• Bulletin of the Korean Chemical Society
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• 제2권3호
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• pp.90-96
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• 1981

The significant structure theory of liquids has been successfully applied to the sodium ammonia solution. In applying the theory to sodium ammonia solution, we assumed there were four species in solution, i.e., sodium cation, solvated electron, triple ion, and free electron and equilibria existed between them. Based on these assumptions, we set up the model explaining the anomalous properties of sodium ammonia solution. The partition function for sodium ammonia solution is composed of the partition functions for the above four species and also for the Debye-Huckel excess free energy term. Agreements between calculated and experimental values of the thermodynamic quantities, such as molar volume, vapor pressure, partial molar enthalpy and entropy, and chemical potential as well as viscosity are quite satisfactory.

• 한국가시화정보학회지
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• 제20권2호
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• pp.38-44
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• 2022

Due to increasingly strict emission regulations for carbon-based fuels in the shipping industry, there is a significant motivation to investigate the alternative fuel. Ammonia is one of the attractive alternative fuels as a carbon-free fuel. Since ammonia has different properties such as high vapor pressure and low boiling point compared to conventional fuels, further research into ammonia spray behavior is important. In this work, the spray characteristics of ammonia and other fluids (ethanol, n-decane) were compared by using numerical simulation. The results show that the spray characteristics of ammonia differs from those of the others due to the occurrence of flash boiling. The narrow-dispersed spray with accelerated velocity at the center have been observed for ammonia. It is also found that droplets of ammonia achieve smaller diameter with more uniform distribution, leading to better atomization behavior compared to the others.

• 미생물학회지
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• 제26권3호
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• pp.270-277
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• 1988

Microorganisms isolated from soil (150 strains), fungi (39 strains), yeasts (9 strains) and Streptomyces species (39 strains) were assayed for L-phenylalanine ammonia-lyase(PAL) activity. 17 strains of fungi and 46 strains of soil isolates were proved to produce PAL, Aspergillus panamensis, Penicillium varioti and 11 soil isolates showed comparatively large PAL activity. When PAL activity was assayed with cell-free extracts of these 13 strains and 7 strains of Rhodotorula and Rhodosporidium geni, Rhodosporidium toruloides (IFO 0559) showed the highest PAL activity with 0.333 units per g of the wet cell weight.

• 대한환경공학회지
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• 제22권5호
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• pp.981-987
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• 2000

축산분뇨에 대한 처리도 및 암모니아에 대한 독성을 평가하기 위하여 UASB 반응조를 운전하였다. 반응조의 운전결과 유기부하량 $2.6kg\;COD/m^3.day$과 수리학적 체류시간 3일에서 70%의 COD 제거효율을 얻을 수 있었으나, 유기부하량과 수리학적 체류시간을 각각 $7kg\;COD/m^3.day$과 2일로 유지한 경우 COD 제거율이 급격히 감소되었다. 반응조 슬러지의 유리암모니아에 대한 독성을 평가하기 위하여 수행된 회분식 실험 결과, 각 단계별 슬러지의 메탄균 활성은 0.5, 0.47 및 $0.3kgCH_4-COD/kgVSS.day$로 반응조내 유리암모니아 농도가 $500mg-N/{\ell}$에서는 메탄균의 활성이 4%, 유리암모니아 농도가 $1000mg-N/{\ell}$에서는 메탄균의 활성이 40% 감소되었다. 이러한 결과로부터 유리암모니아 농도가 $500mg-N/{\ell}$ 이하에서는 반응조 미생물에 미치는 저해정도가 작은 것으로 판단된다. 한편 $1000mgVSS/{\ell}$ 이내의 휘발성 고형물질을 포함하는 폐수는 혐기성균에 의해 쉽게 분해되므로 UASB 반응조를 안정적으로 운영할 수 있다.

• Journal of Plant Biology
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• 제27권4호
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• pp.253-261
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• 1984

Leaf discs isolated from the pea seedling grown in nutrient solution containing 5mM ammonia or nitrate exhibited a half level of photorespiration as compared with the nitrogen free control. The manifestation of the ammonia effect appeared somewhat earlier than that of nitrate effect, but this difference subsided as the culture periods was extended. The total amount of ${CO}_2$ fixed by leaves from nitrogen-supplemented seedlings showed approximately 1.5 fold increase over the control with the ammonia effect being manifested earlier than the nitrate effect. The activities of peroxisomal serine: glyoxylate aminotransferase were always higher with ammonia than nitrate, the two types of nitrogen source, however, had similar effect on conversion rate of glyoxylate into glycine. These results indicate that exogenous ammonia does not act directly as an effector of this aminotransferase in vivo. But changes in the level of the pool size of glycine and serine, both of which are the intermediates of photorespiratory process, suggest that exogenous ammonia inhibit the transformation of serine from glycine metabolically.

