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이재박(Jaepark Lee),이승로(Seungro Lee),이창언(Chang-Eon Lee),윤희중(Hee-Jung Yun),이황의(Hwang-Eui Lee),장기현(Gi-Hyun Jang) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.40
This study was about the development of green high-efficiency condensing heat exchanger which does not need a technical importation from foreign country and is able to produce it by own technology. The efficiency of BAND A, SEBBUK was set more than 90 %, and CO and NOx emissions were targeted less than 50 ppm and 40 ppm, respectively. The pilot unit was made using a heat exchanger Benchmarking of developed countries, and the shape and the position of tube were adjusted to reduce CO and NOx emissions at the same time.
Lee, Seungro,Shin, Cheol Hee,Choi, Sun,Kwon, Oh Chae Elsevier 2018 ENERGY Vol.164 No.-
<P><B>Abstract</B></P> <P>A computational investigation on the characteristics of nitrogen oxides (NO<SUB>x</SUB>) emissions for counterflow nonpremixed water (H<SUB>2</SUB>O)-laden methane (CH<SUB>4</SUB>)/air flames is conducted since a detailed observation of NO<SUB>x</SUB> formation for fuel having naturally high H<SUB>2</SUB>O vapor content is necessary. Using a detailed kinetic mechanism, NO<SUB>x</SUB> emissions are predicted for low and high flame strain rates (<I>a</I>), and the reaction paths are investigated. With H<SUB>2</SUB>O addition NO<SUB>x</SUB> emissions are reduced due to the chemical process as well as the thermal process such as diluting and cooling effects, the latter is more dominant than the former in NO<SUB>x</SUB> reduction, and the thermal and prompt NO mechanisms become less dominant for the chemical process. With increasing <I>a</I>, NO<SUB>x</SUB> emissions are also reduced, and it is mainly due to the thermal process. Reaction NH + O = NO + H in the prompt pathway is the major reaction step that results in reducing NO emissions via the chemical process due to H<SUB>2</SUB>O addition for both low- and high-stretched flames, though reaction N + OH = NO + H in the thermal pathway is also the major reaction step for the high-stretched flames. In addition, for the high-stretched flames the NO<SUB>2</SUB> pathway in NO production becomes relatively more important with H<SUB>2</SUB>O addition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> With H<SUB>2</SUB>O addition NO<SUB>x</SUB> emissions are reduced mainly due to the thermal effects. </LI> <LI> NH + O = NO + H in the prompt NO pathway becomes less significant with H<SUB>2</SUB>O addition. </LI> <LI> In high-stretched flames N + OH = NO + H is also less significant with H<SUB>2</SUB>O addition. </LI> <LI> In high-stretched, H<SUB>2</SUB>O-added flames the NO<SUB>2</SUB> pathway is relatively important. </LI> <LI> With increasing strain rates, NO<SUB>x</SUB> emissions in H<SUB>2</SUB>O-laden flames are also reduced. </LI> </UL> </P>
Lee, Seungro,Ha, Heonrok,Dunn-Rankin, Derek,Kwon, Oh Chae Pergamon Press 2017 Energy Vol.134 No.-
<P><B>Abstract</B></P> <P>Structure and extinction limits of counterflow nonpremixed water (H<SUB>2</SUB>O)-laden methane (CH<SUB>4</SUB>)/air flames at various pressures are computationally investigated to better understand combustion processes of fuel having naturally high H<SUB>2</SUB>O (vapor) content under elevated pressures. Using a detailed kinetic mechanism and a statistical narrow-band radiation model, the flame structure and extinction limits are predicted for elevated pressures and a wide range of flame strain rates and compared with those at atmospheric pressure. Results show that with increasing pressure the maximum flame temperature increases and the extinction limits are generally extended due to the reduced amount of dissociation and the enhanced radiation reabsorption of H<SUB>2</SUB>O, indicating that flames can sustain more H<SUB>2</SUB>O vapor at elevated pressure. The concentration of active radicals and the flame thickness decrease with increasing pressure. The observed flammable range of the H<SUB>2</SUB>O to CH<SUB>4</SUB> molar ratio at elevated pressures is comparable to that found in self-sustained combustion of CH<SUB>4</SUB> hydrates at atmospheric pressure, and the chemical effects of H<SUB>2</SUB>O addition on flame structure are insignificant. Elevated pressure enhances the formation of soot precursors such as acetylene (C<SUB>2</SUB>H<SUB>2</SUB>), implying an opposite tendency from the water addition effects.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Maximum flame temperature increases with increasing pressure. </LI> <LI> Extinction limits are extended with elevated pressure. </LI> <LI> Enhanced recombination and radiation reabsorption of H<SUB>2</SUB>O cause these tendencies. </LI> <LI> Elevated pressure enhances formation of soot precursor C<SUB>2</SUB>H<SUB>2</SUB>. </LI> <LI> Thermal effect of H<SUB>2</SUB>O addition on flame structure at elevated pressure is dominant. </LI> </UL> </P>
