• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.398-401
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• 2007

The performance characteristics of Polyethylene-Nitrous oxide (PE-N2O) hybrid rocket motor with the variation of the grain geometry was investigated. To compare the performance parameters under the different port number, single and four port grains were used in this study. In order to improve the performance by enhancing mixing between fuel and oxidizer, the fuel grain having the mixing chamber was additionally studied. From the motor firing tests, it is found that the motor having 4-port fuel grain with the mixing chamber showed the highest performance among all cases. Therefore we have confirmed that with only the geometrical change of the fuel grain, it was possible to give quite influential improvement on the motor performance

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.4-4
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• 2017

Atmospheric carbon dioxide enrichment ($eCO_2$) often increases soil nitrous oxide ($N_2O$) emissions, but the underlying mechanisms are not fully understood. Emerging evidence suggests that $eCO_2$ alters plant N preference in favor of ammonium ($NH_4{^+}-N$) over nitrate ($NO_3{^-}-N$). Yet, whether and how this attributes to the enhancement of $N_2O$ emissions has not been investigated. We examined the effects of $eCO_2$ on soil $N_2O$ emissions in the presence of two N forms ($NH_4{^+}-N$ or $NO_3{^-}-N$), using wheat (Triticum aestivum L.) as a model plant. Our results showed that N forms dominated $eCO_2$ effects on plant and microbial N utilization, and thus soil $N_2O$ emissions. Elevated $CO_2$ significantly increased the rate and the sum of $N_2O$ emissions by three to four folds when $NO_3{^-}-N$, but not $NH_4{^+}-N$, was supplied. Enhanced $N_2O$ emission was related to the reduced plant $NO_3{^-}-N$ uptake in wheat. We propose a new conceptual model in which $eCO_2$-inhibition of plant $NO_3{^-}-N$ uptake and/or $CO_2$-enhancement of soil labile C enhances the N and/or C availability for denitrifiers and increases the intensity and/or the duration of $N_2O$ emissions. Together, these findings suggest that to enhance plant N use efficiency and reduce $N_2O$ emission, crop breeding and management need to consider altered plant preference of N sources under future $CO_2$ scenarios.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.232-235
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• 2003

In general, the parameters of climate change include aerosol chemical compounds, aerosol optical depth, greenhouse gases(carbon dioxide, CFCs, methane, nitrous oxide, tropospheric ozone), ozone distribution, precipitation acidity and chemical compounds, persistent organic pollutants and heavy metals, radioactivity, solar radiation including ultra-violet and standard meteorological parameters. Over the last ten years, the monitoring activities of Korea regarding to the climate change have been progressed within the WMO GAW and ACE-Asia IOP programs centered at the observation sites of Anmyeon and Jeju Gosan islands respectively. The Greenhouse gases were pointed out that standard air quality monitoring techniques are required to enhance data comparability and that data presentation formats need to be harmonized and easily understood. Especially, the impact of atmospheric aerosols on climate depends on their optical properties, which, in turn, are a function of aerosol size distribution and the spectral reflective indices. Aerosol optical depth and single scattering albedo in the visible are used as the two basic parameters in the atmospheric temperature variation studies. The former parameter is an indicator of the attenuation power of aerosols, while the latter represents the relative strength of scattering and absorption by aerosols. For aerosols with weak absorption, surface temperature decreases as the optical depth increases because of the domination of backscattering. For aerosols with strong absorption, however, warming could occur as the optical depth increases. The objective of the study is to characterize the means, variability, and trends of Greenhouse gases and aerosol properties on a regional basis using data from its baseline observatories in Korea peninsula. A further goal is to understand the factors that control radiative forcing of the greenhouse and aerosol.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.12
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• pp.587-613
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• 1999

Environmental problems such as global climate change, depletion, ocean and air pollution, and resource degradation-compounded by an expanding world population-respect no border and threaten the health, prosperity and jobs of all mankind. Our efforts to promote democracy, free trade, and stability in the world will fall short unless people have a livable environment. We have an enormous stake in the management of the world's resources. By increasing demand for timber, natural gas, coal and consumer's goods have destroyed the grounds for living. Greenhouse gas emissions anywhere in the world have threatened coastal communities, and then changed the Earth's climate system. The burning of coal, oil, and other fossil fuels is increasing substantially the concentration of heat-trapping gasses such as carbon dioxide, methane, and nitrous oxide in our air. The earth's temperature and sea levels are rising as a result. Since 1972 there has been a marked growth in the number and scope of environmental treaties. In particular, after the 1992 Rio Conference, international legal instruments became more concentrated on addressing environment within the context of sustainable development and incorporated a number of new concepts and innovative approaches. A preliminary analysis of recent conventions and in particular those associated with the Rio Conference indicates various ideas, concepts and principles which have come to the fore including sustainable development, equity, common concern of humankind, common but differentiated responsibilities and global partnership. However, international trade also has an environmental impact which must be minimized or countered. Positive measures are to be preferred to achieve environmental goals, but where trade provisions are necessary, they should be appropriately used within environmental conventions to facilitate the reduction and limitation of the negative impacts of trade and to enhance the complementarity of the multilateral trade regime with the imperatives of environmental protection, in the interests of environmental protection and sustainable development generally. The international community has to recognize and endorse this need to achieve complementarity between trade and environment issues.

