• Korean Chemical Engineering Research
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• 제58권4호
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• pp.588-595
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• 2020

지속적으로 강화되는 환경오염 물질 배출 규제로 인해, 질소 산화물(NO_x)의 배출량 예측 및 관리는 산업 현장에서 많은 관심을 받고 있다. 본 연구에서는 인공지능 기반 질소산화물 배출량 예측모델 개발을 위한 연구모형을 제안하였다. 제안된 연구모형은 데이터의 전처리 과정부터 인공지능 모델의 학습 및 평가까지 모두 포함하고 있으며, 시계열 특성을 가지는 NO_x 배출량을 예측하기 위하여 순환 신경망 중 하나인 Long Short-Term Memory (LSTM) 모델을 활용하였다. 또한 의사결정나무 기법을 활용하여 LSTM의 time window를 모델 학습 이전에 선정하는 방법을 채택하였다. 본 연구에서 제안된 연구모형의 NO_x 배출량 예측 모델은 가열로에서 확보한 조업 데이터로 학습되었으며, 최적 모델은 hyper-parameter를 조절하여 개발되었다. 개발된 LSTM 모델은 학습 데이터 및 평가 데이터에 대하여 모두 93% 이상의 NO_x 배출량 예측 정확도를 나타내었다. 본 연구에 제안된 연구모형은 시계열 특성을 가지는 다양한 대기오염 물질의 배출량 예측모델 개발에 응용될 수 있을 것으로 기대된다.

• 에너지공학
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• 제19권3호
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• pp.177-181
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• 2010

열교환기는 용도에 따라 여러가지 형태가 존재하지만 중요한 것은 열교환기의 성능을 향상시킴으로서 열교환기의 크기를 소형화하는 것이라 할 수 있다. 그러나 보일러처럼 열교환기가 버너 앞에 위치할 경우 열교환기의 효율도 중요하지만 환경오염물질의 배출특성도 고려되어야 한다. 따라서 본 연구에서는 비예혼합화염보다 화염길이가 짧고 당량비 조절을 통해 $NO_x$ 및 CO 배출을 제어할 수 있는 예혼합방식의 버너 앞에 원형관 열교환기를 설치한 후 열교환기 관사이의 거리 및 당량비를 변화시킬 때 $NO_x$와 CO의 배출특성과 열교환기의 열효율을 실험적으로 구하였다.

• 한국대기환경학회지
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• 제27권6호
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• pp.772-790
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• 2011

In this paper, we use the HDDM (High-order Decoupled Direct Method)-driven ozone sensitivity to predict change in ozone concentrations in response to domain-wide $NO_x$(Oxides of Nitrogen) and VOC (Volatile Organic Compound) emission controls over the Seoul Metropolitan Area during June 11~19, 2007. In order to validate the applicability of HDDM to $NO_x$ and VOC control scenarios, the HDDM results are compared to Brute Force Method (BFM). For VOC controls, NME (Normalized Mean Error) between BFM and HDDM remains less than 2% until the domain-wide VOC emissions are reduced by 80%. The NME for a 40% reduction in the domain-wide $NO_x$ emissions is less than 5% but increases abruptly after further reductions in the $NO_x$ emissions (i.e., 80% reduction). The results indicates that it may be inaccurate to use ozone sensitivity coefficients estimated at a given base emission condition in predicting ozone after $NO_x$ reductions larger than ~50% of the domain total in the SMA. Therefore, HDDM application on piecewise emissions is desirable to predict ozone response to emission controls with accuracy (i.e., truck emissions rather than the domain total). For computational efficiency, HDDM shows approximately 30% faster than the BFM sensitivity approach.

