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Establishment of Process of Manufacture of Ti-6Al-4V Alloy Sintering Body by MIM
Otsuka A.,Suzuki K.,Achikita M. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Ti-6Al-4V has low specific gravity, high corrosion resistance and superior mechanical properties but it is very difficult to control oxygen content in MIM process. It is necessary to use powders with coarse particle size to decrease oxygen content of powders, so feedstocks with poor fluidity and sintered bodies with lower density are obtained in such cases. Fine titanium hydride-dehydride powders were blended with atomized powders to accomplish higher fluidity and sintered density. Sintered bodies had higher sintered density and mechanical properties equivalent to those of wrought materials by controlling oxygen content less than 0.35mass%.
Numerical Analysis of Flow in Radial Turbine (Effects of Nozzle Vane Angle on Internal Flow)
OTSUKA, Kenta,KOMATSU, Tomoya,TSUJITA, Hoshio,YAMAGUCHI, Satoshi,YAMAGATA, Akihiro Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.2
Variable Geometry System (VGS) is widely applied to the nozzle vane for the radial inflow turbine constituting automotive turbochargers for the purpose of optimizing the power output at each operating condition. In order to improve the performance of radial turbines with VGS, it is necessary to clarify the influences of the setting angle of nozzle vane on the internal flow of radial turbine. However, the experimental measurements are considered to be difficult for the flow in radial turbines because of the small size and the high rotational speed. In the present study, the numerical calculations were carried out for the flow in the radial turbine at three operating conditions by applying the corresponding nozzle vane exit angles, which were set up in the experimental study, as the inlet boundary condition. The numerical results revealed the characteristic flow behaviors at each operating condition.
Otsuka, Masaaki,Hyung, Siek,Tajitsu, Akito IOP Publishing 2015 The Astrophysical journal Supplement series Vol.217 No.2
<P>We report on an investigation of the extremely metal-poor and C-rich planetary nebula (PN) K648 in M15 using the UV to far-infrared data obtained using Subaru, the Hubble Space Telescope, the Far Ultraviolet Spectroscopic Explorer, Spitzer, and Herschel. We determined the nebular abundances of 10 elements. The enhancement of F ([F/H] = +0.96) is comparable to that of the halo PN BoBn1. The central stellar abundances of seven elements are determined. The stellar C/O ratio is similar to the nebular C/O ratios from recombination lines and from collisionally excited lines (CELs) within error, and the stellar Ne/O ratio is also close to the nebular CEL Ne/O ratio. We found evidence of carbonaceous dust grains and molecules including Class B 6-9 and 11.3 mu m polycyclic aromatic hydrocarbons and the broad 11 mu m feature. The profiles of these bands are similar to those of the C-rich halo PNe H4-1 and BoBn1. Based on the theoretical model, we determined the physical conditions of the gas and dust and their masses, i.e., 0.048 and 4.95 X 10(-7) M-circle dot, respectively. The observed chemical abundances and gas mass are in good agreement with an asymptotic giant branch nucleosynthesis model prediction for stars with an initial 1.25 M-circle dot plus a 2.0 X 10(-3) M-circle dot partial mixing zone (PMZ) and stars with an initial mass of 1.5 M-circle dot without a PMZ. The core mass of the central star is approximately 0.61-0.63 M-circle dot. K648 is therefore likely to have evolved from a progenitor that experienced coalescence or tidal disruption during the early stages of evolution, and became a similar to 1.25-1.5 M-circle dot blue straggler.</P>
DUST AND CHEMICAL ABUNDANCES OF THE SAGITTARIUS DWARF GALAXY PLANETARY NEBULA Hen2-436
Otsuka, Masaaki,Meixner, Margaret,Riebel, David,Hyung, Siek,Tajitsu, Akito,Izumiura, Hideyuki IOP Publishing 2011 The Astrophysical journal Vol.729 No.1
