• 한국환경과학회지
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• 제3권4호
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• pp.357-365
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• 1994

Air pollution characteristics and the influence of sea breeze on air pollution concentration were studied using the data measured at 7 air quality continuous monitoring stations in Pusan, 1993. Maximum air pollution concentration in Pusan was Gamjeondong for $SO_2$, Sinpyeongdong for TSP, Daeyeondong for $O_3, Kwangbokdong for $NO_2$, Beomcheondong for CO and all substances were under annual ambient air quality standards. Increased rate of concentration for sea breeze was 24.4% for 502, 31.5% for TSP, 8.0% fort $O_3, 26.7% for $NO_2$, 15.7% for CO. Frequencies distribution of $SO_2$, TSP, $O_3$, $NO_2$, and CO concentration for sea breeze moved toward high concentration class.

• 에너지공학
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• 제20권3호
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• pp.191-199
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• 2011

본 연구에서는 Drop Tube Furnace(DTF)를 이용한 $O_2/N_2$, $O_2/CO_2$ 조건에서 산소 농도(12, 21, 31%)에 따른 아역청탄 입자의 연소특성 및 질소산화물 배출특성에 관한 실험과 수치해석을 수행하였다. $O_2/N_2$, $O_2/CO_2$ 조건에서 산소 농도가 증가함에 따라 촤 연소율이 증가하였고 $O_2/CO_2$ 조건하에서 이산화탄소 경계층에서 석탄입자 표면으로의 산소 확산계수가 낮아지기 때문에 촤 연소율이 감소하였다. 산소 농도가 증가함에 따라 배출되는 NO의 농도는 증가하지만 완전 연소 조건인 31%의 산소 농도에서는 오히려 NO의 농도가 감소하였다. 반면, NO 배출 지수는 산소가 증가함에 따라 점차 감소하였다. $O_2/CO_2$ 조건에서 NO의 농도는 Thermal NO의 결여로 인해 $O_2/N_2$ 조건보다 작게 나타났다.

• 한국대기환경학회지
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• 제9권1호
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• pp.107-115
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• 1993

This study was carried out to find the characteristics of surface ozone concentration data obtained during 1988-1991 by the Korea Ministry of Environment. Seasonal data (spring, summer, autumn and winter) wre obtained in May, August, November and February respectively at Kwanghwamun in Seoul. The pollutants analyzed in this study are $SO_2, TSP, CO, NO, NO_2 and NO_2/NO$. Atmospheric factors such as solar radiation, wind speed, relative humidity, cloud amount and atmospheric temperature are also analyzed. The influence of pollutants and atmospheric factors that affect ozone concentration were analyzed by statistical method. The results are summarized as follows : 1. The ozone concentration varied seasonally. The maximum values were 23 ppb in spring, 33 ppb in summer, 16 ppb in autumn and 13 ppb in winter. So the seasonal ozone value was highest in Summer. 2. Te diurnal concentration of ozone was highest during 2-4 P. M. and was very low in the morning and evening. 3. The maximal correlation coefficients of each season between ozone concentration and the influencing pollutants or atmospheric factors asr as follows ; a. spring, r = 0.44(solar radiation) b. summer, r = -0.59(relative humidity) c. autumn, r = -0.55(relative humidity) d. winter, r = -0.58($NO_2$) 4. The major factor affecting the ozone concentration in spring was solar radiation, Relative humidity was the first affecting factor in summer, autumn and $NO_2$ concentration was dominant in winter.

• Journal of Advanced Marine Engineering and Technology
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• 제24권3호
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• pp.70-78
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• 2000

The effects of recirculated exhaust gas on the characteristics of ;$NO_x$ and soot emissions under a wide range of engine load have been experimentally investigated by a water-cooled, four-cylinder, indirect injection, four cycle and marine diesel engine operating at two kinds of engine speeds. The purpose of the present study is to develop the EGR control system for reducing $NO_x$ and soot emissions simultaneously in diesel engines. The EGR system is used to reduce NOx emissions, and a novel diesel soot removal apparatus with a cylinder-type scrubber for the experiment system which has 6 water injectors(A water injector is made up 144 nozzles with 1.0mm in diameter) is specially designed and manufactured to reduce the soot contents in the recirculated exhaust gas to intake system of the engines. The intake oxygen concentration obtained by the intake air flow and the oxygen concentration in the recirculated exhaust gas, and the exhaust oxygen concentration measured in exhaust manifold are used to analyse and discuss the influences of EGR on NOx and soot emissions. The experiments are performed at the fixed fuel injection timing of $15.3^{\circ}$ BTDC regardless of experimental conditions. It is found that $NO_x$ emissions decrease and soot emissions increase owing to the drop of intake oxygen concentration and exhaust oxygen concentration as EGR rate rises. Also, one can conclude that it is sufficient for the scrubber EGR system with a novel diesel soot removal apparatus to reduce $NO_x$ emissions, but not to reduce soot emissions.

