• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.269-274
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• 2018

All the $Ni-Co-Ce-ZrO_2$ mixed oxides are prepared by co-precipitations methods. Methanation of CO and $H_2$ reaction is screened tested over different fractions of cerium (2, 4, 7 and 12 wt.%) over $Ni-Co/ZrO_2$ bimetallic catalysts are investigated. The mixed oxides are characterized by XRD, CO-Chemisorption, TGA and screened methanation of CO and $H_2$ at $360^{\circ}C$ for 3000 min on stream at typical ratio $CO:H_2=1:1$. In $Ni-Co/CeZrO_2$ series 2 wt.% Ce loading catalyst shows most promising catalyst for $CH_4$ selectivity than $CO_2$, which directs more stability with less coke formation. The high activity is attributed to the better bimetallic synergy and the well-developed crystalline phases of NiO, $ZrO_2$ and $Ce-ZrO_2$. Other bimetallic mixed oxides NCoZ, $NCoC^{4-12}Z$ has faster deactivation with low methanation activity. Finally, 2 wt.% Ce loading catalyst was found to be optimal coke resistant catalyst.

• Korean Journal of Pharmacognosy
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• v.1 no.3
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• pp.93-99
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• 1970

There have been reported by several workers for the isolation and determination of the amine derivatives as Metbylephedrine Hydrochloride and Ephedrine Hydrochloride adopting neutralization method, steam distillation method, non-aqous titration method, ion-exchange resin method, titration method after acetylation, colorimetric method, gravimetric method, iodine titration method and gas chromatography. Those methods mentioned in above, can be practically applied for the sample which is not mixed one mith the other amine compounds. Presently, it has not shown on the isolative determination of the mixed sample of amine derivatives. In this paper, it is discussed on the isolative determination of Methylephedrine Hydrochloride as the tertiary amine compound and Ephedrine Hydrochloride as the secondary amine compound. According to the results of the experiment, it could be summarized as follows: 1. There is no time-variation on the color reaction of Methylephedrine Hydrochloride and Ephedrine Hydrochloride with the color reagent, bromcresolgreen. And Methylephedrine Hydrochloride and Ephedrine Hydrochloride, respectively, can be determined spectrophotometrically by means oft his color reaction. 2. For the isolation of Methylephedrine Hydrochloride and Ephedrine Hydrochloride from the mixed sample, Methylephedrine Hydrochloride can be eluted by chloroform, while Ephedrine Hydrochloride by the mixed solvent of chloroform and ethylalcohol (2:1), from the celite column adsorbed at pH6.4 followed by extraction with ether undersodium hydroxide alkali re action. 3. When the sample is mixed with quinine hydrochloride, dihydrocodeine bitartate, and noscapine, these mixed compounds can be eliminated by means of stram distillation. 4. When the sample is mixed with chlorpheniramine maleate, dextromethorphan hydrobromide and diphenhydramine hydrochloride, the mixed compounds can be eliminated by means of steam distillation and celite adsorption column chromatography, In conclusion, the isolative determination method for Methylephedrine Hydrochloride and Ephedrine Hydrochloride studied in this paper, indicates with the excellent reproducibility and accuracy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.8
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• pp.337-342
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• 2016

A marine SCR System is emerging as an alternative to comply with NOx Tier III Emission standards, a restriction on greenhouse gas from vessels implemented by the International Maritime Organization. The system is greatly affected by the uniformity of the fluid flowing into the catalyst, so the performance of the catalyst of an SCR system needs to be guaranteed. This study conducted research on a mixed evaporator of an SCR system, which is one of the factors affecting the uniformity of the fluid. When the angle of the mixed evaporator is set to $90^{\circ}$, the fluid uniformity is at its highest at 83%, under the condition that the length of the mixed evaporator be 3.5 D. When the length was 3.5 D and less, the fluid uniformity had a tendency to improve relative to the case without a bent pipe. However, a longer mixed evaporator results in a more perfect liquidity development in the pipe with a liquidity distribution similar to the case where no curved pipe is formed in front of the catalyst. A lower angle for the mixed evaporator results in a lower flow uniformity, and a longer length of the mixed evaporator results in a lower difference in the flow uniformity caused by the angle. The flow uniformity can be improved by 6% with a mixed evaporator, which confirmed that all factors applied to an SCR system have a close relationship with the efficiency.

