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京都大学 / 新制・課程博士 / 博士(医学) / 甲第23804号 / 医博第4850号 / 新制||医||1058(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 井上 治久, 教授 林 康紀, 教授 竹内 理 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Think tanks are identified as policy research institutions that conduct interdisciplinary research on social or policy issues and provide consultation with the government, enterprises and the general public. Civil think tanks place social value prior to profits and uphold research independence. Through producing research content on social issues, civil think tanks make contribution with publications, advocacy, and action promotion. Civil think tanks are facing challenging complexity and obstacles in development due to their independence from governments and universities. To resolve these difficulties, civil think tanks require an innovative business model and a matching management mechanism. This thesis aims to understand the business model performed by civil think tanks and explore a practical management model to support this business. Specific recommendations will be made to the case organization. The case study was performed in collaboration with Youthink Center, one of China’s leading civil think tanks which provides young people with a platform to learn, take advocacy, and action on global frontier issues about sustainable development. A systematic literature review was conducted to elaborate concepts connected to think tanks and understand existing management frameworks. Data regarding this research project was collected through internal and external interviews and documentations.The case-study resulted in an evaluation on the business model of Youthink Center and a proposed management framework in accordance with the business. Key aspects of succeeding in a think tank are to insist on the value proposition of social responsibility and to enhance content creation and influence expansion ability with digital tools. To make this business model operate effectively, think tanks are expected to focus on project management processes, talent gathering, evaluation mechanism, and deeper collaborations on knowledge and technology. Understanding these areas will guide the social think tanks to increase working efficiency and enhance social influence. / Tankesmedjor (think tanks) identifieras som politiska forskningsinstitutioner som bedriver tvärvetenskaplig forskning om sociala eller politiska frågor och erbjuder samråd med regeringen, företag och allmänheten. Civila tankesmedjor lägger socialt värde före vinst och upprätthåller forskningsoberoende. Genom att producera forskningsinnehåll om sociala frågor bidrar civila tankesmedjor med publikationer, förespråkande och handlingsfrämjande. Civila tankesmedjor står inför utmanande komplexitet och hinder i utvecklingen på grund av deras oberoende från regeringar och universitet. För att lösa dessa svårigheter kräver civila tankesmedjor en innovativ affärsmodell och en matchande hanteringsmekanism. Denna uppsats syftar till att förstå den affärsmodell som utförs av civila tankesmedjor och utforska en praktisk ledningsmodell för att stödja denna verksamhet. Specifika rekommendationer kommer att ges till fallorganisationen. Fallstudien utfördes i samarbete med Youthink Center, en av Kinas ledande civila tankesmedjor som ger ungdomar en plattform för att lära sig, ta förtal och agera i globala gränsfrågor om hållbar utveckling. En systematisk litteraturgranskning genomfördes för att utarbeta begrepp kopplade till tankesmedjor och förstå befintliga ledningsramar. Data om detta forskningsprojekt samlades in genom interna och externa intervjuer och dokument. Fallstudien resulterade i en utvärdering av affärsmodellen för Youthink Center och en föreslagen ledningsram i enlighet med verksamheten. Nyckelaspekter för att lyckas med en tankesmedja är att insistera på värdet av socialt ansvar och att förbättra innehållsskapandet och påverka expansionsförmågan med digitala verktyg. För att få denna affärsmodell att fungera effektivt förväntas tankesmedjor att fokusera på projektledningsprocesser, talangsamling, utvärderingsmekanismer och djupare samarbete om kunskap och teknik. Att förstå dessa områden kommer att vägleda de sociala tankesmedjorna för att öka arbetseffektiviteten och förbättra det sociala inflytandet.

