• 산업기술연구
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• 제21권B호
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• pp.155-161
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• 2001

In this study, we analyzed the $NO_X$ removal efficiency and particle size distribution by the pulsed corona discharge process and investigated the effect of several process variables. The NO removal efficiencies and the particle characteristics were measured and analyzed as the function of initial concentrations of NO, $H_2O$, and $NH_3$, applied voltage, pulse frequency and residence time. As the frequency of applied voltage increases, or as the applied voltage increases or as the residence time increases, the NO removal efficiency increases. The change of initial $NH_3$ and $H_2O$ concentrations do not affect the NO removal efficiency significantly. The particle concentration and size increases with the increases of initial NO concentration, residence time and applied voltage.

• 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.

• 한국축산식품학회지
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• 제36권2호
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• pp.262-266
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• 2016

This study evaluated the growth kinetics of Salmonella spp. in processed meat products formulated with low sodium nitrite (NaNO₂). A 5-strain mixture of Salmonella spp. was inoculated on 25-g samples of sausages formulated with sodium chloride (NaCl) (1.0%, 1.25%, and 1.5%) and NaNO₂ (0 and 10 ppm) followed by aerobic or vacuum storage at 10℃ and 15℃ for up to 816 h or 408 h, respectively. The bacterial cell counts were enumerated on xylose lysine deoxycholate agar, and the modified Gompertz model was fitted to the Salmonella cell counts to calculate the kinetic parameters as a function of NaCl concentration on the growth rate (GR; Log CFU/g/h) and lag phase duration (LPD; h). A linear equation was then fitted to the parameters to evaluate the effect of NaCl concentration on the kinetic parameters. The GR values of Salmonella on sausages were higher (p<0.05) with 10 ppm NaNO₂ concentration than with 0 ppm NaNO₂. The GR values of Salmonella decreased (p<0.05) as NaCl concentration increased, especially at 10℃. This result indicates that 10 ppm NaNO₂ may increase Salmonella growth at low NaCl concentrations, and that NaCl plays an important role in inhibiting Salmonella growth in sausages with low NaNO₂.

• 마이크로전자및패키징학회지
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• 제15권4호
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• pp.101-106
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• 2008

이산화질소를 감지할 수 있는 센서물질로 Pd과 탄소 나노튜브(CNT)가 첨가된 $SnO_2$ 박막을 스핀코팅으로 제조하였으며, 동 시편의 이산화질소에 대한 감지 특성을 $200^{\circ}C$ 및 $1ppm{\sim}5ppm$의 $NO_2$ 농도 하에서 측정하였다. 센서시편의 전기저항은 $NO_2$ 기체의 노출과 농도에 따라 증가 하였으며, Pd이 3wt%로 첨가된 시편의 감도는 26.5로 첨가전의 감도에 비하여 10배 증가하였다. 또한 $SnO_2$ 모체에 첨가한 CNT의 량에 따라서도 감도는 증가 하였으며, 0.225wt% CNT 첨가 시 5ppm의 $NO_2$ 농도에서 감도 값은 72이었다.

• 한국대기환경학회지
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• 제33권6호
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• pp.605-615
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• 2017

Efficient simultaneous reduction conditions for $NO_x$ and $NH_3$-slip was investigated in SCR (Selective Catalytic Reduction) process with load variation by applying dual catalysts (SCR catalyst, $NH_3$ decomposition catalyst) system. $N_2O$ formation characteristics were analyzed to look into possible undesirable reaction pathways. In the experiments of catalyst characteristics, various operational variables were tested for the combined catalytic system, such as $NH_3/NO_x$ ratio, temperature, oxygen concentration and $H_2O$. The reaction characteristics of $NO_x$, $NH_3$ and $N_2O$ were analyzed and optimal conditions could be evaluated for the combustion facility with varied load. In terms of $NO_x/NH_3$ simultaneous reduction and $N_2O$ formation suppression, optimal condition was considered NSR 1.2 and temperature $300^{\circ}C$. At this operational condition, $NO_x$ conversion was 98%, $NH_3$ reduction efficiency was 95%, generated $N_2O$ concentration 9.5 ppm with inlet $NO_x$ concentration of 100 ppm. In $NH_3-SCR$ process with $NH_3$ decomposition catalyst, $NO_x$ and $NH_3$ can be considered to be reduced simultaneously at limited conditions. The results of this study may be utilized as basic data at facilities requiring simultaneous $NO_x$ and $NH_3$ reduction for facilities with load variation.

