• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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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 $H_2O$.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.299-305
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• 2017

Activated carbon fibers (ACFs) were surface-modified by electron beam (E-beam) irradiation and used as a gas sensor electrode to investigate the effect of E-beam on nitric oxide (NO) gas sensing performance. XPS results showed that the oxygen component of ACFs surface treated by E-beam decreased and $sp^2$ bonded carbon of ACFs surface increased. These results were attributed to the structural transformation of ACFs surface irradiated by E-beam. NO gas sensitivity of the electrode composed of ACFs irradiated by100 kGy increased from about 4% to 8%, and the response time was also meaningfully enhanced from 360 s to 120 s. This is due to the fact that the $sp^2$ carbon bond increased by E-beam irradiation of activated carbon fibers, which significantly affects the resistance change of the electrode in NO gas sensing.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1293-1300
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• 2014

The temperature data influences on various policies of the country. In this article, the autoregressive error (ARE) model has been considered for analyzing the monthly and seasonal temperature data at the northern part of the Chungcheong Namdo, Seosan monitoring site in Korea. In the ARE model, five meteorological variables, four greenhouse gas variables and five pollution variables are used as the explanatory variables for the temperature data set. The five meteorological variables are wind speed, rainfall, radiation, amount of cloud, and relative humidity. The four greenhouse gas variables are carbon dioxide ($CO_2$), methane ($CH_4$), nitrous oxide ($N_2O$), and chlorofluorocarbon ($CFC_{11}$). And the five air pollution explanatory variables are particulate matter ($PM_{10}$), sulfur dioxide ($SO_2$), nitrogen dioxide ($NO_2$), ozone ($O_3$), and carbon monoxide (CO). The result showed that the monthly ARE model explained about 39-63% for describing the temperature. However, the ARE model will be expected better when we add the more explanatory variables in the model.

• Journal of Platform Technology
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• v.9 no.4
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• pp.79-89
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• 2021

In this paper, the fine dust (PM10) and ultrafine dust (PM2.5) measurement platforms are designed to be mobile and fixed using oneM2M, the international standard for IoT. The fine dust measurement platform is composed and designed with a fine dust measurement device, agent, oneM2M platform, oneM2M IPE, and monitoring system. The main difference between mobile and fixed is that the mobile uses the MQTT protocol for interconnection between devices and services without blind spots based on LTE connection, and the fixed uses the LoRaWAN protocol with low power and wide communication range. Not only fine dust, but also temperature, humidity, atmospheric pressure, volatile organic compounds (VOC), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), and noise data related to daily life were collected. The collected sensor values were managed using the common API provided by oneM2M through the agent and oneM2M IPE, and it was designed into four resource types: AE and container. Six functions of operability, flexibility, convenience, safety, reusability, and scalability were analyzed through the fine dust measurement platform design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.294-305
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• 2022

Recently, drones have been widely used to solve environmental problems such as environmental protection and natural disaster monitoring. This study focuses on the problem of the search altitude of drones when using drones to search for air pollution in order to maintain the urban air environment. In particular, when exploring air pollution in cities using drones, various experiments are conducted to determine the appropriate search altitude for each air pollution source and each communication module. Through the experiment, the maximum measurable altitude for the most common air pollutants, such as CO (carbon monoxide), NO₂ (nitrogen dioxide), O₃ (ozone), and P10, P2.5 (fine dust), was identified, and the effective search altitude for each air pollution source was determined. As a result of the experiment, three types of drone search altitudes including legally measurable altitudes were suggested. The communication module measurable altitude was 60m to 120m depending on the communication module, and the effective measurable altitude was analyzed from 10m to 100m.

• Clean Technology
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• v.16 no.1
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• pp.19-25
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• 2010

In this work, the conversion of crystalline cellulose into polyols in the presence of hydrogen was examined over noble metal (Pt, Ru, Ir, Rh, and Pd) catalysts supported on activated carbon. For comparison, Pt/${\gamma}-Al_2O_3$ and Pt/H-mordenite were also investigated. Several techniques: $N_2$ physisorption, X-ray diffraction(XRD), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), temperature-programmed reduction with $H_2$ ($H_2$-TPR) and CO chemisorption were employed to characterize the catalysts. The cellulose conversion was not strongly dependent on the types of the catalyst used. Pt/AC showed the highest yields to polyols among activated carbon-supported noble metal catalysts, viz. Pt/AC, Ru/AC, Ir/AC, Rh/AC and Pd/AC.

• Korean Journal of Remote Sensing
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• v.39 no.2
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• pp.129-142
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• 2023

This study analyzed the ratio of carbon monoxide (CO) and carbon dioxide (CO₂), CO and nitrogen dioxide (NO₂) for cities and regionsin Korea and China using column-averaged carbon dioxide dry-air mole fraction (XCO₂) of the Orbiting Carbon Observatory-2/3, CO and NO₂ vertical column density (named XCO, XNO₂ in thisstudy) of TROPOspheric monitoring instrument from April 2018 to April 2022, and presented the relationship between socioeconomic indicators (population, number of vehicles, Gross Regional Domestic Product) and ratio, and differences in characteristics between Korea and China. First, CO₂ and CO were analyzed after calculating ΔXCO₂ and ΔXCO removing the background value and trend line due to the difference in atmospheric residence time of three gaseous substances (CO₂, CO, and NO₂). Comparing the three values by regions, ΔXCO and ΔXCO₂ were relatively higher in China and XNO₂ were higher in Korea and the ratio of both values (ΔXCO/ΔXCO₂, ΔXCO/XNO₂) was higher in China than in Korea. ΔXCO/ΔXCO₂, ΔXCO/XNO₂ and socioeconomic indicators have a positive correlation suggesting that the concentration of air pollutants and greenhouse gases is higher as the city is large and the economic activity is active. Regarding the differences in the ratio characteristics of Korea and China, the relationship between ΔXCO and ΔXCO₂ showed a negative correlation in Korea and a positive correlation in China. When the relationship between ΔXCO and XNO₂ was examined for summer and winter, the change of ΔXCO by season was not significant in Korea, whereasthe change of ΔXCO and XNO₂ by season waslarge in China resulting in the relationship between two countries appeared differently. These results suggest that seasonal variability and national emission characteristics should be considered in the process of analyzing the ratio of greenhouse gases to air pollutants.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.630-638
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• 2019