고압 다이캐스팅 공정에서 제품 결함을 사전 예측하기 위한 기계 학습 기반의 공정관리 방안 연구
이승로 ( Seungro Lee ),이승철 ( Seungcheol Lee ),한도석 ( Dosuck Han ),김낙수 ( Naksoo Kim ) 한국주조공학회 2021 한국주조공학회지 Vol.41 No.6
본 연구는 고압 다이캐스팅 공정에서 제품 결함을 사전에 예측하기 위한 기계 학습 기반의 공정 관리 모델 개발에 관한 연구이다. 모델은 이전 사이클에서의 온도를 입력받고, 사이클에 걸쳐서 나타나는 특징을 인식하여 다음 사이클의 결함 발생 여부를 예측한다. 기어 박스 형상에 대하여 제안된 알고리즘을 적용하여, 3 사이클의 정보를 통해서 9 8 .9%의 정확도와 9 6.8 %의 재현율로 제품 수축 결함을 사전에 예측하였다. This study presents a process management method for the detection of casting defects during in high-pressure die casting based on machine learning. The model predicts the defects of the next cycle by extracting the features appearing over the previous cycles. For design of the gearbox, the proposed model detects shrinkage defects with data from three cycles in advance with 98.9% accuracy and 96.8% recall rates.
단조 공정의 균일 변형률 분포를 위한 예비성형체 설계 방법
이승로(Seungro Lee),김경민(Kyungmin Kim),김낙수(Naksoo Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Preform design is important for full filling of the die and uniform deformation in forging processes. In this study, a preform design methodology for uniform strain distribution is introduced. The proposed method is based on a convolution neural network (CNN) algorithm. By convolution operation with weight arrays, the model extracts geometrical features of the forging product, forging simulation result, and strain distribution, and connects those features with the corresponding preform. For the different forging products, the saved weight arrays can extract the characteristic features, so that proper preform shape can be easily acquired without any iterations. The proposed design method is utilized for the H-shaped forgings and validated through numerical experiments for rail wheel forging and disk forging. The proposed method has shown to be reliable in preform design procedures, granting uniform deformation with full filling in forging processes.
Diesel Surrogate 상세 반응 기구를 이용한 HCCI엔진의 연소 특성
이원준(Wonjun Lee),이승로(Seungro Lee),이창언(Chang-Eon Lee) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.41
Homogeneous charge compression ignition(HCCI) is the best concept able to provide low NOx and PM in diesel engine emissions. This new alternative combustion process is mainly controlled by chemical kinetics in comparison with the conventional combustion in internal combustion engine. In this paper, detailed kinetic reaction mechanism of diesel surrogate was investigated to understand the diesel HCCI engine combustion. And we was investigated combustion characteristics of the new diesel surrogate(heptane/toluene mixture fuel). Especially we study deep into a ignition timing and emission gas according to heptane/toluene mixture ratio and EGR.
컴팩트 연소실 내 CO튜브 삽입에 따른 오염물질 배출특성
이재박(Jaepark Lee),김종민(Jong-Min Kim),이승로(Seungro Lee),장기현(Gi-Hyun Jang),이창언(Chang-Eon Lee) 한국에너지공학회 2010 한국에너지공학회 학술발표회 Vol.2010 No.4
본 연구는 컴팩트 연소실내 CO 튜브 삽입에 따른 NOx 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 Fluent9t GRI 2.11 상세 반응 기구를 이용하여 수치해석과 실용 연소기를 모사한 단순 모델 열교환기의 실험을 통해 CO튜브 삽입에 관한 NOx 및 CO 배출특성을 검토하였다. 그 결과 연소기와 주열교환기 사이에 CO 튜브를 삽입하여 CO 튜브가 연소기에 근접하고 CO 튜브와 주열교환기 사이를 넓어짐으로써 NOx 및 CO 저감에 효과가 있음을 확인할 수 있었으며, 이로 인해 CO 튜브 삽입에 따른 NOx 및 CO를 동시 저감법을 확인할 수 있었다. This study was the effect of CO tube insert for NOx and CO emission characteristics in a compact combustion chamber. In detail, NOx and CO emission characteristics with changing of distance due to inserting the CO tube between the burner and the main heat exchanger were investigated. For this study, the commercial program, FLUENT, and the GRI 2.11 detail reaction mechanism were used for the numerical study and a simple model heat exchanger was tested for the experimental study. As results, when the CO tube was inserted between the burner and the main heat exchanger, it was verified the simultaneous NOx and CO reduction method because of increasing the residence time and decreasing the flame temperature.