• 한국분말재료학회지
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• 제12권3호
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• pp.201-207
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• 2005

Nickel powders were synthesized by the hydrazine reduction of nickel chloride solution containing ammonia in DEA solutions. The size distribution of nickel powders were investigated as a function of ammonia concentration, hydrazine concentration and the mixed composition ratio of diethanolammine (DEA) and triethanolammine (TEA). Nickel powders with the size in submicron range were obtained at $185^{\circ}C$ for 45 minutes by hydrazine reduction of nickel chloride solution in DEA solutions. The hydrazine concentrations showed significant effects on the particle size and shape distribution of nickel powders under $NH_3/Ni^{2+}$ molar ratio of 2.0 condition. As the mixed volume ratio of TEA and DEA increased, nickel powders with relatively larger particle size and low agglomeration were obtained. Nickel powders with particle size in the ranged from 0.4 to $0.9\;{\mu}m$ were obtained at the 50 $vol.%$ of TEA.

• KSBB Journal
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• 제14권3호
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• pp.358-364
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• 1999

참나무의 전처리에 과산화수소가 미치는 영향을 조사하였다. 반응온도는 $170^{\circ}C$이고 전처리에 사용된 반응용액은 암모니아, 황산 그리고 순수 물이었다.10% 암모니아용액을 사용한 경우 산을 사용하는 경우에 비해 리그닌 제거율은 55%로 상당히 높았지만 헤미셀룰로오스 회수율은 26%로 상당히 낮았다. 그래서 헤미셀룰로오스 회수율을 높이기 위해 암모니아 용액에 산화제인 과산화수소를 첨가하여 반응시켰는데 과산화수소 첨가량의 증가에 따라 리그닌 제거율과 헤미셀룰로오스 회수율의 증가는 크지 않았다. 그리고 과산화수소 첨가량의 증가에 따라 액상으로 용해된 당의 분해가 증가하여 전체 헤미셀룰로오스와 셀룰로오스의 물질수지에 문제가 있었다. 반응기에 주입된 과산화수소는 주로 반응기의 전반부에 충진된 기질과 반응하는 것으로 나타났다. 헤미셀룰로오스 회수율을 높이기 위해서는 알카리용액보다 산성용액에서 기질을 전처리하는 것이 필요하였고 산보다는 물을 사용하였을 때 과산화수소의 효과가 더 컸다.

• 한국재료학회지
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• 제12권1호
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• pp.36-43
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• 2002

In this study, the nanosized ZnS thin films that can be used for fabrication of blue light-emitting diodes, electro-optic modulators, and n-window layers of solar cells were grown by the solution growth technique (SGT), and their surface morphology and film thickness and grain size dependence on the growth conditions were examined. Based on these results, the quantum size effects of ZnS were systematically investigated. Governing factors related to the growth condition were the concentration of precursor solution, growth temperature, concentration of aq. ammonia, and growth duration. X-ray diffraction patterns showed that the ZnS thin film obtained in this study had the cubic structure ($\beta$-ZnS). With decreasing growth temperature and decreasing concentration of precursor solution, the surface morphology of film was found to be improved. Also, the film thickness depends largely on the ammonia concentration. In particular, this is the first time that the surface morphology dependence of ZnS film grown by SGT on the ammonia concentration is reported. The energy band gaps of samples were determined from the optical transmittance values, and were shown to vary from 3.69 eV to 3.91 eV. These values were substantially higher than 3.65 eV of bulk ZnS. It was also shown that the quantum size effect of SGT grown ZnS is larger than that of the ZnS films grown by most other growth techniques.

