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Kamiya, Junichiro; Nii, Keisuke*; Kabumoto, Hiroshi; Kondo, Yasuhiro; Tamura, Jun; Harada, Hiroyuki; Matsui, Yutaka; Matsuda, Makoto; Moriya, Katsuhiro; Ida, Yoshiaki*; et al.
e-Journal of Surface Science and Nanotechnology (Internet), 21(4), p.344 - 349, 2023/05
no abstracts in English
Nii, Keisuke*; Ida, Yoshiaki*; Ueda, Hideki*; Yamaguchi, Takanori*; Kabumoto, Hiroshi; Kamiya, Junichiro; Kondo, Yasuhiro; Tamura, Jun; Harada, Hiroyuki; Matsui, Yutaka; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.601 - 604, 2023/01
no abstracts in English
Nii, Keisuke*; Ida, Yoshiaki*; Ueda, Hideki*; Yamaguchi, Takanori*; Kabumoto, Hiroshi; Kamiya, Junichiro; Kondo, Yasuhiro; Tamura, Jun; Harada, Hiroyuki; Matsui, Yutaka; et al.
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.334 - 337, 2021/10
no abstracts in English
He spin filter at a pulsed neutron sourceOkudaira, Takuya; Ueda, Yuki; Hiroi, Kosuke; Motokawa, Ryuhei; Inamura, Yasuhiro; Takata, Shinichi; Oku, Takayuki; Suzuki, Junichi*; Takahashi, Shingo*; Endo, Hitoshi*; et al.
Journal of Applied Crystallography, 54(2), p.548 - 556, 2021/04
Times Cited Count：6 Percentile：46.32(Chemistry, Multidisciplinary)Neutron polarization analysis (NPA) for small-angle neutron scattering (SANS) experiments using a pulsed neutron source was successfully achieved by applying a He spin filter as a spin analyzer for the scattered neutrons. The He spin filter covers a sufficient solid angle for performing SANS experiments, and the relaxation time of the He polarization is sufficient for continuous use over a few days, thus reaching the typical duration required for a complete set of SANS experiments. Although accurate evaluation of the incoherent neutron scattering, which is predominantly attributable to hydrogen atoms in samples, is practically difficult using calculations based on the sample elemental composition, the developed NPA approach with consideration of the influence of multiple neutron scattering enabled reliable decomposition of the SANS intensity distribution into the coherent and incoherent scattering components. To date, NPA has not been well established as a standard technique for SANS experiments at pulsed neutron sources. This work is anticipated to greatly contribute to the accurate determination of the coherent neutron scattering component for scatterers in various types of organic sample systems in SANS experiments at J-PARC.
Kajino, Mizuo*; Inomata, Yayoi*; Sato, Keiichi*; Ueda, Hiromasa*; Han, Z.*; An, J.*; Katata, Genki; Deushi, Makoto*; Maki, Takashi*; Oshima, Naga*; et al.
Atmospheric Chemistry and Physics, 12(24), p.11833 - 11856, 2012/12
Times Cited Count：47 Percentile：72.22(Environmental Sciences)A new aerosol chemical transport model, Regional Air Quality Model 2 (RAQM2), was developed to simulate Asian air quality. We implemented a simple version of a modal-moment aerosol dynamics model and achieved completely dynamic solution of a gas-to-particle mass transfer over a wide range of aerosol diameters from 1 nm to super micro m. To consider a variety of atmospheric aerosol properties, a category approach is utilized: aerosols are distributed into 4 categories, Aitken, accumulation, soot aggregates, and coarse mode. A regional-scale simulation was performed for the entire year of 2006, covering Northeast Asian region. Statistical analysis showed the model reproduced the regional-scale transport and transformation of the major inorganic anthropogenic and natural air constituents within factors of 2 to 5. Modeled size distributions of total weight and chemical components were consistent with the observations, indicating simulations of aerosol mixing types were successful.
Kobayashi, Masaki*; Niwa, Hideharu*; Harada, Yoshihisa*; Horiba, Koji*; Oshima, Masaharu*; Ofuchi, Hironori*; Terakura, Kiyoyuki*; Ikeda, Takashi; Koshigoe, Yuka*; Ozaki, Junichi*; et al.
