• 한국대기환경학회지
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• 제24권1호
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• pp.16-29
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• 2008

Nitrous acid (HONO) can be produced by heterogenous reactions of nitrogen dioxide on surface materials and direct emission from combustion sources. However, a little is known of indoor HONO levels or the relationship between residential HONO, NO, and $NO_2$ concentrations in occupied houses. Therefore, we measured simultaneously NO, $NO_2$, and HONO concentrations in living room of an apartment using continuous analyzers to study the production of HONO (June $22{\sim}30$, 2006). The 4-min average concentrations of indoor NO, $NO_2$, and HONO were 4.3 (range: $0.4{\sim}214.3$), 10.3 ($2.0{\sim}87.3$), and 1.8 ppb ($0.3{\sim}7.7$), respectively. Peak levels of HONO up to 7.7 ppb and 24-hr averages as high as 1.7 ppb were measured. In agreement with previous studies, indoor HONO concentrations increased during operation of an unvented gas range. Examination of the observed kinetics suggests that the secondary production of indoor HONO, possibly as a result of heterogeneous reactions involving $NO_2$ and $H_2O$ is associated with $[NO_2]^2[H_2O]\;(r^2=0.88)$ rather than with $[NO][NO_2][H_2O]\;(r^2=0.75)$. Three combustion experiments at nighttime were also carried out to investigate the effects of vented combustion on the HONO, NO, and $NO_2$ concentrations. It was found to release HONO for $10{\sim}15$ minutes after NO and $NO_2$ source was turned off, and peak values were finally attained. Compared to unvented combustion, peak $NO_2$ and HONO concentrations were 3.2 and 2.0 times lower at weak vented combustion (air flow: $340\;m^3/hr$) and 4.9 and 2.4 times lower at strong vented combustion (air flow: $540\;m^3/hr$), respectively, emphasizing importance of operating ventilation hood fan during combustion to improve indoor air quality.

• Environmental Engineering Research
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• 제10권5호
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• pp.239-246
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• 2005

The effect of Pt addition over $V_2O_5-WO_3/TiO_2$ catalyst supported on PRO-66 was investigated for NO reduction in order to develop the catalytic filter working at low temperature. Catalytic filters, $Pt-V_2O_5-WO_3/TiO_2/PRD$, were prepared by co-impregnation of Pt, V, and W precursors on $TiO_2$-coated ceramic filter named PRD (PRD-66). Titania was coated onto the pore surface of the ceramic filter using a vacuum aided-dip coating method. The Pt-loaded catalytic filter shifted the optimum working temperature from $260-320^{\circ}C$(for the catalytic filter without Pt addition) to $190-240^{\circ}C$, reducing 700 ppm NO to achieve the $N_x$ slip concentration($N_x\;=\;NO+N_2O+NO_2+NH_3$) less than 20 ppm at the face velocity of 2 cm/s. $Pt-V_2O_5-WO_3/TiO_2$ supported on PRD showed the similar catalytic activity for NO reduction with that supported on SiC filter as reported in a previous study, which implies the ceramic filter itself has no considerable interaction for the catalytic activity.

• 동력기계공학회지
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• 제14권6호
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• pp.13-19
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• 2010

이 논문에서는 디젤자동차용 LNT와 SCR 촉매의 NO, $NH_3$ 흡착 및 탈리의 기본 특성과 수열화 온도와 시간 및 정량화된 황피독 농도에 대한 de-$NO_x$ 촉매의 내구성을 평가하였다. LNT 촉매는 열적으로 열화됨에 따라 Pt 및 Ba의 소결 및 응집으로 활성이 떨어져 $NO_x$ 전환율은 감소하였다. 반면에 Pt의 비활성화로 중간생성물인 $NH_3$ 생성량은 증가하였으며, 이때 생성된 $NH_3$는 LNT+SCR 복합시스템의 SCR 촉매의 환원제 역할을 담당한다. 1.0 g/L 이상의 황이 피독된 LNT 촉매는 탈황을 하여도 질소 산화물 흡장물질(Ba) 의 성능이 회복이 되지 않아 $NO_x$ 전환율은 회복되지 않았으며, 탈황 후 Pt 재활성화로 인해 NO2 및 SCR 환원제인 $NH_3$ 생성량은 증가하였다. SCR 촉매의 $NO_x$ 전환율은 $700^{\circ}C$ 36h, $800^{\circ}C$ 24h로 수열화 시킨 촉매는 전이금속 입자 성장 및 zeolite 구조 파괴로 인하여 급격하게 떨어졌으며, 0.36 g/L 황 피독된 촉매는 zeolite가 가지는 강산성 특정으로 내피독성이 강하여 탈황시 $NO_x$ 전환율은 회복되었다.

