A Study on Development of Micro 3D-PTV using Single Camera

In this paper, a micro-stereoscopic PTV system is developed using single camera system. Two viewing holes are installed just behind the object lens of the microscopic system to construct a stereoscopic viewing. The system consists of one high-definition camera (1028 x 1024 pixel, 500fps), a plate of two-viewing holes and the host computer. Since two image pair for one tracer particle exists on the same image, it is not so easy to find the same particle pairs among many particles in the images. Two calculation methods have been introduced to calculate three-dimensional positions of the particles. One is to introduce a hybrid genetic algorithm (GA) to calculate three-dimensional vector fields. The other one is to utilize the distances between the two image centers of the particles made by the two viewing holes. As for the first calculation, the hybrid genetic algorithm (GA) has been used to find the same particles' image pairs seen on the experimental images. An epipolar line was used to reduce the number of candidates for one particle. In the genetic algorithm, crossover operation, mutation operation and reproduction operation are introduced. Percentile values of these three values are changed to find the most optimal pairring conditions. In order to make a performance test for the constructed algorithm, the camera parameters obtained in the process of camera calibrations have been used for generating a set of virtual image. Using the constructed virtual images the optimal calculation conditions have been found. That is, it has been empirically verified that optimal percentile values for the GA algorithm are crossover 100%, mutation 20%, Reproduction 50%, respectively. Further, the optimal diameter of the two holes were 3.5mm and the distance between the two holes were 5mm. The measurement errors for X, Y and Z coordinates could be estimated using the results of camera calibration as 0.083μm, 0.045μm and 0.083μm, respectively. And the deviations of the measurement error could be estimated as 0.725μm, 0.452μm, 4.108μm. As for the second calculation method for the calculation of three-dimensional vector fields, the distance between the photographic centers of the two images that have been constructed by the two holes. A relation between Z-positions and the distances are calculated before the main experiment so that the Z positions of any unknown particles can be predicted. The center points of the distance have been regarded as the photographical coordinates on X and Y axises. The constructed micro-stereoscopic PTV(a 3D-PTV) has been used to measure the velocity fields of a micro-back-step channel flow. The height of the back-step is 36 μm and the height of the channel is 60 μm with a width of 3mm. The Reynolds number is 0.017. The data obtained by the constructed system have been compared with those of CFD. It has experimentally verified that the velocity profiles shows a good agreement quantitatively and qualitatively. The constructed micro measurement system is planed to be used for the measurements of the wall boundary layers in turbulent flows.제 1 장 서 론 ....................................................................................................1 제 2 장 3D/4D측정 이론 ...................................................................................9 2.1 3D 측정법 개요 ............................................................................................9 2.2 3D-PTV 측정법 .......................................................................................10 2.3 3D-PTV 측정법과 유전알고리즘 ...............................................................21 2.4 고해상 4D-PTV측정법 ...............................................................................27 제 3 장 Single camera Micro 3D-PTV system .......................................30 3.1 측정시스템 구성과 측정원리 .....................................................................30 3.2 오차해석 .....................................................................................................47 3.3 가상영상에 의한 성능평가 .........................................................................54 제 4 장 후향단 Micro 채널 실험 및 고찰 ...................................................62 4.1 실험 장치 및 방법 .......................................................................................62 4.1 실험 결과 .....................................................................................................74 제 5 장 결론 .......................................................................................................9

Crashworthiness optimization of a closed-hat section member using the homogenization method and experiment of design

학위논문(박사)--서울대학교 대학원 :기계항공공학부,2002.Docto

마그네슘이차전지용 마그네슘 이온 삽입이 가능한 새로운 구조의 LiNi0.5Co0.2Mn0.3O2 양극 소재 연구

학위논문 (석사)-- 서울대학교 대학원 : 재료공학부, 2016. 8. 강기석.Mg rechargeable battery is one of the most promising next-generation batteries on the merits of its high theoretical capacity, low cost and safety. However, searching new cathode materials with high energy density has been a great challenge so far due to the sluggish diffusion kinetics of divalent Mg2+ ions in the crystal structure of electrode materials. In this study, we utilize LiNi0.5Co0.2Mn0.3O2 (NCM523), which is widely used electrode material for Li-ion batteries (LIBs), as a cathode material for Mg rechargeable battery. We first discover that NCM523 can be a Mg intercalation host with high energy density along with the water-induced phase transformation from O3 to P3 layered structure. The water-intercalated P3 phase delivers the highest Ni2+/Ni3+/Ni4+ redox potential of 3.1 V vs. Mg/Mg2+ yet reported for Mg cathode materials, with high energy density of 589 Wh kg-1. This unusual behavior in NCM layered oxide, proposed in this work, provides an insight into designing promising cathode materials for Mg rechargeable battery.Chapter 1. Introduction 1 1.1 Motivation and outline 1 Chapter 2. Reaserch backgrounds 4 2.1. Introduction to Mg rechargeable batteries 4 2.2. Layered oxide 5 Chapter 3. Experimental 8 3.1. Characterization of LiNi0.5Co0.2Mn0.3O2 8 3.2. Electrochemical analysis 8 3.3. Ex-situ structural analysis 9 3.3.1. X-ray diffraction 9 3.3.2. High-Resolution transmission electron microscope 9 3.3.3. Fourier transform infrared spectrometry 10 3.3.4. Thermal gravimetric analysis 10 3.3.5. X-ray photoelectron spectroscopy 11 3.3.6. Field-Emission scanning electron microscopy 11 3.3.7. X-ray absorption spectroscopy 11 Chapter 4. Results and discussion 13 4.1. Effect of charge capacity on electrochemical activity 13 4.2. Activation process and de/magnesiation mechanism 17 4.3. Confirmation of de/magnesiation 30 4.4. Monitoring redox reaction of Ni, Co and Mn 33 Chapter 5. Conclusion 37 Reference 38 국문 요약 47Maste

Hepatic resection compared to percutaneous ethanol injection for hepatocellular carcinoma using propensity score matching

Thesis(master`s)--서울대학교 대학원 :의학과 외과학전공,2006.Maste

암세포의 생물리적 환경이 NK 세포 암세포 살해능에 미치는 영향

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Bio-physical environments of tumor cells determine NK cell cytotoxicity

2