<P>We have estimated elemental abundances of the planetary nebula (PN) Hen2-436 in the Sagittarius (Sgr) spheroidal dwarf galaxy using ESO/VLT FORS2, Magellan/MMIRS, and Spitzer/IRS spectra. We have detected candidates of fluorine [F II] lambda 4790, krypton [Kr III] lambda 6826, and phosphorus [P II] lambda 7875 lines and successfully estimated the abundances of these elements ([F/H] = +1.23, [Kr/H] = +0.26, [P/H] = +0.26) for the first time. These elements are known to be synthesized by the neutron capture process in the He-rich intershell during the thermally pulsing asymptotic giant branch (AGB) phase. We present a relation between C, F, P, and Kr abundances among PNe and C-rich stars. The detections of these elements in Hen2-436 support the idea that F, P, Kr together with C are synthesized in the same layer and brought to the surface by the third dredge-up. We have detected N II and O II optical recombination lines (ORLs) and derived the N2+ and O2+ abundances. The discrepancy between the abundance derived from the oxygen ORL and that derived from the collisionally excited line is > 1 dex. To investigate the status of the central star of the PN, nebula condition, and dust properties, we construct a theoretical spectral energy distribution (SED) model to match the observed SED with Cloudy. By comparing the derived luminosity and temperature of the central star with theoretical evolutionary tracks, we conclude that the initial mass of the progenitor is likely to be similar to 1.5-2.0M(circle dot) and the age is similar to 3000 yr after the AGB phase. The observed elemental abundances of Hen2-436 can be explained by a theoretical nucleosynthesis model with a star of initial mass 2.25 M-circle dot, Z = 0.008, and LMC compositions. We have estimated the dust mass to be 2.9x10(-4) M-circle dot (amorphous carbon only) or 4.0x10(-4) M-circle dot (amorphous carbon and polycyclic aromatic hydrocarbon). Based on the assumption that most of the observed dust is formed during the last two thermal pulses and the dust-to-gas mass ratio is 5.58 x 10(-3), the dust mass-loss rate and the total mass-loss rate are < 3.1x10(-8) M-circle dot yr(-1) and < 5.5x10(-6) M-circle dot yr(-1), respectively. Our estimated dust mass-loss rate is comparable to a Sgr dwarf galaxy AGB star with similar metallicity and luminosity.</P>
Otsuka I.,Wada K.,Watanabe A.,Kadomura T.,Yagi M. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Co-based amorphous powder was produced by a new atomization process “Spinning Water Atomization Process (SWAP)”, having rapid super-cooling rate. The composition of the alloys was ((Co0.95Fe0.05)1-xCrx)75Si15B10 (x=0, 0.025, 0.05, 0.075). The powders became the amorphous state even if particle size was up to about 500 μm. The coercive force of powders was about 0.35 - 0.7 Oe. Furthermore, Co-based amorphous powder cores with glass binders were made by cold-pressing and sintering methods. The initial permeability of the core in the frequency range up to 100 kHz was about 110, and the core loss at 100 kHz for Bm = 0.1 T was 350 kW/m3.
‘-어야 하-’와 ‘(し)なければならない’의 양태(樣態)에 대한 대조언어학적 연구
大塚智榮 ( Otsuka Chie ) 한국어문교육연구회 2018 어문연구(語文硏究) Vol.46 No.1
본 연구에서는 한국어 ‘-어야 하-’와 일본어 ‘(し)なければならない’의 樣態를 대조언어학적으로 살펴보았다. ‘-어야 하-’와 ‘(し)なければならない’가 [義務, 必要], [바람], [後悔], [아쉬움], [강력한 義務]라는 樣態의 의미를 나타낼 수 있었다. ‘-어야 하-’와 ‘(し)なければならない’의 樣態실현 환경 대조에서 주어 인칭 결합에서는 [바람]에서 2인칭 주어 결합에 있어서 두 언어 간에 차이가 보였다. [바람]에서 ‘-어야 하-’는 모든 인칭이 가능하였으나 ‘(し)なければならない’는 1인칭 복수 주어나 일반적인 통념을 나타낸 명제의 3인칭 복수 주어가 왔는데 2인칭 주어로는 [바람]을 나타내기 어려웠다. [아쉬움]에서도 ‘-어야 하-’는 1, 2, 3인칭 주어를 볼 수 있었지만 ‘(し)なければならない’는 1, 3인칭 주어로는 나타나지만 2인칭 주어를 취하기 어려웠다 결합 語尾에서는 ‘-어야 하-’보다 ‘(し)なければならない’가 [강력한 義務]를 나타내는 경우가 많았다. In this study, we looked at the aspects of ‘-어야 하-[eoya ha]’ and ‘(し)な ければならない[(shi)nakerebanaranai]’ in a comparative linguistic way. ‘-어 야 하-[eoya ha]’ and ‘(し)なければならない[(shi)nakerebanaranai]’ can represent the meaning of [duty, need], [wish], [regret], [sadness], [strong duty]. ‘-어야 하-[eoya ha]’ and ‘(し)なければならない[(shi)nakerebanaranai]’ can be used to refer to a general event as [wish], but in an individual case ‘(し)なければ ならない[(shi)nakerebanaranai]’ could not indicate [wish]. In the case of the subject of the second person, there was a difference between the two languages with [wish]. ‘-어야 하-[eoya ha]’ can represent [wish] in the subject of the second person. However, ‘(し)なければならない[(shi)nakerebanaranai]’ was difficult to express [wish] in the subject of the second person. In an environment that combines with some ‘Ending’, ‘(し)なければならない[(shi)nakerebanaranai]’ rather than ‘-어야 하-[eoya ha]’ often expressed [strong duty].