2차전지 제조설비의 전극공정에서 생산로트의 크기에 따른 불량률 분석모형

정재우(Jaewoo Chung) 한국산업경영학회 2024 경영연구 Vol.39 No.2

2차전지산업은 수년간 빠르게 성장하였으나 최근 수요 둔화와 글로벌 공급사들의 공격적 투자로 어느 때보다 치열한 시장경쟁이 예고된다. 따라서 제조설비의 생산성을 높여 원가경쟁력을 높이기 위한 노력이 어느 때보다 중요해지고 있다. 2차전지 제조설비에서 병목인 전극공정은 다수의 제품을 한 설비에서 생산하는 반면 한 제품에서 다른 제품으로 교체하는데 긴 준비시간이 필요하다. 따라서 생산로트의 크기를 얼마로 하느냐는 설비 운영의 중요한 의사결정 요인이 되고 있다. 준비교체 손실 관점에서는 생산로트의 크기가 클수록 유리하지만 큰 생산로트는 제조설비의 재공을 증가시키고 이는 다시 전극공정에서 발생한 불량이 이후 조립공정 검사를 통해 발견되는데 걸리는 시간을 증가시켜 불량률을 증가시키는 문제를 초래한다. 본 연구에서는 이 문제에 대하여 대기행렬이론을 활용한 분석모형을 제공함으로써 제조설비의 운영 효율을 높이는 데 도움을 주고자 한다. 분석모형은 생산로트의 크기에 따라 전극공정의 준비교체로 인한 손실과 불량 로트 발생으로 인한 손실에 대하여 근사치를 계산하는 데 초점을 두고 있다. 이를 위하여 GI/G/c 대기행렬모형을 바탕으로 생산로트의 크기에 따라 불량 발생 메카니즘을 계산하는 분석모형을 제안하였다. 이 분석모형의 유용성을 입증하기 위하여 2차전지 제조기업에서 수집한 자료를 바탕으로 수리적 분석을 진행하였다. 이 결과 본 연구에서 제안하는 분석모형을 통해 생산로트의 크기에 따른 수율, 총생산량, 불량률의 변화를 분석할 수 있어 의사결정에 활용될 수 있을 것으로 기대된다. The EV battery industry has grown rapidly over the years, and with the recent slowdown in demand and aggressive investment from global suppliers, fierce market competition is expected, requiring efficient operation of manufacturing lines more than ever. The electrode process, which is a bottleneck process in the EV battery manufacturing line, produces multiple products on a unit line, but switching from one product to another requires a long setup time. Therefore, the size of the production lot is an important decision-making factor in line operation. The larger the production lot size, there is a less setup loss, but a large production lot increases the WIP between electrode line and the subsequent assembly line, which increases the time to detect a defect occurred in the electrode process to be discovered after inspection in the assembly line. This study aims to help increase the operational efficiency of the EV manufacturing line by providing an analytic model using queuing theory. The analysis model focuses on approximating the loss due to setup of the electrode manufacturing line and the loss due to the occurrence of defective parts depending on the size of the production lot. To this end, based on the GI/G/c queuing model, a stochastic model is proposed to explain the defect occurrence mechanism depending on the size of the production lot. This study conducts an numerical analysis based on data collected from an actual EV battery manufacturing line to illustrate the usefulness of this model. As a result, it was found that the stochastic model proposed in this study can be used for decision making by analyzing yield, total production volume, defect rate according to the size of the production lot.

전자제어 커먼레일 압축착화엔진용 고압연료펌프의 DME 적용 성능에 관한 연구

정재우(Jaewoo Chung),김남호(Namho Kim),강정호(Jungho Kang),박상욱(Sangwook Park),이호길(Hokil Lee),최승규(Seungkyu Choi) 한국자동차공학회 2009 한국 자동차공학회논문집 Vol.17 No.2

Recently, the interest in the development of high efficiency Diesel engine technology using alternative fuel has been on the rise and related studies are being performed. Therefore, the DME(Dimethyl Ether), an oxygen containing fuel as an alternative fuel for light oil that can be used for diesel engines since it generates very little smoke. But it is unavoidable that the modification of a fuel supply system in an engine to application of the DME fuel because of DME fuel properties. So, in this study, a DME high pressure pump for a common-rail fuel supply system has been composed and the test results of the pump have been presented. As the results of the tests, it is confirmed that DME pump inlet pressure, pump speed and common-rail pressure effects on the volumetric efficiencies of the pump. Finally, it is defined that the optimum plunger volume of a DME pump has to be extended to the minimum 150% compared to a Diesel pump plunger volume considering DME fuel properties and volumetric efficiencies characteristics at same specifications of the high pressure pump.

