• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.16-19
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• 2019

A thinner film has superior electrical properties and a better amorphous structure. Amorphous structures can be effective in improving conductivity through a depletion effect. Research is needed on the Schottky contact, where potential barriers are formed, as a way to identify these characteristics. $SiO_2/SnO_2$ thin films were prepared to examine the amorphous structure and Schottky contact, $SiO_2$ thin films were prepared using Ar = 20 sccm. $SnO_2$ thin films were deposited using mixed gas with a flow rate of argon and oxygen at 20 sccm, and $SnO_2$ thin films were added by magnetron sputtering and treated at $100^{\circ}C$ and $150^{\circ}C$. To identify the conditions under which the amorphous structure was constructed, the XRD patterns were investigated and C-V and I-V measurements were taken to make Al electrodes and perform electrical analysis. The depletion layer was formed by the recombination of electrons and holes through the heat treatment process. $SiO_2/SnO_2$ thin films confirmed that the pores were well formed when heat treated at $100^{\circ}C$ and an electric current was applied over the micro area. An amorphous $SiO_2/SnO_2$ thin film with heat treatment at $100^{\circ}C$ showed no reflection at $33^{\circ}\;2{\theta}$ in the XRD pattern, and a reflection at $44^{\circ}2\;{\theta}$. The macroscopic view (-30 V

• Clean Technology
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• v.28 no.2
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• pp.131-137
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• 2022

The semiconductor process currently emits various by-products and unused gases. Emissions containing pollutants are generally classified into categories such as organic, acid, alkali, thermal, and cabinet exhaust. They are discharged after treatment in an atmospheric prevention facility suitable for each exhaust type. The main components of organic exhaust are volatile organic compounds (VOC), which is a generic term for oxygen-containing hydrocarbons, sulfur-containing hydrocarbons, and volatile hydrocarbons, while the main components of alkali exhaust include ammonia and tetramethylammonium hydroxide. The purpose of this study was to determine the combustion characteristics and analyze the NO_X reduction rate by maintaining a direct combustion and temperature to process organic and alkaline exhaust gases simultaneously. Acetone, isopropyl alcohol (IPA), and propylene glycol methyl ether acetate (PGMEA) were used as VOCs and ammonia was used as an alkali exhaust material. Independent and VOC-ammonia mixture combustion tests were conducted for each material. The combustion tests for the VOCs confirmed that complete combustion occurred at an equivalence ratio of 1.4. In the ammonia combustion test, the NO_X concentration decreased at a lower equivalence ratio. In the co-combustion of VOC and ammonia, NO was dominant in the NO_X emission while NO₂ was detected at approximately 10 ppm. Overall, the concentration of nitrogen oxide decreased due to the activation of the oxidation reaction as the reaction temperature increased. On the other hand, the concentration of carbon dioxide increased. Flameless combustion with an electric heat source achieved successful combustion of VOC and ammonia. This technology is expected to have advantages in cost and compactness compared to existing organic and alkaline treatment systems applied separately.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.1-7
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• 2024

Mn-M/Al₂O₃ (M = Cu, Fe, Co, and Ce) catalysts were prepared for simultaneous oxidation of NO, CO, and CH₄, and their oxidation activities were compared. The Mn-Cu/ Al₂O₃ catalyst with the best simultaneous oxidation activity was characterized by XRD, Raman, XPS, and O₂-TPD analysis. The result of XRD indicated that Mn and Cu existed as complex oxides in the Mn-Cu/Al₂O₃ catalyst. Raman and XPS results showed that electron transfer between Mn ions and Cu ions occurred during the formation of the Mn-O-Cu bond in the Mn-Cu/Al₂O₃ catalyst. The XPS O 1s and O₂-TPD analyses showed that the Mn-Cu/Al₂O₃ catalyst has more adsorbed oxygen species with high mobility than the Mn/Al₂O₃ catalyst. The high simultaneous oxidation activity of the Mn-Cu/Al₂O₃ catalyst is attributed to these results. Gas-phase NO promotes the oxidation reactions of CO and CH₄ in the Mn-Cu/Al₂O₃ catalyst while suppressing the NO oxidation reaction. These results were presumed to be because the oxidized NO was used as an oxidizing agent for CO and CH₄. On the other hand, the oxidation reactions of CO and CH₄ competed on the Mn-Cu/Al₂O₃ catalyst, but the effect was not noticeable because the catalyst activation temperature was different.