• 공업화학
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• 제27권3호
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• pp.265-269
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• 2016

수소가 청정 에너지 원으로서의 중요성이 증가하면서 수소의 생산원인 암모니아 기체가 큰 주목을 받고 있다. 그러나 암모니아가 금속을 잘 부식시키고 유독성을 가지고 있기 때문에 암모니아의 저장과 운반을 가능하게 하는 흡착제의 연구가 다각도로 진행되고 있다. 이 중 공유결합 유기구조 물질(covalent organic framework)의 하나인 COF-10은 붕소를 포함한 큰 기공을 가진 물질이다. 암모니아 흡착과정에서 COF-10의 구조 안에 있는 붕소는 루이스 산으로 작용하여 암모니아와 강한 결합을 한다. 본 논문에서는 이러한 COF-10을 합성하여 BET, XRD, FT-IR을 통해 구조를 확인한다. 또한 TPD와 등온 흡착 실험을 통해 실제 암모니아의 흡착능력에 대한 분석을 진행하였다. COF-10는 9.79 mmol/g으로 우수한 암모니아 흡착 능력을 보였으며 암모니아 흡착제로서 활용 가능할 것으로 사료된다.

• 대한환경공학회지
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• 제22권4호
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• pp.651-659
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• 2000

천연중화제의 스크러버 타입의 탈취장치에 의한 암모니아 제거반응 특성 및 중화반응에의 산화반응의 관여여부에 대하여 연구하였다. 중화제 희석비 및 유입유량, 공기유량, 암모니아 초기 농도를 운전인자로 선정하여 이들이 암모니아 제거효율에 미치는 영향을 살펴본 결과, 중화제 희석비는 1.0%, 중화제 유입유량은 $60m{\ell}/min$이 적절하고, 암모니아 초기농도 및 공기유량에 대해서는 loading rate를 함께 고려하면 제거효율에 큰 영향성은 나타내지 않았다. 암모니아의 중화반응에 산화반응의 관여여부를 살펴본 결과, 암모니아의 아질산염 및 질산염으로의 산화반응이 확인되었으며, 중화제량이 증가할수록 그 산화반응의 진행정도도 증가함을 확인하였다. 즉, 중화제에 의한 흡수현상과 함께 부분적으로 산화반응이 관여함을 확인하였다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권5호
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• pp.316-322
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• 2002

A newly isolated heterotrophic marine bacterium, Vibrio alginolyticus, was used to remove a high load of ammonia gas under non-sterile condition. The cells were inoculated onto an inorganic packing material in a fixed-bed reactor (biofilter), and a high load of ammonia, in the range of ammonia gas concentration of 170 ppm to 880 ppm, was introduced continuously. Sucrose solution and 3% NaCl was supplied intermittently to supplement the carbon source and water to the biofilter. The average percentage of gas removed exceeded 85% for 107-day operation. The maximum removal capacity and the complete removal capacity were$19\;g-N\;kg^{-1}$ dry packing material $day^{-1}$ and $16\;g-N\;kg^{-1}$ dry packing material $day^{-1}$, respectively, which were about three times greater than those obtained in nitrifying sludge inoculated onto the same packing material. On day 82, the enhanced pressure drop was restored to the normal one by NaOH treatment, and efficient removal characteristics were later observed. During this operation, the non-sterile condition had no significantly adverse effect on the removability of ammonia by V. alginolyticus.

• 한국식품영양과학회지
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• 제18권1호
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• pp.115-122
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• 1989

