• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.360-365
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• 2014

Vapor-phase hydrogen peroxide(VPHP) has been used as a sterilant in the field of medical and pharmaceutical application due to low corrosive than chlorine contained sterilant. In addition, it is well known that VPHP is effective for decontamination of chemical warfare agents by adding ammonia gas. In this study, the decontamination efficiency was confirmed about CEPS, DFP and dimethoate as simulants of HD, GD and VX using VPHP respectively. For this purpose, VPHP generated from self configured device was injected into decontamination chamber and maintained for reaction time. After the decontamination, the residues are analyzed by GC/MS and decontamination efficiency was calculated. Through by-product for each simulants, the similarities in reaction mechanism of chemical warfare agents were confirmed. CEPS was completely decontaminated at 30% relative humidity within 60 min. By adding ammonia gas, DFP and dimethoate were completely decontaminated within 30 and 150 min respectively.

• Journal of Animal Environmental Science
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• v.1 no.2
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• pp.165-171
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• 1995

Aerobic treatment of animal slurries represents an increasingly popular option for farmers in the management of animal wastes. This study was performed to find out the chemical characteristics of dairy slurry associated with liquid-solid separation. Total solids concentration varies widely depending on the slurry manure handling systems. Hydrogen ion exponent(pH), volatile solids(VS), ammonia nitrogen(NH$_3$-N), nitrate nitrogen (NO$_3$-N), and chemical oxygen demand(COD) essentially depends on the total solids content of animal liquid wastes. Total solids content of the dairy slurry ranges from 6.6 to 7.5% depending on the feed slurry and separator. Separated liquids from dairy slurry have been successfully downed for up to about 21, 900mg/$\ell$ of the COD value. It has also been found that separated slurry decreased from 37.8 to 26.0mg/$\ell$ of the NO$_3$-N concentration.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.512-518
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• 2008

The present work studied the selective catalytic reduction (SCR) of NO to $N_2$ by $NH_3$ over $V/TiO_2$ focusing on NOx control for the stationary sources. The SCR process depends mainly on the catalyst performance. The reaction characteristics of SCR with $V/TiO_2$ catalysts were closely examined at low and high temperature. In addition, adsorption and desorption characteristics of the reactants on the catalyst surface were investigated with ammonia. Seven different $TiO_2$ supports containing the same loading of vanadia were packed in a fixed bed reactor respectively. The interaction between $TiO_2$ and vanadia would form various non-stoichiometric vanadium oxides, and showed different reaction activities. There were optimum calcination temperatures for each samples, indicating different reactivity. It was finally found from the $NH_3-TPD$ test that the SCR activity was nothing to do with $NH_3$ adsorption amount.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.5
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• pp.557-565
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• 2022

The effect of flow configuration in ammonia-fed solid oxide fuel cell are investigated by using a three-dimensional numerical model. Typical flow configurations including co-flow and counter-flow are considered. The ammonia is directly fed into the stack without any external reforming process, resulting in an internal decomposition of NH3 in the anode electrode of the stack. The result showed that temperature profile in the case of counter-flow is more uniform than the co-flow configuration. The counter-flow cell, the temperature is highest at the middle of the channel while in the case of co-flow, the temperature is continuously increased and reached maximum value at the outlet area. This leads to a higher averaged current density in counter-flow compared to that of co-flow, about 5%.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.723-732
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• 2022

Cracking ammonia inside solid oxide fuel cell (SOFC) stack is a compact and simple way. To prevent sharp temperature fluctuation and increase cell efficiency, the decomposition reaction should be spread on whole cell area. This leading to a question that, how does anode thickness affect the conversion rate of ammonia and the cell voltage? Since the 0D model of SOFC is useful for system level simulation, how accurate is it to use equilibrium solver for internal ammonia cracking reaction? The 1D model of ammonia fed SOFC was used to simulate the diffusion and reaction of ammonia inside the anode electrode, then the partial pressure of hydrogen and steam at triple phase boundary was used for cell voltage calculation. The result shows that, the ammonia conversion rate increases and reaches saturated value as anode thickness increase, and the saturated thickness is bigger for lower operating temperature. The similar cell voltage between 1D and 0D models can be reached with NH₃ conversion rate above 90%. The 0D model and 1D model of SOFC showed similar conversion rate at temperature over 750℃.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.1
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• pp.40-47
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• 2024

Ammonia is drawing attention as carbon free fuel due to its ease of storage and transportation compared to hydrogen. This study suggests ammonia fueled solid oxide fuel cell (SOFC) system with electrochemical hydrogen compressor (EHC)-based recirculation. Performance of electrochemical hydrogen pump is based on the experimental data under varying hydrogen and nitrogen concentration. As a result, the suggested system shows 62.04% net electrical efficiency. The efficiency is 10.33% point higher compared to simple standalone SOFC system (51.71%), but 0.02% point lower compared to blower-based recirculation system (62.06%). Further improvement in the EHC-based SOFC recirculation system can be achieved with EHC performance improvement.

