• 에너지공학
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• 제10권4호
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• pp.379-386
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• 2001

본 연구는 산업용 고부하 버너연소에서의 NO$_{x}$ 저감에 관한 실험적 연구이다. 본 연구에서는 NO$_{x}$의 정량적 농도 분포 측정을 위하여 레이저 유동 형광법을 사용하였다. XeCL 엑시머 레이저를 사용하여 NO A-X (0, 0) 진동밴드를 226 nm로 여기하였다. 또한 P$_{21}$+Q$_1$(14.5)/R$_{12}$+Q$_2$(20.5)/P$_1$(23.5) 전이를 여기라인으로 하였으며 다른 간섭의 영향을 최소화 하였다. 본 실험에서 이중선회 확산화염에서의 NO 농도 분포를 측정하였으며, 이 스월버너에서의 화염의 후류에 있어서 NO 농도는 1차/2차 공기비가 증가할 때 감소함을 알수 있었다.

• 한국연소학회지
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• 제4권2호
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• pp.63-74
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• 1999

The effects of EGR and premixedness on NO formation have been numerically investigated. The flame structure is classified into three categories; premixed flame($=1)$, rich/lean premixed flame(${\alpha}=0.6$ and 0.8) and diffusion flame(${\alpha}=0$). NO formation/destruction mechanisms are assorted to thermal, reburn and Fenimore mechanisms. The temperature of unburned gas is arranged to 298 and 500 K to have access to the condition in a real internal combustion engine. The results show that all three NO formation/destruction reaction rates in the fuel rich flame zone could be decreased by EGR for rich/lean premixed flames, while those in the fuel lean flame zone are not significantly changed. Near the stagnation plane, however, only the thermal NO reaction rate is decreased. The contribution of reburn and Fenimore mechanisms for the net NO production becomes less significant as the premixedness of a flame increases. The larger amount of NO reduction with EGR is expected under the higher temperature and/or higher fuel/air premixedness conditions due to the increased contribution of the thermal mechanism. The role of Fenimore and reburn mechanisms could be important for rich premixed and diffusion flames; therefore, the effect of EGR on NO reduction could vary with fuel/air premixedness. The premixedness of a partially premixed flame changes the flame structure and could affect the NO production characteristics.

• Journal of Korean Society for Atmospheric Environment
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• 제21권E3호
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• pp.75-85
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• 2005

A mathematical sensitivity analysis of the flow-through dynamic flux chamber technique, which has been utilized usually for various trace gas flux measurement from soil and water surface, was performed in an effort to provide physical and mathematical understandings of parameters essential for the NO flux calculation. The mass balance equation including chemical reactions was analytically solved for the soil NO flux under the steady state condition. The equilibrium concentration inside the chamber, $C_{eq}$, was found to be determined mainly by the balance between the soil flux and dilution of the gas concentration inside the chamber by introducing the ambient air. Surface deposition NO occurs inside the chamber when the $C_{eq}$ is greater than the ambient NO concentration ($C_{0}$) introducing to the chamber; NO emission from the soil occurs when the $C_{eq}$ is less than the ambient NO concentration. A sensitivity analysis of the significance of the chemical reactions of NO with the reactive species (i.e. $HO_{2},/CH_{3}O_{2},/O_{3}$) on the NO flux from soils was performed. The result of the analysis suggests that the NO flux calculated in the absence of chemical reactions and wall loss could be in error ranges from 40 to $85\%$ to the total flux.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권2호
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• pp.121-129
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• 1999

Photosynthesis and transpiration rates were simultaneously measured in attached sunflower leaves(Helianthus annuusL. cv. Russian Mammoth) during exposure to $NO_2$ and $O_3$ to determine the effect of mixed gan on photosynthesis and the stomatal aperture. The application of $O_3$ alone reduced both the net photosynthetic and transpiration rates. An analysis of the $CO_2$ diffusive resistances indicated that the main cause affecting photosynthesis reduction during $O_3$ exposure was not the internal gas phase of the leaf $(rCO_2^{liq})$ but rather the liquid phase or mesophyll diffusive resistance $(rCO_2^{liq})$, suggesting that there is a very concomitant relation between photosynthetic reduction and $rCO_2^{liq}$. The application of NO2 alone caused a marked reduction of the net photosynthesis yet no significant reduction of transpiration, indicating that NO2 affects the $CO_2$ fixation processes with no inluence on the stomatal aperture. A greter reduction in the photosynthesis of sunflower plants was caused by the application of $NO_2$ alone as compared to a combination of $NO_2$ and $O_3$. $NO_2$ alone reduced the photosynthetic rate by 90%, whereas a mixture of NO2 and O3 reduced it by 50%.

• 대한기계학회논문집
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• 제19권2호
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• pp.559-567
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• 1995

The combustion process within a porous inert medium (PIM) burner is numerical studied. A detailed chemical reaction scheme including thermal and prompt NO$_{x}$ reactions is used to predict the formation and destruction of pollutants such as NO$_{x}$ and CO. The reaction paths for NO$_{x}$ formation are divided to quantify the amount of NO$_{x}$ formed through thermal NO$_{x}$ reaction or through prompt NO$_{x}$ reaction. Emission index is calculated to compare the actual mass of NO$_{x}$ or CO produced through the combustion of unit mass of fuel. It is found NO formation in PIM burner is confined in flame zone and formation is suppressed due to heat loss at down-stream of the flame. Higher production of NO through prompt NO reaction path is observed due to the higher concentration of fuel derivative species and its higher diffusion at flame front. For all equivalence ratios, CO emission within PIM burner is lower than that from the one-dimensional freely-propagating flame. PIM burner flame has better NO$_{x}$ emission index from .psi. = 0.75 to .psi. = 1.1. to .psi. = 1.1.