• 한국자동차공학회논문집
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• 제20권4호
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• pp.142-149
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• 2012

The reduction characteristics of $NO_2$ to NO are experimentally studied over a platinum-based catalyst, especially at lower temperatures below about $200^{\circ}C$. In the present work, two types of steady-state experiments, engine bench and synthetic gas bench tests, are carried out in sequence. Steady-state engine bench tests with the DOC mounted on a light duty 4-cylinder 2.0 liter turbocharged diesel engine are performed and prove that CO plays a major role in $NO_2$ abatement at temperatures below the light-off temperature of CO oxidation, about $200^{\circ}C$. Synthetic gas bench tests are then performed using synthetic gas mixtures with CO, $C_3H_6$, NO, $NO_2$, $O_2$, $H_2O$ and $N_2$ in the $140{\sim}450^{\circ}C$ T-range and show that both CO and $C_3H_6$ are capable of reducing $NO_2$. It is noted that the reaction rate of $NO_2$ with $C_3H_6$ is much higher than that with CO. At temperatures below about $200^{\circ}C$, the reduction of $NO_2$ to NO is promoted with increasing CO concentration and $NO_2$/$NO_X$ ratio and with decreasing $O_2$ concentration, as well as with the presence of $H_2O$.

• 원예과학기술지
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• 제17권2호
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• pp.136-137
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• 1999

신나팔나리의 발아률(發芽率) 및 상품성 향상을 위하여 $GA_3$, 염류(鹽類) 및 저온(低溫) 등을 이용하여 종자 priming 처리한 결과 파종 후 10일째 초기 발아률(發芽率)은 $Ca(NO_3)_2$ 200mM 및 $KNO_3$ 200mM 처리구가 높았으나 최종 발아률(發芽率)에서는 처리구간에 유의차가 없었으며 발아세는 $Ca(NO_3)_2$ 200mM 처리구에서 가장 높게 나타났다. 초기 생육은 $Ca(NO_3)_2$ 200mM, $KNO_3$ 200mM 처리구가 엽수(葉數)가 많았고 구경(球徑)이 컸으며 건물중(乾物重)도 무거웠다.

• 한국대기환경학회지
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• 제9권3호
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• pp.216-221
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• 1993

This study was carried out to determine the concentration of gaseous nitrate$(HNO_3)$ particulate nitrate$(NO_3^-)$ and conversion rate of NOx to nitrate in atmosphere in Seoul from Oct 1991 to July 1992. The average concentration of gaseous nitrate in daytime(09:00 - 17:00) was 9.93, 3.37, 7.40 and 10.40$\mug/m^3$ and, in highttime was 6.21, 7.31, 4.79 and 3.86$\mug/m^3$ respectively. The concentratin of $HNO_3$ was greater in summer and daytime than winter and nighttime. But the concentration of $NO_3^-$ was greater in winter and nighttime than in summer and daytime. The average conversion rate of NOx to $HNO_3$(Fn) indaytime was 13.18, 3.78, 9.13 and 23.13% and, in nighttime was 3.06, 1.37, 1.70 and 8.72% during fall, winter, spring and summer respectively. But the average conversion rate of NOx to $NO_3^-$(Fn') in daytime was 5.79, 5.77, 2.63 and 3.90% and in nighttime was 5.95, 6.51, 3.25 and 4.84% respectively. The average conversion rate of NOx to total nitrate $(HNO_3 + NO_3^-)$(Fn') was 12.72, 7.81, 7.82 and 18.40% respectively. The average conversion rate of NOx to $HNO_3$(Fn) was greater than $NO_3^-$(Fn') about 1.6 times.

• 환경위생공학
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• 제16권4호
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• pp.21-30
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• 2001

Vehicles, especially diesel-using, are a major source of airborne particulate matter(PM), nitrogen dioxide($NO_2$) and so on in metropolitan cities such as Seoul. Therefore workers, who are mainly merchants, near roadside may be highly exposed to air pollutants from exhausted emissions of vehicles. This means that occupational type and location can affect the workers＇health by exposure to outdoor pollutions of ambient as well as indoor pollutions of working condition, respectively. In this study, we simultaneously measured the PM3.5 and $NO_2$concentrations in indoor and outdoor of shoes repair shops in Seoul, which were generally located at roadside in Korea. Shoes repairmen were highly exposed to PM3.5 and $NO_2$ both indoor and outdoor of repair shops comparing with other sub-population groups. High exposure to air pollutants for shoes repairmen was considered to be outdoor source from exhausted emission of vehicles and indoor source from working condition. The $PM3.5/NO_2$ concentration ratio was $1.17{\pm}$0.59 in roadside, of which ratio was higher 7han ratios of other studies. This result suggested that major air pollutant in Seoul was fine particle. Also, this PM3.5 to $NO_2$ ratio will be used in environmental exposure and risk assessment by estimation of PM3.5 concentration as measuring the only $NO_2$ concentration with small and accurate $NO_2$ passive sampler.

