京都大学 / 新制・課程博士 / 博士(理学) / 甲第23006号 / 理博第4683号 / 新制||理||1672(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 野上 大作, 教授 一本 潔, 教授 太田 耕司 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21687号 / 医博第4493号 / 新制||医||1036(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 竹内 理, 教授 清水 章, 教授 遊佐 宏介 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Structure-property relationships of two crystal structures were investigated using computational methodologies in two different length scales:electronic and atomistic length scales. Electronic structure calculations were performed using density functional theory (DFT) with generalized gradient approximation (GGA), GGA+U (U is “on-site” electronelectron repulsion) and hybrid functional forms. Atomistic calculations were performed utilizing the semi-empirical interatomic formulation, Modified Embedded Atom Method (MEAM). Classical molecular dynamics simulations were performed on the atomistic length scale in order to investigate thermal properties. In the first study, structural, elastic and thermal properties of cementite (Fe3C) were investigated using a Modified Embedded Atom Method (MEAM) potential for iron-carbon (Fe-C) alloys. Previously developed Fe and C single element potentials were used to develop a Fe-C alloy MEAM potential, using a statistically-based optimization scheme to reproduce structural and elastic properties of cementite, the interstitial energies of C in bcc Fe as well as heat of formation of Fe-C alloys in L12 and B1 structures. The stability of cementite at high temperatures was investigated by molecular dynamics simulations. The nine single crystal elastic constants for cementite were obtained by computing total energies for strained cells. Polycrystalline elastic moduli for cementite were calculated from the single crystal elastic constants of cementite. The formation energies of (001), (010), and (100) surfaces of cementite were also calculated. The melting temperature and the variation of both the specific heat and volume with respect to temperature were investigated by performing a two-phase (solid/liquid) molecular dynamics simulation of cementite. The predictions of the potential are in good agreement with first-principles calculations and experiments. In the second study the site occupancy and magnetic properties of Zn-Sn substituted M-type Sr-hexaferrite (SrFe12-x(Zn0.5Sn0.5)xO19 with x = 1) were investigated using firstprinciples total-energy calculations. We find that in the ground-state configuration Zn-Sn ions preferentially occupy 4f1 and 4f2 sites unlike the model previously suggested by Ghasemi et al. where Zn-Sn ions occupy 2b and 4f2 sites. Our model predicts a rapid increase in saturation magnetic moment (Ms) as well as decrease in magnetic anisotropy compared to the pure M-type Sr-hexaferrite, which is consistent with experimental observations.

Nuclear magnetic resonance is a method, which provides information about the magnitude of hyperfine field present on izotope's nuclei with non-zero spin. The hyperfine field is sensitive to the local ordering of atoms surrounding the nuclei. The hyperfine field changes can be observed in response to changes in surroundings caused by substitution. The NMR spektra of 57Fe nuclei in the hexagonal ferrites with magnetoplumbit structure which contain cation substitution of trivalent cations Nd, Pr in crystallographic position of divalent cations Sr are measured and interpreted in this work. All experiment are measured at 4.2 K and we investigate the influence of the cation substituion on hyperfine field in thr measured oxides.

近年來M型社會及平價奢華趨勢已成為一個熱門的議題，不論在消費面或是社會面等都造成踴躍的討論，由於財富分眾組成的改變，形成了逐漸改變的消費觀，也帶來了一種新成形的生活形態。在這樣的消費環境之下，M型的行銷模式也儼然成為一種新顯學，「平價奢華」的產品或服務，成為M型社會新形成產業趨勢之最佳範例。而在諸多品牌中，帶起一股「快速時尚(fast fashion)」風潮的西班牙品牌ZARA，帶起了大眾精品(masstige)之熱潮，而經歷了品牌大轉型，強調品牌年輕化，且大膽直營過季折扣店，成功從退流行的媽媽包品牌，翻身成為大受歡迎品牌的COACH，則是以買得起的奢華 (accessible luxury)為主要的策略，因此本研究以此兩個具代表性的品牌作為研究主題。 本研究選擇採用個案研究的方式，以Michael Porter的價值鏈之角度來解構ZARA及COACH在變動環境下，於經營模式(business model)上所做的突破及調整，並在個案分析中，從產業中最細微的各個構面去探討兩個品牌在經營上的創新之舉，及對兩公司在現有資源之掌握及策略運用進行連結，瞭解兩者如何結合自有資源及核心能耐來產生創新的力道。希望藉由這兩個各自往M型兩端移動的品牌之創新模式探究，能更加深入且具體地瞭解到兩個公司的創新經營之道，以提供台灣其他相關業者參考，提升台灣相關產業之競爭力。 / Recently,“M-type society”and the trend of“affordable lux-ury”have been very popular issues and raised many discussions. Due to the change in financial formation in society, it formed the changing concept of consumption and a new lifestyle. In this kind of situation, the philosophy of“M-type society”has been a very significant new contention. Some products or service with the concept of “affordable luxury” has been the best expanple of the industrial trend. Like Spanish brand—Zara, which brought the “fast fa-shion”and “masstige” fetish to the world, is a very outstanding example of it. Also, American luxury brand—Coach, which went through the revitalization of the brand image and emphasized on the image of“affordable luxury”, is a good example as well. Therefore, this research take the two representative brands as the subjects of this study. Case-study research method is used in this study, and the value chain theory from Michael Porter will be the analytical tool to analyze and explain ZARA and COACH’s innovative business model and find out the management meaning in the two cases to provide some useful suggestions for related organizations in Taiwan.

