9%.

• Journal of the Korea Institute of Building Construction
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• v.22 no.2
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• pp.137-148
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• 2022

Recently, in the concrete industry, the development and commercialization of low-carbon products of ready-mixed concrete have emerged as part of the efforts to realize carbon neutrality. This study aims to investigate the current status of environmental product declaration(EPD) of ready-mixed concrete and to analyze the characteristics of carbon emissions by compressive strength, life cycle stage, and region. To this end, the related certification system requiring the calculation of carbon emissions in the concrete industry was analyzed. The target of analyzing the current status of carbon emissions was set as a product of ready-mixed concrete that acquired EPD certification based on the life cycle assessment method. In addition, the trend of carbon emissions according to each characteristic was reviewed by analyzing carbon emissions by the life cycle of ready-mixed concrete products, analyzing carbon emissions by standard, and analyzing carbon emissions by region. As a result, the carbon emissions in the pre-production stage were 99% compared to total carbon emissions., and as it increased from 18MPa to 40MPa, carbon emissions also increased. Even with the same specifications, the carbon emissions in the capital region were higher than in the southern region.

• Journal of the Korea Institute of Building Construction
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• v.12 no.4
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• pp.451-459
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• 2012

At the Korea Land and Housing Corporation(LH), concretes with high design strength of 50 MPa and 80 MPa that are composed only of ordinary Portland cement, blast furnace slag, and fly ash are developed. To determine whether the developed high strength concretes have the same properties when they are produced in batch plant(B/P) condition in the ready mixed concrete plant, and as existing high strength concretes, field tests are performed and material properties are evaluated. To investigate the material properties of the high strength concretes before and after pumping, compressive strength, flowability, air content, hydration temperature, pumping and compactability are evaluated. In field tests, before and after pumping, flowability satisfied the relevant criteria. In terms of air content, while it was slightly decreased after pumping, it satisfied the requirements. Hydration temperature criteria were satisfied, and compactability was excellent as well. The study found that the developed ternary high strength concretes have the same properties as existing high strength concretes. They can also be useful for the construction of high-rise buildings, as they are economical.