• Korean Journal of Materials Research
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• v.28 no.8
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• pp.466-473
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• 2018

Nickel oxide(NiO) thin films, nanorods, and carbon nanotube(CNT)/NiO core-shell nanorod structures are fabricated by sputtering Nickel at different deposition time on alumina substrates or single wall carbon nanotube templates followed by oxidation treatments at different temperatures, 400 and $700^{\circ}C$. Structural analyses are carried out by scanning electron microscopy and x-ray diffraction. NiO thinfilm, nanorod and CNT/NiO core-shell nanorod structurals of the gas sensor structures are tested for detection of $H_2S$ gas. The NiO structures exhibit the highest response at $200^{\circ}C$ and high selectivity to $H_2S$ among other gases of NO, $NH_3$, $H_2$, CO, etc. The nanorod structures have a higher sensing performance than the thin films and carbon nanotube/NiO core-shell structures. The gold catalyst deposited on NiO nanorods further improve the sensing performance, particularly the recovery kinetics.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.879-886
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• 2000

$H_2S$ adsorption characteristics of activated carbon adsorbent impregnated with NaOH were investigated. The concentrations of NaOH reagent were 1~8N and the particle size of activated carbon was $8{\times}30$ mesh. The experimental results showed that the BET surface area decreases from $1050m^2/g$ to $783m^2/g$ and acidity of activated carbon decreases from 0.541 meq/g-AC to 0 meq/g-AC, while pH increases from 9.56 to 10.86 when the impregnation ratio increases from 0.87% to 5.8%. It was also found that the $H_2S$ adsorption equilibrium capacity of activated carbon impregnated with NaOH increases with increasing temperature and $H_2S$ concentration and varies in the range of 17.87~30.34 mg/g-AC at adsorption temperature of $45^{\circ}C$, which is 2~3 times larger than that of pure activated carbon.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.6
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• pp.811-817
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• 2013

A two-stage bioreactor system using sulfur-oxidizing bacteria was studied to abate high strength hydrogen sulfide ($H_2S$) from biogas. The two-stage bioreactor consisted of a $H_2S$ absorption column (0.5 L) and a microbial oxidation column (1 L) in series, and the liquid medium was continuously recirculated through the columns. The objectives of this study were to determine the feasibility of the bioreactor for biogas desulfurization and to investigate the effect of the medium circulation rate on the system performance. An averaged concentration of $H_2S$ introduced to the bioreactor was 530 ppm, corresponding to an overall loading rate of $44.4g/m^3/hr$. During the initial 20 days period at the medium recirculation rate of 8 reactor volumes per hour (12 L/hr), the dissolved oxygen (DO) concentration in the oxidation column was 6 mg/L, while the DO in the absorption column was 0.5 mg/L showing that the oxygen contents of the biogas stream was not altered. Because of the biological oxidation of $H_2S$ in the oxidation column, the sulfate concentration increased from 200 mg/L to 5,600 mg/L in the liquid medium. The removal efficiency of $H_2S$ was greater than 99% in the initial operation period. After the initial period, the medium recirculation rate between the two columns was stepwise changed eight times from 1.0 to 40 vol/hr (1.5~60 L/hr). At the recirculation rate of faster than 4 vol/hr, the $H_2S$ removal efficiencies were found to be high, but the efficiency declined at the lower recirculation rates than the threshold.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.280-285
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• 2005

The method of chemical absorption has been presented to separate and recover acid gases like $CO_2\;and\;H_2S$. But, this method has some problems such as loss of valuable amine and operational problems (forming, corrosion and fouling) by degradation. In this study, we investigated the degradation characteristics of aqueous AMP solution containing additives such as HMDA, MDEA and piperazine. The degradation was affected by temperature and process time. AMP solution absorbing $CO_2\;and\;H_2S$ was degraded 105% and 23% more than pure AMP at $120^{\circ}C$ respectively. In addition, all the additives were degraded significantly as the temperature increased. The order of the degraded amount of additives mixed in the AMP solution containing absorbed $CO_2$ was as followings : HMDA > piperazine > MDEA.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.22-27
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• 2004

The activated paper mill sludge was treated with WF and some additives (sodium sulfide, nickel nitrate, ethyl acetate) for methane fermentation at $35^{\circ}C$. Optmum C/N ratio was 60 out of three conditions (20, 30 and 60). The Period of 40% of methane content possibly ignition, was 2 days shorter than with non-treatment during 10 days. Nevertheless, the total amount of methane production showed the 1/8 level of control far the same period. The yield and content of methane were increased by the addition of sodium Sulfur and ethyl acetate. Sulfur was an essential factor in methane fermentation of paper mill sludge.

