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%.

Soft-magnetic Characteristics of Co-based Amorphous Powder Produced by Spinning Water Atomization Process (SWAP)

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.

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>

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.

CHEMICAL ABUNDANCES AND DUST IN THE HALO PLANETARY NEBULA K648 IN M15: ITS ORIGIN AND EVOLUTION BASED ON AN ANALYSIS OF MULTIWAVELENGTH DATA

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>

THE ORIGIN AND EVOLUTION OF THE HALO PN BoBn 1: FROM A VIEWPOINT OF CHEMICAL ABUNDANCES BASED ON MULTIWAVELENGTH SPECTRA

Otsuka, Masaaki,Tajitsu, Akito,Hyung, Siek,Izumiura, Hideyuki IOP Publishing 2010 The Astrophysical journal Vol.723 No.1

「留學生30万人計畵」に基づく 外國人留學生に對する支援體制の構築 -高知大學の事例を中心に-

( Kaoru Otsuka ),( Cuifang Lin ) 한국일어교육학회 2012 일본어교육연구 Vol.0 No.22

本稿は、「留學生30万人計畵」實現に向けての地方大學における留學生の受入れから卒業後の進路までを見 据えた體系的な體係策について「高知大學留學生に關する調査」の結果に基づき提言したものである。①敎員 の留學生受入れ體制の構築、②海外の協定校へのリクル一ト活動の推進、③大學獨自の入試制度の導入、④魅 力あるカリキュラムの導入、⑤民間住宅の借り上げ廣充等宿舍の充實、⑥大學獨自の奬學金の繼續·廣充、⑦留 學生に一定樺を確保する授業料免除制度の改善、⑧交換留學生廣充のための日本語補講授業の單位化、⑨留學 生の就職支援體制の構築、⑩卒業後のフォロ一アップ體制の充實等の問題点において地方大學ならではの提 言を行った。 Based on the results of the Investigation Concerning the International Students of Kochi University, this article puts forward proposals about the systematic measures relating to issues from international student recruitment to career paths after graduation at the local universities according to the 300,000 International Student Recruitment Plan. Ten main points are proposed as follows: 1. Construction of teachers` system for the recruitment of international students and sharing of information within a whole university. 2. Promotion of recruitment activities like briefing sessions at the overseas agreement-signed universities. 3. Promotion of admissions to universities and introduction of their own entrance exam system. 4. Introduction of attractive curriculums like acquisition of double degrees. 5. Expansion of leased private housing and building more International Houses. 6. Reinforcement of scholarship system by their own universities. 7. Improvement of tuition exemption system that secures a certain number of international students. 8. Acquisition of credits by taking Japanese supplementary classes for increasing the number of exchange students. 9. Construction of employment support system for international students through society-academia collaboration. 10. Reinforcement of follow-up system after graduation in overseas branch offices.

Interval Reduced-order Switched Positive Observers for Uncertain Switched Positive Linear Systems

Naohisa Otsuka,Daiki Kakehi,Przemysław Ignaciuk 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4

In this paper, existence conditions and a design procedure of reduced-order switched positive observers for continuous- and discrete-time switched positive linear systems with uncertainty are established. In the analyzed class, arbitrary switching is permitted, whereas the uncertainty expressed via matrix inequalities concerns both the initial state and system parameters. Positive lower and positive upper interval switched observers are obtained. The proposed observers are of (n− p) order, where n is the dimension of the state vector and p is the rank of the output matrix, i.e., p-dimensional measurement information. Moreover, as a special case, existence conditions and a design procedure of reduced-order positive observers for uncertain positive linear systems without switching are provided. The theoretical findings are illustrated by two numerical examples for continuous- and discrete-time systems.

‘-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].

Spatial relationship of F-region field-aligned irregularities and medium-scale traveling ionospheric disturbances observed with the MU radar and all-sky airglow imagers

Yuichi Otsuka,Kazuo Shiokawa,Tadahiko Ogawa,Tatsuhiro Yokoyama,Mamoru Yamamoto 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8