Journal of Power Sources, 196(20), p.8346 - 8351, 2011/10
Times Cited Count：32 Percentile：64.69(Chemistry, Physical)The electronic structure of Co atoms in CoPc-based carbon catalysts, which were prepared by pyrolyzing a mixture of CoPc and phenol resin polymer up to 1000
C, has been investigated using XAFS analysis and HXPES. The Co K XAFS spectra show that most of the Co atoms are in the metallic state and small quantities of oxidized Co components are present in the samples even after acid washing to remove Co atoms. Based on the difference in probing depth between XAFS and HXPES, it was found that after acid washing, the surface region with the aggregated Co clusters is primarily composed of metallic Co. Since the electrochemical properties remain almost unchanged even after the acid washing process, the residual metallic and oxidized Co atoms themselves will hardly contribute to the ORR activity of the CoPc-based carbon cathode catalysts, implying that the active sites of the CoPc-based catalysts primarily consist of light elements such as C and N.
Niwa, Hideharu*; Kobayashi, Masaki*; Horiba, Koji*; Harada, Yoshihisa*; Oshima, Masaharu*; Terakura, Kiyoyuki*; Ikeda, Takashi; Koshigoe, Yuka*; Ozaki, Junichi*; Miyata, Seizo*; et al.
Journal of Power Sources, 196(3), p.1006 - 1011, 2011/02
Times Cited Count：95 Percentile：90.63(Chemistry, Physical)We report on the electronic structure of three different types of N-containing carbon-based cathode catalysts for polymer electrolyte fuel cells observed by hard X-ray photoemission spectroscopy. C 1s spectra show the importance of 
carbon network formation for the oxygen reduction reaction (ORR) activity. Samples having high oxygen reduction reaction activity in terms of oxygen reduction potential contain high concentration of graphite-like nitrogen. Based on a quantitative analysis of our results, the oxygen reduction reaction activity of the carbon-based cathode catalysts will be improved by increasing concentration of graphite-like nitrogen in a developed carbon network.
Kurihara, Osamu; Kim, E.*; Ueda, Junichi*; Yamada, Yuji*; Kido, Hiroko*; Oguri, Tomomi*; Nemoto, Shintaro*; Nemoto, Makoto*; Akashi, Makoto*
Progress in Nuclear Science and Technology (Internet), 1, p.248 - 251, 2011/02
To replay the demand from the sites of radiation emergency medicine, we developed a prototype of a computer system for assessing radioactive contamination accidentally remained in the wound or on the skin surface. This system implements numerical calibration of detectors measuring the contaminant by using a Monte Carlo simulation-based radiation transport code, MCNPX coupled to a numerical phantom modeling the contaminants and the surrounding tissue. By the help of functional graphical user interfaces (GUIs) provided by the system, a user can perform desired simulations without complicated procedures in creating input files for MCNPX. In the present work, benchmark calculations of MCNPX were conducted to verify the simulations, and we optimized detection-related parameters not sufficiently provided by suppliers. The developed system would be useful for better assessments of the radioactive contamination.
Ueda, Yoshio*; Fukumoto, Masakatsu*; Watanabe, Jun*; Otsuka, Yusuke*; Arai, Takashi; Asakura, Nobuyuki; Nobuta, Yuji*; Sato, Masayasu; Nakano, Tomohide; Yagyu, Junichi; et al.
Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10
Deposition profiles of tungsten released from the outer divertor were studied in JT-60U. A neutron activation method was used for the first time to accurately measure deposited tungsten. Surface density of tungsten in the thick carbon deposition layer can be measured by this method. Tungsten was mainly deposited on the inner divertor (around inner strike points) and on the outer wing of the dome. Toroidal distribution of the W deposition was significantly localized near the tungsten released position, while other metallic impurities such as Fe, Cr, Ni were distributed more uniformly. These data indicate that inward drift in the divertor region played a significant role in tungsten transport in JT-60U.
Ueda, Shuzo; Nishio, Satoshi; Yamada, Reiji; Seki, Yasushi; Kurihara, Ryoichi; Adachi, Junichi*; Yamazaki, Seiichiro*; Dream Design Team
Fusion Engineering and Design, 48(3-4), p.521 - 526, 2000/09
Times Cited Count：6 Percentile：41.49(Nuclear Science & Technology)no abstracts in English
Nishio, Satoshi; Ueda, Shuzo; Kurihara, Ryoichi; Kuroda, Toshimasa*; Miura, H.*; Sako, Kiyoshi*; Takase, Kazuyuki; Seki, Yasushi; Adachi, Junichi*; Yamazaki, Seiichiro*; et al.
