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Fabrication of a Three-dimensional Terahertz Photonic Crystal Using Monosized Spherical Particles
Takagi Kenta,Seno Kazunori,Kawasaki Akira 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Three-dimensional artificial crystals with periodicity corresponding to terahertz wave lengths were fabricated by self-assembling monosized metal spherical particles. The metal crystals were weakly sintered to utilize them as templates. The metal templates were inverted to air spheres crystal embedded in dielectric resin though infiltration and etching. The resulting resin inverted crystals clearly presented the photonic stop gaps within terahertz wave region and the frequencies of the gaps were confirmed to agree well with calculation by plane wave expansion method.
Fabrication of Artificial Crystal Architectures by Micro-manipulation of Spherical Particles
Takagi Kenta,Kawasaki Akira,Watanabe Ryuzo 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
We newly designed and manufactured a new arranging system for a three-dimensional artificial crystal of monosized micro particles. In this system, a robotic micro-manipulator accurately locates the spherical particle onto the lattice point, and subsequently fiber lasers micro-weld the contact points between the neighboring particles. Actually, one- and two-dimensional arrays were constructed using monosized tin particles with the diameter of 400 m. Moreover, due to optimization of the process parameters, we successfully constructed the artificial crystals of simple cubic and diamond structures. In particular, the diamond structure which can represent a large photonic band gap is expected to progress toward a practical photonic crystal device.
윤성원,Kenta Suzuki,Hideki Takagi,Hiroshi Hiroshima,Yoshinori Kinoshita,Katsuhiro Hayashi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8
High-aspect-ratio microstructures (HARMS) of polyimides have many applications, such as components of microelectromechanical systems and X-ray gratings. This study demonstrates the fabrication of HARMS with vertical and smooth sidewalls in a thick, soluble block-copolymer polyimide (SBCP) film by an UV-assisted thermal imprint process. A preheating condition was controlled as a parameter that dominated the imprint pattern fidelity. After investigating a proper prebaking condition, patterns with a width of 3.4 μm and a height of 35.1 μm with a high-aspect ratio of 10 were successfully structured in an SBCP film that has a thickness of approximately a hundred micrometers. The process has potential as a low-cost fine pattern fabrication process for polyimide-based polymers.
Köbayashi Kenta,Iguchi Kazunobu,Takagi Etsuro 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.3
Polygraphus proximus Blandford (Coleoptera: Curculionidae: Scolytinae) is a non-aggressive monogynous bark beetle that has caused mass mortality in fir (Abies spp.) forests in the last decade. Although gallery structures made by polygynous beetles may influence their reproductive success, the gallery structure and the number of eggs laid by the monogynous tree-killing bark beetle P. proximus has not been investigated in detail in the natural setting of their native range. We, therefore, investigated the length of mother galleries of P. proximus and the number of eggs oviposited by the beetles in relation to gallery systems with different numbers of arms. The number of eggs oviposited in two-armed galleries was significantly greater than that observed in one- and threearmed galleries. Additionally, the length of one- or two-armed galleries with no oviposition was significantly shorter than that in galleries consisting of more than two arms. Our data may suggest that the optimal number of arms in a gallery system (in terms of the number of eggs oviposited) was two.
Köbayashi Kenta,Iguchi Kazunobu,Takagi Etsuro 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.2
Polygraphus proximus Blandford (Coleoptera: Curculionidae: Scolytinae) is a non-aggressive monogynous bark beetle that has caused mass mortality in fir (Abies spp.) forests in the last decade. Although gallery structures made by polygynous beetles may influence their reproductive success, the gallery structure and the number of eggs laid by the monogynous tree-killing bark beetle P. proximus has not been investigated in detail in the natural setting of their native range. We, therefore, investigated the length of mother galleries of P. proximus and the number of eggs oviposited by the beetles in relation to gallery systems with different numbers of arms. The number of eggs oviposited in two-armed galleries was significantly greater than that observed in one- and threearmed galleries. Additionally, the length of one- or two-armed galleries with no oviposition was significantly shorter than that in galleries consisting of more than two arms. Our data may suggest that the optimal number of arms in a gallery system (in terms of the number of eggs oviposited) was two.
Masuda Satoshi,Takagi Kenta,Dong Wei,Kawasaki Akira 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Monosized germanium micro particles are prepared by a newly developed Pulsated Orifice Ejection Method. The obtained particles are categorized into two kinds of the microstructures as refined and coarse ones. The morphological difference is estimated to be determined by the undercooling level during nucleation. Actually, the increase in the temperature of the melt was effective in coarsening the microstructure, because the temperature of the melt intensely relates to the undercooling level. The transition temperature of coarse and refined microstructures is found to be 1300-1350K. Furthermore, a triggered nucleation could improve the crystallinity of the particles in the short separation.
Dong Wei,Masuda Satoshi,Takagi Kenta,Kawasaki Akira 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Mono-sized silicon particles were effectively fabricated by a novel way named pulsated orifice ejection method (POEM). The particles are with very narrow particles size distribution and very small standard deviation of mean particle size. There are two different types spherical silicon particles were found. One consists of many grains mainly in random boundaries. The other consists of two or three grains with only twin orientation relationships, even single crystal in cross-section was also found within this type of spherical silicon particles.
Cold Compaction behavior of nano and micro aluminum powder under high
김다솜,박광재,김경주,조승찬,Yusuke hirayama,Kenta Takagi,권한상 한국복합재료학회 2019 Composites research Vol.32 No.3
In this study, micro-sized and nano-sized pure aluminum (Al) powders were compressed by unidirectional pressure at room temperature. Although neither type of Al bulk was heated, they had a high relative density and improved mechanical properties. The microstructural analysis showed a difference in the process of densification according to particle size, and the mechanical properties were measured by the Vickers hardness test and the nano indentation test. The Vickers hardness of micro Al and nano Al fabricated in this study was five to eight times that of ordinary Al. The grain refinement effect was considered to be one of the strengthening factors, and the Hall–Petch equation was introduced to analyze the improved hardness caused by grain size reduction. In addition, the effect of particle size and dispersion of aluminum oxide in the bulk were additionally considered. Based on these results, the present study facilitates the examination of the effect of particle size on the mechanical properties of compacted bulk fabricated by the powder metallurgy method and suggests the possible way to improve the mechanical properties of nano-crystalline powders.