• Journal of Sensor Science and Technology
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• v.31 no.3
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• pp.168-174
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• 2022

Hydrogen sulfide(H₂S) gas is a high-risk gas that can cause suffocation or death in severe cases, depending on the concentration of exposure. Various studies to detect this gas are still in progress. In this study, we demonstrate a colorimetric sensor that can detect H₂S gas using its direct color change. The proposed nanofiber sensor containing a dye material named Lead(II) acetate, which changes its color according to H₂S gas reaction, is fabricated by electrospinning. The performance of this sensor is evaluated by measuring RGB changes, ΔE value, and gas selectivity. It has a ΔE value of 5.75 × 10^-3 ΔE/s·ppm, showing improved sensitivity up to 1.4 times that of the existing H₂S color change detection sensor, which is a result of the large surface area of the nanofibers. The selectivity for H₂S gas is confirmed to be an excellent value of almost 70 %.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.290-294
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• 2023

Among various types of harmful gases, hydrogen sulfide is a strong toxic gas that is mainly generated during spillage and wastewater treatment at industrial sites. Hydrogen sulfide can irritate the conjunctiva even at low concentrations of less than 10 ppm, cause coughing, paralysis of smell and respiratory failure at a concentration of 100 ppm, and coma and permanent brain loss at concentrations above 1000 ppm. Therefore, rapid detection of hydrogen sulfide among harmful gases is extremely important for our safety, health, and comfortable living environment. Most hydrogen sulfide gas sensors that have been reported are electrical resistive metal oxide-based semiconductor gas sensors that are easy to manufacture and mass-produce and have the advantage of high sensitivity; however, they have low gas selectivity. In contrast, the electrochemical sensor measures the concentration of hydrogen sulfide using an electrochemical reaction between hydrogen sulfide, an electrode, and an electrolyte. Electrochemical sensors have various advantages, including sensitivity, selectivity, fast response time, and the ability to measure room temperature. However, most electrochemical hydrogen sulfide gas sensors depend on imports. Although domestic technologies and products exist, more research is required on their long-term stability and reliability. Therefore, this study includes the processes from electrode material synthesis to sensor fabrication and characteristic evaluation, and introduces the sensor structure design and material selection to improve the sensitivity and selectivity of the sensor. A sensor case was fabricated using a 3D printer, and an Ag reference electrode, and a Pt counter electrode were deposited and applied to a Polytetrafluoroethylene (PTFE) filter using PVD. The working electrode was also deposited on a PTFE filter using vacuum filtration, and an electrochemical hydrogen sulfide gas sensor capable of measuring concentrations as low as 0.6 ppm was developed.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.74-83
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• 2016

Bacillus subtilis SRCM 101269 having safety and amo gene isolated from Korean traditional fermented food and their investigated characterization to apply the cow manure such as cellulase and xylanase activities, 16S rRNA sequencing, and ability of removal of livestock manure odor. Cow manure application results for the removal of livestock manure odor, the ammonia gas was reduced more than two-folder compared to the control group after 6 days, and reduced to less than 10 ppm after 9 days. In the case of cow manure added fowl droppings and other wood-based mixture components, ammonia gas maintained constant after 3 days of fermentation. However, in the case of sample inoculated B. subtilis SRCM 101269, ammonia gas reduced in course of fermentation time, and concentration of hydrogen sulfide also reduced for 65 ppm. Changes of nitrite concentration according to fermentation time no showed different for cow manure, however nitrite concentration in mixed livestock manure increased when compared to control. And then sulfate concentration in cow manure decreased, and no showed different when compared to the initial fermentation. No apparent change of sulfate concentration in mixed livestock manure detected. Through the previously studies, B. subtilis SRCM 101269 has high potential in industrial application manufacturing the cow manure as removal of livestock manure odor.