• Journal of Animal Science and Technology
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• v.58 no.6
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• pp.22.1-22.15
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• 2016

Background: Dietary manipulation is a common practice to mitigate gaseous emission from livestock production facilities, and the variation of fat level in the diet has shown great influence on ruminal volatile fatty acids (VFA) and enteric methane generation. The changes in dietary fat levels influence rumen chemistry that could modify manure nutrient composition along with odor and gaseous emissions from manure management facilities. Methods: A field experiment was carried out on beef cattle feedlots to investigate the effect of four levels of dietary fat concentrations (3 to 5.5 %) on the manure composition and gaseous emissions (methane-$CH_4$, nitrous oxide-$N_2O$, carbon dioxide-$CO_2$ and hydrogen sulfide-$H_2S$) from the feedlot pen surface. The experiment was carried out over a 5-month period from June to October during North Dakota's summer-fall climatic condition. Air and manure sampling was conducted five times at a 20-30 day intervals. Results: Overall, this research indicated that fat levels in diet have no or little effect on the nutrient composition of manure and gaseous emission from the pens with cattle fed with different diet. Though significant variation of gaseous emission and manure composition were observed between different sampling periods, no effect of high fat diet was observed on manure composition and gaseous emission. Conclusions: It can be concluded that addition of fat to animal diet may not have any impact on gaseous emission and manure compositions.

• Environmental and Resource Economics Review
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• v.23 no.2
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• pp.249-280
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• 2014

IPCC requires the national uncertainties which show how credible the emission of greenhouse gases is. But the Korean government did not submit the total uncertainties, only the detailed uncertainties by items. Also it uses the default values of IPCC including some missing values. This paper tries to estimate the total uncertainties of energy by categories, which accounts for 85.3% in national emission of greenhouse gases. Concretely, it uses Tier 1 method suggested by IPCC. As a result of the analysis, the uncertainties in energy category are 3.4% similar to Finland's. But there was a big difference among greenhouse gases; carbon dioxide 2.7%, methane 116% and nitrous oxide 473%. So this paper suggests Korean government need to improve not only the activity but also the emission factor of data in order to reduce the national uncertainties in energy category.

• Journal of Dairy Science and Biotechnology
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• v.33 no.2
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• pp.93-102
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• 2015

The aim of this study was to investigate the physiological characteristics and immunomodulatory activity of Lactobacillus fermentum 450 isolated from raw milk. L. fermentum 450 showed optimum growth at $40^{\circ}C$ and exhibited immunomodulatory effects on $interleukin-1{\alpha}$, tumor necrosis $factor-{\alpha}$, and nitrous oxide at concentrations of >2,500 pg/mL, >2,000 pg/mL, and $11.55{\pm}2.95{\mu}M$, respectively. Of the 16 antibiotics tested, L. fermentum 450 exhibited the highest sensitivity to rifampicin, followed by penicillin-G, and the highest resistance to kanamycin, followed by neomycin and polymyxin B. The strain showed high acid phosphatase activity and was comparatively tolerant to bile juice and acid. Moreover, the strain displayed high resistance to Salmonella Typhimurium (63.86%). These results demonstrate that L. fermentum 450 has potential for use as a probiotic with immunomodulatory activity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.89-96
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• 2006

In this study, fluid flow and thermal characteristics in a catalyst bed for nitrous oxide catalytic decomposition which is introduced as a hybrid rocket ignition system for small satellites were theoretically considered. To analyze the thermal phenomena of the catalyst bed, a so-called porous medium approach has been opted for modeling the honeycomb geometry of the catalyst bed. Using a Brinkman-extended Darcy model for fluid flow and the one-equation model for heat transfer, the analytical solutions for both velocity and temperature distributions in the catalyst bed are obtained and compared with experimental data to validate the porous medium approach. Based on the analytical solutions, parameters of engineering importance are identified to be the porosity of the catalyst bed, effective volumetric ratio, the ratio of the radius of the catalyst bed to the radius of a pore, heat flux generated by a heater, and pumping power. Their effects on thermal phenomena of the catalyst bed are studied.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.823-829
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• 1997

The patients visiting pediatric dental office have been being younger than the previous, and they were often combined with systemic disease. But, we aren't able to perform the verbal communication, because of their impediment and youthfullness. And, we can't carry out the behavior control via physical restraint, as the developed social structure and the attitude of children and their parents. So, the importance and concerning of conscious sedation using sedative medicine are increased by time and time. Among the various conscious sedation, Chloral Hydrate and Nitrous Oxide inhalation are most popularly used, and barbiturates, benzodiazepine, opioids and hydroxyzine are used often. But, these medications have some side-effects and adverse reactions, may be failed to sedate the children. And limited use of medically compromised patients, especially for ASA class III, IV or more dangerous patients. We, the Department of Pediatric Dentistry, Chosun University have met some dangerous situation due to unfavorable pharmacogenic reactions, but we can control the situation and get well healed results. The below results are common situations and their solutions during conscious sedation. 1. By the intravenous administration, thrombophlebitis is the most common side-effects, but it may be healed with time without any special treatment. 2. Under the definitive guidelines about conscious-sedation, we can perform a safe conscious sedation for ASA class III patients. 3. When adversed reaction of Benzodiazepine is occured, it could be cared effectively with benzodiazepine antagonist, named Flumazenil.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.525-532
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• 1998

The autism is a complex disorder, characterized language impairment, perceptual-motor difficulties, and social disturbance. The autistic children have hyperactivity, lack of communication' lack of cooperation, inappropriate patient/dentist interaction, so they require professionally recognized behavioral management technique during dental treatment such as behavior modification, phamacological agents, and general anesthesia. A behavior management technique can be chosen by factors such as the severity of autism and possible accompanying disabilities, degree of cooperation, oral and general conditions of children. A non-pharmacological behavior modification may be selected for the autistic children who are able to communicate with dentist with mild dental caries, without compromised medical history. In case of excessively hyperactive, destructive, antisocial, and/or severe communicative disorder, a sedation technic with chloral hydrate, hydroxyzine, midazolam or nitrous oxide gas might to be performed. General anesthesia is preferred for severe communicative and/or behavioral disorder, elder age, excessive dental care need, and living a remote area.