• 대한환경공학회지
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• 제29권12호
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• pp.1329-1336
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• 2007

본 연구에서는 간헐적으로 발생되는 고농도의 NO를 효율적으로 제거할 수 있는 혼합 공정으로 선택적촉매환원(Selective Catalytic Reduction, SCR)과 활성탄소섬유(Activated Carbon Fiber, ACF)흡착이 결합된 신 개념의 공정을 설계하고 특성을 고찰하였다. NO를 흡착한 ACF에 열과 진공을 동시에 가하여 재생 실험을 수행한 결과, $140^{\circ}C$에서 600 mmHg의 진공으로 탈착하였을 때 가장 높은 재생효율을 보였다. SCR공정에는 상용촉매를 사용하였으며, 반응온도 $300^{\circ}C$, $NO/NH_3$몰비 1.0인 조건에서 실험을 수행하였다. ACF 재생공정에서 발생한 NO를 SCR공정으로 처리하였을 경우 98%의 매우 우수한 제거효율을 보였다. 그러나 지속적으로 유입되는 300ppm의 NO와 ACF에서 탈착되는 NO를 기존의 SCR공정에서 동시에 처리하였을 때 약 1분간 고농도의 NO가 배출되었다. 따라서 ACF의 재생시 발생하는 고농도의 NO를 기존의 SCR공정에서 병행처리할 때는 탈착속도를 조절하거나 고농도로 배출되는 짧은 시간 동안 $NH_3$농도를 높여서 주입할 필요가 있으며, 소규모의 SCR공정을 추가로 설치하여야 한다. SCR과 ACF를 결합한 공정을 이용하여 NO를 처리하였을 때, 간헐적으로 2배의 농도를 가지는 NO가 유입되어도 80% 이상의 탈질 효율을 가지는 공정의 구현이 가능하였으며, 반복 사용에도 활성이 유지되어 안정적인 운전이 가능함을 입증하였다.

• Applied Science and Convergence Technology
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• 제26권6호
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• pp.218-222
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• 2017

This study was conducted to remove $NO_x$, which is the main cause of fine dust and air pollution as well as acid rain. $NO_x$ was tested using 3% NO (diluted in He) as a simulated gas. Experiments were sequentially carried out by oxidizing NO to $NO_2$ and absorbing $NO_2$. Especially, we focused on the changes of NO oxidation according to both oxidant ($NaClO_2$) concentration change (1~10 M) and oxidant pH change (pH = 1~5) by adding HCl. In addition, we tried to suggest a method to improve $NO_2$ absorption by conducting $NO_2$ reduction reaction with reducing agent (NaOH) concentration (40~60%). It was found that NO removal efficiency increased as both concentration of oxidant and flow rate of NO gas increased, and NO decreased more effectively as the pH of hydrochloric acid added to the oxidant was lower. The $NO_2$ adsorption was also better with increasing NaOH concentration, but the NO removal efficiency was ~20% lower than that of the selective NO reduction. Indeed, this experimental method is expected to be a new method that can be applied to the capture and removal of fine dust caused by air pollution because it is a method that can easily remove NO gas by a simple device without expensive giant equipment.

• 한국수산과학회지
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• 제30권5호
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• pp.782-793
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• 1997

식물 플랑크톤의 인위적인 용승조건 하에서 생리적 적응 (shift-up)을 알아보기 위하여, 안정동위원소인 $^{15}N-KNO_3$를 이용하여 실험실에서 Dunaliella tertiolecta의 질산염 흡수 능력을 측정하였다. 그 결과 예상과는 달리 최대 질소비 질산염 흡수 속도 $(V_{NO3})$와 초기 질산염 농도 사이에는 유의성 있는 상관관계가 나타나지 않았다. 그러나 최대 질산염 운반 속도 $(\rho_{NO3})$와 $25\;{\mu}M$ 이하의 초기 질산염 농도 사이에는 강한 상관성이 나타났으며, 이는 배양 세포의 생리적인 상태에 의한 영향에도 기인한다. $\rho_{NO3}$의 증가는 주로 입자성 유기 질소 농도의 증가와 함께 부분적으로는 $V_{NO3}$의 증가에 기인한다. 식물 플랑크톤 개체군이 심하게 shift-down되었을 경우 질산염 흡수의 생리적 적응은 높은 초기 질산염 농도에서 주목할 만큼 저해되었다. 최대 $V_{NO3}$ 또는 $\rho_{NO3}$이 나타나는 시기는 초기 질산염 농도와 관련이 있다. 높은 초기 질산염 농도에서는 $V_{NO3}$와 $\rho_{NO3}$의 최대치가 낮은 초기 질산염 농도에서보다 $1\~2$일 정도 늦게 나타났다. 이는 Zimmerman et al. (1987)의 shift-up 모델에서의 예측과 상반되는 결과이다. Shift-up 과정은 명백히 내부적인 시간순서와 초기 질산염 농도에 의하여 조절되지만, $V_{NO3}$의 크기는 질산염 농도의 변화에 거의 영향을 받지 알았다.