• Tuberculosis and Respiratory Diseases
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• v.42 no.4
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• pp.555-568
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• 1995

Background: It is most physiologic to measure the diffusing capacity of the lung by using oxygen, but it is so difficult to measure partial pressure of oxygen in the capillary blood of the lung that in clinical practice it is measured by using carbon monoxide, and single-breath diffusing capacity method is used most widely. However, since the process of withholding the breath for 10 seconds after inspiration to the total lung capacity is very hard to practice for patients who suffer from cough, dyspnea, etc, the intra-breath lung diffusing capacity method which requires a single exhalation of low-flow rate without such process was devised. In this study, we want to know whether or not there is any significant difference in the diffusing capacity of the lung measured by the single-breath and intra-breath methods, and if any, which factors have any influence. Methods: We chose randomly 73 persons without regarding specific disease, and after conducting 3 times the flow-volume curve test, we selected forced vital capacity(FVC), percent of predicted forced vital capacity, forced expiratory volume within 1 second($FEV_1$), percent of forced expiratory volume within 1 second, the ratio of forced expiratory volume within 1 second against forced vital capacity($FEV_1$/FVC) in test which the sum of FVC and $FEV_1$ is biggest. We measured the diffusing capacity of the lung 3 times in each of the single-breath and intra-breath methods at intervals of 5 minutes, and we evaluated which factors have any influence on the difference of the diffusing capacity of the lung between two methods[the mean values(ml/min/mmHg) of difference between two diffusing capacity measured by two methods] by means of the linear regression method, and obtained the following results: Results: 1) Intra-test reproducibility in the single-breath and intra-breath methods was excellent. 2) There was in general a good correlation between the diffusing capacity of the lung measured by a single-breath method and that measured by the intra-breath method, but there was a significant difference between values measured by both methods($1.01{\pm}0.35ml/min/mmHg$, p<0.01) 3) The difference between the diffusing capacity of the lung measured by both methods was not correlated to FVC, but was correlated to $FEV_1$, percent of $FEV_1$, $FEV_1$/FVC and the gradient of methane concentration which is an indicator of distribution of ventilation, and it was found as a result of the multiple regression test, that the effect of $FEV_1$/FVC was most strong(r=-0.4725, p<0.01) 4) In a graphic view of the difference of diffusing capacity measured by single-breath and intra-breath method and $FEV_1$/FVC, it was found that the former was divided into two groups in section where $FEV_1$/FVC is 50~60%, and that there was no significant difference between two methods in the section where $FEV_1$/FVC is equal or more than 60% ($0.05{\pm}0.24ml/min/mmHg$, p>0.1), but there was significant difference in the section, less than 60%($-4.5{\pm}0.34ml/min/mmHg$, p<0.01). 5. The diffusing capacity of the lung measured by the single-breath and intra-breath method was the same in value($24.3{\pm}0.68ml/min/mmHg$) within the normal range(2%/L) of the methane gas gradient, and there was no difference depending on the measuring method, but if the methane concentration gradients exceed 2%/L, the diffusing capacity of the lung measured by single-breath method became $15.0{\pm}0.44ml/min/mmHg$, and that measured by intra-breath method, $11.9{\pm}0.51ml/min/mmHg$, and there was a significant difference between them(p<0.01). Conclusion: Therefore, in case where $FEV_1$/FVC was less than 60%, the diffusing capacity of the lung measured by intra-breath method represented significantly lower value than that by single-breath method, and it was presumed to be caused largely by a defect of ventilation-distribution, but the possibility could not be excluded that the diffusing capacity of the lung might be overestimated in the single-breath method, or the actual reduction of the diffusing capacity of the lung appeared more sensitively in the intra-breath method.

• Journal of Nutrition and Health
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• v.48 no.2
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• pp.180-191
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• 2015

Purpose: There is a lack of data on the energy cost of children's everyday activities, adult values are often used as surrogates. In addition, the influence of body weight on the energy cost of activity when expressed as metabolic equivalents (METs) has not been vigorously explored. Methods: In this study 20 elementary school students 9~12 years of age completed 18 various physical activities while energy expenditure was measured continuously using a portable telemetry gas exchange system ($K_4b^2$, Cosmed, Rome, Italy). Results: The average age was 10.4 years and the average height and weight was 145.1 cm and 43.6 kg, respectively. Oxygen consumption ($VO_2$), energy expenditure and METs at the time of resting of the subjects were 5.41 mL/kg/min, 1.44 kcal/kg/h, and 1.5 METs, respectively. METs values by 18 physical activities were as follows: Homework and reading books (1.6 METs), playing game with a mobile phone or video while sitting (1.6 METs), watching TV while sitting on a comfortable chair (1.7 METs), playing video game or mobile phone game while standing (1.9 METs), sweeping a room with a broom (2.7 METs) and playing a board game (2.8 METs) belong to light intensity physical activities. By contrary, speedy walking and running were 6.6 and 6.7 METs, respectively, which belong to high intensity physical activities over 6.0 METs. When the effect of body weight on physical activity energy expenditure was determined, $R^2$ values increased with 0.116 (playing a game at sitting), 0.176 (climbing up and down stairs), 0.246 (slow walking), and 0.455 (running), which showed that higher activity intensity increased explanation power of body weight on METs value. Conclusion: This study is important for direct evaluation of energy expenditure by physical activities of children, and it could be used directly for revising and complementing the existing activity classification table to fit for children.