• Corrosion Science and Technology
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• 제21권6호
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• pp.514-524
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• 2022

Carbon emissions from fuel consumption have been pointed by scientists as the cause of global warming. In particular, fossil fuels are known to emit more carbon when burned than other types of fuels. In this regard, International Maritime Organization has announced a regulation plan to reduce carbon dioxide emissions. Therefore, recently, Liquefied Natural Gas propulsion ships are responding to such carbon reduction regulation. However, from a long-term perspective, it is necessary to use carbon-free fuels such as hydrogen and ammonia. Nitrogen oxides might be generated during ammonia combustion. There is a possibility that incompletely burned ammonia is discharged. Therefore, rather than being used as a direct fuel, Ammonia is only used to reduce NO_X such as urea solution in diesel vehicle Selective Catalyst Reduction. Currently, LPG vehicle fuel feed system studies have evaluated the durability of combustion injectors and fuel tanks in ammonia environment. However, few studies have been conducted to apply ammonia as a ship fuel. Therefore, this study aims to evaluate corrosion damage that might occur when ammonia is used as a propulsion fuel on ships.

• 멤브레인
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• 제28권5호
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• pp.297-306
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• 2018

본 총설은 분리막기술이 적용된 수소생산에 대한 개론으로, 특히, 암모니아를 수소운반체로 이용하는 수소생산에 대한 연구결과를 중점적으로 서술하였다. 암모니아를 수소운반체로 적용한 수소생산은 추가적인 탄소생성이 없다는 점 외에 여러 측면에 있어 이점이 있다. 많은 연구들이 고순도 수소 분리 및 생산을 위한 분리막 개발을 위해 진행되고 있으며, 이들 중 팔라듐을 기본으로 한 분리막(예를 들어, 다공성 세라믹 또는 다공성 금속 지지체와 팔라듐 합금의 얇은 선택층으로 이루어진 분리막)에 대한 연구가 활발하다. 반면에, 효율적인 암모니아 분해를 위해서는 주로 루테늄 촉매가 적용되고 있으며, 루테늄과 지지체 및 촉진제로 이루어진 루테늄에 기반을 둔 촉매에 대한 연구발표가 다수 존재한다. 수소생산을 위한 분리막 반응기 형태로는 충전층, 유동층, 그리고 마이크로반응기 등이 있으며, 이들의 최적화 및 원활한 물질전달 연구는 현재진행형이다. 또한, 높은 암모니아 분해율, 고순도 수소생산 및 높은 수소생산율을 얻기 위해 분리막과 촉매의 다양한 조합에 대한 연구 및 분리막과 촉매의 역할을 동시에 구현할 수 있는 분리막에 대한 연구가 발표되고 있다.

• 청정기술
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• 제21권1호
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• pp.45-52
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• 2015

본 연구에서는 양식 폐수 중 암모니아를 제거하는 전기분해 공정에 극전환을 도입하여 전극 표면에 불용성 금속화합물이 형성되는 오염 현상을 방지하고자 하였다. 한편 극전환으로 인한 전류 손실이 유리염소 이온의 생성에 미치는 영향을 파악함으로서 최적의 극전환 주기를 찾고자 하였다. 먼저 극전환 주기가 짧아지면서 전류손실로 인해 유리염소 이온의 형성 효율이 떨어지는 것을 확인하였으며 이는 암모니아 제거 효율이 감소함을 의미한다. 이에 극전환 주기에 따른 폐수 중의 칼슘과 마그네슘의 농도를 측정해 본 결과 극전환 주기를 60초 이하로 유지하면 극전환에 의한 불용성 금속화합물의 분해를 통해 전극 표면의 오염 현상을 충분한 수준에서 방지할 수 있음을 확인하였다. 따라서 높은 유리염소 이온의 생성효율 유지와 전극 오염 방지라는 두 가지 운전목적 사이에서 최적의 극전환 주기는 60초이었다.

• Journal of Microbiology and Biotechnology
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• 제4권3호
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• pp.191-194
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• 1994

Acetoin and ammonia, the precursors of tetramethylpyrazine (TMP) having "nutty " or "roasted" flavors, were produced by cultivating Lactococcus lactis ssp. lactis biovar. diacetilactis FC1. The effects of the volume concentration ratio (VCR) of cell-free medium on the formation of TMP were investigated using a rotary evaporator at $70^{\circ}C than at 80^{\circ}C$. As the VCR increased, the formation of TMP and the conversion ratio of acetoin to TMP increased. More TMP were formed at $70^{\circ}C than at 80^{\circ}C$. As the VCR increased, the concentration of acetoin decreased implying the formation of TMP from acetoin and ammonia.

• Bulletin of the Korean Chemical Society
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• 제15권5호
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• pp.387-390
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• 1994

The conversion of trans-cinnamic acid to phenylalanine using phenylalanine ammonia lyase (PAL) was examined. The optimum concentration of trans-cinnamic acid for the reaction was observed at 100 mM in cells and at 20 mM in cell free extracts, respectively. The production of L-phenylalanine was increased in both experiments as the concentration of ammonia was increased up to 10 M. The optimal pHs for the maximal conversion of trans-cinnamic acid to L-phenylalanine were 9.5 and 9.0 in experiments carried out with cells and with cell free extracts, respectively.