• Title/Summary/Keyword: $NO_2$ gas

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Technique for Using Fly Ash as a Bedding Materials at Livestock House (석탄회의 축사 깔짚 이용기술)

  • 고영두;김재황;김두환;고병두;이수칠;이종찬;김삼철
    • Journal of Animal Environmental Science
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    • v.5 no.1
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    • pp.37-44
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    • 1999
  • This study was carried out to improve utilization of substitute fly-ash in bedding material of animal waste treatments. The amount used of fly-ash used in a pigpen or beef stall was 50% lower than that of existing bedding material of animal waste treatments. From the results, substitution effect of fly-ash put over the floor of the stable became much better. Effects of processed fly ash as a spread straw decreased ammonia(NH3) and Hydrogensulfide (H2S) gas at beef stall, but there was no benefit of replacement terms. Effect of processed fly ash as a spread straw increased 4∼5 times replacement terms more than control NH3 and H2S gas was decreased. A lot of maggots and porasites were grown at sawdust pig farm, but fly ash inhibited to grow maggots and paraeters. In conclusion, as substituting fly-ash for 5% sawdust(DM basis) in making animal waste into a compost with fly ash, we can reduce the sawdust purchasing costs and produce the high quality of a compost, especially a pollutant as NH3 and H2S gas, etc. from the process of biodegradation, and as substituting fly-ash(1,540 won per ton ; can be extended the replacement period of spreading straw approximatively 4∼5 times) for sawdusts(111,000 won per ton) will increase a real income in livestock house.

Optimization of Anaerobic Process by Enzyme Treatment of High Concentration Organic Substances in Food Wastewater

  • Tae-Hwan JEONG;Woo-Taeg KWON
    • Journal of Wellbeing Management and Applied Psychology
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    • v.6 no.2
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    • pp.33-37
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    • 2023
  • Purpose: Since 2013, marine dumping of wastewater has been banned, and research on eco-friendly and efficient land treatment has emerged. This study compared and tested changes in biogas production and anaerobic process efficiency depending on whether or not enzyme pretreatment was performed during anaerobic digestion from single-phase and two-phase to medium-temperature. Research design, data and methodology: The total sugar, direct sugar, pH, and acidity before and after fermentation were analyzed by G/C by anaerobic fermentation of the liquor wastewater, food wastewater 1, and food wastewater 2 at 30℃ for 67 hours, and the amount of methane gas generated was analyzed by balloon volume. Results: It was found that stable organic acid concentration and pH were found in the enzyme-treated food wastewater 2, and the amount of methane gas generated was also increased. Conclusions: When anaerobic digestion of the liquor wastewater and the food wastewater together, the performance of enzyme pretreatment resulted in increased digestive efficiency. It will be the basic data that can contribute to carbon neutrality and greenhouse gas reduction by increasing the production of biogas.

Determination of selenium in milk powder by octopole reaction cell ICP-MS (Octopole Reaction Cell이 장착된 ICP-MS에 의한 분유 중 셀레늄의 정량)

  • Cho, Sung-Eel;Kim, Mi-Ju;Kim, Yong-Ha;Min, Young-Keun;Kim, Young-Sang
    • Analytical Science and Technology
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    • v.19 no.3
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    • pp.203-210
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    • 2006
  • The determination of trace selenium in milk powder has been studied by octopole reaction cell(ORC)-ICP-MS. The interferences by polyatomic ions and other concomitant molecular species could be removed remarkably by using $H_2$ as reaction gas in ORC. Compared to the normal mode (no cell gas), the $H_2$ cell gas mode improved the accuracy and precision. The quantitative result was average 102.7% and it was slightly higher than certified standard value of milk powder and the RSD was 7.6%.

Effects of Film Packaging and Gas Composition on the Distribution and Quality of Ginseng Sprouts (새싹인삼의 필름포장과 가스조성이 품질특성에 미치는 영향)