• 한국농림기상학회지
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• 제13권4호
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• pp.165-170
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• 2011

전국 65개 산림지역을 대상으로 확산형 패시브 샘플러를 이용하여 2002년부터 2009년까지 월 단위로 대기 중 이산화질소($NO_2$) 농도를 측정하고 도시지역에서의 결과와 비교함으로써 산림지역에서의 이산화질소농도의 시간적 및 공간적 분포 특성을 규명하였다. 연구기간 동안 산림 내 $NO_2$의 농도는 서서히 감소하는 경향을 보였으며, 전국 산림의 연평균 농도는 8ppb로 도시지역의 평균값(19.4ppb)과 생태적 기준값(14.6ppb) 보다 낮았다. 계절별로는 $NO_2$의 농도가 산림지역과 도시지역 모두에서 동절기(3.8ppb)에 높고 하절기(2.8ppb)에 낮은 경향을 보였는데, 도시지역이 더 뚜렷한 계절변화를 보였. 지역별로는 다른 지역에 비해 수도권 지역과 인접한 경기와 충남에서 이산화질소의 연평균 농도가 높게 나타났다. 이러한 지역간 이산화질소 농도 차이의 원인을 규명하기 위해 질소산화물 배출량과 이산화질소 농도 간의 상관관계를 분석한 결과, 유의적인 정의 상관성이 나타남에 따라 질소산화물 배출원의 규모와 근접성이 대기 중 이산화질소의 농도를 결정짓는 중요한 인자임을 시사하였다.

• 한국환경과학회지
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• 제23권5호
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• pp.861-871
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• 2014

This study analyzes the characteristics of ozone weekend effect(OWE) in Busan. $O_3$ concentration on Sunday was over 10% higher than that on weekdays in all areas except for Kwangbokdong, Taejongdae, and Joadong. Such a difference was higher in the industrial area than in the residential area. $O_3$ generation was facilitated by the decrease in $NO_X$ emission on Sunday in VOC-limited regime where the VOC/$NO_X$ ratio is low. Low NO concentration in the Sunday morning decreased inhibition of $O_3$. NO-$O_3$ crossover time on Sunday was shorter than that on weekdays which in turn extended the accumulated duration of $O_3$. Future studies can include whether the entire Busan is VOCS-limited or the coastal area is VOCS-limited while the inland area is $NO_X$-limited.

• 한국전기전자재료학회논문지
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• 제17권6호
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• pp.586-591
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• 2004

We studied the dependence of hot-tarrier-induced degradation characteristics on nitrogen concentration in NO(Nitrided-Oxide) gate of nMOS, under ac and dc stresses. The $\Delta$V$_{t}$ and $\Delta$G$_{m}$ dependence of nitrogen concentration were observed, We observed that device degradation was suppressed significantly when the nitrogen concentration in the gate was increased. Compared to $N_2$O oxynitride, NO oxynitride gate devices show a smaller sensitivity to ac stress frequency. Results suggest that the improved at-hot carrier immunity of the device with NO gate may be due to the significantly suppressed interface state generation and neutral trap generation during stress.ess.

• Journal of Advanced Marine Engineering and Technology
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• 제26권6호
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• pp.679-687
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• 2002

In this study, a cycle simulation using a two-zone model is carried out to investigate the effect of intake charging conditions such as oxygen concentration, temperature and pressure on NO emissions in a DI diesel engine. The model is validated against measurements in terms of cylinder pressure, torque, BSFC and NOx emissions with 2902 cc DI diesel engine. Calculated results can be summarized as follows. The oxygen concentration in the intake charge is decreased with increasing of EGR rate and equivalence ratio. As the intake oxygen concentration is reduced, the combustion pressure and the burned gas temperature decrease and, as a result, NO formation decreases. Also, the results show that as the intake pressure increases and the intake temperature decreases, NO emissions are effectively reduced.

• 대한한방내과학회지
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• 제24권2호
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• pp.358-364
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• 2003

Effects of Cheunhwasangamibang on serum glucose and lipid composition were investigated in high fat diet induced diabetic rat. Plasma glucose and free fatty acids concentration showed a high reduction in Cheunhwasangamibang groups compared to those of control group and these values decreased to increasing Cheunhwasangamibang concentration. Plasma ${\beta}$-lipoprotein and triglyceride concentration showed a low values in Cheunhwasangamibang groups, however these values showed no significantly different in 4 ml and 6 ml treatment groups. Total cholesterol concentration showed no significantly different in control group and 2 ml Cheunhwasangamibang group, however these values in 4 ml and 6 ml treatment groups showed a reduction compared to those of control group. Plasma LDL-cholesterol concentration showed a reduction in Cheunhwasangamibang group and HDL-cholesterol showed no significantly different in all treatment groups.

• Journal of Korean Society for Atmospheric Environment
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• 제14권E호
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• pp.9-17
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• 1998

Oxides of nitrogen play important roles in atmospheric chemistry. Soil has been recognized as a major natural source of NO, and its emission depends on soil parameters such as soil nitrogen availability, soil moisture and temperature. It is necessary to understand effects of these controlling parameters on soil NO emission. In order to understand soil moisture effects on NO emission, variations of NO concentration and existence of its equilibrium concentration were observed from ammonium fertilized Japanese upland soil prepared for different soil moisture conditions. The closed chamber technique was employed for this study. The significant increases in NO with soil moisture were found. Maximum was occurred at sample ID4 (55% of water-filled pore space (WFPS)), but it decreased as soil moisture increased. No significant NO concentration was emitted from soil sample without fertilizer, but there was significant NO in fertilized soil samples. The magnitudes of NO from soil increased with time and reached at steady state within ten minutes approximately. These results suggest that nitrogen input from fertilizer takes charge in the first step of sharp increase in NO emission, and then soil moisture becomes important factor to control NO emission from the soils. NO concentrations from soil were compared to those one-day after the experiment. Results from the comparison analysis suggest that the soil NO flux might have been stimulated by soil disturbances like mixing, and this is much more effective in dry soils rather than in wet soils. It was found that much less NO came out from soils after a day; suggesting that most of NO was released from the soils within a day after fertilizer application during our experiment. The length of NO releasing time span may depend on the amounts of fertilizer applied, soil moisture condition, and other soil physical parameters.