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RISS 인기검색어
- 검색키워드
- 저자 : Arakawa, (검색결과 114 건)
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Fluoride retention amounts following toothbrushing and mouthrinsing with a weak fluoride solution
Yuki Arakawa,Wenqun Song,Shinji Toda,Kazuaki Kawamura,Tomoka Kubota,Hirohisa Arakawa 대한예방치과학회 2009 International Journal of Clinical Preventive Denti Vol.5 No.2
Objectives: The aim of this study was to determine the effectiveness of caries prevention from intraoral fluoride retention following tooth brushing with a weak fluoride solution. Methods: Six subjects (average age is 37.5 years old) performed tooth brushing with a weak fluoride solution (100 ppm F as NaF) and fluoride mouth-rinsing (100 ppm F as NaF) as positive control just before going to bed on separate day. At the time of rising in the next morning, the subjects collected their unstimulated total saliva, and we examined salivary fluoride concentration. Two fluoride modalities were performed randomly each three times. Results: The mean salivary fluoride concentrations upon arising were 0.07 ppm (range: 0.01 - 0.22 ppm) in tooth brushing with a weak fluoride solution experiments and 0.14 ppm (range: 0.02 - 0.37 ppm) in fluoride mouth-rinsing experiments. Conclusion: Though salivary fluoride concentrations upon arising after tooth brushing with a weak fluoride solution was lower than after fluoride mouth-rinsing, it was higher than 0.05 ppm of optimal therapeutic level which enhances remineralization. The results suggested that tooth brushing with a weak fluoride solution just before going to bed was effective on caries prevention for young children. On the other hand, salivary fluoride concentrations after fluoride mouth-rinsing was significantly higher than tooth brushing with a weak fluoride solution, since fluoride might be reserved on oral mucous membrane. Objectives: The aim of this study was to determine the effectiveness of caries prevention from intraoral fluoride retention following tooth brushing with a weak fluoride solution. Methods: Six subjects (average age is 37.5 years old) performed tooth brushing with a weak fluoride solution (100 ppm F as NaF) and fluoride mouth-rinsing (100 ppm F as NaF) as positive control just before going to bed on separate day. At the time of rising in the next morning, the subjects collected their unstimulated total saliva, and we examined salivary fluoride concentration. Two fluoride modalities were performed randomly each three times. Results: The mean salivary fluoride concentrations upon arising were 0.07 ppm (range: 0.01 - 0.22 ppm) in tooth brushing with a weak fluoride solution experiments and 0.14 ppm (range: 0.02 - 0.37 ppm) in fluoride mouth-rinsing experiments. Conclusion: Though salivary fluoride concentrations upon arising after tooth brushing with a weak fluoride solution was lower than after fluoride mouth-rinsing, it was higher than 0.05 ppm of optimal therapeutic level which enhances remineralization. The results suggested that tooth brushing with a weak fluoride solution just before going to bed was effective on caries prevention for young children. On the other hand, salivary fluoride concentrations after fluoride mouth-rinsing was significantly higher than tooth brushing with a weak fluoride solution, since fluoride might be reserved on oral mucous membrane.
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Fluoride retention amounts following toothbrushing and mouthrinsing with a weak fluoride solution
Yiki Arakawa, Wenqun Song, Shinji Toda, Kazuaki Kawamura, Hirohisa Arakawa 대한임상예방치과학회 2009 International Journal of Clinical Preventive Denti Vol.5 No.1
Objectives: The aim of this study was to determine the effectiveness of caries prevention from intraoral fluoride retention following tooth brushing with a weak fluoride solution. Methods: Six subjects (average age is 37.5 years old) performed tooth brushing with a weak fluoride solution (100 ppm F as NaF) and fluoride mouth-rinsing (100 ppm F as NaF) as positive control just before going to bed on separate day. At the time of rising in the next morning, the subjects collected their unstimulated total saliva, and we examined salivary fluoride concentration. Two fluoride modalities were performed randomly each three times. Results: The mean salivary fluoride concentrations upon arising were 0.07 ppm (range: 0.01 - 0.22 ppm) in tooth brushing with a weak fluoride solution experiments and 0.14 ppm (range: 0.02 - 0.37 ppm) in fluoride mouth-rinsing experiments. Conclusion: Though salivary fluoride concentrations upon arising after tooth brushing with a weak fluoride solution was lower than after fluoride mouth-rinsing, it was higher than 0.05 ppm of optimal therapeutic level which enhances remineralization. The results suggested that tooth brushing with a weak fluoride solution just before going to bed was effective on caries prevention for young children. On the other hand, salivary fluoride concentrations after fluoride mouth-rinsing was significantly higher than tooth brushing with a weak fluoride solution, since fluoride might be reserved on oral mucous membrane.