• 에너지공학
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• 제19권3호
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• pp.182-187
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• 2010

본 연구는 컴팩트 연소실내 CO 튜브 삽입에 따른 $NO_x$ 및 CO 배출 특성에 관한 연구로써, CO 튜브 삽입에 따른 연소기와 CO튜브 사이의 거리와, CO튜브와 주열교환기 사이의 거리에 따른 배출 특성을 검토하였다. 본 연구를 위해 상용프로그램인 Fluent와 GRI 2.11 상세 반응 기구를 이용하여 수치해석과 상용 열교환기 실험을 통해 CO튜브 삽입에 관한 CO 및 $NO_x$ 배출특성을 검토하였다. 그 결과 연소기와 주열교환기 사이에 CO 튜브를 삽입하여 CO 튜브가 연소기에 근접하고 CO 튜브와 주열교환기 사이를 넓어짐으로써 $NO_x$ 및 CO 저감에 효과가 있음을 확인할 수 있었으며, 이로 인해 CO 튜브 삽입에 따른 $NO_x$ 및 CO를 동시 저감법을 확인할 수 있었다.

• 대한기계학회논문집B
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• 제37권5호
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• pp.481-488
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• 2013

10 %의 암모니아가 첨가된 메탄 연료의 비예혼합 확산화염에서, 산소/이산화탄소 및 산소/질소의 산화제 내에 산소 비율의 변화에 따른 질소산화물($NO_x$)의 생성 특성을 실험 및 수치해석적으로 조사하였다. 동축류 제트 화염의 실험에서, 산소/이산화탄소의 산화제인 경우, 측정된 $NO_x$은 산소 비율의 증가에 따라 약간 증가하는 경향을 보였다. 반면에, 산소/질소의 산화제인 경우, $NO_x$은 0.7의 산소 비율에서 최대로 측정되었으며, 산소 비율에 따라 비단조적인 경향을 보였다. 결과적으로, 암모니아가 첨가된 메탄 화염에서 배출되는 $NO_x$는 일반 공기의 조건보다 순산소 연소 조건의 경우가 더 크게 측정되었다. 한편, 다양한 산화제의 조건에 대하여 $NO_x$ 생성 특성을 분석하기 위해서, 동일한 화학반응 메커니즘을 적용하여 1 차원 및 2 차원의 수치해석을 수행하였다. 그 결과, 산소/질소의 산화제에서 2 차원의 수치해석 결과가 실험적으로 측정된 $NO_x$의 배출 특성을 비교적 잘 예측하였다.

• 대한기계학회논문집
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• 제19권3호
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• pp.858-867
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• 1995

Characteristics of premixed flames in counter-flow system are numerically studied using a detailed chemical reaction mechanism including gas phase radiation. Without radiation effect accounted, low CO and high NO$_{x}$ emission indices are observed, when strain rate decreases, due to increased residence time and higher flame temperature. Higher NO$_{2}$ production has been also observed when two premixed flames are interacting or cold air stream is mixed with burned gas. The rate of NO$_{x}$ production and destruction is dependent upon the diffusional strength of H and OH radicals, the existence of NO and the concentration of HO$_{2}$. For radiating flames, the peak temperature and NO$_{x}$ production rate decreases as the strain rate decreases. At high strain rate, it is found that the effect of radiation on flame is little due to its negligible radiating volume. It is also found that NO$_{x}$ production from the interacting premixed flame is reduced due to reduced temperature resulting from radiation heat loss. It is concluded that the radiation from gas has significant effect of flame structure and on emission characteristics.ristics.

• 한국대기환경학회지
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• 제26권1호
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• pp.69-76
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• 2010