운송시간의 예측을 통한 물류정체 통제 모형

정재우(Jaewoo Chung),허연호(Yeonho Hur) 한국경영과학회 2012 經營 科學 Vol.29 No.1

The automated material handling systems today are playing ever more important roles in semiconductor/LCD fabrication facilities. Recently they became more flexible, intelligent, and speedy than in the past. The facilities have been fully automated because the size and weight of the unit loads used in the facilities were being increased beyond the limits that a human operator can handle. This research develops an efficient procedure to streamline the delivery of unit loads by the automated material handling system (AMHS). For this task, the research employs the event scheduling theory that has been successfully used in the both academia and industry. The developed procedure was applied to an actual LCD fabrication facility and improved the performance of an existing material handling system.

디젤엔진의 EGR 순환계 형식에 따른 과급기 작동 특성에 관한 연구

정재우(Jaewoo Chung),강정호(Jeongho Kang),이호길(Hogil Lee) 한국자동차공학회 2009 한국 자동차공학회논문집 Vol.17 No.6

In recently, various researches on technical method for reduction of PM and NOx from Diesel engine have been performed. Especially, it is considered that adoption of VGT and EGR system is essential technical method to reduce the PM and NOx emissions. And, to reduce NOx emissions, many attempt to adopt of special EGR loop systems including low pressure EGR loop are ongoing now. But, EGR system is composed with turbocharger system, so characteristics of EGR system are related with or restricted by turbocharger or boost system. In this study, it is investigated on the turbocharger operating characteristics and EGR loop characteristics in 2 types of EGR loop systems (High pressure loop EGR system and Low pressure loop EGR systems) to support basic information on the optimal EGR and VGT systems for PM and NOx reduction in Diesel engine. From theses test, it is understood that LP loop EGR systems has more safe characteristics on compressor surge limit and higher EGR rate at same A/F conditions compared with HP loop EGR system.

불확실성을 고려한 장기 전원 포트폴리오의 평가

정재우(Jaewoo Chung),민대기(Daiki Min) 한국경영과학회 2012 한국경영과학회지 Vol.37 No.3

This paper presents a portfolio model for a long-term power generation mix problem. The proposed portfolio model evaluates generation mix by considering the tradeoffs between the expected cost for power generation and its variability. Unlike conventional portfolio models measuring variance, we introduce Conditional Value-at-Risk (CVaR) in designing the variability with aims to considering events that are enormously expensive but are rare such as nuclear power plant accidents. Further, we consider uncertainties associated with future electricity demand, fuel prices and their correlations, and capital costs for power plant investments. To obtain an objective generation by each energy source, we employ the sample average approximation method that approximates the stochastic objective function by taking the average of large sample values so that provides asymptotic convergence of optimal solutions. In addition, the method includes Monte Carlo simulation techniques in generating random samples from multivariate distributions. Applications of the proposed model and method are demonstrated through a case study of an electricity industry with nuclear, coal, oil (OCGT), and LNG (CCGT) in South Korea.

프리우스 Ⅲ의 차량 출력 분석에 기초한 연비 예측 방안에 관한 연구

정재우(Jaewoo Chung),서영호(Youngho Seo),최용준(Yongjun Choi),최성은(Sungeun Choi),김형구(Hyounggu Kim),정기윤(Kiyun Jung) 한국자동차공학회 2011 한국 자동차공학회논문집 Vol.19 No.6

Both an optimal design of the engine operating strategy and fuel economy prediction technique for a HEV under the vehicle driving condition are very crucial for the development of vehicle fuel economy performance. Thus, in this study, engine operating characteristics of PRIUS Ⅲ were analyzed with vehicle running conditions and the correlations between vehicle tractive power and fuel consumption were introduced. As a result, fuel economy performance of PRIUS Ⅲ with various test modes were predicted and verified. Errors of predicted fuel economy were between -5% and -1%.

