• 한국산업융합학회 논문집
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• 제25권5호
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• pp.835-842
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• 2022

In this study, the membrane degassing process of the sweep gas - vacuum combination type was proposed for ammonia wastewater treatment. The effect of pH, initial ammonia concentration and scale-up on ammonia degassing performance was investigated. As a result, as the pH and the initial ammonia concentration increased, the degassing permeate flux was improved. On the other hand, the ammonia mass transfer coefficient increased as the initial ammonia reduced, which seems to be due to the driving force of the sweep gas-vacuum combination type membrane degassing system proposed in this study. In addition, 80 mg NH₃/min of the ammonia degassing rate was achieved using a 6×28 inch size module. Better degassing performance is expected if consideration for maintaining vacuum pressure is involved in the scale-up design.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.760-763
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• 2007

The properties of carbon nanotube obtained by thermal chemical vapor deposition (CVD) process were investigated as a function of ammonia $(NH_3)$ gas in hydrocarbon gas, Fe catalyst thickness, and growth temperature. Fe catalyst was prepared by DC magnetron sputter and pre-treated with ammonia gas. CNTs were then grown with ammonia-acetylene gas mixture by thermal CVD. The diameter of these CNTs shows a strong correlation with the gas rate, the catalyst film thickness and temperature. From our results, it was found that the factors of grown CNTs positively acted to improve CNT quality.

• Korean Chemical Engineering Research
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• 제48권2호
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• pp.253-258
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• 2010

암모니아수를 이용한 이산화탄소 흡수분리공정에서 흡수액의 재생조건(온도, 압력)이 이산화탄소 흡수성능에 미치는 영향을 조사하였다. 실험에 사용된 흡수액은 탄산암모늄($(NH_4)_2CO_3$)을 물에 용해시키어 $CO_2$ 로딩($mol\;CO_2/mol\;NH_3$)이 0.5, 용액 내의 암모니아수 농도가 14, 20, 26 및 32 wt%로 되도록 제조하였고, 이산화탄소의 흡수에 앞서 재생압력(6~18 bar)을 조절하면서 $120{\sim}160^{\circ}C$의 온도범위로 제조된 흡수액을 가열하여 재생하였다. 재생된 흡수액을 기포 반응기에 넣고 12 vol%의 $CO_2$를 함유한 기체를 주입하여 흡수반응을 수행하였다. 실험결과 26 wt%의 암모니아수가 대체적으로 $CO_2$ 흡수량이 높았으며, 특히 재생온도가 $150^{\circ}C$, 재생압력이 14 bar일 때의 $CO_2$ 흡수량은 본 연구의 실험조건에서 $45ml\;CO_2/g$ solution으로 가장 높은 값을 보였다. 적정을 통해 재생된 용액을 분석한 결과 재생압력이 높아질수록 암모니아 손실량은 감소하고, 재생온도가 높아질수록 암모니아 손실량이 증가하였다. 또한 암모니아 농도증가에 따라 암모니아 손실량이 비례적으로 증가하였다. Electrolyte NRTL 모델을 사용하여 Aspen Plus에 적용한 결과 실험 데이터와 거의 일치함을 보였다.

• 폴리머
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• 제31권6호
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• pp.479-484
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• 2007

본 연구는 점착제 분사방식으로 고성능 hybrid ion exchange fiber(HIEF)를 제조하고 이들의 암모니아 흡착성능 및 기본물성을 측정하였다. HIEF의 이온교환용량은 수지 부착량이 증가함에 따라 증가하였으며 단일 수지와 이온교환섬유의 이온교환용량보다 크게 나타났다. 또한 암모니아의 제거율은 HIEF의 충전밀도가 증가할수록 증가하였으며 흡착 파과시간은 270분으로 섬유나 수지에 비해 길게 나타났고 최대 암모니아 흡착량은 94%이었다. 또한 암모니아 흡착 파과시간은 유량 및 농도가 증가함에 따라 빠르게 진행되었다. 암모니아 반응속도 상수(k)는 유입되는 가스농도의 증가에 따라 증가하였으며, 질량이 증가할수록 감소하였으며 가스 유속이 증가할수록 반응속도 상수(k)가 증가하였다.

• 한국유기농업학회지
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• 제8권2호
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• pp.89-96
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• 2000

To reduce loss of nitrogen and generation of ammonia gas during composting, poultry manure and sawdust were mixed at the equivalent ratio and calcium chloride, fused superphosphate and vermiculite were added. Ammonia and sulfurous gas during composting, and NH4-N and NO3-N contents of composts were periodically measured. With the treatments of 0.5∼3% calcium chloride and 3% fused superphosphate, ammonia and sulfurous gas during composting significantly decreased, and especially generation of gases sharply reduced and a increase of calcium chlorde. Extractable NH4-N content in composts treasted with calcium chloride and fused superphosphate were high but extractable NO3-N markedly decreased. In conclusion, the results suggest that it is necessary the additon of 1∼3% calcium chloride or 3% fused superphosphate to reduce loss of nirogen and generation of offensive odor during composting of poultry manure mixed with sawdust.

• 한국미생물·생명공학회지
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• 제37권4호
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• pp.408-412
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• 2009

A study on the screening and isolation of microorganism was performed for the removal of main malodor, such as ammonia, produced from the livestock farm. The main malodor components in livestock farm are ammonia, volatile fatty acids, sulfur compounds and trimethylamine. Damages to man and livestock were originated from malodors mainly due to ammonia, and thus ammonia reduction experiments were performed. Sludge of sewage treatment plant was inoculated in the sesame dregs culture, from which ammonia gas was produced. An aerobically grown, pure cultured isolated from the 10th enrichment culture was analyzed by 16S rRNA sequencing and identified as Alcaligenes sp. NS-1. This strain NS-1 precultured in the sesame dregs was found to remove ammonia gas with an efficiency of approximately 99-100% at an average concentration of 40 ppmv of ammonia gas. When the strain NS-1 sprayed to pig excrements, the removal efficiency at an average concentration of 100 ppmv of ammonia was approximately 60% after 16 hr.

