• 한국자동차공학회논문집
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• 제3권2호
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• pp.95-101
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• 1995

Experiments have been conducted to investigate the characteristics of formaldehyde and nitrous oxide formation from the catalytic reaction of methane. Catalysts used in the experiment were Pd. Pd/Pt/Rh loaded on ${\gamma}-Al_2O_3$ and ${\gamma}-Al_2O_3-La_2O_3$ monolith. In the catalytic reaction of methane. as the concentration of NO, $O_2$ and $CH_4$ increased, the formaldehyde emission was increased. The concentration of $N_2O$ increased as NO and CO increased. It was also found that the formaldehyde emission was produced by the gas reaction of methane in high temperature above 950K.

• 접착 및 계면
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• 제21권2호
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• pp.51-57
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• 2020

최근 산업활동을 통해 배출되는 유해 오염물질 제거에 대한 관심이 증가하고 있다. 본 연구에서는 수증기 활성화 법을 이용하여 활성탄소섬유를 제조하고, 이의 유해가스 흡착 및 전기화학적 감응 특성을 분석하였다. 활성탄소섬유의 균일한 기공 구조, 활성 반응 면적 및 반응 위치를 조절하기 위하여, 활성화 온도(750-850 ℃) 및 활성화 시간(30-240 min)을 조절하였고, 다양한 활성화 조건을 통해 제조된 활성탄소섬유의 SO₂와 NO 가스 흡착 및 가스 센서를 통한 감응 특성을 분석하였다. 특히, 850 ℃에서 45 min동안 수증기 활성화 반응을 통해 제조된 활성탄소섬유가 가장 높은 비표면적(1,041.9 ㎡/g)과 기공 특성(0.42 ㎤/g)을 보였으며, 우수한 SO₂ (1.061 mg/g) 및 NO (1.210 mg/g) 가스 흡착 특성을 보였다.

• 한국태양에너지학회 논문집
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• 제29권5호
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• pp.45-52
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• 2009

Fossil power plants firing lower grade coals or equipped with modified system for $NO_x$ controls are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. In order to develop a on-line combustion tuning system, field test was conducted at operating power boiler. During the field test the exhaust gases' $O_2,\;NO_x$ and CO was monitored by using a spatially distributed monitoring grid located in the boiler's high temperature vestibule and upper convective rear pass region. At these locations, the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. using these monitored information we can improving combustion at every point within the furnace, therefore the boiler can operate at reduced excess $O_2$ and gas temperature deviation, reduced furnace exit gas temperature levels while also reducing localized hot spots, corrosive gas conditions, slag or clinker formation and UBC. Benefits include improving efficiency, reducing $NO_x$ emissions, increasing output and maximizing availability. Discussion concerning the reduction of greenhouse gases is prevalent in the world. When taking a practical approach to addressing this problem, the best way and short-term solution to reduce greenhouse gases on coal-fired power plants is to improve efficiency. From this point of view the real time optimized combustion tuning approach is the most effective and implemented with minimal cost.

• 한국산학기술학회논문지
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• 제8권2호
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• pp.179-184
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• 2007

본 연구에서는 전산유체역학 기법을 도입하여 17대 버스가 주차된 지하주차장의 환기특성을 분석하였다. 그 결과 지하주차장내 버스 4대가 운행할 때 CO와 $NO_x$의 평균농도는 각각 1.3과 0.3 ppm으로 나타났다. 또한 15대 버스가 공회전할 때 지하주차장내의 CO와 $NO_x$의 평균농도는 2.9와 0.8 ppm으로 각각 나타났다 따라서 두 가지 경우의 결과가 허용기준을 충족하여 지하주차장에 설치될 환기설비의 용량 및 위치는 적정한 것으로 판단된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.489-489
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• 2012

The vibrational distribution of $N_2$ (B, v') in after-glows in $N_2$ RF flowing plasma was investigated. The optical emission of the after-glow was studied as function of distance from plasma. In a tube 2.1 cm, the gas pressure varied 8 Torr with 1000sccm nitrogen gas flowing late.. The discharges were excited by two ring-electrode powered by RF 13.56 MHz 100 Watt. $N_2$ (B, v') vibrational distribution was analyzed to see depends of position in after-glow. Dissociation rate of $N_2$ varied showing maximum in the late after-glow region. We studied $N_2$ RF capacitive flowing plasmas and afterglows by emission spectroscopy and by NO titration to determine the density of N-atoms.

• 대한화학회지
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• 제30권2호
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• pp.207-215
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• 1986

본 연구는 대기중의 질소산화물($NO_x$)을 효율적으로 제거하기 위하여 기존의 방법을 개선한 것으로서, $NH_3$를 이용한 환원법을 개량하였다. 상대습도 60%에서 50 ppm의 $NO_x$는 1% hr-1의 분해율을 나타낸 반면 5배 이상의 $NH_3$를 첨가함으로써 50 ppm $NO_x$인 경우에는 6% $hr^{-1}$, 20ppm인 경우는 10% $hr^{-1}$의 제거율을 나타내었다. 그러나 실제 배기기체에서는 과량의 수분과 탄화수소나 일산화탄소같은 환원성 기체가 포함되고 미량의 금속이온들이 공존되므로 최고 15% $hr^{-1}$까지 $NO_x$의 제거가 촉진되었다. 또한 SO_2와 같은 산성기체의 공존은 분해율을 감소시켰다. 이 $NO_x$의 분해현상은 주로 계에 가해진 수증기의 응축으로 생긴 수막에 NO_x가 용해되는 동시에 염기성인 $NH_3$기체도 용해되어 이루어진 이들 이온들의 환원반응에 기인된다고 생각된다.