• Textile Coloration and Finishing
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• v.16 no.2
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• pp.1-7
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• 2004

The dyeability of cotton fabrics treated with liquid ammonia was investigated using low-temperature and high-temperature reactive dyes. From the results of dyeing rates of direct dye, the inversion time was shown at 600 hours at $40^{\circ}C$, and however it was shown at 10 minutes at $80^{\circ}C$. This was applied to reactive dyeings. In the low-temperature reactive dyes, the color strength of the fabrics treated with liquid ammonia was lower than that of mercerized fabrics. By contrast, in the high-temperature reactive dyes, the color strength of the fabrics treated with liquid ammonia was higher than that of mercerized one.

• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.399-406
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• 2015

A sequencing batch reactor was operated under different pH conditions to see the influence of free ammonia (FA) and free nitrous acid (FNA) to microbial community on ammonium partial nitrification. Long-term influences of FA and FNA were evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis and fluorescence in situ hybridization. Nitrite accumulation was successfully achieved at pH 8.2 and 6.3. The shifts in the microbial community were observed when influent ammonia concentration increased to 1 g $NH_4$-N/L at pH 8.2, and then when pH was dropped to 6.3. Both Nitrosomonas and Nitrosospira were selected during the startup of the reactor, and eventually became dominant members as ammonia-oxidizing bacteria. The results of molecular microbiological analysis strongly suggested that the composition of microbial community was changed according to the method used to control nitrite-oxidizing bacteria.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.22.1-22.1
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• 2009

차세대 CMOS 공정에서 유전상수가 높은 게이트 절연막과 함께 게이트 전극이 관심을 끌고 있다. 게이트 전극은 전도도가 높아야 하고 p-MOS, n-MOS에 맞는 일함수를 가져야 하며 열적 특성이 안정해야 한다. 탄탈룸 계열 탄화물이나 질화물은 게이트 전극으로 관심을 끌고 있는 물질이며 이를 원자층 화학증착법으로 박막화 하는 공정이 관심을 끌고 있다. 원자층 화학공정에서는 전구체의 역할이 중요하며 이의 기상반응 메카니즘, 표면 반응 메카니즘을 제대로 이해해야 한다. 본 연구에서는 TBTDET (tert-butylimido tris-diethylamido tantalum) 전구체의 반응 메커니즘을 FTIR(Fourier Transform Infrared)을 이용해 진단하였다. 또한 수소, 암모니아, 메탄을 이용한 열화학 원자층 증착, 플라즈마 원자층 증착 공정을 수행하여 박막을 얻고 이들의 특성을 평가하였다. 각 공정에 따라 반응 메커니즘이 달라지고 박막의 조성이 달라지며 또한 박막의 물성도 달라진다. 특히 박막에 형성되는 TaC, TaN, Ta3N5, Ta2O5 (증착 후 산소의 유입에 의해 형성됨) 등의 조성이 공정에 따라 달라지며 박막의 물성도 달라진다. 반응메카니즘의 연구를 통해 각 공정에서 어떠한 조성의 박막이 얻어지는 지를 규명하였고 박막의 밀도에 따라 산소유입량이 어떻게 달라지는 지를 규명하였다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.36-42
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• 2005

This study examined the feasibility of producing sulfuric acid and ammonia water from ammonium sulfate solution using two-compartment electrodialysis with a bipolar membrane (EDBM). Electrodialysis experiments were carried out with 20 wt% ammonium sulfate at different current densities and sulfuric acid concentrations in a concentrate compartment. The current efficiency increased with the current density from 25 to $100\;mA/cm^2$. Nevertheless, the efficiency was relatively low compared with that of general desalting electrodialysis, owing to the diffusion of sulfuric acid from the concentrate compartment to the diluate. The diffusion rate through the anion exchange membrane increased with the sulfuric acid concentration in the concentrate compartment, which decreased the current efficiency. Conversely, the electrical resistance decreased with increasing current density owing to the Joulian heat generated during water dissociation in the transition region of the bipolar membrane under a high electric field. From the experimental results, we concluded that operating at a higher current density is effective from the perspective of current efficiency and electrical resistance when producing sulfuric acid and ammonia water from ammonium sulfate using a two-compartment EDBM process. Further studies on the effects of increasing the sulfuric acid concentration on current efficiency are required to apply the EDBM process practically.