• Advances in nano research
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• v.13 no.1
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• pp.1-12
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• 2022

The existence of active material in the environment causes the small-scale systems to be sensitive to the actual environment. Carbon dioxide is one of the active materials that exists a lot in the air conditions of the living environment. However, in some applications, the carbon dioxide-coated is used to improve the performance of systems against the destructive factors such as the corrosion; nevertheless, in the current research, the stability analysis of a carbon dioxide capture mechanism-coated beam is investigated according to the mathematical simulation of a rectangular composite beam utilizing the modified couple stress theory. The composite mechanism of carbon dioxide trapping is made of a polyacrylonitrile substrate that supports a cross-link polydimethylsiloxane gutter layer as the carbon dioxide mechanism trapping. Three novel types of carbon dioxide trapping mechanism involving methacrylate, poly (ethylene glycol) methyl ether methacrylate, and three pedant methacrylates are considered, which were introduced by Fu et al. (2016). Finally, according to introducing the methodology of carbon dioxide (CO₂) trapping, the impact of various effective parameters on the stability of composite beams will be analyzed in detail.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.319-321
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• 2010

• Korean Journal of Radiology
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• v.20 no.1
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• pp.50-57
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• 2019

In pediatric thoracic CT, respiratory motion is generally treated as a motion artifact degrading the image quality. Conversely, respiratory motion in the thorax can be used to answer important clinical questions, that cannot be assessed adequately via conventional static thoracic CT, by utilizing four-dimensional (4D) CT. However, clinical experiences of 4D thoracic CT are quite limited. In order to use 4D thoracic CT properly, imagers should understand imaging techniques, radiation dose optimization methods, and normal as well as typical abnormal imaging appearances. In this article, the imaging techniques of pediatric thoracic 4D CT are reviewed with an emphasis on radiation dose. In addition, several clinical applications of pediatric 4D thoracic CT are addressed in various thoracic functional abnormalities, including upper airway obstruction, tracheobronchomalacia, pulmonary air trapping, abnormal diaphragmatic motion, and tumor invasion. One may further explore the clinical usefulness of 4D thoracic CT in free-breathing children, which can enrich one's clinical practice.

• Korean Journal of Radiology
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• v.22 no.10
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• pp.1719-1729
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• 2021

Objective: Emphysema and small-airway disease are the two major components of chronic obstructive pulmonary disease (COPD). We propose a novel method of quantitative computed tomography (CT) emphysema air-trapping composite (EAtC) mapping to assess each COPD component. We analyzed the potential use of this method for assessing lung function in patients with COPD. Materials and Methods: A total of 584 patients with COPD underwent inspiration and expiration CTs. Using pairwise analysis of inspiration and expiration CTs with non-rigid registration, EAtC mapping classified lung parenchyma into three areas: Normal, functional air trapping (fAT), and emphysema (Emph). We defined fAT as the area with a density change of less than 60 Hounsfield units (HU) between inspiration and expiration CTs among areas with a density less than -856 HU on inspiration CT. The volume fraction of each area was compared with clinical parameters and pulmonary function tests (PFTs). The results were compared with those of parametric response mapping (PRM) analysis. Results: The relative volumes of the EAtC classes differed according to the Global Initiative for Chronic Obstructive Lung Disease stages (p < 0.001). Each class showed moderate correlations with forced expiratory volume in 1 second (FEV₁) and FEV₁/forced vital capacity (FVC) (r = -0.659-0.674, p < 0.001). Both fAT and Emph were significant predictors of FEV₁ and FEV₁/FVC (R² = 0.352 and 0.488, respectively; p < 0.001). fAT was a significant predictor of mean forced expiratory flow between 25% and 75% and residual volume/total vital capacity (R² = 0.264 and 0.233, respectively; p < 0.001), while Emph and age were significant predictors of carbon monoxide diffusing capacity (R² = 0.303; p < 0.001). fAT showed better correlations with PFTs than with small-airway disease on PRM. Conclusion: The proposed quantitative CT EAtC mapping provides comprehensive lung functional information on each disease component of COPD, which may serve as an imaging biomarker of lung function.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.4
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• pp.381-388
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• 2000

Ceramic foam prepared with cordierite as a starting material by foam method was tested to evaluate the feasibility as a filter for the dust collection in hot gas. Two different types of agents Benzethonium chloride (BZTC, C27H42NO2Cl) and Sodium Lauryl Sulfate(SLS, CH3(CH2)11OSO3Na) were used as foaming agents in foaming process. Porosityof ceramic foam was about 80% and mean pore size were 100${\mu}{\textrm}{m}$ for SLS agent and 200 ${\mu}{\textrm}{m}$ for BZTC. It was observed that ceramic foam was composed of continuous macro-pore structure with opening windows interconnecting macro-pores. The surface of ceramic foam support of was coated with cordierite particles ranged from 20${\mu}{\textrm}{m}$ to 50${\mu}{\textrm}{m}$ Meso-pore size in the coating layer on ceramic foam was below 10${\mu}{\textrm}{m}$. While air permeability of the support increased with increasing macro-pore size coated ceramic filters showed a constant permeability without regard to the macro-pore size of the support. The permeabuilities of support varied in the range of 600$\times$10-13m2 to 1000$\times$10-13m2. For the case of coated ceramic filter it was about 200$\times$10-13m2. As a result of particle trapping test by using fly ash the particle removal efficiency was over the 99.9%.