While increased use of motor cycles in the recent years for various demands could worsen air quality, only few studies have been conducted on estimation of emission factors and characterization of emissions from motorcycle. In this study, emissions from selected six models of motorcycle based on largest market share and production rate were investigated. To investigate gaseous and carbonaceous air pollutants, such as carbon monoxide (CO), total hydrocarbon (THC), nitrogen oxide ($NO_x$), elemental carbon (EC) and organic carbon (OC), total 124 motorcycles between 2003 and 2007 model year were tested with regulatory driving conditions, such as CVS-40 and CVS-47 mode. These motorcycles were further sub-categorized based on their displacement (< 50 cc, 50~150 cc, and $\geq$ 150 cc), type of stroke (2- and 4 strokes) and model year (2003~2005 and 2006~2007). Tested motorcycles with recent model year (2006~2007) exhibited less emissions of regulatory gaseous and carbonaceous air pollutants compared to old model year (2003~2005). Chemical analysis showed that CO present in highest concentration followed by THC and $NO_x$ for all tested motorcycles. Interestingly, two strokes motorcycle produced higher THC emission but less CO and $NO_x$ than those of four strokes. For all types of displacement and stroke, emission factors (gram per kilometer) of THC and CO except $NO_x$ with recent model year (2006~2007) showed decreased trend compared to old model year (2003~2005). In addition to this, due to mixed combustion between gasoline fuel and lubricant, two strokes motorcycle showed OC > EC emission trend.

• 한국자동차공학회논문집
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• 제22권7호
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• pp.70-75
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• 2014

The experiment was done on traveling at the speed of 20km/h, 60km/h and 100km/h using the performance testing mode for chassis dynamometer. The experimental method were employed to measure the waveform of secondary ignition coil and exhaust emission. In this experiment, the correlation between the secondary waveform coming from ignition coil and exhaust emission were measured in decrepit vehicle. The secondary waveform characterized by the value of effective discharge energy. The following results are obtained by analyzing the data relativity between the effective discharge energy and exhaust emission. The variation rate of effective discharge energy was largest 60km/h, 20km/h, 100km/h velocity in the ordered named. As the vehicle velocity increases, the average variation rate of CO and $NO_X$ decreases and that of HC and $CO_2$ decrease. The value of effective discharge energy, CO, $NO_X$ and fuel consumption is measured badly in case of car with failures in MAP, spark plug and good in case of car with before and after maintenance regardless of vehicle velocities. The value of effective discharge energy is to be nearly parabolic shape as vehicle velocity increases. As the value of effective discharge energy increases, the value of $NO_X$, HC and $CO_2$ decrease, the value of CO increase. The most sensible factors of exhaust emission were CO, $NO_X$, and the small variation factors were HC, $CO_2$.

• 한국입자에어로졸학회지
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• 제17권4호
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• pp.133-148
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• 2021

This study aims to estimate the amount of air pollutants emitted from heavy industry facilities in North Korea. To compare the emission in 2017 from the heavy industry sector in North Korea with South Korea, the heavy industry sector was classified with the South Korean classification (Matching Heavy Industry sector) and air pollutant emissions by Matching Heavy Industry sector in North Korea were estimated. The CO, NO_x and SO_x emissions of Matching Heavy Industry sector in North Korea are 22%, 73%, and 31% of the emission in South Korea, respectively. The air pollutant emissions in the Matching Heavy Industry sector in North Korea for CO, NO_x and SO_x were 0.6%, 124%, and 24% of the total air pollutant emission in North Korea estimated from EDGAR, respectively. As for the distribution of emissions by administrative district of the Matching Heavy Industry sector in North Korea, NO_x was concentrated in the western part of North Korea, and CO and SO_x emissions were concentrated in Hamgyong-bukto.

• 한국공작기계학회논문집
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• 제12권6호
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• pp.104-111
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• 2003

In order to collect the engine performance data and determine optimum engine conditions, engine performance test based on interface unit were tested This paper was carried out that engine' performance was developed using interface unit between personal computer and diesel engine. The results of the study are summarized as follows: Interface unit was developed. By using PAL, simulation was carried in order to logic's inspection. From this tea NO$_{x}$ were decreased, otherwise PM were increased. By using EGR system PM were increased by twice in the high load ranges, it was not seen to come into effect in the low load ranges. This system was tested D-l3 mode, the results were decreased more than 50% in the NO$_{x}$ emission.