• 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.

• 한국환경과학회지
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• 제28권7호
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• pp.595-606
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• 2019

This research investigated the characteristics of CO, $CO_2$, and $NO_2$ concentrations at main subway stations in Busan. The annual mean CO concentrations at the Suyeong and Nampo stations were 0.75 ppm and 0.48 ppm, respectively. Annual $CO_2$ concentration at the Seomyeon 1- platform was 649 ppm. The $NO_2$ concentrations at the Seomyeon 2- waiting room and the Yeonsan station were 0.048 ppm and 0.037 ppm, respectively. CO concentration was highest at two times of the day, and was proportional to the number of passengers commuting to and from work. The CO and $CO_2$ concentrations were highest in winter, but $NO_2$ concentration was highest in spring. CO and $CO_2$ concentrations were highest on Saturday and lowest on Sunday. The correlation of CO and $NO_2$ concentrations measured at the subway stations with those at the ambient air quality station were highest at the Seomyeon 1 and 2- waiting room and Jeonpodong. The correlation was lowest at the Yeonsan and Yeonsandong station. The number of days when $CO_2$ concentration exceeded 700 ppm over the last three years at the Seomyeon 1- platform was 174. The findings of this research are expected to deepen understanding of the fine particle characteristics at subway stations in Busan and be useful for developing a strategy for controlling urban indoor air quality.

• 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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• 제28권3호
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• pp.249-260
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• 2012

Monitoring of climate change and atmospheric environment by satellite measurements has been increased in recent years. In this study, nitrogen dioxide ($NO_2$) measurements from Ozone Monitoring Instrument (OMI) were compared with surface measurements over the Korean peninsula. $NO_2$ from OMI measurements showed high values and also showed seasonal variations such as high concentration in winter and low in summer over metropolitan areas while $NO_2$ concentration at national background station was low and did not clearly show seasonal variations. Surface measurements showed similar temporal and spatial variations to those of satellite measurement. The comparison between satellite measurements and surface measurements showed that the correlation between them was higher in urban area (r=0.64 at Seoul and r=0.63 at Daegu) than in national background stations (r=0.37 at Jeju) because the concentration in urban area was relatively high so that the variation of $NO_2$ concentration could be detected better than at national background stations by satellite. Satellite can effectively measure the emission and transport of pollutants with no limitations in spatial coverage.

• 한국대기환경학회지
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• 제32권5호
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• pp.536-546
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• 2016

The diurnal variations of $O_3$ and $NO_2$ in an urban park and the effects of air temperature and wind speed on the diurnal variations are investigated. $O_3$ and $NO_2$ concentrations were observed at a site in an urban park of Seoul from 27 July 2015 to 9 August 2015. The $O_3$ and $NO_2$ concentrations observed in the urban park are compared to those observed at the Gangnam air quality monitoring station (AQMS). The $O_3$ concentration is higher in the urban park than at the Gangnam AQMS in the daytime because the amount of $O_3$ dissociated by NO is smaller as well as partly because the amount of $O_3$ produced in the oxidation process of biogenic volatile organic compounds (VOCs) is larger in the urban park than at the Gangnam AQMS. The $NO_2$ concentration is lower in the urban park than at the Gangnam AQMS during day and night because the observation site in the urban park is relatively far from roads where $NO_x$ is freshly emitted from vehicles. The difference in $NO_2$ concentration is larger in the daytime than in the nighttime. To examine the effects of air temperature and wind speed on the diurnal variations of $O_3$ and $NO_2$, the observed $O_3$ and $NO_2$ concentrations are classified into high or low air temperature and high or low wind speed days. The high $O_3$ and $NO_2$ concentrations in the daytime appear for the high air temperature and low wind speed days. This is because the daytime photochemical processes are favorable when the air temperature is high and the wind speed is low. The scatter plots of the daytime maximum $O_3$ and minimum $NO_2$ concentrations versus the daytime averages of air temperature and wind speed show that the daytime maximum $O_3$ and minimum $NO_2$ concentrations tend to increase as the air temperature increases or the wind speed decreases. The daytime maximum $O_3$ concentration is more sensitive to the changes in air temperature and wind speed in the urban park than at the Gangnam AQMS.