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Avalanche-like Quenches in Cable in Conduit Conductors
Kazutaka Seo,Arata Nishimura,Yoshimitsu Hishinuma 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
Superconducting conductors carrying large currents of more than several tens of kA are required for magnetic confinement fusion apparatuses. A cable-in-conduit conductor (CICC), which has around a thousand parallel and twisted thin superconducting strands in a stiff conduit, is a promising candidate for such large and high-magnetic-field superconducting systems. We developed a numerical code AQUAPS (Avalanche-like QUench Analysis for Parallel Superconducting strands) simulating electromagnetic and thermal phenomena in a conductor consisting of parallel superconducting strands. A specific phenomenon in the CICC is so-called avalanche-like quench. When one strand becomes resistive due to current saturation or a mechanical disturbance, e.g. frictional heating, it loses the transport current and the current re-distributes into neighboring strands. Neighboring strands are electromagnetically well coupled and electrically contact each other. Therefore, neighboring strands receive supplemental current from the original strand and this results in a following quench. We call this phenomenon ’avalanche-like quench’. With the newly developed numerical code AQUAPS, we have simulated quenches in multi-strand cables with both Nb3Sn and NbTi strands and compared these. For the Nb3Sn cable, the critical temperature (Tc) may be much larger than the liquid-helium bath temperature (T0), in spite of the fact that current sharing temperature (Tcs) is almost equal to T0. This situation is very different from that in the NbTi cable. We analyzed this issue intensively and present some discussion.0chh9mu
A Bureaucrat’s Vision of a Modernized Japan
Kazutaka Kojima 계명대학교 사회과학연구소 2018 한국사회과학연구 Vol.37 No.1
In this paper I present a picture of Sensai Nagayo, the first Director of the Central Hygiene Bureau in the Home Ministry. Today Nagayo is well known as the first Director of the Bureau, but in fact, researchers do not know how he understood the Western-style public health system, and what kind of public health system he envisaged. Nagayo recognized the importance of the public health system for a modernized Japan. The system he discovered was sanitation or Gesundheitspflege. When Nagayo realized their importance, he proposed seimu- teki- unyo (the application of policies) based on medical science and associated sciences (e.g., natural science, engineering, meteorology, statistics). During the implementation of these health protection policies, Nagayo started to think two functions were important: the first one being the government, which was led by staff in towns and villages, police officers, and doctors under the Home Ministry; and the second being the residents or Eisei kumiai (the association for public health in each area). In conclusion, Nagayo realized he had to work on the creation of a cooperative system between the government and the residents. Public health for a modernized Japan was formed out of the bureaucratic vision of a technocratic government official, Sensai Nagayo.
PBL Based Engineering Education to Cultivate Leadership Spirit in Postgraduate Students
Kazutaka Yokota,Masatomo Maruoka,Junji Takaki,Shinichi Watanabe 한국공학교육학회 2012 공학교육연구 Vol.15 No.5
Utsunomiya University started a 3-year project to develop an education program for postgraduate students to cultivate leadership spirits. The program is centered on a PBL in which each group of students is required to find an engineering or social problem themselves and start a project to solve the problem. Projects vary widely, from a straight product development to a summer program for children or local area development. Student groups are advised by senior engineers from industries. They give advice as to how a project should be managed and run, but will not give instructions. The PBL is compulsory for all students in the engineering master course students. The new education program also includes a series of lectures by engineers to show engineers’ job, activities, and career in the industry. Internship programs are also provided, in which students will be given opportunities to actively apply their knowledge and skills to real engineering tasks offered by the industry. The students are expected to gain something more than just experiences.
Circadian variations in salivary chromogranin a concentrations during a 24-hour period in dogs
Kazutaka Kanai,Mariko Hino,Yasutomo Hori,Ruriko Nakao,Fumio Hoshi,Naoyuki Itoh,Seiichi Higuchi 대한수의학회 2008 Journal of Veterinary Science Vol.9 No.4
The purpose of this study was to determine if salivary chromogranin a secretion in dogs exhibits a circadian rhythm. Saliva sampling was performed during three different sessions occurring in three nonconsecutive 24-h periods. Sixteen healthy adult beagle dogs (8 males and 8 females) were moved to a sampling room and housed individually in cages. Saliva samples were obtained every 4 h from 12:00 p.m. to 12:00 p.m. the following day. In the interest of habituation, saliva was obtained hourly from each dog 3 h before the experiment was started. Salivary chromogranin A concentrations were measured using an enzyme-linked immunosorbent assay. No circadian rhythm was detected for salivary chromogranin A secretion, and no differences in salivary chromogranin A concentrations measured every 4 h were demonstrated during the 24-h cycle in dogs.
Roles of Participatory Action-oriented Programs in Promoting Safety and Health at Work
Kazutaka, Kogi Occupational Safety and Health Research Institute 2012 Safety and health at work Vol.3 No.3
Reflecting the current international trends toward proactive risk assessment and control at work with practical procedures, participatory action-oriented approaches are gaining importance in various sectors. The roles of these approaches in promoting the safety and health at work are discussed based on their recent experiences in preventing work-related risks and improving the quality of work life, particularly in small-scale workplaces. The emphasis placed on the primary prevention at the initiative of workers and managers is commonly notable. Participatory steps, built on local good practices, can lead to many workplace improvements when the focus is on locally feasible low-cost options in multiple aspects. The design and use of locally adjusted action toolkits play a key role in facilitating these improvements in each local situation. The effectiveness of participatory approaches relying on these toolkits is demonstrated by their spread to many sectors and by various intervention studies. In the local context, networks of trainers are essential in sustaining the improvement activities. With the adequate support of networks of trainers trained in the use of these toolkits, participatory approaches will continue to be the key factor for proactive risk management in various work settings.
Cholesterol Depletion Influences Lateral Diffusion of Insulin Receptor
Kazutaka Oda,Kazuya Kabayama 한국당과학회 2012 한국당과학회 학술대회 Vol.2012 No.1
Microdomains are constructed by cholesterol, sphingomyelin, and gangliosides in plasma membrane. The microdomains, which are dynamic structure in the cellular membrane, controls lateral diffusion and signaling of membrane molecules such as growth factor receptors (GFR). However, we still could not figure out the generalized mechanisms. We hope to demonstrate that an alteration of lipid component in microdomain affects lateral diffusion of membrane receptor. Therefore, we established experimental system in which monitored the membrane organization of receptors by analyzing its lateral diffusion parameters in the plasma membrane of living cells using fluorescence recovery after photobleaching (FRAP). In the FRAP analysis, we used CHO-K1 cells stably expressed the insulin receptor fused green fluorescence protein (IR-EGFP). Then, fluorescence recovery curves of IR-EGFP in the bleach area was detected and performed nonlinear curve fitting. Next, we performed FRAP analysis in these cells treated with Methyl-β-cyclodextrin (MβCD) to change the lipid component. In this study, we indicated that the ratio of mobile fraction of IR-EGFP in control and MβCD treated cells were about 87.5% and 78.5%, respectively. However, there was little to distinguish diffusion coefficients of IR-EGFP in the both cells. In this condition, we checked insulin signal transduction pathway by co-expression of IR-EGFP and IRS1-ECFP. Interestingly, we have confirmed that phosphorylation of IRS1 was decreased though the phosphorylation of IR was slightly increased. At present, we are trying measurement of lateral diffusion of IR molecules at the change of membrane environment, such as treatment with inhibitor of glycosylceramide synthase (D-PDMP).