Fusion Engineering and Design, 48(3-4), p.271 - 279, 2000/09
Times Cited Count：19 Percentile：73.67(Nuclear Science & Technology)no abstracts in English
Nishio, Satoshi; Ueda, Shuzo; Aoki, Isao; Kurihara, Ryoichi; Kuroda, Toshimasa*; Miura, H.*; Kunugi, Tomoaki; Takase, Kazuyuki; Seki, Yasushi; Shinya, K.*; et al.
Fusion Engineering and Design, 41, p.357 - 364, 1998/00
Times Cited Count：51 Percentile：95.08(Nuclear Science & Technology)no abstracts in English
Ueda, Shuzo; Nishio, Satoshi; Seki, Yasushi; Kurihara, Ryoichi; Adachi, Junichi*; Yamazaki, Seiichiro*; DREAM-Design-Team
Journal of Nuclear Materials, 258-263, p.1589 - 1593, 1998/00
Times Cited Count：43 Percentile：93.15(Materials Science, Multidisciplinary)no abstracts in English
Takahashi, Keita; Yamaguchi, Toshihiko; Saito, Junichi; Ueda, Masashi; Nakaishi, Sumitaka*
no journal, ,
In order to visualize the phenomenon under opaque liquid sodium, which is coolant of fast reactors, we tried to made an ultrasonic visualization device. A buffer rod was implemented to cope with high temperatures, and as a result of improvements in frequency, shape, etc., a resolution of 0.5 mm was obtained under sodium. Using this device, the transmittance of ultrasonic waves at the interface between liquid sodium and stainless steel was investigated. As the result, it was confirmed that the temperature of sodium and the roughness of the surface of stainless steel affect the transmitting behavior of ultrasonic waves.
Fukumoto, Masakatsu*; Yamawaki, Akifumi*; Soga, Yukihiro*; Otsuka, Yusuke*; Ueda, Yoshio*; Taniguchi, Masaki; Inoue, Takashi; Sakamoto, Keishi; Yagyu, Junichi; Arai, Takashi; et al.
no journal, ,
no abstracts in English
Kozuka, Shohei*; Saito, Junichi; Ueda, Mikito*; Matsushima, Hisayoshi*
no journal, ,
no abstracts in English
Watanabe, Jun*; Fukumoto, Masakatsu*; Soga, Yasuyuki*; Otsuka, Yusuke*; Ueda, Yoshio*; Asakura, Nobuyuki; Arai, Takashi; Nakano, Tomohide; Sato, Masayasu; Yagyu, Junichi; et al.
no journal, ,
no abstracts in English
Fukumoto, Masakatsu*; Yamawaki, Akifumi*; Otsuka, Yusuke*; Ueda, Yoshio*; Taniguchi, Masaki; Inoue, Takashi; Sakamoto, Keishi; Yagyu, Junichi; Arai, Takashi; Takagi, Ikuji*; et al.
no journal, ,
Tungsten is considered as a candidate material for first wall armor of DT fusion reactors. However, it is anticipated that tritium might accumulate in the damage defects that caused by neutron irradiation. The present study measured deuterim accumulation in tungsten specimen after high energy hydrogen ion beam irradiation for generation of irradiation damages and then low energy deuterium beams for their accumulation. As a result, the deuterium accumulation in irradiated tungsten was enhanced as high as six times than that of original specimen.
Ochiai, Kentaro; Watanabe, Jun*; Ueda, Yoshio*; Takakura, Kosuke; Nakano, Tomohide; Yagyu, Junichi; Konno, Chikara
no journal, ,
In order to investigate tungsten (W) erosion and transport in JT-60U plasma, we have applied the Neutron Activation Analysis (NAA) to the measurement of the W retention on the CFC tiles. The analysis has been carried out Fusion Neutronics Source (FNS) facility of Japan Atomic Energy Agency. 
W(n,
)
W reaction, which has a large cross section for low energy neutrons was used for analysis. The sample tiles were installed in a beryllium assembly, which produced many low energy neutrons effectively from DT neutrons, and were irradiated with DT neutrons. The W retention was deduced with the yield of 686-keV ray emitted from W in the sample. From our result, it was shown that We could analyze W retention up to 10
W atoms/cm
W within experimental error of 10% and it was demonstrated that the NAA was very useful for the measurement of W retention.
Naganuma, Kazuki*; Matsueda, Makoto; Yanagisawa, Kayo; Oikawa, Hiroshi*; Hashimoto, Junichi*; Takagai, Yoshitaka*
no journal, ,
