• 자원리싸이클링
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• 제26권5호
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• pp.61-66
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• 2017

이산화바나듐은 적외선 투과를 차단하거나 창을 통해 건물 내부열 손실을 막아주는 광선택적 유리코팅 소재로 알려졌는데, 본 연구에서 이와 같은 열변색 특성을 가진 이산화바나듐을 수소와의 환원반응을 통하여 제조하는 방법에 대해 연구하였다. 환원반응에 의한 이산화바나듐의 제조는 반응이 쉽게 진행되고, 스퍼터, 빔 증발기 등과 같은 반도체 장비가 필요 없이 공정이 단순하고 대량생산에 용이한 장점을 갖고 있는데, 본 연구에서 수소와의 환원반응에 대한 반응온도, 반응시간, 환원가스의 농도 및 사후 열처리 조건, 첨가제로서 텅스텐의 첨가 등에 대해 실험을 수행하였으며, 최적조건을 도출하여 제조된 이산화바나듐 분말의 특성과 열변색 특성에 대해 조사하였다. 본 연구를 통해 개발된 이산화바나듐이 전자소재 및 에너지 저감 소재로서 많이 활용될 것으로 기대되고 있다.

• 대한원격탐사학회지
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• 제19권3호
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• pp.217-221
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• 2003

The Measurement of Pollution in the Troposphere (MOPITT) instrument is an eight-channel gas correlation radiometer that launched on the Earth Observing System (EOS) Terra spacecraft in 1999. Its main objectives are to measure carbon monoxide (CO) and methane (CH4) concentrations in the troposphere. This study analyzes tropospheric carbon monoxide distributions using MOPITT data and compare with ozone distributions in Northeast Asia. In general, seasonal CO variations are characterized by a peak in spring and decrease in summer. Also, this study revealed that the seasonal cycles of CO are maximum in spring and minimum in summer with average concentrations ranging from 118ppbv to 170ppbv. The monthly average of CO shows a similar profile to those of O3. This fact clearly indicates that the high concentration of CO in spring is caused by two possible causes: the photochemical CO production in the troposphere, or the transport of the CO in the northeast Asia. The CO and $O_3$ seasonal cycles in the Northeast Asia are influenced extensively by the seasonal exchange of the different types of air mass due to the Asian monsoon. The continental air masses contain high concentrations of $O_3$ and CO due to higher continental background concentrations and sometimes due to the contribution of regional pollution. In summer the transport pattern is reversed. The Pacific marine air masses prevail over Korea, so that the marine air masses bring low concentrations of CO and $O_3$, which tend to give the apparent minimum in summer.

• Smart Structures and Systems
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• 제24권4호
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• pp.541-552
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• 2019

Construction development and greenhouse gas emissions have globally required a strategic management to take some steps to stain and maintain the environment. Nowadays, recycled aggregates, in particular ceramic waste, have been widely used in concrete structures due to the economic and environmentally friendly solution, requiring the knowledge of recycled concrete. Also, one of the materials used as a substitute for concrete cement is wollastonite mineral to decrease carbon dioxide (CO2) from the cement production process by reducing the concrete consumption in concrete. The purpose of this study is to investigate the effect of wollastonite on the mechanical properties and durability of conventional composite concrete, containing recycled aggregates such as compressive strength, tensile strength (Brazilian test), and durability to acidic environment. On the other hand, in order to determine the strength and durability of the concrete, 5 mixing designs including different wollastonite values and recovered aggregates including constant values have been compared to the water - cement ratio (w/c) constant in all designs. The experimental results have shown that design 5 (containing 40% wollastonite) shows only 6.1% decrease in compressive strength and 4.9% decrease in tensile strength compared to the control plane. Consequently, the use of wollastonite powder to the manufacturing of conventional structural concrete containing recycled ceramic aggregates, in addition to improving some of the properties of concrete are environmentally friendly solutions, providing natural recycling of materials.

