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RETRIEVAL OF LOCAL INTERPLANETARY DUST EMISSIVITY BY ASTRO-F
HONG S. S.,KWON S. M.,PYO J.,UENO M.,ISHIGURO M.,USUI F.,WEINBERG J. L. The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.4
This is a proposal to probe local part of the interplanetary dust (IPD) cloud complex and retrieve mean volume emissivity of the local IPDs at mid-infrared wavelengths. This will be done by monitoring, with Infrared Camera (IRC) aboard the ASTRO-F, the annual modulation of the zodiacal emission. In pointing mode of the ASTRO-F mission the spacecraft can make attitude maneuvering over approximately ${\pm}1^{\circ}$ range centered at solar elongation $90^{\circ}$ in the ecliptic plane. The attitude maneuvering combined with high sensitivity of the IRC will provide us with a unique opportunity observationally to take derivatives of the zodiacal emission brightness with respect to the solar elongation. From the resulting differential of the brightness over the ${\pm}1^{\circ}$ range, one can directly determine the mean volume emissivity of the local IPDs with a sufficient accuracy to de-modulate the annual emissivity variations due to the Earth's elliptical motion and the dis-alignment of the maximum IPD density plane with respect to the ecliptic. The non-zero eccentricity ($e_{\oplus}$= 0.0167) of the Earth's orbit combined with the sensitive temperature dependence of the Planck function would bring modulations of amplitude at least $3.34\%$ to the zodiacal emission brightness at mid-infrared wavelengths, with which one may determine the IPD temperature T(r) and mean number density n(r) as functions of heliocentric distance r. This will in turn fix the power-law exponent $\delta$ in the relation $T(r) = T_o(r/r_o)^{-\delta}$ for the dust temperature and v in $n(r) = n_o(r/r_o)^-v$ for the density. We discuss how one may de-couple the notorious degeneracy of cross-section, density, reference temperature $T_o$ and exponent $\delta$.
A SURVEY OF T TAURI STARS WITH AKARI
Takita, S.,Kataza, H.,Kitamura, Y.,Ueno, M.,Oyabu, S.,Ishihara, D.,Ita, Y. The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We have carried out a survey of T Tauri stars (TTSs) in a 1,800-square-degrees region toward the Taurus-Auriga star forming region with the AKARI Mid-Infrared All-Sky Survey. By combination of AKARI, 2MASS, and UCAC surveys, we created new criteria to chose TTS candidates. We also considered Asymptotic Giant Branch stars and galaxies, which have similar infrared colors, to separate TTSs from these sources. On the basis of our criteria, we find 27 new TTS candidates. To verify our criteria, we performed follow-up observations for them and confirmed that 23 are TTSs.
Valence states and spin structure of spinel FeV2O4with different orbital degrees of freedom
Kang, J.-S.,Hwang, Jihoon,Kim, D. H.,Lee, Eunsook,Kim, W. C.,Kim, C. S.,Kwon, Sangil,Lee, Soonchil,Kim, J.-Y.,Ueno, T.,Sawada, M.,Kim, Bongjae,Kim, Beom Hyun,Min, B. I. American Physical Society 2012 Physical review. B, Condensed matter and materials Vol.85 No.16
Search for GUT monopoles at Super-Kamiokande
The Super-Kamiokande Collaboration,Ueno, K.,Abe, K.,Hayato, Y.,Iida, T.,Iyogi, K.,Kameda, J.,Koshio, Y.,Kozuma, Y.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakayama, S.,Obayashi, Y.,Sekiya, H.,Shiozawa, M. North-Holland ; Elsevier Science Ltd 2012 Astroparticle physics Vol.36 No.1
GUT monopoles captured by the Sun's gravitation are expected to catalyze proton decays via the Callan-Rubakov process. In this scenario, protons, which initially decay into pions, will ultimately produce ν<SUB>e</SUB>,ν<SUB>μ</SUB> and ν@?<SUB>μ</SUB>. After undergoing neutrino oscillation, all neutrino species appear when they arrive at the Earth, and can be detected by a 50,000 metric ton Water Cherenkov detector, Super-Kamiokande (SK). A search for low energy neutrinos in the electron total energy range from 19 to 55MeV was carried out with SK and gives a monopole flux limit of F<SUB>M</SUB>(σ<SUB>0</SUB>/1mb)<6.3x10<SUP>-24</SUP>(β<SUB>M</SUB>/10<SUP>-3</SUP>)<SUP>2</SUP>cm<SUP>-2</SUP>s<SUP>-1</SUP>sr<SUP>-1</SUP> at 90% C.L., where β<SUB>M</SUB> is the monopole velocity in units of the speed of light and σ<SUB>0</SUB> is the catalysis cross section at β<SUB>M</SUB>=1. The obtained limit is several orders of magnitude more stringent than the current best cosmic-ray supermassive monopole flux limit for β<SUB>M</SUB><10<SUP>-2</SUP> and also two orders of magnitude lower than the result of the Kamiokande experiment, which used a similar detection method.
Tanaka, T.,Abe, K.,Hayato, Y.,Iida, T.,Kameda, J.,Koshio, Y.,Kouzuma, Y.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakayama, S.,Obayashi, Y.,Sekiya, H.,Shiozawa, M.,Suzuki, Y.,Takeda, A.,Takenaga, Y.,Ueno, IOP Publishing 2011 The Astrophysical journal Vol.742 No.2
<P>We present the result of an indirect search for high energy neutrinos from Weakly Interacting Massive Particle (WIMP) annihilation in the Sun using upward-going muon (upmu) events at Super-Kamiokande. Data sets from SKI-SKIII (3109.6 days) were used for the analysis. We looked for an excess of neutrino signal from the Sun as compared with the expected atmospheric neutrino background in three upmu categories: stopping, non-showering, and showering. No significant excess was observed. The 90% C. L. upper limits of upmu flux induced by WIMPs of 100 GeV c(-2) were 6.4 x 10(-15) cm(-2) s(-1) and 4.0 x 10(-15) cm(-2) s(-1) for the soft and hard annihilation channels, respectively. These limits correspond to upper limits of 4.5 x 10(-39) cm(-2) and 2.7 x 10(-40) cm(-2) for spin-dependent WIMP-nucleon scattering cross sections in the soft and hard annihilation channels, respectively.</P>
Performance Characteristics of Single-Stage AC-DC Full-Bridge Converter
S. Hattori,F. Kurokawa,K. Ueno 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
A single-stage ac-dc converter consisting of full-bridge converter is proposed for battery charger applications. Desired feature for the battery charger such as a low cost, small volume, high efficiency and high reliability are achieved by means of the proposed solution. The proposed approach is superior to conventional two-stage ac-dc converter widely used for EV charger applications. The two-stage ac-dc converter is apt to be costly and large. However a single-stage ac-dc converter is suitable to a low cost, small volume due to a reduced number of components. In this paper, a digital control single-stage ac-dc converter consisting of full-bridge converter and series connection of secondary transformer is presented in order to achieve downsizing, high efficiency, high power factor and high reliability for a battery charger. The feasibility and practical value of the proposed approach are verified by the experimental results from a 0.8 / 1.6kW product prototype.