• 열처리공학회지
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• 제32권5호
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• pp.201-211
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• 2019

Low carbon steel (S20C steel) and SPCC steel sheet have been austenitic nitrided at $700^{\circ}C$ in a closed pit type furnace by changing the flow rate of ammonia gas and heat treating time. When the flow rate of ammonia gas was low, the concentration of residual ammonia appeared low and the hardness value of transformed surface layer was high. The depth of the surface layer, however, was shallow. With increasing the concentration of residual ammonia by raising up the ammonia gas flow, both the depth of the surface layer and the pore depth increased, while the maximum hardness of the surface layer decreased. By introducing a large amount of ammonia gas in a short time, a deep surface layer with minimal pores on the outermost surface was obtained. In this experiment, while maintaining 10~12% of residual ammonia, the flow rate of inlet ammonia gas, 7 liter/min, was introduced at $700^{\circ}C$ for 1 hour. In this condition, the thickness of the surface layer without pores appeared about $60{\mu}m$ in S20C steel and $30{\mu}m$ in SPCC steel plate. Injecting additional methane gas (carburizing gas) to this condition played a deteriorating effect due to promoting the formation of vertical pores in the surface layer. For $1^{st}$ transformed surface layer for S20C steel, maintaining 10~12% residual ammonia condition via austenitic nitriding process resulted in ${\varepsilon}$ phase with relatively high nitrogen concentration (just below 4.23 wt.%N) among the mixed phases of ${\varepsilon}+{\gamma}$. The ${\varepsilon}$ phase was formed a specific orientation perpendicular to the surface. For $2^{nd}$ transformed layer for S20C steel, ${\gamma}$ phase was rather dominant (just above 2.63 wt.%N). For SPCC steel sheet, there appeared three phases, ${\gamma}$, ${\alpha}(M)$ and weak ${\varepsilon}$ phase. The nitrogen concentration would be approximately 2.6 wt.% in these phases condition.

• Journal of Electrochemical Science and Technology
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• 제13권1호
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• pp.63-70
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• 2022

Compared with hydrogen, ammonia has the advantages of high gravimetric hydrogen densities (17.8 wt.%), ease of storage and transportation as a chemical hydrogen storage medium, while its application in small-scale on-site hydrogen production scenarios is limited by the need for complex separation equipment during high purity hydrogen production. Therefore, the study of PEMFC, which can directly utilize ammonia decomposition gas, can greatly expand the application of fuel cells. In this paper, the output characteristics, fuel efficiency and the variation trend of hydrogen concentration and local current density in the anode channel of fuel cell with the output voltage of PEMFC fueled by ammonia decomposition gas were studied by experiment and simulation. The results indicate that the maximum output power of the hybrid fuel decreases by 9.6% compared with that of the pure hydrogen fuel at the same inlet hydrogen equivalent. When the molar concentration of hydrogen in the anode channel is less than 0.12, the output characteristics of PEMFC will be seriously affected. Employing ammonia decomposition gas as fuel, the efficiency corresponding to the maximum output power of PEMFC is approximately 47%, which is 10% lower than the maximum efficiency of pure hydrogen.

• 센서학회지
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• 제25권6호
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• pp.423-430
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• 2016

This study used a single metal oxide semiconductor (MOS) sensor to classify the major odorous gases hydrogen sulfide ($H_2S$), ammonia ($NH_3$) and toluene ($C_6H_5CH_3$). In order to classify these odorous substances, the voltage on the MOS sensor heater was gradually reduced in 0.5 V steps 5.0 V to examine the changes to the response by the cooling effect on the sensor as the voltage decreased. The hydrogen sulfide gas showed the highest sensitivity compared to odorless air under approximately 2.5 V and the ammonia and toluene gases showed the highest sensitivity under approximately 5.0 V. In other words, the hydrogen sulfide gas reacted better in the low temperature range of the MOS sensor, and the ammonia and toluene gases reacted better in the high-temperature range. In order to analyze the response characteristics of the MOS sensor by temperature in a pattern, a two-dimensional (2D) x-y pattern analysis was introduced to clearly classify the hydrogen sulfide, ammonia, and toluene gases. The hydrogen sulfide gas was identified by a straight line with a slope of 1.73, whereas the ammonia gas had a slope of 0.05 and the toluene gas had a slope of 0.52. Therefore, the 2D x-y pattern analysis is suggested as a new way to classify these odorous substances.

• 한국가스학회지
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• 제27권3호
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• pp.35-40
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• 2023

과충전, 이상 온도 상승 등 이상 상황이 발생하는 조건에서 암모니아 용기의 파열 사고의 예방을 위해서는 용기에 부착된 가용전식 안전밸브의 작동 메카니즘 분석을 통한 사고 예방대책 마련이 필요하다. 본 연구에서는 가압 조건에서 암모니아 용기에 작용하는 응력 분석, 온도 변화에 따른 밀도 변화 분석, 그리고 용기 충전량과 온도 및 압력 변화에 대한 상관관계를 제시하였다. 또한, 암모니아 용기의 최대 충전량을 계산하고, 상평형 선도를 통해 해당 충전량에서의 온도·압력을 산출했다. 이를 바탕으로 가용전식 안전밸브의 적정 용융점을 도출하고 용융 온도 실험을 통해 이를 검증하였다. 이와 같은 연구 결과를 바탕으로 암모니아 용기 파열 사고의 예방을 위한 조건을 제시하였다.