균일한 다공성 주름진 실리카 나노입자의 제조와 응용: 화학적 기계적 평탄화, 태양 전지, 전기유변유체

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 화학생물공학부, 2018. 2. 장정식.Mesoporous silica nanomaterials have received much attention due to their dramatic increased surface to volume ratio. These porous structures have been used extensively in a variety of applications such as catalyst supporters, adsorption, separation, drug delivery, electrodes, and hard templates for fabrication of nanocomposites due to their unique features. Among various structures of mesoporous silica nanomaterials, spherical mesoporous silica nanoparticles have attracted much attention because they provide excellent pore accessibility and smooth molecular diffusion. Therefore, various methods for the fabrication of spherical mesoporous silica nanoparticles with a range of pore structure types have been reported, and have contributed to the development of fields such as packing materials for chromatography, drug delivery, cosmetics, and adsorption. However, despite the variety of methods for preparing spherical mesoporous silica nanoparticles, it should be still required to develop fabrication methods of spherical mesoporous silica nanoparticles with uniformity and high yields. This dissertation introduces a method for fabricating uniform hierarchical mesoporous wrinkled silica nanoparticles. Furthermore, formation mechanism of the uniform spherical mesoporous silica naoparitcles was discussed by investigating the factors affecting the particle size and pore size of the naoparitcles. Thus, a complete method for high-yield production of uniform hierarchical mesoporous wrinkled silica nanoparticles with tunable particle size and pore size is provided. The prepared uniform mesoporous silica nanoparticles manifested better performance than non-porous silica nanoparticles of the same size in applications of abrasives in chemical mechanical planarization, scattering materials in dye sensitized solar cells, and hard templates for fabricating nanocomposite of ER fluids, demonstrating the superiority of the mesoporous structure. This dissertation suggests that silica nanoparticles with mesoporous structure offer the potential for performance enhancement in applications where non-porous silica spheres are currently used.1. Introduction 1 1.1. Background 1 1.1.1. Nanostructured Materials 1 1.1.1.1. Nanomaterials 1 1.1.1.2. Silica Nanomaterials 2 1.1.1.3. Mesoporous Silica Nanomaterials 7 1.1.1.4. Spherical Mesoporous Silica Nanomaterials 8 1.1.2. Applications 12 1.1.2.1. Chemical Mechanical Planarization 12 1.1.2.2. Dye Sensitized Solar Cells 14 1.1.2.3. Electrorheological Fluids 17 1.2. Objectives and Outlines 18 1.2.1. Objectives 18 1.2.2. Outlines 18 2. Experimental Details 22 2.1. Fabrication of Uniform Hierarchical Mesoporous Wrinkled Silica Nanoparticles 22 2.1.1. Fabrication of uniform hierarchical mesoporous wrinkled silica nanoparticles (WSNs) 22 2.1.2. Characterization of hierarchical mesoporous wrinkled silica nanoparticles 23 2.1.3. The chemical mechanical polishing performance evaluation of the WSNs as slurry abrasives 23 2.1.4. Performance of dye sensitized solar cells with scattering layer of WSNs 24 2.2. Fabrication of Hierarchical Mesoporous Wrinkled Silica Nanoparticle based-SiO2/TiO2 Hollow Nanoparticles 26 2.2.1. Fabrication of hierarchical mesoporous wrinkled silica nanoparticle based-SiO2/TiO2 hollow nanoparticles 26 2.2.2. Characterization of hierarchical mesoporous wrinkled silica nanoparticle based-SiO2/TiO2 hollow nanoparticles 27 2.2.3. Electrorheological properties of electrorheological fluid based on hierarchical mesoporous wrinkled silica nanoparticle based-SiO2/TiO2 hollow nanoparticles 27 3. Results and Disccusions 29 3.1. Fabrication of Uniform Hierarchical Mesoporous Wrinkled Silica Nanoparticles 29 3.1.1. Fabrication of uniform hierarchical mesoporous wrinkled silica nanoparticles (WSNs) 29 3.1.2. Characterization of hierarchical mesoporous wrinkled silica nanoparticles 39 3.1.3. The chemical mechanical polishing performance evaluation of the WSNs as slurry abrasives 57 3.1.4. Performance of dye sensitized solar cells with scattering layer of WSNs 65 3.2. Fabrication of Hierarchical Mesoporous Wrinkled Silica Nanoparticle based-SiO2/TiO2 Hollow Nanoparticles 80 3.2.1. Fabrication of hierarchical mesoporous wrinkled silica nanoparticle based-SiO2/TiO2 hollow nanoparticles 80 3.2.2. Characterization of hierarchical mesoporous wrinkled silica nanoparticle based-SiO2/TiO2 hollow nanoparticles 83 3.2.3. Electrorheological properties of electrorheological fluid based on hierarchical mesoporous wrinkled silica nanoparticle based-SiO2/TiO2 hollow nanoparticles 98 4. Conclusion 112 Reference 115 국문초록 123Docto

A Study on the design of ship`s bow form using surface panel method

학위논문(박사)--서울大學校 大學院 :造船海洋工學科,1996.Docto

메모리 효율적 양방향 트랜스포머를 활용한 긴 비디오의 엔드 투 엔드 생성 모델링 연구

학위논문(석사) - 한국과학기술원 : 전산학부, 2023.8,[iv, 26 p. :]Autoregressive transformers have shown remarkable success in video generation. However, the transformers are prohibited from directly learning the long-term dependency in videos due to the quadratic complexity of self-attention, and inherently suffering from slow inference time and error propagation due to the autoregressive process. In this paper, we propose Memory-efficient Bidirectional Transformer (MeBT) for end-to-end learning of long-term dependency in videos and fast inference. Based on recent advances in bidirectional transformers, our method learns to decode the entire spatio-temporal volume of a video in parallel from partially observed patches. The proposed transformer achieves a linear time complexity in both encoding and decoding, by projecting observable context tokens into a fixed number of latent tokens and conditioning them to decode the masked tokens through the cross-attention. Empowered by linear complexity and bidirectional modeling, our method demonstrates significant improvement over the autoregressive transformers for generating moderately long videos in both quality and speed.한국과학기술원 :전산학부

Planning research for eco-friendly development of Korea grand canal

한국해양연구