• 센서학회지
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• 제33권5호
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• pp.242-247
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• 2024

Pure and 0.3 wt% Au-doped In₂O₃ hollow spheres were synthesized via ultrasonic spray pyrolysis of droplets containing an In-source and sucrose in air and their gas sensing characteristics to 1 ppm ethanol, 1 ppm toluene, 1 ppm xylene, 2 ppm nitrogen dioxide (NO₂), and 30 ppm carbon monoxide (CO) were measured at 400 - 450℃. The pure In₂O₃ hollow spheres exhibited relatively low gas responses and sluggish recovery kinetics. In contrast, the doping of Au into In₂O₃ hollow spheres significantly increased the gas response (S= resistance ratio) to 1 ppm ethanol (S= 20.6) at 400℃ with low cross-responses (S = 1.3-8.8) to other interference gases. Furthermore, the hollow spherical morphology of In₂O₃ provides a large surface area and facilitates rapid gas diffusion, resulting in fast response and recovery times. The sensor exhibited excellent performance with a low detection limit of 1.6 ppb. These findings indicate that the Au-In₂O₃ hollow spheres are promising candidates for advanced ethanol-sensing applications, particularly in breath-alcohol monitoring for ignition interlock devices.

• 한국대기환경학회지
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• 제23권6호
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• pp.699-707
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• 2007

This study was carried out to investigate the reaction characteristics of corona/catalyst hybrid $DeNO_x$ process. The experiments were performed by using the multi-staged pin-to-hole type corona reactor which is enable to control the pin-to-hole gap and to insert the catalyst. Also, used for this study, were catalysts which commercially used Pt, Pd and $TiO_2$, and oxygen and hydrocarbon ($C_2H_4$) as reagents. In the syn-gas test, at high temperatures in the range of $100{\sim}200^{\circ}C$, the corona-only $DeNO_x$ process did not reduce the $NO_x$ concentration effectively. However in the presence of ethylene and oxygen as reagents, the $NO_x$ removal efficiency was better at these high temperatures than corona-only $DeNO_x$ process. In addition, coronal catalyst hybrid process with $TiO_2$ showed more efficiency of $NO_x$ removal than Pt and Pd catalyst, because the $TiO_2$ catalyst was more active than Pt and Pd catalyst to converse the $NO_2$ to $HNO_3$. Furthermore, at the condition of real diesel exhaust gas, the $DeNO_x$ efficiency of corona/catalyst hybrid process was not good at higher reaction temperature and plasma density.

• 에너지공학
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• 제22권2호
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• pp.128-135
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• 2013

산지마다 상이한 성분을 갖는 천연가스의 가스호환성 및 연소특성을 판정하기 위해서는 많은 시간과 비용이 소비되고 그 범위도 넓어 어려움이 있어, 천연가스를 모사하는 등가가스를 대체하여 사용하는 방법이 사용되고 있다. 등가가스는 천연가스와 발열량, 압축계수, 상대밀도, CO 배출농도 및 연소속도에 차이가 거의 없다고 알려져 있지만, 실제 가스기기에 대한 화염형상, NOx 배출농도 및 효율에 대한 연구는 아직 보고되고 있지 않다. 본 연구에서는 천연가스를 모사하는 등가가스를 대상으로 기존에 보고된 CO 배출농도, 연소속도 및 화염온도 등을 재확인하고, 화염형상, NOx 배출농도 및 효율에 대해서 수치해석 및 실험을 통해 비교 검토함으로써 등가가스의 유효성을 검토하였다. 그 결과 천연가스와 등가가스의 차이는 미세하였으며, 등가가스를 이용하여 천연가스의 연소특성 및 호환성 범위를 검토하는데 문제가 없을 것으로 판단되었다.

• Food Science and Biotechnology
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• 제15권2호
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• pp.298-302
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• 2006

Kochujang was fermented using hot red pepper, meju prepared with soybean and rice, and malt-digested syrup. To reduce salt content, mustard powder (1.2%, w/w) was added to Korean traditional kochujang with 4-10% salt, and microbial characteristics, enzyme activities, and gas formation in kochujang were evaluated during fermentation for 120 days at $25^{\circ}C$. Yeast numbers of all treatments maintained 2.43-2.86 log CFU/g up to 60 days fermentation, indicating salt concentration had no effect on yeast count. Activities of ${\alpha}$- and ${\beta}$-amylases, and neutral and acidic proteases of kochujang added with mustard powder were slightly higher than those of control group. Total accumulative volume of gas produced during fermentation of kochujang without mustard powder (control group) was 5,892 mL/pack, but decreased to 34-99 mL/pack in low-salted kochujang (4 and 6% salt) added with mustard powder. Major gas produced was carbon dioxide (79-80%) with oxygen content less than 1.25%(v/v). Results indicate salt concentration of kochujang could be lowered up to 6-8% by addition of mustard powder without gas formation and quality alteration during distribution.