  • Chang, Eun Ha;Lee, Ji Hyun;Choi, Ji Weon;Shin, Il Sheob;Hong, Yoon Pyo
    • Korean Journal of Medicinal Crop Science
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    • v.28 no.2
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    • pp.152-166
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    • 2020
  • Background: Ginsenosides, which have various physiological activities, are known to be abundant in the leaves and roots of ginseng. Ginseng sprouts can be used as a fresh vegetable and roots, stems, and leaves of ginseng can be consumed. This study aimed to investigate the effect of carbon dioxide treatment and the modified atmosphere (MA) packaging method in suppressing quality deterioration during the distribution of ginseng sprouts. Methods and Results: Ginseng sprouts were packed using Styrofoam, barrier film + non gas treatment, barrier film + gas treatment, 15 ㎛ polyamide (PA) double film + non gas treatment, 15 ㎛ PA double film + gas treatment, 25 ㎛ PA film + non gas treatment, or 25 ㎛ PA film + gas treatment. Quality parameters including gas composition, relative humidity, chlorophyll SPAD (Soil Plant Analysis Development) value, firmness, and rate of quality loss in ginseng sprouts were monitored at the following temperatures: 20℃, and 10℃. Ginseng sprouts packaged with 25 ㎛ PA film showed loss in quality because of wilting owing to low relative humidity within the film. Chlorophyll and firmness did not differ between film and gas treatments. The time point at which the combined loss from softening and decay owing to fungal, and bacterial infection and wilt reached 20% was considered the limit of distribution. At 20℃, the packaging not included in the 20% distribution loss rate limit or up to 7 days was 15 ㎛ PA double film + gas treatment. At 10℃, the packaging not included in the 20% distribution loss rate limit for up to 18 days were barrier film + gas treatment and 15 ㎛ PA double film + gas treatment. Conclusions: The film packaging suitable for the distribution of ginseng sprouts was found to be the barrier film and PA film with low gas permeability and maintaining hygroscopicity at 95% relative humidity. To prevent the loss in quality of ginseng sprouts, gas treatment (8% of O2 and 18% of CO2) in the film was found to be more suitable than no gas treatment for inhibition of decay.

Microbial Community Structure in Hexadecane- and Naphthalene-Enriched Gas Station Soil

  • Baek, Kyung-Hwa;Kim, Hee-Sik
    • Journal of Microbiology and Biotechnology
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    • v.19 no.7
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    • pp.651-657
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    • 2009
  • Shifts in the activity and diversity of microbes involved in aliphatic and aromatic hydrocarbon degradation in contaminated soil were investigated. Subsurface soil was collected from a gas station that had been abandoned since 1995 owing to ground subsidence. The total petroleum hydrocarbon content of the sample was approximately 2,100 mg/kg, and that of the soil below a gas pump was over 23,000 mg/kg. Enrichment cultures were grown in mineral medium that contained hexadecane (H) or naphthalene (N) at a concentration of 200 mg/l. In the Henrichment culture, a real-time PCR assay revealed that the 16S rRNA gene copy number increased from $1.2{\times}10^5$to $8.6{\times}10^6$with no lag phase, representing an approximately 70-fold increase. In the N-enrichment culture, the 16S rRNA copy number increased about 13-fold after 48 h, from $6.3{\times}10^4$to $8.3{\times}10^5$. Microbial communities in the enrichment cultures were studied by denaturing gradient gel electrophoresis and by analysis of 16S rRNA gene libraries. Before the addition of hydrocarbons, the gas station soil contained primarily Alpha- and Gammaproteobacteria. During growth in the H-enrichment culture, the contribution of Bacteriodetes to the microbial community increased significantly. On the other hand, during N-enrichment, the Betaproteobacteria population increased conspicuously. These results suggest that specific phylotypes of bacteria were associated with the degradation of each hydrocarbon.

A study on the pure Al weldability using a pulsed Nd : YAG laser (펄스형 Nd:YAG 레이저를 이용한 Al의 용접 특성연구)

  • 김덕현
    • Journal of Welding and Joining
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    • v.11 no.1
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    • pp.52-61
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    • 1993
  • Laser welding of ASTM no. 1060 Al plate with a pulsed Nd: YAG laser of 200W average power was performed for end capping of KMRR nuclear fuel elements In this research, we performed basic welding experiments. Firstly, laser output parameters which affect laser welding parameters were studied by changing laser input parameters for effective welding of 1060 Al plates. We found that laser power density and pulse energy are important parameters for smooth bead shape. Secondly, welding parameters which affect weld width-to-depth ratio were studied by changing power density and pulse energy, shielding gas, and defocusing. We found that power density must be higher than 0.3 Mw/cm$^{2}$ pulse energy must be higer than 3 J. travel speed must not exceed 200mm/sec, laser focus must be existed beneath 2-3mm from plate surface and helium is proper shielding gas. Thirdly, we studied the weld defects of Al-1060 such as crack and porosity in lap-joint welding. We designed new welding geometry for crack free welding of Al-1060 plates, and obtained crack free weldment but with lack of fusion. However, with Ti, Zr grain refiner elements, we can weld Al plates without solidification hot crack. Finally, we studied the origin of porosity by changing shielding gas. And we found that porosity was resulted from entrapment of shielding gas by the collapsing keyhole.