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.230-237
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• 1995

Airborne and waterborne ascospores and conidia of Botryosphaeria dothidea were collected in apple orchards at Suwon and Chunan in 1992 through 1994. Both waterborne and airborne spores were first detected in mid April to early May. Thereafter, spores were abundant in early June to late August and present until early December. Rainwater collections contained much more conidia than ascospores during the apple growing seasons. Airborne ascospores catches, which were also detected on humid days without measurable rainfall, were much more than airborne conidia catches. High amounts of ascospores were detected in early times of apple growing season, whereas most conidia catches occurred in later times of the season. The number of waterborne conidia and airborne ascospores was positively correlated with mean daily maximum, minimum, and average air temperatures during the trapping periods (p=0.01). However, no significant correlation was found between the number of spores and the total precipitation during the trapping periods.

• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.315-320
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• 2003

Headspace volatile compounds of oxidized fish oil were analyzed by the combination of hexane solvent or solid phase microextraction, gas chromatography and mass selective detector. The optimum condition of headspace analysis by hexane trapping was 23 min absorption time, 96$^{\circ}C$ sample temperature and 20 mL/min air flow rate. The numbers of volatile compounds identified by solvent trapping and SPME were 35 and 14, respectively. Groups having the largest amount and many kinds were hydrocarbons and aldehydes, respectively. The numbers of aldehydes were 15 and 6 for solvent trap and SPME, respectively. These basic data could be used as indicators for the quality changes of fish oil.

• Clinical and Experimental Pediatrics
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• v.56 no.5
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• pp.191-195
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• 2013

Severe childhood asthma is a complicated and heterogeneous disorder with distinct phenotypes. Children with severe asthma have more persistent symptoms despite receiving treatment, more atopy, greater airway obstruction, and more air trapping than those with mild-to-moderate asthma. They also have higher morbidity and substantial airflow limitations that persist throughout adulthood. Identification of the phenotype clusters and endotypes of severe asthma can allow further modulation of the natural history of severe asthma and may provide the pathophysiologic rationale for appropriate management strategies.

• Atmosphere
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• v.31 no.3
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• pp.295-309
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• 2021

Diurnal variations of air temperature and relative humidity in the Urban Canopy Layer (UCL) of the Seoul metropolitan area are examined using the Weather Research and Forecasting model coupled with the Seoul National University Urban Canopy Model. The canopy layer air temperature is higher than 2-m air temperature and exhibits a more rapid rise and an earlier peak in the daytime. These result from the multiple reflections of shortwave radiation and longwave radiation trapping due to the urban geometry. Because of the absence of vegetation in the UCL and the higher canopy layer air temperature, the canopy layer relative humidity is lower than 2-m relative humidity. Additional simulations with building height changes are conducted to examine the sensitivities of the canopy layer meteorological variables to the urban canyon aspect ratio. As the aspect ratio increases, net sensible heat flux entering the UCL increases (decreases) in the daytime (nighttime). However, the increase in the volume of the UCL reduces the magnitude of change rate of the canopy layer air temperature. As a result, the canopy layer air temperature generally decreases in the daytime and increases in the nighttime as the aspect ratio increases. The changes in the canopy layer relative humidity due to the aspect ratio change are largely determined by the canopy layer air temperature. As the aspect ratio increases, the canopy layer relative humidity is generally increased in the daytime and decreased in the nighttime, contrary to the canopy layer air temperature.

• Tuberculosis and Respiratory Diseases
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• v.65 no.6
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• pp.457-463
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• 2008

Background: The attenuation of the lung parenchyma increases on expiration as a consequence of decreased air in the lung. Expiratory CT scans have been used to show air trapping in patients with chronic airway disease and diffuse parenchymal disease and also in asymptomatic smokers. Although there have been several reports investigating the regional air trapping on a expiratory CT scan, there have been only a few reports evaluating the changes of whole lung attenuation with considering its clinical significance, and especially in healthy subjects. The purpose of this study was to evaluate the correlation of an expiratory increase of lung attenuation with age and smoking in healthy subjects. Methods: Asymptomatic subjects who underwent a low dose chest CT scan as part of a routine check-up and who showed normal spirometry and a normal inspiratory CT scan were recruited for this study. We excluded the subjects with significant regional air trapping seen on their expiratory CT scan. Lung attenuation was measured at 24 points of both the inspiratory and expiratory CT scans, respectively, for 100 subjects. The correlations between an expiratory increase of the lung attenuation and the amount of smoking, the patient's age and the results of spirometric test were assessed. Results: There were 87 men and 13 women included in this study. Their median age was 49.0 years old (range:25~71). Sixty current smokers, 24 ex-smokers and 16 non-smokers were included. As age increased, the expiratory increase of lung attenuation was reduced at every measuring points (r=-0.297~-0.487, Pearson correlation). The statistical significance was maintained after controlling for the effect of smoking. Smoking was associated with a reduction of the expiratory increase of lung attenuation. But the significance was reduced after controlling for the patient's age. The $FEV_1$, FVC, $FEV_1/FVC$ and $FEF_{25{\sim}75%}$ were not associated with an expiratory increase of lung attenuation. Conclusion: The expiratory increase of lung attenuation in subjects with a normal inspiratory CT scan was negatively correlated with age. It was also reduced in heavy smokers. It may reflect aging and the smoking related changes.