Septic tanks are utilized by many households across North America for wastewater treatment. Despite the economic and environmental importance of septic tanks, there has been limited innovation in septic tank design and research on the microbial communities responsible for wastewater treatment within these systems. InnerTube systems are septic tanks that employ a novel design to reduce solid accumulation in comparison to conventional septic tanks. For this project, 16S metabarcoding was employed to characterize conventional and InnerTube septic tank microbial communities and evaluate relationships between community composition, system design, and treatment efficacy. Wastewater was sampled along the length of InnerTubes to determine patterns of microbial succession and how they may impact InnerTube function. Wastewater was separated into liquid and solid fractions to identify differentially abundant taxa in each fraction. Populations of methylotrophic methanogens increased with distance from the InnerTube inlet. Solid communities were differentially more abundant in methanogens than liquid communities. Higher rates of solid degradation in InnerTubes may be due to longitudinal stratification of substrates and functionally distinct communities and the activity of methanogenic biomass. Septic tanks throughout Ontario were also surveyed to evaluate the effect of system design (conventional vs. InnerTube) and operational flow (single-pass vs. recirculation) on microbial community composition and to identify taxa correlated with chemical oxygen demand (COD) reduction. Single-pass InnerTube communities were more abundant in Pseudomonas which was attributed increased availability of long-chain fatty acid substrates. Recirculating conventional communities were more abundant in Arcobacter and Desulfomicrobium which was attributed to greater resistance to oxidative stress. Desulfovibrio and Brevundimonas were positively correlated with COD reduction. These putative hydrogen producers may facilitate greater COD reduction by forming syntrophic relationships with hydrogenotrophic methanogens. The findings of this project may be used to develop bioaugmentation inoculum, system designs, or operational strategies to optimize septic tank performance. / Thesis / Master of Science (MSc) / Septic systems (anaerobic digesters) are extensively used for on-site wastewater treatment. We evaluated the use of next-generation DNA sequencing to (1) assess the variability of septic system microbial communities and (2) to investigate relationships between communities and septic system type/performance. Microbial communities within septic systems were determined to be heterogeneous. Analyses also indicated that communities were highly variable between septic systems. Despite this variability, specific system types exhibited distinct microbial profiles. System performance was positively correlated with the abundance of hydrogen-producing bacteria. These results demonstrate the potential of next-generation DNA sequencing as a new tool to augment traditional wastewater analyses.

Solar Domestic Hot Water (SDHW) systems collect energy from the sun to heat the household water. In the context of a system energy balance, numerical simulations were conducted using the commercial software “TRNSYS-17” to study the SDHW system performance (solar fraction) influenced by the critical parameters in various sizes of the thermal storage tank (TES) tank. The key parameters were the magnitude of the collector mass flow rate, degree of thermal stratification within the TES tank, and the duration of the mass flows through the collector. An empirical correlation was obtained to determine the operating collector mass flow rate and TES volume to deliver the peak system performance. The correlation was preliminarily verified with different weather data. The studies showed that the optimal collector mass flow rate occurred when the same amount of total daily household demand passed through the collector. Furthermore, when the twofold amount of the household demand passed through the collector, the optimal dimensionless tank volume became insensitive to the change of collector flow rate and remained constant at 0.84. Researchers discovered that promoting thermal stratification within the TES tank would enhance system performance. Thermal stratification within a TES improves the system performance by sending colder water to the solar collector and hotter water to the household. This research challenges the research community’s focus on thermal stratification by showing that solar fraction is directly related to the solar collector heat losses. As such, the role of the TES tank is to supply cold fluid to the collector to minimize collector losses. Thermal stratification in the top portion of the tank is thus unimportant in influencing solar fraction. In this research, the pump is turned on/off by monitoring the temperature difference between the collector inlet and outlet. Different pump control strategies at different collector mass flow rates were implemented to adjust the pump-on time. The studies showed the system performance was negligibly affected (~0.5%) by employing different pump control strategies while the collector mass flow rate was held constant. / Thesis / Master of Applied Science (MASc)