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Analysis of dew point and corrosion resistance for power plant economizer tube with exhaust gas temperature and sulfuric acid concentration (발전소 절탄기 튜브의 배기가스 온도와 황산 농도에 따른 노점 및 내식성 분석)

  • Choi, Jae-Hoon;Lee, Seung-Jun
    • Journal of Surface Science and Engineering
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    • v.55 no.6
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    • pp.433-440
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    • 2022
  • Environmental pollution caused by power plant exhaust gas is highlighted and eco-friendly regulations are being strengthened. However, due to the abundant reserves and low prices of coal, still the most used for power generation in the world. Therefore, flexible operation of coal-fired power plants to reduce emissions has become an inevitable option. However, lowering the output increases the possibility of acid dew point corrosion as the exhaust gas temperature decreases. The dew point corrosion occurs when condensable gases such as SO3, HCl, NO2 and H2O cools below the saturation temperature. SO3 is already well known to cause severe low- temperature corrosion in coal-fired power plants. Therefore, this study aims to prevent damage that may occur during operation by analyzing the dew point and corrosion resistance with exhaust gas temperature and sulfuric acid concentration of the power plant economizer tube.

A Comparison Study of Forecasting Time Series Models for the Harmful Gas Emission (유해가스 배출량에 대한 시계열 예측 모형의 비교연구)

  • Jang, Moonsoo;Heo, Yoseob;Chung, Hyunsang;Park, Soyoung
    • Journal of the Korean Society of Industry Convergence
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    • v.24 no.3
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    • pp.323-331
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    • 2021
  • With global warming and pollution problems, accurate forecasting of the harmful gases would be an essential alarm in our life. In this paper, we forecast the emission of the five gases(SOx, NO2, NH3, H2S, CH4) using the time series model of ARIMA, the learning algorithms of Random forest, and LSTM. We find that the gas emission data depends on the short-term memory and behaves like a random walk. As a result, we compare the RMSE, MAE, and MAPE as the measure of the prediction performance under the same conditions given to three models. We find that ARIMA forecasts the gas emissions more precisely than the other two learning-based methods. Besides, the ARIMA model is more suitable for the real-time forecasts of gas emissions because it is faster for modeling than the two learning algorithms.

Effect of Construction Joint on Leakage Resistance of Gas in Reinforced Concrete Pressure Vessels (철근콘크리트 압력용기에서 시공이음이 가스의 누설저항에 미치는 영향)

  • Yi, Seong-Tae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.2
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    • pp.87-94
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    • 2017
  • In the nuclear power plant, the steel or polymer liner plates are adopted to prohibit the inner concrete surface from contacting with gas or liquid materials. If there is an accident, the plate may be damaged, and, in this case, concrete shall have the final responsibility to safety requirements. In this paper, an experimental research was carried out to investigate the effects of construction joint and wet and loading conditions on the permeability of concrete. The test results showed that, under a construction joint in the wet condition, leakage of gas pressure has been started from $1kg/cm^2$. However, when there are no construction joints, it is initiated from $2kg/cm^2$. In addition, under the air dried and unloading condition, regardless of with or without the presence of the construction joint, since the gas passage that exist in concrete is constant, leakage has a constant tendency to increase. Finally, under the loading condition, as described in Reference 1, since leakage is inversely proportional to the thickness of the wall, and, considering the wall thickness of the actual plant, it is found that there will not be no problem in the sealing of the gas.

Characteristics and Preparation of Gas Sensors Using Nano SnO2:CNT (나노 SnO2:CNT를 이용한 가스센서의 제작 및 특성연구)

  • Yu, Il
    • Korean Journal of Materials Research
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    • v.26 no.9
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    • pp.468-471
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    • 2016
  • $SnO_2:CNT$ thick films for gas sensors were fabricated by screen printing method on alumina substrates and were annealed at $300^{\circ}C$ in air. The nano $SnO_2$ powders were prepared by solution reduction method using tin chloride ($SnCl_2.2H_2O$), hydrazine ($N_2H_4$) and NaOH. Nano $SnO_2:CNT$ sensing materials were prepared by ball-milling for 24h. The weight range of CNT addition on the $SnO_2$ surface was from 0 to 10 %. The structural and morphological properties of these sensing material were investigated using X-ray diffraction and scanning electron microscopy and transmission electron microscope. The structural properties of the $SnO_2:CNT$ sensing materials showed a tetragonal phase with (110), (101), and (211) dominant orientations. No XRD peaks corresponding to CNT were observed in the $SnO_2:CNT$ powders. The particle size of the $SnO_2:CNT$ sensing materials was about 5~10 nm. The sensing characteristics of the $SnO_2:CNT$ thick films for 5 ppm $H_2S$ gas were investigated by comparing the electrical resistance in air with that in the target gases of each sensor in a test box. The results showed that the maximum sensitivity of the $SnO_2:CNT$ gas sensors at room temperature was observed when the CNT concentration was 8wt%.