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쾌삭 303계 스테인리스강 소형 압연 선재 제조 공정의 생산품질 예측 모형
서석준(Seokjun Seo),김흥섭(Heungseob Kim) 한국산업경영시스템학회 2021 한국산업경영시스템학회지 Vol.44 No.4
This article suggests the machine learning model, i.e., classifier, for predicting the production quality of free-machining 303-series stainless steel(STS303) small rolling wire rods according to the operating condition of the manufacturing process. For the develop-ment of the classifier, manufacturing data for 37 operating variables were collected from the manufacturing execution system(MES) of Company S, and the 12 types of derived variables were generated based on literature review and interviews with field experts. This research was performed with data preprocessing, exploratory data analysis, feature selection, machine learning modeling, and the evaluation of alternative models. In the preprocessing stage, missing values and outliers are removed, and oversampling using SMOTE(Synthetic oversampling technique) to resolve data imbalance. Features are selected by variable importance of LASSO(Least absolute shrinkage and selection operator) regression, extreme gradient boosting(XGBoost), and random forest models. Finally, logistic regression, support vector machine(SVM), random forest, and XGBoost are developed as a classifier to predict the adequate or defective products with new operating conditions. The optimal hyper-parameters for each model are investigated by the grid search and random search methods based on -fold cross-validation. As a result of the experiment, XGBoost showed relatively high predictive performance compared to other models with an accuracy of 0.9929, specificity of 0.9372, -score of 0.9963, and logarithmic loss of 0.0209. The classifier developed in this study is expected to improve productivity by enabling effective management of the manufacturing process for the STS303 small rolling wire rods.
홍희경,문선희,서석준,김정화,정성운,정택호,홍유덕,성기재,김선문,Hong, Heekyoung,Mun, Sunhee,Seo, Seokjun,Kim, Jounghwa,Jung, Sungwoon,Chung, Taekho,Hong, Youdeog,Sung, Kijae,Kim, Sunmoon 한국액체미립화학회 2018 한국액체미립화학회지 Vol.23 No.2
Emission characteristics of regulated pollutants (CO, NOx, HC and PM) and hazardous air pollutants (HAPs) from diesel heavy duty trucks equipped with EGR+pDPF and SCR for Euro 5 emission standards were investigated using a chassis dynamometer. In the case of regulated pollutants, diesel heavy duty trucks with EGR+pDPF emitted 79% less CO than those with SCR. Also, those with the SCR emitted 36% less NOx than those with the EGR+pDPF. The results of VOCs have show that alkanes emissions for heavy duty trucks with the EGR+pDPF and the SCR have been higher than alkenes, cycloalkanes and aromatics. In the case of individual VOCs, the highest of propene emissions for 11.3~16.1% occupied. For aromatics group, benzene emissions are the highest percentage for 4.4~15.5%. In the future, the results of present study will provide basic data to set up HAPs emissions inventory for mobile source.
RV차량 및 소형승합차량의 휘발성유기화합물 배출특성 연구
문선희,홍희경,김선문,서석준,정성운,정택호,홍유덕,김정화,Mun, Sunhee,Hong, Heekyoung,Kim, Sunmoon,Seo, Seokjun,Jung, Sungwoon,Chung, Taekho,Hong, Youdeog,Kim, Jounghwa 한국액체미립화학회 2018 한국액체미립화학회지 Vol.23 No.2
Volatile organic compounds (VOCs) are well known as ozone precursors from photochemical reactions and contribute to the formation of photochemical smog which pose health hazards. Also, some of these compounds directly affect the human health due to their toxicity such as benzene. In this study, NMVOCs composition in exhaust gas from recreational vehicle (RV) and (MPV) were characterized using a chassis dynamometer. The results for NMVOCs have reported that alkanes emission was higher than alkenes, aromatics and cycloalkanes due to reactive of diesel oxidation catalysts. The NMVOCs composition according to carbon number was highly distributed between C3 and C6~C8. During the engine cold start condition, NMVOCs emission was higher compared to the engine hot start condition due to the increased catalytic activity. The NMVOCs emission with DPF increased compared to that without DPF. The results of this study will be provide to calculate VOCs emissions from mobile source.
도로변 초미세먼지의 실시간 질량농도 및 부피농도 측정을 이용한 시간별 밀도 분석-광흡수 eBC에 대한 OPS 보정 중심
김은영(Eunyoung Kim),서석준(Seokjun Seo),김선문(Sunmoon Kim),정성운(Sungwoon Jung),이용민(Yongmin Lee),오세호(Sea-Ho Oh),박규태(Gyutae Park),김경훈(Kyunghoon Kim),김정화(Jounghwa Kim),홍유덕(Youdeog Hong),이태형(Taehyoung Lee),배민석(Mi 한국대기환경학회 2018 한국대기환경학회지 Vol.34 No.6
자동차 배출가스 중 BTEX의 비율과 C<sub>2</sub>-benzenes의 상관성 연구
문선희 ( Sunhee Mun ),정택호 ( Taekho Chung ),정성운 ( Sungwoon Jung ),김선문 ( Sunmoon Kim ),서석준 ( Seokjun Seo ),이승환 ( Seounghwan Lee ),김정화 ( Jounghwa Kim ),홍유덕 ( Youdeog Hong ),홍희경 ( Heekyoung Hong ) 한국액체미립화학회 2018 한국액체미립화학회지 Vol.23 No.4
Benzene, toluene, ethylbenzene and xylene (BTEX) were well known as ozone precursors from photochemical reactions and contribute to the formation of photochemical smog which pose health hazards. Also, some of these compounds directly affect the human health due to their toxicity such as benzene. In this study, BTEX ratios and correlation of C<sub>2</sub>-benzenes (xylenes, ethylbenzene) in vehicle exhaust from recreational vehicle (RV) and multi-purpose vehicle (MPV) were characterized using a chassis dynamometer. VOCs were collected by tedlar bag and a GC/MS system was used for their quantification. Among all of the BTEX, toluene has the highest concentration(more than 30% in composition of BTEX). The average ratio of toluene to benzene emissions (T/B ratio=2.2) was found in vehicle exhaust. The average m,p-xylene/ethylbenzene and m,p-xylene/o-xylene ratios were 1.0 and 3.0 respectively. As a result, it showed a good correlation between the C<sub>2</sub>-benzenes (R2=0.98~0.99). In the future, it can be used as a marker for effect evaluation to atmospheric environment by vehicle exhaust.