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A Deep Learning Model for Robust Wafer Fault Monitoring With Sensor Measurement Noise
Lee, Hoyeop,Kim, Youngju,Kim, Chang Ouk Institute of Electrical and Electronics Engineers 2017 IEEE transactions on semiconductor manufacturing Vol. No.
<P>Standard fault detection and classification (FDC) models detect wafer faults by extracting features useful for fault detection from time-indexed measurements of the equipment recorded by in situ sensors (sensor signals) and feeding the extracted information into a classifier. However, the preprocessing-and-classification approach often results in the loss of information in the sensor signals that is important for detecting wafer faults. Furthermore, the sensor signals usually contain noise induced by mechanical and electrical disturbances. In this paper, we propose the use of a stacked denoising auto-encoder (SdA), which is a deep learning algorithm, to establish an FDC model for simultaneous feature extraction and classification. The SdA model can identify global and invariant features in the sensor signals for fault monitoring and is robust against measurement noise. Through experiments using wafer samples collected from a work-site photolithography tool, we confirmed that as the sensor measurement noise severity increased, the SdA's classification accuracy could be as much as 14% higher than those of the twelve models considered for comparison, each of which employed one of three feature extractors and one of four classifiers.</P>
Effect of beam slope on the static aerodynamic response of edge-girder bridge-deck
Lee, Hoyeop,Moon, Jiho,Chun, Nakhyun,Lee, Hak-eun Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.2
2-edge box girder bridges have been widely used in civil engineering practice. However, these bridges show weakness in aerodynamic stability. To overcome this weakness, additional attachments, such as fairing and flap, are usually used. These additional attachments can increase the cost and decrease the constructability. Some previous researchers suggested an aerodynamically stabilized 2-edge box girder section, giving a slope to the edge box instead of installing additional attachments. However, their studies are limited to only dynamic stability, even though static aerodynamic coefficients are as important as dynamic stability. In this study, focus was given to the evaluation of static aerodynamic response for a stabilized 2-edge box girder section. For this, the slopes of the edge box were varied from $0^{\circ}$ to $17^{\circ}$ and static coefficients were obtained through a series of wind tunnel tests. The results were then compared with those from computational fluid dynamics (CFD) analysis. From the results, it was found that the drag coefficients generally decreased with the increasing box slope angle, except for the specific box slope range. This range of box slope varied depending on the B/H ratio, and this should be avoided for the practical design of such a bridge, since it results in poor static aerodynamic response.
해상풍력 주민수용성 제고를 위한 서남해 해상풍력단지 내 수산업 공존방안 추진 현황
이호엽(Hoyeop Lee),한관우(Kwan-Woo Han),경두현(Doo-hyun Kyung),강금석(Keum-Seok Kang) 한국해양환경·에너지학회 2021 한국해양환경·에너지학회 학술대회논문집 Vol.2021 No.10
본 연구에서는 해상풍력의 주민수용성 제고를 위한 수산업 공존방안을 실증하고자 한다. 해상풍력단지가 개발되게 되면, 지역 어민은 해상풍력단지 내 바다를 사용하는데 제약이 따른다. 이에 따라 수산업 생산이 축소되고 경제적 손실을 입을 수 있게 된다. 본 연구에서는 서남해 해상풍력 실증단지 내에 수산업 공존 어업설비(연승수하식)를 실증/운영하여, 지역 어민에게 새로운 경제 모델을 제안하고자 한다. 이를 위해, 상업 규모(4ha) 공존 어업설비를 설계하고, 수치해석과 수조모형실험, 앵커 현장실험을 통해 구조적 안전성을 입증한다. 또한, 통합운영시스템을 개발하여 풍력과 수산업을 동시에 통합 관리하고, 약 1년간 양식을 수행하여 공존어업의 경제성을 분석하고자 한다. In this research, the coexistence fishing in the wind turbine complex is demonstrated to improve of resistance acceptability. According to develop the wind turbine complex, the local resistance has restrict of fishing in the wind turbine complex. From the this reason, the local resistance might have a loss of money for fishing. In this project, the coexistence fishing(long-line suspended) will be demonstrated and operated in the southwest wind turbine complex. Above this, the new economical earnings model will be suggested to the resistance. In the progress, the first, the coexistence fisheries facility for business scale(4ha) is designed. Second, the structural stability is verified by numerical simulation and hydraulic test for the facility. Third, integrated operating system is developed and it administer wind power-fishery in same time. Finally, this project will perform the coexistence fishing during 12 months and analysis the economic feasibility of the coexistence fishery.
Seungtaek Oh,Hoyeop Lee,Sung-Soon Yhim,Hak-Eun Lee,Nakhyun Chun 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.1
Damping ratio and frequency have influence on dynamic serviceability or instability such as vortex-induced vibration and displacement amplification due to earthquake and critical flutter velocity, and it is thus important to make determination of damping ratio and frequency accurate. As bridges are getting longer, small scale model test considering similitude law must be conducted to evaluate damping ratio and frequency. Analysis conditions modified by similitude law are applied to experimental test considering different scale ratios. Generally, Nyquist frequency condition based on natural frequency modified by similitude law has been used to determine sampling rate for different scale ratios, and total time length has been determined by users arbitrarily or by considering similitude law with respect to time for different scale ratios. However, Nyquist frequency condition is not suitable for multimode system with noisy signals. In addition, there is no specified criteria for determination of total time length. Those analysis conditions severely affect accuracy of damping ratio. The focus of this study is made on the determination of minimum analysis conditions for different scale ratios. Influence of signal to noise ratio is studied according to the level of noise level. Free initial value problem is proposed to resolve the condition that is difficult to know original initial value for free vibration. Ambient and free vibration tests were used to analyze the dynamic properties of a system using data collected from tests with a two degree-of-freedom section model and performed on full bridge 3D models of cable stayed bridges. The free decay is estimated with the stochastic subspace identification method that uses displacement data to measure damping ratios under noisy conditions, and the iterative least squares method that adopts low pass filtering and fourth order central differencing. Reasonable results were yielded in numerical and experimental tests.
Oh, Seungtaek,Lee, Hoyeop,Yhim, Sung-Soon,Lee, Hak-Eun,Chun, Nakhyun Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.1
Damping ratio and frequency have influence on dynamic serviceability or instability such as vortex-induced vibration and displacement amplification due to earthquake and critical flutter velocity, and it is thus important to make determination of damping ratio and frequency accurate. As bridges are getting longer, small scale model test considering similitude law must be conducted to evaluate damping ratio and frequency. Analysis conditions modified by similitude law are applied to experimental test considering different scale ratios. Generally, Nyquist frequency condition based on natural frequency modified by similitude law has been used to determine sampling rate for different scale ratios, and total time length has been determined by users arbitrarily or by considering similitude law with respect to time for different scale ratios. However, Nyquist frequency condition is not suitable for multimode system with noisy signals. In addition, there is no specified criteria for determination of total time length. Those analysis conditions severely affect accuracy of damping ratio. The focus of this study is made on the determination of minimum analysis conditions for different scale ratios. Influence of signal to noise ratio is studied according to the level of noise level. Free initial value problem is proposed to resolve the condition that is difficult to know original initial value for free vibration. Ambient and free vibration tests were used to analyze the dynamic properties of a system using data collected from tests with a two degree-of-freedom section model and performed on full bridge 3D models of cable stayed bridges. The free decay is estimated with the stochastic subspace identification method that uses displacement data to measure damping ratios under noisy conditions, and the iterative least squares method that adopts low pass filtering and fourth order central differencing. Reasonable results were yielded in numerical and experimental tests.