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RISS 인기검색어
- 검색키워드
- 저자 : Uchiumi, Masaharu (검색결과 5 건)
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( Kazuo Uchiumi ) 한국체육학회 2016 국제스포츠과학 학술대회 Vol.2016 No.1
Purpose: ‘Sport for all’ policy was born in Western Welfare States since 1960s. The central and local governments have responsibility to provide sporting facilities, coaches and classes for people’s participation. Method: Since 1964 Tokyo Olympics people’s participation to sport was spread supported by the high economic growth. But from 1985 as a peak year, the sports facilities have been decreasing. Recently, about 1,000 facilities, including public and commercial, have been disappearing every year. Sport budgets for participation from the central and the local governments have been declining. Under the neo-liberal policy, Japanese GDP has been the third in the world, and many multinational corporations got a huge profit every year, but on the other hand delivery of the national wealth, people are worrying about low social welfare, increasing part-timers, long over-time working without payment, low salaries. So that people cannot have enough disposable money and disposable time for their leisure experiences. Participation sport and spectators of professional sports, especially baseball and J-league soccer, also have been decreasing. Result: Two areas of sport in colleges in Japan, ‘Physical education’ and ‘sport clubs’. PE was compulsory since the last war until 1992 University Reform. Since then PE became an elective subject because due to the congestion of curriculum. PE needed a lot of facilities, finances and had not been thought as an academic subject in universities. Since then, students’ experiences of sport have been decreasing. Universities need to raise more students by the declining birth rate. Especially for private universities, top ranking sport clubs are very beneficial as advertising tools. So, many universities adopt special admission policy like the acceptance of the recommended students with high sporting performances. But some of them have low academic levels. In Japan, there is no any collegiate sports policy organization like NCAA in the USA. Conclusion: Top clubs are a recruiting reservoir for the professional sports. Their sporting level has been higher and higher, and they need more finance. The government does not support those club anything. So, those clubs become more commercializing. Many universities adopt a sports service policy to their local communities as not only a Community Contribution policy, but also a revenue increasing policy. In Japan top baseball players proceed to the professionals as following, Primary school level → local baseball clubs, little leagues Junior High Schools → Extra Curricular Baseball Clubs High School → University, Company, Professional University → Company, Professional Company → Professional After graduating from universities, many of them cannot continue their careers as top athletes. So universities are required to teach them as students like ‘the second career.’
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Rotordynamic Characteristics of Floating Ring Seals in Rocket Turbopumps
Yuichiro Tokunaga,Hideyuki Inoue,Jun Hiromatsu,Tetsuya Iguchi,Yasuhiro Kuroki,Masaharu Uchiumi 한국유체기계학회 2016 International journal of fluid machinery and syste Vol.9 No.3
Floating ring seals offer an opportunity to reduce leakage flows significantly in rotating machinery. Accordingly, they have been applied successfully to rotating machinery within the last several decades. For rocket turbopump applications, fundamental behavior and design philosophy have been revealed. However, further work is needed to explore the rotordynamic characteristics associated with rotor vibrations. In this study, rotordynamic forces for floating ring seals under rotor’s whirling motions are calculated to elucidate rotordynamic characteristics. Comparisons between numerical simulation results and experiments demonstrated in our previous report are carried out. The three-dimensional Reynolds equation is solved by the finite-difference method to calculate hydrodynamic pressure distributions and the leakage flow rate. The entrance loss at the upstream inlet of the seal ring is calculated to estimate the Lomakin effect. The friction force at the secondary seal surface is also considered. Numerical simulation results showed that the rotordynamic forces of this type of floating ring seal are determined mainly by the friction force at the secondary seal surface. The seal ring is positioned almost concentrically relative to the rotor by the Lomakin effect. Numerical simulations agree quite well with the experimental results.
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Rotordynamic Characteristics of Floating Ring Seals in Rocket Turbopumps
Tokunaga, Yuichiro,Inoue, Hideyuki,Hiromatsu, Jun,Iguchi, Tetsuya,Kuroki, Yasuhiro,Uchiumi, Masaharu Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.3
Floating ring seals offer an opportunity to reduce leakage flows significantly in rotating machinery. Accordingly, they have been applied successfully to rotating machinery within the last several decades. For rocket turbopump applications, fundamental behavior and design philosophy have been revealed. However, further work is needed to explore the rotordynamic characteristics associated with rotor vibrations. In this study, rotordynamic forces for floating ring seals under rotor's whirling motions are calculated to elucidate rotordynamic characteristics. Comparisons between numerical simulation results and experiments demonstrated in our previous report are carried out. The three-dimensional Reynolds equation is solved by the finite-difference method to calculate hydrodynamic pressure distributions and the leakage flow rate. The entrance loss at the upstream inlet of the seal ring is calculated to estimate the Lomakin effect. The friction force at the secondary seal surface is also considered. Numerical simulation results showed that the rotordynamic forces of this type of floating ring seal are determined mainly by the friction force at the secondary seal surface. The seal ring is positioned almost concentrically relative to the rotor by the Lomakin effect. Numerical simulations agree quite well with the experimental results.
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