• Journal of Animal Science and Technology
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• v.50 no.3
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• pp.321-330
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• 2008

본 연구는 흑운모 분말 급여시 육성돈에 생산성, 면역관련 혈액학적 지표, 혈청 내 스트레스 농도 및 분내 유해가스 발생에 미치는 영향을 구명하고자 실시하였다. 시험 동물은 [(Landrace ×Yorkshire)×Duroc] 3원 교잡종 육성돈 96두를 공시하였으며, 시험 개시시의 체중은 29.45±1.35kg으로 사양시험을 42일간 실시하였다. 시험설계에서 공시돈은 돈방당 4두씩 1) CON(Basal diet), 2) Solt2(Basal diet+Solto-B 0.2%), 3) Solt4(Basal diet+Solto-B 0.4%) 및 4) Solt6 (Basal diet+Solto-B 0.6%)로 4처리구에 각각 6돈방씩 완전 임의배치 하였다. 질소 소화율에서는 solt4 처리구가 CON과 solt2 처리구에 비해 유의적으로 높게 나타내었다(Linear effect = 0.016). 총 에너지에서는 Solt4와 Solt6 처리구가 CON 처리구에 비해 유의적으로 높게 나타내었다(Linear effect=0.008, Quadratic effect=0.019). 면역 및 스트레스 관련 혈액성상에서는 처리간의 차이가 없었다. 황화수소는 5 day와 10 day에서 대조구에 비해 Solt 처리구가 유의적으로 감소를 하였다(5 day, Linear effect=0.009, Quadractic effect=0.037; 10 day, Linear effect = 0.009). 아세트산는 5 day에서 대조구에 비해 Solt 처리구가 유의적으로 감소를 하였다(Linear effect <0.001, Quadractic effect < 0.001). 15 day에서도 CON과 Solt6 처리구가 Solt2와 Solt4 처리구에 비해 유의적으로 감소를 하였다(Quadractic effect=0.023). 메캅탄은 5 day와 10 day에서 CON 처리구에 비해 Solt 처리구가 유의적으로 감소를 하였다(5 day, Linear effec= 0.029, Quadractic effect=0.037; 10 day, Linear effect=0.029). 암모니아는 5 day, 10 day 및 15 day에서 Solt2와 Solt4 처리구가 CON과 Solt6 처리구에 비해 유의적으로 감소하였다(5 day, Quadractic effect=0.038; 10day, Quadractic effect = 0.045; 15day, Quadractic effect = 0.038). 결론적으로, 육성돈에 흑운모 분말 급여시 분내 유해가스 함량에 유의적인 감소를 나타내었다.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.4
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• pp.264-269
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• 2022

The present study investigated effects of microbial additives on the floor of Hanwoo steer manure in barn. The treatment following: without additives (CON); additives (AMA). Each treatment used 3 barns as replication and each barn contained 5 Hanwoos. The Hanwoo steer manure in barns was sub-sampled from 5 sides of pen at 0, 4 and 12 weeks. The sub-samples were used for analyses of chemical compositions, microbial counts, gas emissions and compost maturity. The concentrations of moisture, organic matter, total nitrogen and carbon-to-nitrogen (C/N ratio) of Hanwoo steer manure before the microbial additives were each 59.1%, 83.2%, 1.78% and 50.0%, respectively. The counts of lactic acid bacteria, Yeast, Bacillus subtilis, and Escherichia coli (E. coli) were each 5.94, 6.83, 7,28 and 5.52 cfu/g, but Salmonella was not detected. The ammonia-N gas was 4.67 ppm, but hydrogen sulfide gas was not detected. After 4 weeks, moisture, organic matter, total nitrogen, pH and yeast count were lowest (p<0.05). The lactic acid bacteria, yeast, Escherichia coli (E. coli) and ammonia-N gas were not effects of microbial additives. All treatments was not detected at Salmonella count and hydrogen sulfide emission, and compost maturity was completed. After 12 weeks, the lactic acid bacteria and Bacillus subtilis were highest in AMA, while moisture, yeast and E. coli were lowest (p<0.05). The ammonia-N gas was not effect by microbial additive. Salmonella and hydrogen sulfide emission were not detected in all treatments, and compost maturity was completed. Therefore, in present study, the microbial additive did not affect of gas and compost maturity, but the pathogenic microorganism such as E. coli, were inhibited by microbial additives.