• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.105-108
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• 1998

Pt-WO$_3$-Si$_3$N$_4$-SiO$_2$-Si-Al 캐패시터를 이용한 NO$_2$ 가스 센서를 개발하였다. 표준 실리콘 MNOS구조에 촉매 게이트로 Pt와 가스 흡착층으로 WO$_3$를 이용함으로서 전통적인 세라믹 가스 센서보다 낮은 온도에서 NO$_2$ 가스를 감지할 수 있었다. 은도 변화와 NO$_2$ 가스 농도의 변화에 따라서 디바이스의 NO$_2$ 가스 감도를 조사하였다. Pt-WO$_3$ 계면에서 NO$_2$ 이온농도의 변화에 기초로 한 가스 감지 모델을 제시하였다. 제시된 가스 감지 모델을 계면에서의 가스 반응 속도론에 의하여 분석함으로서 확인하였다.

• Journal of Environmental Science International
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• v.14 no.1
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• pp.9-14
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• 2005

This study evaluated the hazard caused by $NO_{2}$, an oxidant generated in the process of welding. We com­pared hematological and biochemical parameters in workers who chronically inhale $NO_{2}$ and office workers not exposed to $NO_{2}$. $NO_{2}$ exposure affected the hematological and biochemical parameters. Increasing $NO_{2}$ concen­trationincreased the number of leukocytes, while decreasing the number of erythrocytes. Blood urea nitrogen, cre­atinine, uric acid, and lactate dehydrogenase were increased, while total protein and triglycerides were decreased. The mean concentration of $NO_{x}(NO_{2}^{-}/NO_{3}^{-})$ in the serum of welders and the control group was $35.97{\pm}2.85\;and\;55.40{\pm}5.81\;{\mu}mol/L,$ respectively. The difference was significant (p < 0.05), although $NO_{2}^{-}$ was not detected in the serum.

• Journal of the Korean Chemical Society
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• v.38 no.7
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• pp.485-495
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• 1994

Several new symmetric and asymmetric homo and hetero dinuclear complexes of the type $[Cl(dppp)(NO)_2M({\mu}-pyz)M'(NO)_2(dppp)Cl][ClO_4]_2$ and $[Cl(phen)(NO)_2M({\mu}-pyz)M'(NO)_2(dppp)Cl][ClO_4]_2$(M,M'= Mo or W; phen = 1,10-phenanthroline; dppp = 1,3-bis(diphenylphosphino)propane; pyz = 1,4-pyrazine) were synthesized in three-steps starting from $[M(NO)_2Cl_2]_n(M = Mo, W)$. The final products were purified by eluting it through silica gel column ($2{\times}20$ cm) with acetone as the eluent. Characterization of these complexes and some related complexes was accomplished through UV-vis., $^1H$-NMR, $^{13}C$-NMR and IR spectroscopies as well as elemental analysis. The infrared spectra indicate that the NO groups occupy cis-positions of the octahedral. The $^1H$ and $^{13}C-NMR$ data for the new compounds revealed a dimeric structures with bridged pyz.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.68-74
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• 1999

The atmospheric concentrations of Nitrogen Dioxide ($NO_2$) and Total Suspended Particulates (TSP) at the traffic road side were measured n Asan area, Choongchumg-namdo during May 1998 and January, 1999.The results of the study are as follows;1. The aversge value of airbone $NO_2$ and TSP levels were 28.5ppb and 5.9mg/me in Asan area. 2. The concentration distribution of NO2 and TSP is high for the season of winter. On a daily pattern, somewhat high value is appeared in the afternoon. 3. For the station, terminal, and Shinchang, the average value of $NO_2$ is 33.6ppb, 27.9ppb and 24.1ppb in sequence, and the ones of TSP is 6.3mg/m3, 6.0mg/m3 and 5.3mg/m3 in order.4. The high levels of $NO_2$ and TSP were positively related to traffic volume.

• Journal of the Korean Chemical Society
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• v.39 no.11
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• pp.856-862
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• 1995

The tungsten oxo-nitrosyl complexes (n-Bu4N)2[W5O12(NO)2{RC(NH2)NHO}2{RC(NH)NO}2] (R=(CH3)2CH, CH3CH2CH2, CH3SCH2) have been synthesized by the reactions of polyoxotungsten complex (n-Bu4N)2[W6O19] and tungsten dinitrosyl monomeric complex [W(NO)2(acac)(CH3CN)2](BF4) with butylamidoxime derivatives. The prepared complexes have been characterized by elemental analysis, infrared, UV-visible, 1H NMR and 13C NMR spectroscopy. The pentanuclear species was formed by the interaction of the electron-withdrawing {W(NO)2}2+ unit between the two dinuclear tungsten {W2O5}2+ cores. We can estimate to exist large proton interactions viewed from the four doublet in 1H NMR spectrum of (n-Bu4N)2[W5O12(NO)2{(CH3)2CHC(NH2)NHO}2{(CH3)2CHC(NH)NO}2]. We also drew informations of the two different coordination mode and symmetry of the complexes because two ligands appear in 13C NMR spectra instead of four. The {W(NO)2}2+ unit has been cis-form and C2v symmetry in geometric structure.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.4
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• pp.264-268
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• 1998

