• Progress in Superconductivity and Cryogenics
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• v.10 no.4
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• pp.38-42
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• 2008

Miniature J-T cryocooler using nitrogen or argon has been widely adopted in cooling infrared sensor for space/military application and cryosurgery. Argon or nitrogen, however, has relatively low specific cooling power compared to nitrous oxide, but the ultimate operating temperature is much lower than nitrous oxide. On the other hand, nitrous oxide has large specific cooling power, but the operating temperature is limited to its boiling point (>183K). To compromise the different characteristics of these gases, the performance of miniature J-T cryocooler using argon and nitrous oxide mixture is investigated in this paper. Three different compositions of mixture (25/75, 50/50, and 75/25 molar fraction) are blended and tested. The results are compared with the experiments of pure argon and pure nitrous oxide. The experimental results show some encouraging potentiality of mixed refrigerant J-T cryocooler. The critical clogging problem, however, was observed with argon and nitrous oxide mixture, and the lowest achievable temperature with this mixture was limited to the freezing point of nitrous oxide. The paper discusses detailed clogging process of the mixture and suggests an alternative.

• Journal of the Korean Society of Safety
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• v.28 no.2
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• pp.42-48
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• 2013

The $CO_2$ suppression characteristics and flame structure of nitrogen-diluted methane counterflow non-premixed flame were studied experimentally and numerically. To mimic a situation where combustion product gases are entrained into a compartment fire, fuel stream was diluted with $N_2$. A gas-phase suppression agent, $CO_2$, was diluted in the air-stream to investigate the suppression characteristics by the agent. For numerical simulation, an one-dimensional OPPDIF code was used for comparison with experimental results. An optically-thin radiation model(OTM) was adopted to consider radiation effects on the suppression characteristics. It was confirmed experimentally and numerically that suppression limit decreased with increasing nitrogen mole fraction in the fuel stream. A turning point was found only when a radiation heat loss was considered and the extinguishing concentration for turning point was differently predicted compared to the experiment result. Critical extinguishing concentration when neglecting radiation heat loss was also differently predicted compared with the experimental result.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.2
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• pp.147-156
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• 2000

In this study, the optimal operation parameters of MLE(Modified Ludzack-Ettinger) process treating the liquid supernatant separated from the slurry excreta of swine feedlot was studied as a promising biological treatment process. The nitrogen removal characteristics with different volume ratio between nitrification and denitrification reactor and the operational effect with different nitrogen loading rate, and different C/N($COD_{Cr}/TKN$) ratio were investigated. Based on the laboratory results, pilot MLE plant was operated to examine the effect of ambient temperature for five months including winter. The denitrification reactor which is 20% of total volume was proposed as the most optimal volume fraction for nitrification and denitrification. The optimum ratios of F/M and $F_N/M$ were increased with increase of the C/N ratio. However, optimum F/M ratio was changed more rapidly than $F_N/M$ ratio with increase of the C/N ratio. Therefore, MLE process is desirable to be controlled by F/M ratio in the range of high C/N ratio and by $F_N/M$ ratio in the range of low C/N ratio. Pilot MLE plant showed the higher removal efficiencies of COD and TKN in winter than in summer and was operated most stably at the temperature of $20{\sim}25^{\circ}C$ for mixed liqour.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.61-62
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• 2012

The present study has numerically investigated the effects of fuel-side dilution and pressure on flame structure and extinction scalar dissipation rate of turbulent syngas nonpremixedd flames. Numerical results indicate that for highly diluted case, peak temperature is decreased and stoichiometric mixture fraction is increased. By decreasing the pressure and the nitrgen dilution levelcreased, the extinction scalar dissipation rate is increased.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.374.1-374.1
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• 2002

The barks o.f Pinus densiflara representative Pinus species graws in Korea, have been used for oriental traditional medicine as the remedies for rheumatitis. hemorrhage and cancer. Water soluble fraction of 80% acetone extracts from the barks af Pinus densiflera (PDB) showed nitrogen monoxide(NO) production inhibitory activity in IFN-${\gamma}$. LPS stimulated RAW 264.7 cell. (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.385.1-385.1
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• 2002

Cordyceps has been used as a tonic for replenishing vital function in Chinese traditional medicines. As an attempt to obtain fundamental data for the kidney function, MeOH Ex. and its hexane. ethyl acetate, butanol and water fractions of cultivated Cordyceps pruinosa on mercuric chloride induced renal failure rats were investigated. Urin volume. blood parameters(urea nitrogen. uric acid. creatinine) and urinary electrolytes content (natrium. potassium. chloride) were determined. MeOH extract and butanol fraction showed diuretic effect. (omitted)

• The Korean Journal of Zoology
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• v.15 no.2
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• pp.92-93
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• 1972