• Journal of Plant Biotechnology
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• 제48권3호
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• pp.148-155
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• 2021

Gibberellins (GAs) are essential phytohormones for plant growth that influence developmental processes and crop yields. Recent functional genomic analyses of model plants have yielded good characterizations of the canonical GA signaling pathways and related genes. Although Panax ginseng has long been considered to have economic and medicinal importance, functional genomic studies of the GA signaling pathways in this crucial perennial herb plant have been rarely conducted. Here, we identified and performed functional analysis of the GA signaling-related genes, including PgGID1s, PgSLY1s, and PgRGAs. We confirmed that the physiological role of GA signaling components in P. ginseng was evolutionarily conserved. In addition, the important functional domains and amino acid residues for protein interactions among active GA, GID1, SCF^SLY1, and RGA were also functionally conserved. Prediction and comparison of crystallographic structural similarities between PgGID1s and AtGID1a supported their function as GA receptors. Moreover, the subcellular localization and GA-dependent promotion of DELLA degradation in P. ginseng was similar to the canonical GA signaling pathways in other plants. Finally, we found that overexpression of PgRGA2 and PgSLY1-1 was sufficient to complement the GA-related phenotypes of atgid1a/c double- and rga quintuple-mutants, respectively. This critical information for these GA signaling genes has the potential to facilitate future genetic engineering and breeding of P. ginseng for increased crop yield and production of useful substances.

• 한국재료학회지
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• 제31권9호
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• pp.525-531
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• 2021

Carbon-encapsulated Ni catalysts are synthesized by an electrical explosion of wires (EEW) method and applied for CO₂ methanation. We find that the presence of carbon shell on Ni nanoparticles as catalyst can positively affect CO₂ methanation reaction. Ni@5C that is produced under 5 % CH₄ partial pressure in Ar gas has highest conversions of 68 % at 350 ℃ and 70 % at 400 ℃, which are 73 and 75 % of the thermodynamic equilibrium conversion, respectively. The catalyst of Ni@10C with thicker carbon layer shows much reduced activity. The EEW-produced Ni catalysts with low specific surface area outperform Ni catalysts with high surface area synthesized by solution-based precipitation methods. Our finding in this study shows the possibility of utilizing carbon-encapsulated metal catalysts for heterogeneous catalysis reaction including CO₂ methanation. Furthermore, EEW, which is a highly promising method for massive production of metal nanoparticles, can be applied for various catalysis system, requiring scaled-up synthesis of catalysts.

• 한국농공학회논문집
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• 제63권3호
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• pp.97-105
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• 2021

Most of the rural development projects for the welfare of residents are mainly new construction and remodeling projects for community buildings such as village halls and senior citizens. However, in the case of the construction industry, it has been studied that 23% of the total carbon dioxide emissions generated in Korea are generated in the building-related sector. (GGIC, 2015) In order to reduce the emission of environmental pollutants resulting from construction of rural community buildings, there is a need to establish a system for rural buildings by predicting the environmental impact. As a result of this study, the emissions of air pollutants from buildings in rural communities were analyzed by dividing into seven stages: material production, construction, operation, maintenance, demolition, recycling, and transportation activities related to disposal. As a result, 12 kg of carbon dioxide (CO), 0.06 kg of carbon monoxide (CO), 0.02 kg of methane (CH), 0.04 kg of nitrogen oxides (NO), 0.02 kg of sulfurous acid gas (SO), and non-methane volatile organics per 1m of buildings in rural communities It was analyzed that 0.02 kg of compound (NMVOC) and 0.00011 kg of nitrous oxide (NO) were released. This study proved that environmentally friendly design is possible with a quantitative methodology for the comparison of operating energy and air pollutant emissions through the design specification change based on the statement of the rural community building. It is considered that it can function as basic data for further research by collecting major structural changes and materials of rural community buildings.

• 멤브레인
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• 제31권2호
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• pp.133-144
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• 2021

알칼리 수전해 시스템은 다양한 수소 생산 공정 중에서 가장 온실가스 발생량이 적은 그린 수소를 생산하는 방식 중 가장 오래된 기술이다. 알칼리 수전해 시스템은 알칼리 조건에서 사용되며, 고분자 전해질막 수전해와는 다르게 니켈, 코발트, 은 등의 안정한 전이금속을 전극촉매로 사용할 수 있다. 이 시스템은 가격이 저렴하고 대용량화가 용이하다는 장점을 가지고 있다. 이러한 장점으로 알칼리 수전해 시스템은 20세기 초부터 MW급 수소발생장치에 적용되어 왔으며 현재 20여 개의 제조업체에서 상용제품을 판매하고 있는 안정화된 기술이다. 본 논문에서는 알칼라인 수전해의 기본원리 및 사용되는 촉매, 전극, 격막 등에 대해 알아보고 그 중 핵심소재인 격막의 연구개발 동향에 대해 살펴보고자 한다.