• Journal of Powder Materials
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• v.16 no.5
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• pp.316-325
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• 2009

Fe based (Fe$_{68.2}$C$_{5.9}$Si$_{3.5}$B$_{6.7}$P$_{9.6}$Cr$_{2.1}$Mo$_{2.0}$Al$_{2.0}$) amorphous powder, which is a composition of iron blast cast slag, were produced by a gas atomization process, and sequently mixed with ductile Cu powder by a mechanical ball milling process. The experiment results show that the as-prepared Fe amorphous powders less than 90 $\mu$m in size has a fully amorphous phase and its weight fraction was about 73.7%. The as-atomized amorphous Fe powders had a complete spherical shape with very clean surface. Differential scanning calorimetric results of the as-atomized Fe powders less than 90 $\mu$m showed that the glass transition, T$_g$, onset crystallization, T$_x$, and super-cooled liquid range $\Delta$T=T$_x$-T$_g$ were 512, 548 and 36$^{\circ}C$, respectively. Fe amorphous powders were mixed and deformed well with 10 wt.% Cu by using AGO-2 high energy ball mill under 500 rpm.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.3
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• pp.105-112
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• 2013

The microstructural changes of Fe-20Mn-12Cr-1Cu alloy have been studied during high temperature gas nitriding (HTGN) at the range of $1000^{\circ}C{\sim}1150^{\circ}C$ in an atmosphere of nitrogen gas. The mixed microstructure of austenite and ${\varepsilon}$-martensite of as-received alloy was changed to austenite single phase after HTGN treatment at the nitrogen-permeated surface layer, however the interior region that was not affected nitrogen permeation remained the structure of austenite and ${\varepsilon}$-martensite. With raising the HTGN treatment temperature, the concentration and permeation depth of nitrogen, which is known as the austenite stabilizing element, were increased. Accordingly, the depth of austenite single phase region was increased. The outmost surface of HTGN treated alloy at $1000^{\circ}C$ appeared Cr nitride. And this was in good agreement with the thermodynamically calculated phase diagram. The grain growth was delayed after HTGN treatment temperature ranges of $1000^{\circ}C{\sim}1100^{\circ}C$ due to the grain boundary precipitates. For the HTGN treatment temperature of $1150^{\circ}C$, the fine grain region was shown at the near surface due to the grain boundary precipitates, however, owing to the depletion of grain boundary precipitates, coarse grain was appeared at the depth far from the surface. This depletion may come from the strong affinity between nitrogen and substitutional element of Al and Ti leading the diffusion of these elements from interior to surface. Because of the nitrogen dissolution at the nitrogen-permeated surface layer by HTGN treatment, the surface hardness was increased above 150 Hv compared to the interior region that was consisted with the mixed microstructure of austenite and ${\varepsilon}$-martensite.

• Journal of Chest Surgery
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• v.33 no.2
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• pp.125-131
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• 2000

Background: Hyperinflation during lung ischemia has been known to improve pulmonary functions after reperfusion which may be exerted through a pulmonary vasodilation and avoidance of atelectasis by an increased surfactant release and been known whether the improvement of pulmonary function was the effect of hyperinflation itself or the oxygen content in inflation gas. Therefore we attempted to clarify the effect of hyperinflation with oxygen in pulmonary inflation gas during warm ischemia on pulmonary function after reperfusion to solve the problem of ischemia-reperfusion injury after lung transplantation. Material and Method: sixteen mongrel dogs were randomly divided into two groups: the left lung was inflated to 30-35 cm H2O with 100% oxygen in oxygen group and 100% nitrogen in nitrogen group. The inflated left lung was maintained with warm ischemia for 100 minutes. Arterial and mixed venous blood gas analysis and hemodynamics were measured before ischemia and 30, 60, 120, 180 and 240 minutes afer reperfusion. Lung biopsy was taken for the measurement of lung water content after the end of reperfusion. Result: In oxygen group arterial oxygen tension the difference of arterial and mixed venous oxygen tension and the difference of alveolar-arterial oxygen tension at 30-minute after reperfusion were not significantly different from those before ischemia and were stable during the 40hour reperfusion. However in nitrogen group these values were significantly deteriorated at 30-minute after reperfusion. there was no significant difference between two groups in hemodynamic data peak airway pressure and lung water content. Conclusion : The results indicated that the oxygenation one of the most important pulmonary functions was improved by pulmonary inflation with 100% oxygen during warm ischemia but the hemodynamics were not. Oxygen as a metabolic substrate during warm ischenia was believed to make the pulmonary tissues to maintain aerobic metabolism and to prevent ischemic damage of alveoli and pulmonary capillary.