Ox-RBC로부터 Moddy法에 依하여 Ox-RCM抗原을 抽出하여 몇가지 分析을 實施하였다. Lyophilized 한 Ox-RCM protein의 化學的 分析 結果 total protein은 $55\\pm 1.3%$, total nitrogen은 9.2%, carbohydrate 8.5% 그리고 total acid soluble phosphorus는 $0.96\\pm 0.1%$였다. Polyacrylamide gel electrophoresis한 結果 Ox-RCM은 12 $\\sim$ 15個, Pre-VRS fraction은 8個 및 PHR 分劃은 9個의 pattern을 나타냈다. Amino acid의 分析 結果로 cystine이 4.93 $\\sim$ 3.72 moles/100 moles 이고 glycine이 最高로 26.7 $\\sim$ 13.5 moles/100 moles였고 最低로 methionine 이었으나 試料의 抽出方法에 따라 그 値의 變動을 볼 수 있다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.3
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• pp.288-295
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• 1989

This study was conducted to establish the most appropriate nitrogen levels and planting densities which can attribute to increase of aromatic substances in tobacco variety, Hyangcho, maintaining its original aroma. An increase of nitrogen fertilization from 3 to 12 kg per 10a increased total alkaloid content 2.0% to 3.3%, while an increased nitrogen fertilization decreased the contents of total sugar, starch, fatty acid etc., Which seem to be the positive components relating to tobacco aroma the contents of alkaloids were decreased and total fatty acids were increased as the planting densities increased. The higher contents of 2. 3-methylbutanoic and 3-methylpentanoic acid was obtained at the density of 3 plant per pit (12,498 plant/10a). The components determined in the neutural fraction such as solanone, furfural, furfurylalcohol and benzyl alcohol were presented in higher amount at the higher densities. The volatile acids such as 2. 3-methylbutanoic acid 3-methylpentanoic acid decreased and also the contents of butanol, furfutal, furfuryl alcohol, hexanol, cinnamil, acetophenone, benzyl acetate and solanone etc., were decreased as the nitrogen level increased from 3 to 12 kg per l0a.

• The Korean Journal of Ceramics
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• v.4 no.4
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• pp.279-285
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• 1998

The $UO_2$ pellets are usually sintered under hydrogen gas atmosphere. Hydrogen gas may cause unexpected early failure of the refractory bricks in the sintering furnace. In this work, nitrogen was mixed with hydrogen to investigate the effect of nitrogen gas on a failure machanism of the refractory bricks and on the microstructure of the $UO_2$ pellet. The hydrogen-nitrogen mixed gas experiments show that the larger nitrogen the mixed gas contains, the less the refractory materials are reduced by hydrogen. The weight loss measurements at $1400^{\circ}C$ for fire clay and chamotte refractories containing high content of $SiO_2$ indicate that the weight loss rate for the mixed gas is about half of that for the hydrogen gas. Based on the thermochemical analyses, it is proposed that the weight loss is caused by hydrogen-induced reduction of free $SiO_2$ and/or $SiO_2$ bonded to $Al_2O_3$ in the fire clay and chamotte refractories. However, the retardation of the hydrogen-induced $SiO_2$ reduction rate under the mixed gas atmosphere may be due to the reduction of the surface reaction rate between hydrogen gas and refractory materials in proportion to volume fraction of nitrogen gas in the mixed gas. On the other hand, the mixed gas experiments show that the test data for $UO_2$ pellet still meet the related specification values, even if there exists a slight difference in the pellet microstructural parameters between the cases of the mixed gas and the hydrogen gas.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.39-39
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• 2013

We present a study of correlations between the elemental abundances and galaxy morphologies of 91 blue compact galaxies (BCGs) at z=0.20-0.35 with Sloan Digital Sky Survey (SDSS) DR7 data. We classify the morphologies of the galaxies as either 'disturbed' or 'undisturbed', by visual inspection of the SDSS images, and using the Gini coefficient and M20. We derive oxygen and nitrogen abundances using the Te method. We find that a substantial fraction of BCGs with disturbed morphologies, indicative of merger remnants, show relatively high N/O and low O/H abundance ratios. The majority of the disturbed BCGs exhibit higher N/O values at a given O/H value compared to the morphologically undisturbed galaxies, implying more efficient nitrogen enrichment in disturbed BCGs. We detect Wolf-Rayet (WR) features in only a handful of the disturbed BCGs, which appears to contradict the idea that WR stars are responsible for high nitrogen abundance. Combining these results with Galaxy Evolution Explorer (GALEX) GR6 ultraviolet (UV) data, we find that the majority of the disturbed BCGs show systematically lower values of the $H{\alpha}$ to near-UV star formation rate ratio. The equivalent width of the $H{\beta}$ emission line is also systematically lower in the disturbed BCGs. Based on these results, we infer that disturbed BCGs have undergone star formation over relatively longer time scales, resulting in a more continuous enrichment of nitrogen. We suggest that this correlation between morphology and chemical abundances in BCGs is due to a difference in their recent star formation histories.