• Korean Journal of Plant Resources
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• v.13 no.3
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• pp.162-170
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• 2000

This study quantified the effects of urban greenspace on microclimate amelioration and atmospheric $CO_2$ reduction for several residential districts selected in Korea and Japan. The study also explored fire obstruction by urban trees to develop systematic planting guidelines. Transpiration by a Zelkova serrata tree (diameter at breast height: 15 cm) in a day of August equaled cooling effect of about 3 air conditioners running for 12 hours. Average air temperature for the growing season was 0.5$^{\circ}C$ and 1.2$^{\circ}C$ cooler, respectively, in districts with 12% and 22% cover of woody plants than in a district with no vegetation. Annual $CO_2$ uptake and $O_2$ production by woody plants were 3 times greater in a district which was 2 times higher in their cover. Woody plants played, in a district with their 22% cover, an important role through offsetting total $CO_2$ emission from the district by about 3% annually, and through producing 10% of annual $O_2$ requirement by all residents within the district. Appropriate planning strategies of residential greenspace, including species selection, planting layout, greenspace enlargement, and maintenance were suggested to improve microclimate amelioration, air purification, and fire obstruction.

• Journal of Forest and Environmental Science
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• v.29 no.4
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• pp.249-256
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• 2013

The aim of the study was to reveal the scope and benefits derives from establishing carbon forests in a country like Bangladesh. Carbon forestry is the modernized forestry practice that evolves no cutting of trees or vegetation rather conserves them in the wood. Trees might be the source of carbon sink at large scale by establishing carbon forests. To find out how and in what extent forests of Bangladesh could contribute to global emission reduction, tree species of economic importance were taken into account about their carbon sequestration potential. Data source was a secondary one. Bangladesh has subtropical evergreen and deciduous forest tree species. Here trees can sequester almost 45-55 percent organic carbon in their biomass. On an average, trees in different types of stands can sequester 150-300 tC/ha. Carbon value of these forests might be 7,500-15,000 USD per hactre (assuming 50 USD per equivalent $tCO_2$). Thus, accounting tree carbon credits of total forested lands of Bangladesh, there might be a lump sum value of $1.89{\times}10^{10}-3.79{\times}10^{10}$ USD. If soil carbon is added, this amount would jump. Alternatively, there are two times higher spaces as marginal lands than this for starting carbon forestry. However, carbon forestry concept is still a theoretical conception unless otherwise their challenges are addressed and solved. Despite of this, forests of Bangladesh might be the key showcase for conserving biodiversity in association with carbon capture. Protected areas in Bangladesh are of government wealth, however, degraded and denuded waste and marginal lands might be the best fit for establishing carbon forests.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.3
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• pp.277-283
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• 2005

Pretreatment procedure was investigated into brucite powders for mineral carbonation materials. Higher magnesium content was found from brucite powders and weight loss due to hydroxy group(-OH) elimination, explained by FT-IR spectra, was found after pretreatment. X-ray diffraction results showed that the crystallographic changing of brucite into magnesium oxides during pretreatment. XPS core spectra also showed chemical transformation of magnesium ingredient from hydroxides to oxide.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.9
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• pp.863-871
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• 2004

The use of fossil fuels like coal, oil and natural gases around the world causes an increase of the carbon dioxide content in the atmosphere. In order to reduce the concentration of the greenhouse gas, the idea of carbon dioxide sequestration in the ocean is proposed to be an effective mitigation strategy to counteract potential global warming due to the greenhouse effect. Therefore, in the present study, calculations of the dissolution behavior of carbon dioxide when liquid carbon dioxide is released at 1,000m and 1,500m in depth by fixed pipeline are performed. The results show that carbon dioxide droplets change to carbon dioxide bubbles in gas phase around 500m in depth, and the droplets are completely dissolved below 500 m in depth if the liquide carbon dioxide is released both at 1,000 m in depth with the initial diameter of 0.007m or less and at 1,500m in depth with the diameter of 0.011m or less.

• Journal of ILASS-Korea
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• v.10 no.4
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• pp.26-31
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• 2005

Today, the research to examine a fact that interaction between the air and the fluid free surface affects the steady state flow and air. We proved the interaction between vortex pairs and free surface on each condition that is created by the end of delta wings. Another purpose of this study is to investigate the effect of surface active material which call change the surface tension and we must consider when we refer to turbulent flow on surface tension. Therefore, this research examined the growth process of vortex pairs on condition of clean, contaminated free surface and wall after we made vortex pairs through counter rotating flaps. The results of this study suggest that vortex pairs in clean free surface rise safely but the vortex pairs in contaminated free surface and rigid, no slip is made secondary vortex or rebounding. However the secondary vortex in rigid, no slip is stronger than before. and we can find the vortex shape which roll up more completely. However, these will disappear by the effect of wall.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.2
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• pp.93-100
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• 2013

Many researches have been carried out to reduce and/or to capture the major global warming gases. Especially, the hydrate formation mechanisms were intensively investigated for carbon dioxide sequestration and storage process applications. In this study, the characteristics of film-type crystal growth mechanism of carbon dioxide hydrate were comprehensively examined. Carbon dioxide hydrate crystal was formed in semi-batch type stir reactor at various pressure conditions while the temperature was fixed to be constant to reduce and minimize the guest gas solubility effects. A supply gas composition was 99.999 % of Carbon dioxide, the observation data was collected by optical microscope adopted CCD camera (Nikon DS-5M/Fi1/2M-U2). This study revealed that the guest gas pressure changes significantly altered the crystal growth mechanism and film growth rate of carbon dioxide hydrate crystal. The critical pressure of the carbon dioxide hydrate of crystal growth mechanism change was found to be 2.0 MPa. The capillary force and gas concentration gradient also significantly changed the film-type crystal growth mechanism of carbon dioxide hydrate crystal.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.503-518
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• 2012

