• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.33-40
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• 2021

The objective of this work is to prove a possibility of void f illing through a carbonation f or the purpose of improving the quality of recycled aggregate. Carbonation can permanently immobilize CO2, which is a greenhouse gas, and thus provides additional benefit on environment. In this work, recycled fine aggregate was reacted using gaseous CO2 and supercritical CO2(scCO2) in a closed chamber, and the changes in physical properties of the recycled f ine aggregate bef ore and af ter carbonation were analyzed using the apparent density, skeletal density, pH, and FE-SEM measurements. Thereafter, a mortar specimen was prepared and a compressive strength was measured. According to the experimental results, it was found that the increase in the apparent density and the true density was higher by the reaction with scCO2, which was conducted at high temperature and high pressure compared to the reaction with gaseous CO2. In addition, the pH of the eluted water was found to have a larger initial decrease than that observed with samples from reaction by gaseous CO2. The shape and amount of calcium carbonate crystals were also found to be larger than that from gaseous CO2. The increase in compressive strength was the largest when using recycled fine aggregate reacted with scCO2. It was clear that quality improvement of recycled fine aggregate was higher with scCO2 than with gaseous CO2.

• Journal of the Korean earth science society
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• v.23 no.3
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• pp.270-279
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• 2002

The concentrations of major greenhouse pollutants which include $CO_2$ and $CH_4$ were determined from the outlet of 42 ventpipes in Nan-Ji-Do area of Seoul during September/October of 2000. Using these data, the concentration distribution of major greenhouse gases was checked and compared. The mean concentrations of $CO_2$ and $CH_4$, computed using the data sets collected from 42 ventpipes, were 27.8 and 50.9%, respectively. Because the concentration levels were different not only between plain and slope areas of each sector but also between chemicals, evaluation of the data sets was made after dividing them separately into four data groups. The results of our analysis clearly indicate that their distribution is rather homogeneous than those of minor constituents of landfill ventilated gases (e.g., Hg).

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.660-667
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• 2010

In this research polyimide, Matrimid 5218, hollow fiber membrane was used to recover sulfur hexafluoride($SF_6$) which is one of the six greenhouse gases from $N_2/SF_6$ mixture gas. Fibers were spun from using dry-wet phase inversion method. The module was manufactured by fabricating fibers after surface coating with silicone elastomer. The scanning electron microscopy(SEM) studies showed that the produced fibers typically had an asymmetric structure; a dense top layer supported by a sponge-like substructure. The developed module had a permeance of 0.78-1.36 GPU for $N_2$ with $N_2/SF_6$ selectivity of 2.44-5.08 at various pressure and temperature. For recovery of $SF_6$, a membrane module and 10 vol.% $SF_6$ from $N_2/SF_6$ mixture gas was used. The effects of various operating condition such as pressure, temperature, and retentate side flow rate were tested. When pressure and temperature were increased and retentate flow rate was decreased, the $SF_6$ purity in recovered gas was increased up to 37.5 vol.% with decreasing recovery ratio. When retentate flow rate was increased pressure and temperature was decreased, the $SF_6$ recovery ratio in retentate side was increased up to 89% with decreasing the $SF_6$ purity in retentate side.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.238-239
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• 2010

근래, 이산화탄소로 대표되는 온실효과 기체의 증가에 동반하여 대류권의 기온이 정정 상승하는 지구 온난화의 경향이 나타나고 있다. 지구 온난화가 지속되면 해수면온도가 상승하고 그에 따라 해빙 면적의 축소와 해수면 상승이 동반된다. 이와 같은 지구 온난화의 상황이 지속되면 이상기상이 지구상 각지에서 빈발할 것이라는 주장도 제기되고 있다. 이 연구에서는 장기간의 태풍 관련 데이터를 이용하여 지구 온난화와 관련한 태풍의 변화 경향을 분석하였다. 연구 결과 지구 온난화와 더불어 태풍의 발생 수는 감소하고 있으며, 태풍의 세기는 서서히 강화되고 있음을 확인하였다. 그리고 태풍의 이동경로 중에서 정상진로는 증가하는 경향을 보이고 서진형진로는 감소하는 추세를 보이고 있다는 사실을 알았다. 우리나라의 경우는 최근에 들어 통해(또는 일본)를 통과하면서 영향을 미치는 태풍의 수가 증가하는 반면 서해를 통과하는 태풍의 수는 감소하는 경향을 보인다. 그리고 우리나라에 가장 큰 기상재해를 입히는 남해를 통과하는 태풍의 수는 시계열 상 큰 변화를 보이지 않는다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1532-1533
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• 2011

고압배전반과 같은 고전압 전력기기의 절연매질로는 고체 절연매질이 사용되기도 하지만 주로 공기나 $SF_6$와 같은 기체가 사용된다. 공기를 절연매질로 사용하고 있는 고압배전반과 같은 경우에는 장시간 운전 시 먼지나 수분 등과 같은 이물질에 의한 열화현상이 보고되고 있으며, $SF_6$를 사용하는 고압배전반의 경우에는 최근 온실효과와 같은 환경오염의 원인으로 지목되고 있는 등의 문제점을 가지고 있다. 따라서 이와 같은 열화현상이나 환경오염 유발과 같은 문제점을 해결하기 위한 방안 중의 하나로서 공기 중의 수분을 제거한 dry air를 이용한 친환경 고압배전반의 개발에 관한 연구가 활발히 이루어지고 있다. 본 연구에서는 dry air의 절연내력특성에 관한 실험을 수행하여 일반 공기의 절연내력특성과 비교하였다.