In this thesis, the possibility of enabling space-mining for the upcoming decade is explored. Making use of recently-proven reusable rockets, we envision a fleet of spacecraft capable of reaching Near-Earth asteroids. To analyze this idea, the goal of this problem is to maximize the asteroid mass retrieved within a spacecraft max life span. Explicitly, the maximum lifetime of the spacecraft fleet is set at 30 years. A fuel supply-chain is proposed and designed so that each spacecraft is refueled before departing for each asteroid. To maximize access to the number of asteroids and retrievable mass for each mission, we propose launching each mission from an orbit with low escape velocity. The L2-Halo orbit at the libration point in the Earth-Moon system was selected due to its easy access from Low-Earth Orbit and for a cislunar synergy with NASA Gateway. Using data from NASA SmallBody and CNEOS databases, we investigated NEAs in the period between 2030 and 2060 could be captured in the ecliptic plane and returned to L2-Halo with two approaches, MARM-1 and MARM-2. Together, these databases provide all information for every asteroid's close approach known today. Returning the asteroid as a whole is explored in the MARM-1 method, while MARM-2 evaluates the possibility of reaching larger asteroids and returning a fragment of their masses, such that it optimizes the available cargo weight per time of flight of each mission. The following results are compared with previous work from the community. The results show a 96% reduction in the cost per kg, with an enormous increase in retrieved mass. With these results, this thesis shows that not solely energy or dynamic optimization will be responsible for proving space mining feasibility, but rather a combination of those and business best practices. Proving feasibility for space mining is a complex and immense problem. Although this thesis opens new possibilities for future work on the field and sparkes the interest of private endeavors, the final solution for this problem still requires additional exploration. / M.S. / In this thesis, the possibility of enabling space-mining for the upcoming decade is explored. Making use of recently-proven reusable rockets, we envision a fleet of spacecraft capable of reaching Near-Earth asteroids, NEAs. To analyze this idea, the goal of this problem is to maximize the asteroid mass retrieved within a spacecraft max life span. Explicitly, the maximum lifetime of the spacecraft fleet is set at 30 years. A fuel supply-chain is proposed and designed so that each spacecraft is refueled before departing for each asteroid. To maximize access to the number of asteroids and retrievable mass for each mission, we propose launching each mission from an orbit with low escape velocity. A location after the Moon, at the L2-Halo orbit, was selected due to its easy access from Low-Earth Orbit and for a synergy with the proposed new space station at the Moon orbit. Using data from NASA databases, we investigated the asteroids in the period between 2030 and 2060 that could be captured and returned with two approaches, MARM-1 and MARM-2. Together, these databases provide all information for every asteroid's close approach known today. Returning the asteroid as a whole is explored in the MARM-1 method, while MARM-2 evaluates the possibility of reaching larger asteroids and returning a fragment of their masses, such that it optimizes the available cargo weight per time of flight of each mission. The following results are compared with previous work from the community. The results show a 96% reduction in the cost per kg, with an enormous increase in retrieved mass. With these results, this thesis shows that not solely energy or dynamic optimization will be responsible for proving space mining feasibility, but rather a combination of those and business best practices. Proving feasibility for space mining is a complex and immense problem. Although this thesis opens new possibilities for future work on the field and sparkes the interest of private endeavors, the final solution for this problem still requires additional exploration.