Korean type of no-tillage cultivation method which was applied on this study used the ridge and the furrow and constantly recycling them as it was suitable for Korea's weather and farming conditions. This no-tillage cultivation was reported to have little negative impact such as reduction of production (Kwon et al., 1997). In addition, it was found to have a lot of benefits as it requires less agro-materials and energy costs as well as shortened working hours because tillage operation is not needed. (Yang et al., 2012). According to an analysis, no-tillage cultivation can reduce greenhouse gas emissions by $344.7kgCO^2$ (58%) in every 10a ($1,000m^2$) compared to ordinary pepper farming technique (Korea averages). Direct-indirect reduction effects from using fertilizer and using less amount of energy were 92% and 44% respectively both of which can be considered very high. Besides the direct effects of no-tillage cultivation, soil management using no-tillage technique raises carbon sequestration effect on soil as time goes on (West & Marland, 2002), that is why the technique is expected to have constant carbon emission reduction effect. For theses reasons, distribution and expansion of Korean type no-tillage cultivation are expected to play a role as major agro-green technologies for achieving our goal of reducing greenhouse gas emissions in agricultural sector.

• Korean Journal of Environment and Ecology
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• v.24 no.5
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• pp.591-600
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• 2010

We estimated and compared C storages and annual $CO_2$ uptakes by 9 dominant tree species planted along the streets. DBH and age by tree species were measured in the sites selected considering the planting status and distributions of tree species, and biomass, C storage, growth rate, and annual $CO_2$ uptake were estimated for each species. As a result, L. tulipifera, M. glyptostroboides, P. occidentalis were classified into fast-growing group, P. serrulata, G. biloba, Z. serrata, S. japonica, A. palmatum showed intermediate growth rates, and P. densiflora was slow-growing. Average C storage per tree was 205kgC/tree and ranged from 518kgC/tree(L. tulipifera) to 41kgC/tree(P. densiflora). Average annual $CO_2$ uptake by urban street trees over their lifespan ranged from $7.6kgCO_2$/tree/y to $99.1kgCO_2$/tree/y and L. tulipifera was the greatest, followed by glyptostroboides and P. occidentalis, and P. densiflora was the lowest. Total annual $CO_2$ uptake by all street trees in Gyeonggi-do, estimated based on the annual $CO_2$ uptake by each species, was as small as approximately 0.67% of that by forest in Gyeonggi-do. However, urban trees are still important because forest area continues to decrease and urbanization occurs annually in Gyeonggi-do, and should be managed considering their multi-functional aspects, including mitigation of heat island effect and building energy saving(indirect $CO_2$ uptake).

• Journal of the Mineralogical Society of Korea
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• v.15 no.3
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• pp.231-240
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• 2002

Microbial metal reduction influences the biogeochemical cycles of carbon and metals as well as plays an important role in the bioremediation of metals, radionuclides, and organic contaminants. The use of bacteria to facilitate the production of magnetite nanoparticles and the formation of carbonate minerals may provide new biotechnological processes for material synthesis and carbon sequestration. Metal-reducing bacteria were isolated from a variety of extreme environments, such as deep terrestrial subsurface, deep marine sediments, water near Hydrothemal vents, and alkaline ponds. Metal-reducing bacteria isolated from diverse extreme environments were able to reduce Fe(III), Mn(IV), Cr(VI), Co(III), and U(VI) using short chain fatty acids and/or hydrogen as the electron donors. These bacteria exhibited diverse mineral precipitation capabilities including the formation of magnetite ($Fe_3$$O_4$), siderite ($FeCO_3$), calcite ($CaCO_3$), rhodochrosite ($MnCO_3$), vivianite [$Fe_3$($PO_4$)$_2$ .$8H_2$O], and uraninite ($UO_2$). Geochemical and environmental factors such as atmospheres, chemical milieu, and species of bacteria affected the extent of Fe(III)-reduction as well as the mineralogy and morphology of the crystalline iron mineral phases. Thermophilic bacteria use amorphous Fe(III)-oxyhydroxide plus metals (Co, Cr, Ni) as an electron acceptor and organic carbon as an electron donor to synthesize metal-substituted magnetite. Metal reducing bacteria were capable of $CO_2$conversion Into sparingly soluble carbonate minerals, such as siderite and calcite using amorphous Fe(III)-oxyhydroxide or metal-rich fly ash. These results indicate that microbial Fe(III)-reduction may not only play important roles in iron and carbon biogeochemistry in natural environments, but also be potentially useful f3r the synthesis of submicron-sized ferromagnetic materials.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.645-651
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• 2008

In this study, the new solubility data at high pressure condition applicable to pre-combustion $CO_2$ capture system were found. Experiments were conducted within the temperature range of $40{\sim}80^{\circ}C$ while increasing the pressure from 0 to 50 bar. The effect of MDEA (N-methyldiethanolamine) concentration was studied by varying the concentration from 30 to 50 wt%. In order to improve the absorption rate of MDEA, piperazine was added in ranging of 5~10 wt% into the MDEA solution as a activator. From this experiment, the equilibrium partial pressure was increased with increasing MDEA concentration in absorbent and reaction temperature. Also absorption rate was increased with increasing the reaction temperature. It was noted that the mixture of piperazine and MDEA aqueous solution showed faster absorption rate by 2.5 times than only the MDEA aqueous solution with 40 wt% cencentration at initial reaction stage and also increased absorption capacity by 16%.