The experiment was conducted to clarify irrigation requirement and percolation rate in rice paddy. The four rice cultural system of no-tin, till, transplanting, and direct seeding condition were treated in the lysimeter filled with sandy loam soil. The amounts of irrigation and soil percolation were measured daily, and irrigation requirement was estimated. The daily percolation was 19.5 l/$\textrm{m}^2$ in no-till direct seeding on flooded paddy surface, 17.4 l/$\textrm{m}^2$ in both of till-direct seeding on flooded surface and no-till transplanting, and 15.2 l/$\textrm{m}^2$ in transplanting plot. This is equivalent to 19.5, 17.4, and 15.2 mm per day, respectively. Highest irrigation requirement was 3,770 l/$\textrm{m}^2$ in no-till direct seeding plots. Others were 3,249, 2,577, and 2,321 l/$\textrm{m}^2$ in till-direct seeding, no-till transplanting and transplanting plot, respectively. The estimated irrigation requirement of no-till transplanting, till-direct seeding and no-till direct seeding was increased by 11, 37, and 59% compared to till-transplanting plot. Percolation rate of no-till transplanting, till direct seeding and no-till direct seeding was increased by 12%, 40%, and 66%, respectively compared to the till-transplanting plot. The percolation rate in paddy soil was increased greatly after reproductive stage of rice.

• Journal of Preventive Medicine and Public Health
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• v.30 no.3 s.58
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• pp.609-622
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• 1997

Nitrogen dioxide $(NO_2)$ has been regarded as one of the main elements among air pollutants, and we measured $NO_2$ levels of near gas range, kitchen, living room and outdoor on 489 apartments in Pusan area. $NO_2$ were sampled by using Palmes tubes (diffusion tube sampler) during August 16-25, 1995 (summer) and January 15-29, 1996 (winter), respectively. Authors wanted to know comparison of $NO_2$ levels in summer and winter, $NO_2$ levels categorized by variables, and variables affected to $NO_2$ levels. According to this study, we conducted to establish the degree of indoor-outdoor air pollution of urban apartments in Korea and methods to reduce indoor air pollution. The results of this study were summarized as follows: 1) Mean $NO_2$ levels of near gas range, kitchen, living room, and outdoor were $25.9{\pm}10.0ppb,\;23.3{\pm}8.0ppb,\;19.9{\pm}6.1ppb,\;and\;19.0{\pm}6.0ppb$ in summer, and $34.5{\pm}16.8ppb,\;28.2{\pm}13.4ppb,\;25.3{\pm}12.5ppb,\;21.8{\pm}9.8ppb$ in winter, respectively. 2) Mean $NO_2$ levels according to the floor levels were not significantly different in summer, and in winter, $NO_2$ levels were decreased as the floor levels were increasing, but those were increased above 16th floor. 3) Variables showing significant correlation(p<0.05) with $NO_2$ levels were as follows; Summer: floor level, family size, number of family during a meal, number using gas range during rice cooking per day, and natural ventilation. Winter: floor level, family size, number of person who have been respiratory disease in a house, number of family during a meal, total number of meals, and number using gas range during rice or side-dish cooking per day. 4) We suggest that the methods of reducing indoor $NO_2$ levels are ventilation during cooking, complete combustion, decreasing number and time of cooking, and substitution of fuels.

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.355-360
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• 1998

Reduction activity of precious metal-loaded HZSM-5 for NO has been studied and was compared to that of Cu-HZSM-5 in the presence of excess oxygen. It was found that among the catalysts used in this study, Ru-HZSM-5 was the most active catalyst for the reduction of NO to $N_2$ in the absence of hydrocarbon reductant. The highest conversion obtained was 45%. No severe inhibition of water vapor to the reduction was observed. It is suggested that the higher catalytic activity of Ru-HZSM-5 may result from the better ability to oxidize NO to $NO_2$ in the presence of excess oxygen. A proposed reaction mechanism for the reduction of NO to $N_2$ in the presence of excess oxygen is that NO is oxidized to $NO_2$ on the surface of Ru-HZSM-5 catalyst and the adsorbed $NO_2$ on the surface is then decomposed to $N_2$. $NO_2$ is supposed to the reaction.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.2
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• pp.191-202
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• 2007

We developed an in-situ analyzer to understand the HONO levels in indoor environments. The in-situ measurement system utilizes a diffusion scrubber and luminol chemiluminescence to measure the HONO concentration with time resolution of 4-minute. Concentrations of NO, $NO_{2}$, and HONO were determined at an indoor air of an apartment for 9 days using the developed in-situ analyzer. Indoor HONO concentrations were highly elevated when a gas range was operated. Enhancements of the indoor NO, $NO_{2}$, and HONO concentrations during combustion indicate that the observed indoor HONO was formed by direct emission. In addition to the direct emission, the indoor HONO was partially generated from heterogeneous reactions of $NO_{2}$ on indoor surfaces, which was supported by strong relationships between peak NO, $NO_{2}$, and HONO concentrations, high HONO/$NO_{2}$ ratio and a weak correlation between NO and HONO concentrations. Additionally, three combustion experiments during the whole measurement period were performed to investigate the effects of unvented and vented gas burning on the HONO, NO, and $NO_{2}$ concentrations and their decay. The decay rate of the HONO concentration was significantly less than the NO and $NO_{2}$ decay rates for all the experiments, indicating that the lifetimes of trace nitrogen species in indoor environment varied in the order approximately HONO>$NO_{2}$>NO.

• Applied Science and Convergence Technology
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• v.26 no.6
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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.