• 대한본초학회지
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• 제36권6호
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• pp.17-25
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• 2021

Objectives : Baicalein (3,3', 4', 5, 6-pentahydroxyflavone), a type of flavonoid, is a well-known antioxidant and anti-inflammatory ingredient found in Scutellaria baicalensis root. The aim of this study is to investigate the effect of baicalein on nitric oxide (NO) production in TM3 mouse Leydig cells stimulated by indomethacin (IN). Methods : TM3 cells were treated with IN (0.5 μM) and baicalein at concentrations of 12.5, 25, 50, and 100 μM for 24 hr, 40 hr, 42 hr, 44 hr, and 64 hr. After treatments, cell viabilities were measured with the modified MTT assay. The production of nitric oxide in cells was measured by Griess reagent assay. Results : Baicalein showed no cytotoxicity on IN-stimulated TM3. NO production in IN-stimulated TM3 treated for 24 hr with baicalein at concentrations of 12.5, 25, 50, and 100 μM was 95.8%, 94.86%, 89.97%, and 81.52% of the control group treated with IN only, respectively; NO production for 40 hr was 97.34%, 97.34%, 95.15%, and 87.42%, respectively; NO production for 42 hr was 89.12%, 90.14%, 89.74%, and 90.26%, respectively; NO production for 44 hr was 83.83%, 84.94%, 85.65%, and 86.85%, respectively; NO production for 64 hr was 94.12%, 95.38%, 94.21%, and 94.12%, respectively. Specifically, baicalein at concentrations of 12.5, 25, and 50 have been shown to most efficiently inhibit NO productions in 48 hr of treatment. Conclusions : Baicalein might have anti-toxicant effect on Leydig cells related with its inhibition of NO production in Leydig cells stimulated with IN.

• 분석과학
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• 제27권4호
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• pp.213-222
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• 2014

국내 배경지역인 제주도 고산측정소에서 2012~2013년에 대기 미세먼지를 채취하여 분석한 결과로부터 연무와 비현상일의 조성특성을 조사하였다. 연무 시 $nss-SO_4{^{2-}}$, $NO_3{^-}$, $NH_4{^+}$ 농도는 비현상일에 비해 조대입자에서 2.1~3.7배, 미세입자에서 3.1~6.5배로 미세입자에서 더 높게 증가하였고, 특히 $NO_3{^-}$ 농도가 미세입자에서 6.5배 상승하였다. 원소성분들 중에는 S, Zn, Pb, K 등이 비현상일보다 조대입자에서 3.0~5.6배, 미세입자에서 3.2~7.7배 증가하나 Al, Fe, Ca 등은 대부분 조대입자에서 농도가 크게 증가하는 경향을 보였다. 역궤적 분석 결과 연무 시 $nss-SO_4{^{2-}}$, $NO_3{^-}$ 농도는 중국으로부터 유입되었을 때 더 높은 농도를 나타내었고, 특히 기류가 중국남부를 통과했을 때 $NO_3{^-}$ 농도가 더 크게 상승하는 경향을 보였다. 또 $NO_3{^-}/nss-SO_4{^{2-}}$ 농도비는 중국에서 기류가 이동했을 때 조대입자에서 상대적으로 높은 비율을 보이나 미세입자에서는 오히려 한반도를 통과했을 때 더 높은 성분비를 나타내었다.

• 원예과학기술지
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• 제34권5호
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• pp.727-735
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• 2016

상토에 기비로 혼합된 질소의 $NO_3:NH_4$ 비율이 토마토 'Dotaerang Dia'의 플러그 묘 생장에 미치는 영향을 구명하기 위하여 본 연구를 수행하였다. 피트모스+코이어 더스트+펄라이트를 3.5:3.5:3.0(v/v/v)인 혼합상토를 조제하였고, 총 질소 농도가 $300mg{\cdot}L^{-1}$이면서, $NO_3:NH_4$ 비율이 100:0, 73:27, 50:50, 27:73, 0:100인 5처리를 만든 후 50구 플러그트레이에 충전하였다. 이후 종자를 파종하고 6주간 재배한 후 지상부 생육, 식물체 무기원소 함량 그리고 상토의 무기원소 농도를 조사 및 분석하였다. 파종 전 $NH_4$비율이 높을수록 상토의 EC가 높았지만, 플러그 묘의 생장이 진행될수록 모든 처리에서 상토의 EC가 낮아졌고 pH가 점차 상승하였다. 플러그 묘 생장은 $NO_3:NH_4$(50:50) 처리에서 초장 29.0cm, 초폭 26.4cm, 지상부 생체중 13.7g, 건물중 1.21g으로 가장 우수하였고 $NO_3:NH_4$(0:100)에서 초장 26.5cm, 초폭 24.1cm 그리고 지상부 생체중과 건물중이 각각 11.2g과 0.92g으로 가장 저조하였다. 모든 처리구의 질소 함량은 2.77-3.22% 범위에 포함되었으며 $NO_3:NH_4$(27:73) 처리에서 Fe, Mn 및 Zn의 함량은 가장 높았고, $NO_3:NH_4$(0:100)에서 가장 낮았다. 이상의 결과를 종합할 때 $NH_4$ 비율을 50% 이하로 조절하는 것이 토마토 플러그 묘의 재배를 위해 바람직하다고 판단하였다.