Hexagonal Material Flow Pattern for Next Generation Semiconductor Fabrication

Jaewoo Chung(정재우),Jungdae Suh(서정대) 대한산업공학회 2010 대한산업공학회지 Vol.36 No.1

The semiconductor industry is highly capital and technology intensive. Technology advancement on circuit design and process improvement requires chip makers continuously to invest a new fabrication facility that costs more than 3 billion US dollars. Especially major semiconductor companies recently started to discuss 450mm fabrication substituting existing 300mm fabrication of which facilities were initiated to build in 1998. If the plan is consolidated, the yield of 450mm facility would be more than doubled compared to existing 300mm facility. In steps of this important investment, facility layout has been acknowledged as one of the most important factors to be competitive in the market. This research proposes a new concept of semiconductor facility layout using hexagonal floor plan and its compatible material flow pattern. The main objective of this proposal is to improve the productivity of the unified layout that has been popularly used to build existing facilities. In this research, practical characteristics of the semiconductor fabrication are taken into account to develop a new layout alternative based on the analysis of Chung and Tanchoco (2009). The performance of the proposed layout alternative is analyzed using computer simulation and the results show that the new layout alternative outperforms the existing layout alternative, unified layout. However, a few questions on space efficiency to the new alternative were raised in communication with industry practitioners. These questions are left for a future study.

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.

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.

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%.

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.

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.

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.

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.

압축기 회전속도를 활용한 압축기 유량율 및 저압 EGR 유량율 산정 방법에 관한 고찰

정재우(Jaewoo Chung),김남호(Namho Kim),이상운(Sangwoon Lee),이범호(Beumho Lee),김덕진(Deokjin Kim) 한국자동차공학회 2018 한국 자동차공학회논문집 Vol.26 No.3

The precise control of the engine gas circulation system is an important technical task in improving the fuel economy and emission performance of a diesel engine. Moreover, the virtual flow sensor using a turbocharger rotational speed signal can be used for the precise control of complicated boost and EGR control systems. Based on this technical background, this study examined the basic calculation logic of the virtual gas flow rate sensor by using the proposed turbocharger rotation speed, and validated it with test results. Specifically, the estimation method of the intake air flow rate and the EGR flow rate of the HP-EGR engine and the estimation method of the EGR flow rate of each loop in the dual-loop EGR engine were presented. To achieve these, a method to improve the accuracy of the calculation results of the compressor flow rate in the engine was presented, and the results of the comparison between the calculation results and the experimental results were discussed.

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.