• Membrane Journal
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• v.29 no.1
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• pp.1-10
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• 2019

Poly(ether block amide) (PEBA) is one of the commercially important class of block copolymer very much suitable specifically for $CO_2$ separation. Gas separation membrane need to have good mechanical strength as well as high gas permeability. The crystalline polyamide (PA) block provides the mechanical strength while the rubbery polyether (PE) group being $CO_2$-philic facilitate $CO_2$ permeation though the membrane. Composition of thermoplastic and rubbery phase in the polymer are changed to fit into suitable gas separation application. Although PEBA has good permeability, the selectivity of the membrane can be enhanced by incorporating molecular sieve without affection much the gas permeability. Mixed matrix membrane (MMM), a class of composite membrane combine the advantage of polymer matrix with the inorganic fillers. However, there are some disadvantages based on the compatibility of the inorganic fillers and polymeric phase. This review covers both the advantage and limitations of PEBA block copolymer based composite membrane.

• Explosives and Blasting
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• v.38 no.4
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• pp.1-15
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• 2020

With the increase of the utilization of underground space in Korea, explosion accidents at the underground facilities such as gas pipes have occurred frequently. In urban area with high population density, individual explosion accidents are likely to spread into large complex accidents. It is necessary to investigate the effect of explosion on the stability of underground structures in urban area. In this study, a sensitivity analysis was carried out to investigate the possible influence of nearby explosion on the stability of underground structure with 8 parameters including explosion conditions and rock properties. From the sensitivity analysis using AUTODYN, the main and interaction effects of each parameters could be determined. From the analysis, it was found that the distance between explosion point and tunnel, charge weight, and Young's modulus are the most important parameters on the stress components around a tunnel.

• Korean Journal of Organic Agriculture
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• v.23 no.2
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• pp.373-390
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• 2015

This study investigated the effect of coated feed using mixed oil on rumen fermentation characteristics. Two experiments were conducted based on materials that were mixed. First, cashew nut and soybean oils were mixed with white mineral oil. And second, different plant extracts were mixed with white mineral oil. At first experiment, inclusion levels of mixed oil on diet (0.03%, 0.1%, 0.5%) were applied as variables. A coated diet was fermented with rumen inoculum according to in vitro rumen fermentation and its parameters were investigated. In the result of first experiment, no negative effects on rumen pH were found. Significantly decreased dry matter digestibility was detected at 0.5% treatment (P<0.05). Total gas productions in control and 0.03% were significantly greater than those of others (P<0.05). Significantly reduced methane productions were found in all treatments compared to the control (P<0.05). Inclusion of mixed oil did not affect on ammonia production. Total volatile fatty acid production was also not influenced by coating with mixed oils. Rumen fermentation parameters were greatly changed according to introduced plant extracts at second experiment. The significantly lowest and greatest ammonia productions were found at treatments with Ixeris dentata and Plantago asiatica, respectively (P<0.05). The significantly greatest acetate and propionate productions were detected at treatments with Crucuma longa and Zizyphus vulgaris 1, respectively (P<0.05). All treatments, except Chrysanthemum idicum, Euyale ferox seed, Moringa leaf and fruit and Zizyphus vulgaris 1, showed significantly increased total volatile fatty acid production compared to the control (P<0.05). Only Paeonia lactiflora showed significantly lesser gas production than the control (P<0.05). In methane production, Ceramium, Zizyphus, Paeonia, Agrimonia, Torilis, Mugwort, Foeniculum, Euphorbia, Taraxacum, Artemisia, Momordica, Curcuma and Moringa reduced methane significantly compared to the control (P<0.05).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.154-159
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• 2018

Intentional releases occur frequently during maintenance in gas supplying companies, which may result in unpleasant odors, and the possible mistaken belief of a gas accident. Therefore, this study developed a chemical process for effective odorant removal in natural gas using an active chemical that is released intentionally during maintenance and inspection. To develop an effective treatment process for removing the odorant from released natural gas, the effluent concentrations of the odorant in the released gas were measured after a chemical oxidation reaction with a sodium hypochlorite solution in a compact gas scrubbing equipment newly devised in this study. The device was based on a mixed gas vent after the solution inject odorant in the gas through the energy of the venting gas. The cascade combination of a venturi pipe and mixing chamber was developed to remove the odorant effectively from the purposely-released natural gas using an oxidative reaction between the mercaptan compounds (odorant) and the sodium hypochlorite solution. On the other hand, the developed method could be applied limitedly to a relatively small gas release from a low-pressure source. Further studies will be needed to apply the developed process to a large-scale gas release from a high-pressure source.