• 한국건설순환자원학회논문집
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• 제9권4호
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• pp.460-468
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• 2021

이산화탄소 및 온실가스의 배출, 과도한 에너지 소비 및 천연자원의 고갈을 막기 위해 콘크리트의 대체재를 찾는 것은 건설업의 해결과제이다. 이러한 문제를 해결하기 위해, 콘크리트보다 환경친화적인 지오폴리머가 주목을 받고 있으며, 실제 시공을 목적으로 강도 및 내구성에 대한 연구가 진행되고 있다. 일반적으로, 지오폴리머의 강도 및 내구성은 알칼리 용액의 종류 및 농도, 전구물질, 양생 온도 및 시간 등 여러 요인에 따라 달라지며, 이는 지오폴리머의 강도와 내구성에 영향을 미치는 화학조성 및 미세구조에 큰 영향을 미친다. 기존의 연구에서 최적의 알칼리 용액의 종류 및 농도, 전구물질, 양생 온도 및 시간을 통하여 지오폴리머의 압축강도 및 내구성이 향상되는 것을 확인하였으며, 본 연구에서는 과거의 연구 결과를 검토하고 이러한 요인이 지오폴리머의 압축강도 및 내구성에 미치는 영향을 체계적으로 종합하였다.

• 한국해양생명과학회지
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• 제6권1호
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• pp.1-8
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• 2021

In marine ecosystems, the biosynthesis and catabolism of dimethylsulfoniopropionate (DMSP) by marine bacteria is critical to microbial survival and the ocean food chain. Furthermore, these processes also influence sulfur recycling and climate change. Recent studies using emerging genome sequencing data and extensive bioinformatics analysis have enabled us to identify new DMSP-related genes. Currently, seven bacterial DMSP lyases (DddD, DddP, DddY, DddK, DddL, DddQ and DddW), two acrylate degrading enzymes (DddA and DddC), and four demethylases (DmdA, DmdB, DmdC, and DmdD) have been identified and characterized in diverse marine bacteria. In this review, we focus on the biochemical properties of DMSP cleavage enzymes with special attention to DddD, DddA, and DddC pathways. These three enzymes function in the production of acetyl coenzyme A (CoA) and CO₂ from DMSP. DddD is a DMSP lyase that converts DMSP to 3-hydroxypropionate with the release of dimethylsulfide. 3-Hydroxypropionate is then converted to malonate semialdehyde by DddA, an alcohol dehydrogenase. Then, DddC transforms malonate semialdehyde to acetyl-CoA and CO₂ gas. DddC is a putative methylmalonate semialdehyde dehydrogenase that requires nicotinamide adenine dinucleotide and CoA cofactors. Here we review recent insights into the structural characteristics of these enzymes and the molecular events of DMSP degradation.

• Journal of Microbiology and Biotechnology
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• 제31권6호
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• pp.890-901
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• 2021

The 11α-hydroxylation of canrenone can be catalyzed by Aspergillus ochraceus in bioreactors, where the geometry of the impeller greatly influences the biotransformation. In this study, the effects of the blade number and impeller diameter of a Rushton turbine on the 11α-hydroxylation of canrenone were considered. The results of fermentation experiments using a 50 mm four-blade impeller showed that 3.40% and 11.43% increases in the conversion ratio were achieved by increasing the blade number and impeller diameter, respectively. However, with an impeller diameter of 60 mm, the conversion ratio with a six-blade impeller was 14.42% lower than that with a four-blade impeller. Data from cold model experiments with a large-diameter six-blade impeller indicated that the serious leakage of inclusions and a 22.08% enzyme activity retention led to a low conversion ratio. Numerical simulations suggested that there was good gas distribution and high fluid flow velocity when the fluid was stirred by large-diameter impellers, resulting in a high dissolved oxygen content and good bulk circulation, which positively affected hyphal growth and metabolism. However, a large-diameter six-blade impeller created overly high shear compared to a large-diameter four-blade impeller, thereby decreasing the conversion ratio. The average shear rates of the former and latter cases were 43.25 s^-1 and 35.31 s^-1, respectively. We therefore concluded that appropriate shear should be applied in the 11α-hydroxylation of canrenone. Overall, this study provides basic data for the scaled-up production of 11α-hydroxycanrenone.