간장저장중 암모니아와 pH가 Aflatoxin $B_1(AFB_1)$의 파괴에 미치는 영향을 검토하였다. $0.05{\sim}0.5%$의 암모니아 용액에서 $AFB_1$은 $30^{\circ}C$의 저장 하루만에 완전히 파괴되었으나 이때 이 용액들은 pH가 10-11정도로 증가 되었다. $NH_3$의 농도에 따라 간장의 pH는 증가 하였지만 간장내의 완충능 때문에 다소 완만하였다. 이때 양조간장은 재래간장에서 보다 그 pH증가 정도가 더 크게 일어났다. 간장시료들과 대조군의 증류수와 20% NaCl용액의 pH를 10으로 증가 시켰을 때 $AFB_1$은 $30^{\circ}C$에서 1일 반응 후 완전히 파괴되었다. pH 5, 7, 9, 10, 11의 완충용액에서 $AFB_1$의 파괴 효과는 pH 5와 7에서는 안정하였지만 pH 9 이상에서는 첨가한 $AFB_1$을 검출할 수 없었다. 여러농도의 $NH_3(0.2-1.0%)$를 함유한 pH 7의 완충용액 에서 $AFB_1$은 $NH_3$의 농도와는 관계없이 저장기간중 안정하였으나 pH 9에서는 파괴(100%)되었다. pH 5의 간장을 $30^{\circ}C$에서 5일간 반응시켰을 때 $AFB_1$은 상당히 안정하였지만 pH 7의 간장 시료에서는 60-70%의 $AFB_1$의 파괴가 일어났으며 이때 간장의 pH는 전혀 변화가 없었다. 그러나 $AFB_1$은 pH 7의 완충용액과 0.2% $NH_3$를 함유한 완충용액에서는 5일의 저장기간중 안정하였다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 2000년도 Proceedings of 2000 International Nano Crystals/Ceramics Forum and International Symposium on Intermaterials
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• pp.143-150
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• 2000

Wet-chemical process using ammonia to precipitate aluminum ion dissolved in a zirconia sol solution is examined. Formation of crystalline bayerite is unfavorable for fine dispersion of zirconia nanoparticles in alumina matrix after heat treatment. To avoid the bayerite formation, it was preferred to make a precipitation with a diluted ammonia or with an ammonia gas flow at high temperature. By optimizing the precipitation process and the calcination temperature, we successfully prepared the uniform microstructure in which tetragonal zirconia particles of ∼30nm is finely dispersed within the alumina grains.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 2002년도 학술대회지
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• pp.486-490
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• 2002

In different approaches ginsenosides were extracted from Korean ginseng roots by ammonia and for comparison with methanol-water and water. The extracts have been analyzed qualitatively and quantitatively to evaluate yield and selectivity of extractions of ginsenosides. Water supplied the lowest yield. The yields of extracts with liquid ammonia were higher than those with methanol-water. However, this is partly due to the conversion of malonyl ginsenoside to normal ginsenosides by ammonia. It was proved by HPLC that malonyl-ginsenosides $m-Rb_1,\;m-Rb_2,$ m-Rc and m-Rd were converted to the corresponding neutral ginsenosides. Furthermore, ginsenosides from ginseng roots were extracted by alkaline methanol-water $(60\%)$ solutions. Alternatively, the extracts of the methanol-water $(60\%)$ extraction were treated with sodium hydroxide solution. Both methods also convert the malonyl-ginsenosides to neutral ginsenosides.

• 한국분말재료학회지
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• 제15권2호
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• pp.148-155
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• 2008

Nano magnetite particles have been prepared by two step reaction consisting of urea hydrolysis and ammonia addition at certain ranges of pH. Three different concentrations of aqueous solution of ferric ($Fe^{3+}$) and ferrous ($Fe^{2+}$) chloride (0.3 M-0.6 M, and 0.9 M) were mixed with 4 M urea solution and heated to induce the urea hydrolysis. Upon reaching at a certain pre-determined pH (around 4.7), 1 M ammonia solution were poured into the heated reaction vessels. In order to understand the relationship between the concentration of the starting solution and the final size of magnetite, in-situ pH measurements and quenching experiments were simultaneous conducted. The changes in the concentration of starting solution resulted in the difference of the threshold time for pH uprise, from I hour to 3 hours, during which the akaganeite (${\beta}$-FeOOH) particles nucleated and grew. Through the quenching experiment, it was confirmed that controlling the size of ${\beta}$-FeOOH and the attaining a proper driving force for the reaction of ${\beta}$-FeOOH and $Fe^{2+}$ ion to give $Fe_3O_4$ are important process variables for the synthesis of uniform magnetite nanoparticles.