• Journal of information and communication convergence engineering
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• v.2 no.1
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• pp.22-25
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• 2004

A highly sensitive ammonia gas sensor using thick-film technology has been fabricated and examined. The sensing material of the gas sensor is FeOx-$WO_{3}-SnO_{2}$ oxide semiconductor. The sensor exhibits resistance increase upon exposure to low concentration of ammonia gas. The resistance of the sensor is decreased, on the other hand, for exposure to reducing gases such as ethyl alcohol, methane, propane and carbon monoxide. A novel method for detecting ammonia gas quite selectively utilizing a sensor array consisting of an ammonia gas sensor and a compensation element has been proposed and developed. The compensation element is a Pt-doped $WO_{3}-SnO_{2}$gas sensor which shows opposite direction of resistance change in comparison with the ammonia gas sensor upon exposure to ammonia gas. Excellent selectivity has been achieved using the sensor array having two sensing elements.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.3
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• pp.287-292
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• 2004

An experimental investigation was carried out to study the performance of a bubble pump for the diffusion absorption refrigerating system. Ammonia was used as the refrigerant and the helium was charged in order to balance the pressure between the low and high pressure side. As experimental variables, the concentration of ammonia charged into system, heat input, and the pressure of helium were selected. Experimental results show that the generation rate of ammonia vapor and the circulation rate of diluted ammonia solution were increased as the heat input increases, but the ratio of the solution to vapor flow rate was decreased. The generation rate of refrigerant vapor and the circulation rate of diluted ammonia solution increased as the system pressure decreased. Finally under the condition of 25 bars, the concentration of rich ammonia solution was not affected by the generation rate of ammonia vapor and the circulation of diluted ammonia solution.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.4
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• pp.432-442
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• 2010

Ammonia is a very important constituent of the atmospheric environment because it is the most dominant gaseous alkaline species present in the atmosphere. Ammonia is known to affect ecosystems at relatively low concentration. Ammonia flux from livestock facilities can be regulated by a number of environmental factors (pH, ammonium ion, temperature, wind speed, etc). The increases in wind speed above manure from 0.0 m/s to 1.0 7m/s resulted in 2.5 times increases in ammonia flux. Wind speed and ammonia flux showed 0.982. A linear relationship with a correlation coefficient (r=0.982). When manure temperature increased from $3^{\circ}C$ to $36^{\circ}C$, the manure pH decreased approximately 0.30 to 0.46. As wind speed above the manure increased from 0.0 m/s to 1.07 m/s, ammonia flux increased approximately 2.5 times. The increasing manure temperature from $3^{\circ}C$ to $10^{\circ}C$, raised ammonia flux from 2.0 to 3.6 times (2.6 times in average similarly). The increases of manure temperature from $3^{\circ}C$ to $25^{\circ}C$ increased ammonia flux from 5.7 to 12.9 times (8.5 times in average). In this study, the correlation coefficient between ammonia flux and manure temperature was found from 0.972 to 0.989. Results of our research showed that ammonium ion concentration, pH of manure and wind speed were important factors in controlling the ammonia flux from manure livestock facilities.

• Textile Coloration and Finishing
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• v.6 no.2
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• pp.47-54
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• 1994

Cotton fiber, NaOH-mercerized cotton fiber, cotton fabric, and NaOH-mercerized cotton fabric have been treated by liquid ammonia at -33.4$^{\circ}C$. The fine structures, bending properties, tensile strengthes, shrinkages for laundering, and wrinkle recoveries were studied. The treatment of cottons with liquid ammonia brought about the transition of crystal lattice ; transforming cellulose I crystal of original cotton to cellulose I and III crystal, and cellulose II crystal of mercerized cotton to cellulose II and III crystals. The degree of crystallinities were decreased in the order of liquid ammonia>NaOH/liquid ammonia>NaOH-treated cotton. However moisture regain and water absorbency for liquid ammonia-treated cotton were lower than that of NaOH-treated cotton because of a difference in swelling actions of the agents. It seems caused by intermicrofibrillar pores produced in swelling processes. The bending rigidity and bending hysteresis were decreased remarkly by liquid ammonia treatment. Therefore softness and dimensional stability were improved. The liquid amminia and NaOH/liquid ammonia-treated cottons moreover show excellent properties in tensile strength, anti-shrinkage for laundering, and wrinkle recovery.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.510-517
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• 2013