Zero power disc를 이용한 터보과급기의 성능 평가 방법에 대한 고찰

정재우(Jaewoo Chung),김남호(Namho Kim),임동현(Donghyun Lim),이상운(Sangwoon Lee),정진은(Jineun Chung),장성식(Seongsik Jang),김기용(Giyong Kim) 한국자동차공학회 2017 한국 자동차공학회논문집 Vol.25 No.5

The technical importance of the turbocharger for improving gasoline engine efficiency and improving reactivity is increasing. In particular, the reduction of friction loss and evaluation of the turbine operating characteristic are important in improving the turbocharger’s performance. This measurement can be confirmed by a runaway experiment using a zero power disc. However, the experimental methods and application limitations are not presented in detail. Therefore, in this study, the runaway test method and the application limit are presented based on the measurement results on the turbocharger for passenger cars.

반도체/LCD 생산에서 연구개발 로트가 양산 생산성에 미치는 영향

정재우(Jaewoo Chung) 한국경영과학회 2018 經營 科學 Vol.35 No.1

Since semiconductor/LCD industry is a high-tech industry, constantly introducing new products into market in time through researching and developing is very important factor to secure competitiveness. In addition, it is also recognized as a core competency to maintain high productivity in mass production for lowering the unit price over very high fixed cost. This study develops a model for analyzing the effect of the speed of the R&D experimental products required for new product development in the semiconductor/LCD fabrication line on the throughput of mass production. Generally, when the research and development of new products enters the final stage, several R&D lots are put into operation, and the process conditions are optimized to start mass production. The faster the turn-around time (TAT) of the R&D lot, the faster the new product development speed is. In order to shorten the TAT of the R&D lot, the throughput of the mass production is inevitably reduced because of several factors such as an increase in setup time and scheduling inefficiency. This paper develops a probabilistic model for analyzing the offset structure of the throughput of the mass production according to the speed level of an R&D lot in the semiconductor/LCD production and conducts an empirical analysis to illustrate how the model can be used in practice. The analysis shows what level of mass production loss occurs when a semiconductor fab manager operates a certain level of TAT for an R&D lot. This model is expected to provide the fabrication manager with important information on the appropriate TAT decision of an R&D lot.

볼베어링 적용 Twin-scroll WGT의 가솔린 엔진 적용 성능에 대한 실험적 고찰

정재우(Jaewoo Chung),김남호(Namho Kim),강우(Woo Kang),이상운(Sangwoon Lee),정진은(Jineun Chung),장성식(Seongsik Jang),김기용(Giyong Kim) 한국자동차공학회 2017 한국 자동차공학회논문집 Vol.25 No.5

In recent years, the demand for and the technical importance of turbochargers have increased as engineers have been coming up with ways to improve the efficiency and the response of the gasoline engine. In particular, technical interest in ball bearing turbochargers to enhance engine performance, low speed performance, and friction performance has grown. In this study, the performance characteristics and the effect of engine application on ball bearing turbochargers for gasoline engines were investigated. Friction and efficiency performance were evaluated through the gas bench, and the effect on the engine was compared with the performance of the journal bearing mounted turbocharger. Through these studies, the effect of improved frictional performance of ball bearing turbochargers for gasoline engines was presented concretely, as well as the application effects, such as improvements in torque and reactivity in the actual engine.

DME를 연료로 하는 커먼레일 디젤 엔진의 연소와 배기 특성에 미치는 분사압력과 EGR의 영향

정재우(Jaewoo Chung),강정호(Jungho Kang),이성만(Sungman Lee),김현철(Hyunchul Kim),강우(Woo Kang) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.4

In this study, the effect of EGR and fuel injection pressure on the characteristics of combustion and emission performance of the common-rail diesel engine is investigated using DME fuel as a smoke-free alternative fuel. Because the heating value and density of DME fuel are lower than those of diesel fuel, the injection duration of the DME engine is relatively longer than the injection duration of the diesel engine with the same injection pressure. However, the higher injection pressure can shorten the injection duration for the DME engine. Although the smoke level of the DME engine is much lower than that of the diesel engine, the NOx is at a level similar to that of the diesel engine. As a proposed solution for this, the EGR technique is empirically applied to the DME engine.<br/> In the experiments, the injection pressure was changed from 200bar to 400bar, and the EGR rate was limited under 40%. With the same injection timing and fuel amount, the experiment results indicated that the increase of injection pressure led to the increase of IMEP while decreasing HC and CO emissions. However, the NOx emission tends to increase as the injection pressure becomes higher. On the other hand, as the EGR rate was increased, NOx emission and A/F were reduced while the HC and CO emissions were increased. Because HC and CO emissions have the critical A/F point where the emissions of HC and CO are rapidly increased, it is proposed that the EGR rate must be limited under the critical EGR rate.