• 한국분무공학회지
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• 제6권3호
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• pp.1-7
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• 2001

In this study, quantitative measurement of nitric oxide concentration distributions visualization were investigated in the laminar $CH_4/O_2N_2$ nixed flame by Planar laser-induced fluorescence(PLIF). The NO A-X (0,0) vibrational band around 226nm was excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interference from Rayleigh scattering and $O_2$ fluorescence. The measurements were taken in $CH_4/O_2N_2$ premixed flame with equivalence ratios varying from $1.0{\sim}1.6$, and a fixed flow rate of 3slpm. NO was found to produce primarily between an inner premixed and an outer nonpremixed flame front, and total NO concentration is raised when equivalence ratios increase. These results suggest that prompt NO is likely to contribute to MO formation in $CH_4/O_2N_2$ premixed flame. Furthermore, this trend was well matched with previous works.

• 환경영향평가
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• 제20권1호
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• pp.49-59
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• 2011

The results of comparing $PM_{10}$ concentration between 'Namsan' and 'Yongsan-gu' air quality monitoring stations show similar values with averaged concentration in the whole Seoul. The correlation factors in both sites were 0.865, 0.828 in 2005, 2006, respectively. For 'Bukhansan' and 'Gangbuk-gu' air quality monitoring stations, different from the results mentioned above, they showed clear differences as altitude changes. PM10 concentration in 'Bukhansan' monitoring stations was 10 ${\mu}g/m^3$ lower than 'Gangbuk-gu' monitoring station which is located near the ground. Also, averaged PM10 concentration in 'Bukhansan' and 'Gangbuk-gu' monitoring stations was lower than that in the whole Seoul. When comparing $NO_2$ concentration between 'Namsan' and 'Yongsan-gu' monitoring stations, $NO_2$ concentration in 'Namsan' monitoring station was lower than 'Yongsan-gu' monitoring station. For $NO_2$ concentration in 'Bukhansan', 'Gangbuk-gu' and 'the whole Seoul', there were the same pattern in 'Gangbuk-gu' and the 'the whole Seoul' and low values in 'Bukhansan' monitoring station. The correlation factors of $NO_2$ concentration in 'Bukhansan' and 'Gangbukgu' was 0.525, 0.549 in 2005, 2006, respectively, which stands for low correlationship.

• 대한기계학회논문집B
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• 제24권9호
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• pp.1247-1254
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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 simultaneous control of $NO_x$ and soot emissions in diesel engines is targeted in this study. The EGR system is used to reduce $NO_x$ emissions, and a novel diesel soot removal device with a cylinder-type scrubber for the experiment system which has 6 water injectors(A water injector has 144 nozzles in 1.0 mm 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 and the mean equivalence ratio calculated by the intake air flow and fuel consumption rate, and the exhaust oxygen concentration measured are used to analyse and discuss the influences of EGR rate on $NO_x$ 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 are decreased and soot emissions are increased owing to the drop of intake oxygen concentration and exhaust oxygen concentration, and the rise of equivalence ratio as the EGR rate rises.