The ammonia-water based power generation cycle utilizing liquefied natural gas (LNG) as its heat sink has attracted much attention, since the ammonia-water cycle has many thermodynamic advantages in conversion of low-grade heat source in the form of sensible energy and LNG has a great cold energy. In this paper, we carry out thermodynamic performance analysis of a combined power generation cycle which is consisted of an ammonia-water regenerative Rankine cycle and LNG power generation cycle. LNG is able to condense the ammonia-water mixture at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the thermodynamic models, the effects of the key parameters such as source temperature, ammonia concentration and turbine inlet pressure on the characteristics of system are throughly investigated. The results show that the thermodynamic performance of the ammonia-water power generation cycle can be improved by the LNG cold energy and there exist an optimum ammonia concentration to reach the maximum system net work production.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.715-723
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• 2016

This study investigated the effect of high concentration of free ammonia on microalgal growth and substrate removal by applying real wastewater nitrogen ratio. To test of this, the conditions of free ammonia 1, 3, 6, 9, 12, 15 mg-N/L are compared. After 3 days of incubation, algal growth of Chlorella vulgaris and carbon removal rate are respectively lower in the reactors of FA 12, 15 mg-N/L compared to the others. This indicates that the high concentration of free ammonia, in this case, above 12 mg-N/L, has negative effect on algal growth and metabolic activity. Also, high concentration of free ammonia causes the proton imbalance, ammonium accumulation in algae and has toxicity for these reasons. So, we have to consider free ammonia in applying the microalgae to wastewater treatment system by the way of diluting wastewater or controlling pH and temperature.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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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.

• Journal of the Korea Convergence Society
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• v.12 no.5
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• pp.185-190
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• 2021

An electrolyzed-acidic water treatment was investigated as a methods for removing ammonia, which is a cause of odor in life environment. The prepared electrolyzed-acidic water was found out as stable solvent capable of neutralizing weak alkaline ammonia by measuring changes in pH and ORP. It was found out that ammonia was removed from the mixture solution of electrolyzed-acidic water and ammonia water by the UV-vis absorbance analysis and electrochemical open-circuit potential measurement. The neutralized ammonia by electrolyzed-acidic water and effectively removed odor was measured using ammonia gas detecter. Consequently, we recommend the electrolyzed-acidic water can effectively and safely remove ammonia in eco-friendly.

• Corrosion Science and Technology
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• v.21 no.6
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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.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.272-278
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• 2013

The hybrid system composed of a photocatalytic reactor and a biofilter was operated under various operating conditions in order to treat malodorous waste air containing ammonia which is a major air pollutant emitted from composting factories and many publicly owned treatment works. Total ammonia removal efficiency of the hybrid system was maintained to be ca. 80% even though its inlet loads were increased at a higher operating stage according to an operating schedule of the hybrid system. The ammonia removal efficiency of photocatalytic reactor was decreased from 65% to 22% as ammonia inlet loads to photocatalytic reactor were increased. In spite of same inlet loads of ammonia to the photocatalytic reactor, the ammonia removal efficiency of photocatalytic reactor with lower ammonia concentration of fed-waste air was higher than that with higher ammonia concentration of fed-waste air. To the contrary, during the first half of the hybrid system operation the ammonia removal efficiency of a biofilter was quite suppressed while, despite of increased ammonia inlet loads, the ammonia removal efficiency of the biofilter was continuously increased to 78% and reached the ammonia removal efficiency similar to what Lee et al. attained. The maximum ammonia elimination capacity of the photocatalytic reactor was observed to be ca. 16 g-N/$m^3$/h. In an incipient stage of hybrid system run, the ammonia elimination capacity of the biofilter showed little sensitivity against ammonia inlet loads to the hybrid system. However, in the 2nd half of its run, the ammonia elimination capacity of the biofilter was increased abruptly in case of high ammonia inlet loads to the hybrid system. In 6th stage of hybrid system run, total ammonia inlet load attained at ca. 80 g-N/$m^3$/h corresponding to 16 g-N/$m^3$/h of ammonia elimination capacity of the photocatalytic reactor. Then, the remaining ammonia inlet load to the 2nd and main process of the biofilter and its elimination capacity was expected and shown to be ca 64 g-N/$m^3$/h and ca 48 g-N/$m^3$/h, respectively. The ammonia elimination capacity of the biofilter was close to 1,200 g-N/$m^3$/day of the maximum elimination capacity of the investigation performed by Kim et al.