An ever present trend in the power conversion industry is to get higher performance at a lower cost. In a computer server system, the front-end converter, supplying the load subsystems, is typically a multiple output power supply. The power supply unit is custom designed and its output voltages are fully regulated, so it is not very efficient or cost effective. Most of the load systems in this application are supplied by point-of-load converters (POLs). By leaving the output voltage regulation aspect to POLs, the front-end converter does not need to be a fully regulated, multiple output converter. It can be replaced by a dc-dc transformer (DCX), which is a semi-regulated or unregulated, single output dc-dc converter. A DCX can be made using a modular design to simplify expansion of the system capacity. To realize this concept, the DCX block must have a current sharing feature. The current sharing method for a resonant DCX is discussed in this work. To simplify the system architecture, the current sharing method is based on the droop method, which requires no communication between paralleled units. With this method, the current sharing error is inversely proportional to the droop voltage. In traditional DCX implementations, the droop voltage depends on the resistive voltage drops in the power stage, which is not sufficient to achieve the desired current sharing error. The resonant converter has the inherent characteristic that its conversion gain depends on the load current, so the virtual droop resistance can realized by the resonant tank and the droop voltage can be obtained without incurring conduction loss. An LLC resonant converter is investigated for its droop characteristic. The study shows the required droop voltage is achievable at very high switching frequency. To lower the switching frequency, a notch filter is introduced into the LLC resonant tank to increase the sensitivity of the conversion gain versus the operating frequency. The design of the multi-element resonant tank is discussed. Depending soly on the resonant tank, the droop characteristic is largely varied with the component tolerance in the resonant tank. The current sharing error becomes unacceptable. The active droop control is imposed to make the output regulation characteristic insensitive to the component tolerance. The proposed resonant DCX has simpler circuit structure than the fully regulated resonant converter. Finally simulation and experimental results are presented to verify this concept. / Master of Science

Over the last few decades, the susceptibility of integrated circuits to electrostatic discharge (ESD) induced damages has justified the use of dedicated on-chip protection circuits. Design of robust protection circuits remains a challenging task because ESD failure mechanisms have become more acute as device dimensions continue to shrink. A lack of understanding of the ESD phenomena coupled with the increased sensitivity of smaller devices and time-to-market demands has led to a trial-and-error approach to ESD-protected circuit design. Improved analysis capabilities and a systematic design approach are essential to accomplish the challenging task of providing adequate protection to core circuit(s). The design of ESD protection circuitry for RFIC's has been relatively slow to evolve, compared to their digital counterparts, and is now emerging as a new design challenge in RF and high-speed mixed-signal IC development. Sub-circuits which are not embedded in a single System-on-Chip (SOC), such as RF Power amplifiers (PAs), are of particular concern as they are more susceptible to the various ESD events. This thesis presents the development of integrated ESD protection circuitry for two RFIC Power Amplifier designs. A prototype PA for 2.4 GHz Wireless Local Area Network (WLAN) applications was redesigned to provide protection to the RF input and the PA Control pins. A relatively new technique known as the L-C tank approach was used to protect the RFinput while a standard diode ring approach was used to protect the control line. The protection techniques studied were subsequently extended to a completely protected three-stage PA targeting 1.9 GHz Digitally Enhanced Cordless Telephone (DECT) applications. An on-chip shunt-L-series-C input matching network was used to provide ESD protection to the input pin of the DECT PA. A much more area efficient (as compared to the diode ring technique) Zener diode approach was used to protect the control and signal lines. The PA's RF performance was virtually unaffected by the addition of the protection circuits. Both PAs were designed in a commercially available 0.5 ìm SiGe-HBT process. The partially protected WLAN PA was fabricated and packaged in a 3mm x 3mm Fine Pitch Quad Flat Package FQFP-N 12 Lead package and had a measured ESD protection rating of ± 1kV standard Human Body Model (HBM) ESD test. The simulated DECT PA demonstrated +1.5kV/-4kV HBM performance. / Master of Science