• Membrane Journal
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• v.27 no.6
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• pp.499-505
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• 2017

The increasing number of natural disasters resulting from anthropogenic greenhouse gas emissions has prompted the development of a gas separation membrane. Carbon dioxide ($CO_2$) is the main cause of global warming. Organic polymeric membranes with inherent flexibility are good candidates for use in gas separation membranes and poly(dimethyl siloxane)(PDMS) specifically is a promising material due to its inherently high $CO_2$ diffusivity. In addition, poly(vinyl pyrrolidine)(PVP) is a polymer with high $CO_2$ solubility that could be incorporated into a gas separation membrane. In this study, poly(dimethyl siloxane)-poly(vinyl pyrrolidine)(PDMS-PVP) comb copolymers with different compositions were synthesized under mild conditions via a simple one step free radical polymerization. The copolymerization of PDMS and PVP was characterized by FTIR. The morphology and thermal behavior of the produced polymers were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Composite membranes composed of PDMS-PVP on a microporous polysulfone substrate layer were prepared and their $CO_2$ separation properties were subsequently studied. The $CO_2$ permeance and $CO_2/N_2$ selectivity through the PDMS-PVP composite membrane reached 140.6 GPU and 12.0, respectively.

• Journal of Korea Water Resources Association
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• v.37 no.4
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• pp.305-314
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• 2004

Climate change mainly due to the increase of green house gases cause different patterns of water cycle within the basin. However, it is common that current planning and management practices do not consider the effect of the climate change. So, this study evaluated the effect of climate change on the water circulation within the watershed. This study used several GCM simulations for the double $CO_2$condition for the generation of temperature and rainfall series using the Markov chain. Daily runoff series for 100 years were generated using a rainfall-runoff model. As results. annual temperature increase by ＋3.2 ∼＋4.6$^{\circ}C$, annual precipitation change －7 ∼ ＋8 %, annual runoff change －14 ∼ ＋7 %, and potential evapotranspiration amount change ＋3 ∼＋4 % for the change of 1 $^{\circ}C$ are found to be expected depending on GCM simulations. Even though the simulation results are very dependent on the GCM predictions considered, overall variability of runoff is expected to become higher than the current state.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.4
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• pp.487-497
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• 2007

Increase of the greenhouse gases emissions during last century has led remarkable changes in our environment and climate system. Continuous monitoring of atmospheric constituents over the world is positively necessary to understand these changes around us. The concentrations of greenhouse gases ($CO_2,\;CH_4,\;N_2O,\;CFCs$) have been continuously measured at Global Climate Change Monitoring station in Gosan, Jeju since January, 2002. In this study, the variation characteristics of greenhouse gases as well as their annual, seasonal and diurnal trend using the data from January, 2002 to December, 2005 were analyzed. The raw data which was used in the analysis were validated with the methods recommended by WDCGG (World Data Center for Greenhouse Gases). The concentration of $CO_2$ was increasing continuously by 2.1 ppm/year, while $CH_4$ did not show any increasing or decreasing trend clearly for 4 years. The concentration of $N_2O$ was slightly increasing and CFCs were decreasing except CFC-12 which has longer lifetime compared with other CFCs. The variations of the greenhouse gases at Gosan were shown to be consistent with the global trend. But the concentration level of $CO_2$ in Korea was more or less higher than abroad.

• Journal of Science Education
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• v.38 no.2
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• pp.430-442
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• 2014

The purpose of this study is to investigate the Preconception about the causes and consequences of climate change. Participants were 196 High school students who live in Seoul and Gyeong-gi Province. And data was collected through questionnaire to confirm preconception about the causes and consequences of Climate Change. After confirming with students preconceptions, 10 people randomly selected and Semi-structured interview were conducted. The findings is students did not know exactly about Ozone depletion, global warming, the greenhouse effect factors and causal relationships. And we can confirm that the student's preconception is affecting.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.2
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• pp.86-90
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• 2012

The gaseous product of nitrogen cycle, nitrous oxide ($N_2O$) is a potent greenhouse gas whose Global Warming Potential (GWP) is about 300 times greater than $CO_2$. The dynamics of $N_2O$ emission are controlled by such environments and soil conditions. The main aim of this study is to investigate variations of $N_2O$ emission and its controlling factors with different land-use patterns in Haean basin. A forest, a radish field and a rice paddy were selected as three different land-use patterns. Their $N_2O$ emissions were measured every month during a growing season. We also collected soil samples with seasons and analyzed soil characteristics including inorganic nitrogen content. $N_2O$ emission was greatest at the radish field likely due to anthropogenic nitrogen addition by fertilization. Soils of forest and rice paddy also contained inorganic nitrogen originated from organic matter. However, the spatial variation was great and it looks that nitrogen cycle and $N_2O$ production were slower than that of radish field. Intensive observation and control of fertilization would be requiredto adjust $N_2O$ emission from agriculture soils.