Nitrous oxide (N₂O) is a greenhouse gas with a global warming potential 310 times higher than that of carbon dioxide. In this study, an N₂O-reducing consortium was obtained by enrichment culture using advanced treatment sludge as the inoculum. The dominant bacteria in the consortium were Sulfurovum (17.95%), Geobacter (14.63%), Rectinema (11.45%), and Chlorobium (8.24%). The consortium displayed optimal N₂O reducing activity when acetate was supplied as the carbon source at a carbon/nitrogen ratio (mol·mol^-1) of 6.3. The N₂O reduction rate increased with increasing N₂O concentration at less than 3,000 ppm. Kinetic analysis revealed that the maximum N₂O reduction rate of the consortium was 163.9 ㎍-N·g-VSS^-1·h^-1. Genes present in the consortium included nosZ (reduction of nitrous oxide to N₂), narG (reduction of nitrate to nitrite), nirK (reduction of nitrite to nitric oxide), and norB (reduction of nitric oxide to nitrous oxide). These results indicate that the N₂O-reducing consortium is a promising bioresource that can be used in denitrification and N₂O mitigation.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.338-346
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• 2015

The present work was undertaken to address the role of protein disulfide isomerase 2 (Pdi2) in the mercury-tolerance of Schizosaccharomyces pombe, using the Pdi2-overexpressing recombinant plasmid pYPDI2 and the corresponding vector plasmid pRS316. When exposed to mercuric chloride, the PDI2 overepxression cells grew significantly better than the vector control cells. They revealed the lower levels of intracellular reactive oxygen species (ROS) and nitric oxide (NO), when incubated with mercuric chloride for 6 h, than the vector control cells. The PDI2 overepxression cells contained the higher levels of total glutathione (GSH) and superoxide dismutase (SOD) activity than the vector control cells, after 6 h of incubation in mercuric chloride. However, the PDI2 overepxression cells contained similar levels of glutathione peroxidase (GPx) activities, compared to those of the vector control cells. Taken together, the S. pombe Pdi2 promotes the tolerance against mercury toxicity through up-regulating total GSH and SOD and subsequently attenuating ROS and NO elevations.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.2
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• pp.203-211
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• 1999

목적: 일산화질소 (nitric oxide; NO)는 생식계를 비롯한 여러 생체내 기관에서 다양하고도 중요한 작용을 하는 것으로 알려져 있으며, 복강액은 난관내강과 연결되어 복강액 내의 세포 성분의 변화는 난관의 미세환경을 변화시켜 수정과 초기 배아 발생에 영향을 줄 수 있다. 본 연구는 배아 발생에 있어서 일산화질소의 역할을 이해하고 복강액 내의 NO농도 변화가 배아 발생에 미치는 역할을 조사하기 위해 수행되었다. 방법: 과배란시킨 1세대 잡종 암컷 생쥐 (C57BL${\times}$CBA/Ca)로부터 1세포기 배아를 얻어 10% synthetic serum substitute가 첨가된 modified human tubal fluid 배양액에서 4일 동안 체외배양하였다(대조군). 실험을 위해 이러한 배양조건에 sodium nitroprusside (SNP)를 $0{\sim}1mM$의 다양한 농도로 배양초기부터 첨가하거나, $200{\mu}M$ SNP를 2-, 4-, 8-세포기의 각기 다른 배아시기에 첨가하였으며, 복강경수술을 받는 42명의 여성으로부터 채취한 복강액을 SSS대신 단백질원으로 사용하여 포배아까지의 배아 발달율을 관찰하였으며, 복강액 내의 NO농도를 Griess방법에 의해 측정하였다. 배아의 apoptotic body는 H33342 염색법으로 조사하였으며 배아 발달율은 3회 이상 반복 실험한 결과의 mean${\pm}$SEM으로 나타내었다. 결과: SNP는 농도에 의존적으로 배발생을 억제하였으나 배아 단계에 대한 특이성은 관찰할 수 없었으며, 특히 $100{\mu}M$ 이상의 고농도의 SNP는 2-세포기 단계에서 배아 발생을 정지시켰다. 또한 단백질원으로 복강액 이용시 배 발생율은 복강액 내의 NO 농도에 따라 현저한 차이가 발견되었으며, $2.5{\mu}M$이상의 NO를 함유한 복강액에서 배양한 배아의 발생율은 현저하게 감소하였다. cGMP analogue인 8-bromo-cGMP를 배양액에 첨가시 배아 발생에는 변화가 없었으며, SNP에 의해 배발생이 정지된 2-세포기 배아에서 apoptotic body를 발견할 수 없었다. 결론: 이상의 결과로 보아 NO는 고농도에서 배아 발생을 저해하며, 복강액 내의 NO와 같은 성분의 변화는 배아 발생에 유해한 효과를 유발할 것으로 사료된다. 이러한 NO의 배아 발생 억제효과는 cGMP로 중재되는 경로나 apoptosis유발과는 관계가 없는 것 같다.