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ADVANCED SPACE PROPULSION ACTIVITIES IN JAPAN
Arakawa, Yoshihiro 한국 항공대학교 항공산업기술연구소 1994 航空宇宙産業技術硏究所 硏究誌 Vol.4 No.-
In ths seminar, the outline of advanced space propulsion sctivities in Japan is introduced. The National Space Development Agency of Japan(NASDA) is developing a high-performance liquid rocket engine for the first stage of the H-Ⅱ launch vehicle. The H-Ⅱ is designed to boost 2-tonne class satellites into geostationary orbit. The rocket engine, which is powered by liquid hydrogen and liquid oxygen and named LE-7, is a staged combustion-cycle engine capable of producing about 100-tonnes of thrust and a high impulse (450 sec in vacuum). The engine is manufactured by Mitsubishi Heavy Industries(MHI) and Ishikawajima Heavy Industries (IHI). Powering the second stage of the H-Ⅱ rocket is the LE-5A liquid engine which is an improved version of LE-5 that thas been used to drive the second stage of the H-I rocket. The LE-5A hydrogen/oxygen engine produces a thrust of 12 tonnes and has a restart capability. Japan is also developing high-performance electric thrusters which should be considered a replace technology in future space missions. Electric heating and/or by electrostatic and electromagnetic forces, produces much higher specific impulses than chemical propulsion. The specific impulse is typically ranged form 500 sec to 10,000sec. Such a high specific impulse produced by electric propulsion offers significant propellant mass saving compared to chemical propulsion. Japan covers a large variety of electric propulsion activities, on electrothermal propulsion(arcjet), electrostatic propulsion(Magneto Plasma Dynamic thruster), electrostatic propulsion(ion engine) and other types of thrusters, from fundamental studies to space flight tests. These activities have been performed by governmental research institutes, such as Institute of Space and Astronautical Science(ISAS), National Aerospace Laboratory(NAL), NASDA, and several universities. Several manufacturers such as Mitsubishi Electric Corporation, IHI, and Toshiba Corporation, join and support these activities. In the arcjet, propellant gas introduced in the electrode region is heated by electric are discharge and attain temperatures of 10,000K or more and expands into vacuum through a nozzle with super sonic flow. As the gas temperature is much higher than that of chemical propulsion, the arcjet produces relatively high specific impulses (500-2,000 sec). The energy conversion efficiency, which is defined as the ratio of jet power to electric input power, is around 30%, although is depends on power level, propellant type, etc. The present research in universities, research efforts are concentrated on the improvement of the efficiency and durability. A MPD thruster has been studied and developed in particularly in ISAS and universitis since 1970. Its thrust is produced mainly by electromagnetic forces due to discharge current and induced or externally applied magnetic field. The feature of this type is 1)easy to produce a high thrust density(high-power thruster), 2)a wide range of specific impulses(1,000-10,000 sec). A space test of a sub-kilowatts thruster designed in ISAS is planned to be conducted onbord a Japanese unmanned free flying platform, which will be launched by the H-Ⅱ rocket in early 1995. Tto improve the performance and to obtain scaling laws, much efforts are concentrated on the plasma acceleration mechanism and discharge phenomena. As for ion engine, this type of thruster is considered the most progressive one and will be operated in space for application to a station keeping of satellites and orbit maneuvering within several years. Ions produced in the discharge chamber are extracted and accelerated by electrostatic fields established between the grids to produce a thrust. Its energy conversion efficiency is in a high level(70-80%) at a specific impulse of more than 3,000 sec. NASDA is developing a 1kW-class ion engine system in cooperation with MHI to utilize it for the station keeping of ETS-Ⅳ satellite which will be launched in 1994. Endurance tests of several thousand hours were performed and are continued before the space flight.
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Arakawa, Masahiro Korean Institute of Industrial Engineers 2010 Industrial Engineeering & Management Systems Vol.9 No.3
Since product design strongly depends on the experience and ability of the designers, and a long lead time is required for the product design stage, introducing a support system related to this experience and ability is an effective technique to reduce the lead time. In this paper, an information system is developed to support the development of engineering mechanisms with the evaluation of the assembly process on the basis of the abstract functions required for new products. The developed system is based on a database system involving the following data structure: (1) a hierarchical structure related to information about the product functions, (2) the relationship between the parts and engineering functions and/or mechanisms of products, and (3) the relationship between the parts and manufacturing characteristics. The system stores the relationships between the product functions, structure of parts, and assembly characteristics. This information can then be interactively retrieved using the data structure described in (1), (2), and (3). A procedure for designing new products is proposed that involves using the information about existing products. This paper presents the characteristics of the proposed procedure and the developed information system. In addition, a case study of the redesign of a simple structured robot by using the proposed procedure is discussed.
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