• 대한의생명과학회지
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• 제24권1호
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• pp.50-54
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• 2018

N-nitroso-N-methylurea (NMU) and N-nitroso-N-ethylurea (NEU), direct alkylating chemical mutagens and carcinogens, are shown to be the upregulators of cellular $NF-{\kappa}B$, regulating various genes that mediate tumorigenesis and carcinogenesis. Nitric oxide (NO), a toxic reactive radical gas, has been known to induce programmed cell death or apoptosis in various cells. Therefore, the assessment of NO production was examined to elucidate the possible contribution of NO release to the chemical carcinogenic potency of NMU and NEU in human skin cells. NMU and NEU did not alter the NO production, but they caused a significant downregulation of the NO generation on lipopolysaccharide (LPS)-induced NO production at concentrations ranging from $2{\sim}5{\mu}M$. The degree of downregulation of NO by NMU and NEU decreased up to 15% and 20%, respectively, compared to the control. These results demonstrate that the LPS-inducible keratinocytes NO synthase is involved in modulating carcinogenic potency by NMU and NEU, and the regulation of the cellular $NF-{\kappa}B$ activity by NMU and NEU is negatively correlated with the level of LPS-induced NO production in human skin cells. The findings of this study suggest the hypothesis that NMU and NEU-induced carcinogenesis may be associated with the downregulation of NO production, and the inducible NO may play an important role in NMU and NEU-induced carcinogenicity in human epidermal keratinocytes.

• 한국응용과학기술학회지
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• 제29권4호
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• pp.570-576
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• 2012

본 연구에서는 무격막식 전기분해 처리된 해수를 산화제로하는 NO 산화반응의 특성에 대해 실험적으로 살펴보았다. 폐순환 정전류 전기분해 시스템을 통해전해 시간이 길어질수록 전해수의 유효 염소농도와 온도, 염소산 이온의 비율이 증가함을 확인하였다. 전해수가 채워진 버블링 반응기에서 전해수의 유효염소농도와 온도에 비례하여 $NO_2$로 산화되는 NO의 양이 증가하였다. 또한 산화되어 생성된 $NO_2$는 전해수에 용해되어 $HNO_3{^-}$ 이온으로 존재함을 확인하였다.

• Journal of Korean Society for Atmospheric Environment
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• 제24권E1호
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• pp.12-23
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• 2008

Relationship between the optimum soil water content and clay content on soil samples from mid-latitude European forest was tested. Soil samples from 4 different experimental sites (two forest sites in the Netherlands and a Danish forest) were collected, and analyzed for the soil physical and chemical characteristics. Water retention curves for the soil samples were determined according to the standard procedure ISO 11274, and pF decreased with increase in soil water contents. NO is simultaneously produced and consumed by microbiological processes, which comprise of nitrification and denitrification. NO consumption and production rates were determined from the soil samples and compared to their corresponding water retention curves in order to find the optimum soil water content and matric potential for maximum NO release from mid-latitude soils. NO consumption rate coefficient (k) in Hollandse Hout was significantly lower than those in other soil sites. Maximum NO production was observed at an intermediate soil moisture ($0.2{\sim}0.3kg/kg$) in all the soil samples. Resulting from the NO consumption and production rates for the soils, the empirical NO fluxes of the different soils were calculated in the laboratory.

• 약학회지
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• 제42권6호
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• pp.598-606
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• 1998

The liver expresses a considerable amount of nitric oxide (NO) upon induction with cytokines or/and endotoxin. The NO synthesized by inducible NO synthase (NOS) of the liver see ms to play a role in various hepatic physiological processes. Here we investigate the effects of NO on acetaminophen (AA)-induced liver injury. The treatment of S-nitros-N-acetyl penicillamine (SNAP, exogenous NO donor) at the dose of 0.1mM decreased AA-induced hepatotoxicity suggesting the possibility of NO to play a role in protection from the hepatotoxicity induced by AA. On the other hand, the excessive NO produced by NO donor (SNAP: 0.5, 2.5, 6.25mM) has been shown to cause a concentration dependent hepatotoxicity, and such damages was decreased by Superoxide and increased by superoxide dismutase, indicating that the hepatotoxicity induced by excessive NO depends on balancing between NO and superoxide. Taken together, the results indicate that NO has biphasic effects on hepatotoxicity.

• Korean Journal of Acupuncture
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• 제24권1호
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• pp.189-197
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• 2007

Objectives : Free radical metabolism seems to occupy a remarkably common position in the mechanisms of aging and aging related disease. This study was designed to find out whether Juglandis Semen herbal acupuncture solution (JSHAS) can scavenge Nitric Oxide (NO) or not. Methods : SNAP was used as NO generator. NO concentration was estimated after 2, 6, 12 and 24 hrs in no treatment group, after treatment with Vitamin C or 1, 10, 100 ${\mu}g/ml$ of JSHAS. Results : There was no significant scavenging effect of JSHAS on NO after 2, 6 hrs but significant effect on NO in 10, 100 ${\mu}g/ml$ group. Conclusions : These results suggest that JSHAS has scavenging effect on NO. This study shows that JSHAS can be used for aging related disease and further studies are required to investigate the antioxidative effects of it.