• 한국대기환경학회지
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• 제24권2호
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• pp.143-152
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• 2008

This study investigates the variation and spatial distribution of nitrogen dioxide($NO_2$) concentrations measured with passive diffusive samplers at 40 curbside points in Daejeon. Average $NO_2$ concentration was $39.8{\pm}18.0\;ppb$ (n=1,127) and the significant difference in concentrations by regional groups (Dong-gu, Jung-gu, Seo-gu, Daedeok-gu, Yuseong-gu) was not observed. The frequency distribution of $NO_2$ concentration was found to be a normal distribution with the high frequency in the concentration range of 30 to 40 ppb (20 to 25%). Average $NO_2$ concentration measured during the rainy periods was lower than that measured during the non-rainy periods and the decrease of concentration by rainfall was about 16% (7 ppb). The variation of $NO_2$ concentrations measured by passive diffusive samplers during the sampling period was similar to that continuously measured at the air quality monitoring station.

• 한국환경과학회지
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• 제11권12호
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• pp.1253-1259
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• 2002

This study analyzes the surface ozone, NO and $NO_2$ concentration data from 1997 to 1999 in Daegu. It investigates effect on precursor during high-ozone episode days. The high-ozone episode is defined when a daily maximum ozone concentration is higher than 100 ppb(ambient air quality standard of Korea) in at least one station among six air quality monitoring stations. The frequency of episodes is 13 days(33 hours). The frequency is the highest in May and September, and the area with the highest frequency is Nowondong and Manchondong. The average value of daily maximum ozone concentration with high ozone episode is 81.6 ppb, and that of 8-hour average ozone concentration is 58.6 ppb. It means that ozone pollution is continuous and wide-ranging in Daegu. The daily variation of NO, $NO_2$ and $O_3$ in high-ozone episodes are inversely proportional one another. Nowondong an industrial area, is affected by pollutants that are emitted from the primary sources, while Manchondong a residential area, is affected by the advection of $O_3$ or by the primary pollutants like VOCs.

• 한국대기환경학회지
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• 제6권1호
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• pp.1-10
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• 1990

The purpose of the study was to analyze air quality in underground shopping centers using pattern recognition methods. In order to perform this, the concentraion of air pollutants such as $CO, NO_2, NO_x, SO_2$, and particulate matters was measured at the 11 different shopping centers in Seoul metropolitan area and the total of 47 samples were obtained at random based on the size of shopping centers. To introduce a new concept of the "average concentration" for the indoor air quality analyses, the various multivariate statistical analyses have been studied. Thus, a cluster analysis was applied to separate the samples into pseudo-patterns and a disjoint principal component analysis was used to generate homogeneous patterns after removing outliers from the pseudo-patterns. The 6 homogeneous patterns were then obtained as follows:the first pattern was a group of clean sites;the second a group of sites having high dust concentration;the third a group of sites having high dust and $NO_x$ concentration;the fourth a group of sites having low dust and $SO_2$ concentraion and high CO concentration;the fifth a group of sites having high $NO_2 and SO_2$ concentration;and the final a group of miscellaneous sites. Thus, the average concentration could be estimated for each pattern.h pattern.

• 한국대기환경학회지
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• 제19권2호
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• pp.167-177
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• 2003

The number size distribution of urban aerosols ranging from 0.02 to 20 ${\mu}{\textrm}{m}$ in diameter was measured by using a scanning mobility particle sizer (SMPS) system and an aerodynamic particle sizer spectrometer (APS) at Seoul from November 30,2001 to January 14, 2002. The gaseous species such as CO, NO, NO$_2$, and $O_3$ were also continuously monitored. The daily average concentration of urban aerosols sorted into three groups (0.02~0.1 ${\mu}{\textrm}{m}$, 0.1~1 ${\mu}{\textrm}{m}$ and 1~10 ${\mu}{\textrm}{m}$) and the typical number, surface, and volume distributions of urban aerosols were discussed in this paper. The weekly variation of aerosol concentration was compared with those of gaseous concentrations. relative humidity, and visibility. The results showed that the particle number concentration seemed to increase in the morning and the number concentration of fine particles less than 1 fm in diameter seemed to increase when the concentrations of CO, NO, and NO$_2$ were high. The number concentration of fine particles was relatively high when the relative humidity was greater than 70％ during the increasing period of relative humidity. The visibility was weakly correlated with the concentration of aerosols ranging 0.1 to 1 ${\mu}{\textrm}{m}$, and the number size distribution for high visibility episode was apparently different from that for low visibility episode.