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高分子 PVDF 振動子를 利用한 点集束超音波探觸子의 특성
韓應敎,黃汐泰,李範成,朴俊緖,小倉幸夫 한국비파괴검사학회 1992 한국비파괴검사학회지 Vol.12 No.2
In this study, we examine the characteristics of beam and the effect of these characteristics on the flaw detection by using different type of two transducers, which are PZT and PVDF film transducer. Consequently, the detection of infinitesimal flaw is more possible than PZT, since it has beam width at focus of 60%∼65% in contrast with PZT's. Moreover we can know PVDF transducer has superiority in detecting ability for sub-suface flaw detection in view of its acoustic impedance is near to water's and its focusing range is narrower than PZT's as 65%∼85% because it has spherical surface.
Ogura, S.,Kosako, T.,Hayashi, Y.,Dohi, H. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.1
Ruminal degradation characteristics of dry matter (DM), neutral detergent fiber (NDF) and crude protein (CP) in fresh leaves of two Japanese native grasses (Zoysia japonica and Miscanthus sinensis) and one sown temperate grass (Dactylis glomerata) were investigated by an in sacco method in spring (mid-May), summer (mid-July) and autumn (mid-September). Japanese native grasses had higher NDF and lower CP concentrations than D. glomerata, and the CP concentration in native grasses decreased in autumn. Ruminal degradability of DM, NDF and CP was lower in native grasses than in D. glomerata (p<0.05) in all seasons. DM and NDF degradability decreased in summer for Z. japonica and D. glomerata, while it decreased in autumn for M. sinensis. CP degradability in Z. japonica was constant throughout the seasons, whereas that in M. sinensis greatly decreased in summer and autumn (p<0.05). It was concluded that Z. japonica could stably supply ruminally digestible nutrients for grazing animals in Japanese native pasture. However, the degradation characteristics of freshly chopped native grasses did not fit the exponential model of $D=a+b(1-e^{-ct})$ proposed by Ørskov and McDonald.
ZVS-PWM Boost Chopper-Fed DC-DC Converter with Load-Side Auxiliary Edge Resonant Snubber
K.Ogura,S.Chandhaket,S.Nagai,T.Ahmed,M.Nakaoka 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.7(1)
This paper presents a high-frequency ZVS-PWM boost chopper-fed DC-DC converter with a single active auxiliary edge-resonant snubber which is used for power conditioner such as solar photovoltaic generation and fuel cell generation The experimental results of boost chopper fed ZVS-PWM DC-DC converter are evaluated in addition to Its switching voltage and current waveforms, and the switching V-I trajectory of the power devices are discussed and compared with the conventional hard switching DC-DC converter treated here The temperature performance of IGBT module, efficiency, and EMI noise characteristics of this ZVS-PWM DC-DC converter using IGBTs are measured and evaluated from an experimental point of view
Characterization of an Intense Laser-Produced Preformed Plasma for Proton Generation
A Sagisaka,A. Noda,A. Fukumi,A. Yogo,A. S. Pirozhkov,H. Daido,K. Nemoto,K. Ogura,M. Nishiuchi,M. Mori,M. Kado,S. Orimo,S. Nakamura,T. Nayuki,T. Shirai,T. Fujii,Y. Oishi,Y. Hayashi,Y. Iwashita,Z. Li 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.I
High-energy protons are generated with a 3-μm-thick tantalum target irradiated with a highintensity laser under the preformed plasma condition. We observe the electron density distributions of preformed plasmas with two-color probe beams as interferometers. The preformed plasma at the front side of the target is generated by pre-pulses of a high-intensity Ti:sapphire laser. In this preformed plasma condition, the maximum proton enegy is 900 keV. The half angle of the generated proton beam (>500 keV) is about 10.
Sinewave-PWM ZVS Inverter using High-frequency Transformer for Utility AC Voltage Ink
S Chandhket,K Ogura,Y Konishi,M Nakaoka 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.7(2)
This paper presents a novel prototype of the utility-interfaced si- nusoidal pulse width modulated (SPWM) inverter using the high-frequency fiyback transformer for the small-scale solar photo- voltaic power conditioner (lkW - 4kW) The proposed SPWM power conditioner circuit with a high-frequency link has a function of electrical isolation, which is vital for solar photovoltaic power conditioner systems with the viewpoint of safety and convenience The discontinuous conduction mode (DCM) operation of the fly. back transformer is also maintained to simplify the topology of the inverter circuit and control scheme first, the operating principle of the proposed circuit is described for the understanding of the circuit parameters establishment. Then, the digitally constructed SPWM control scheme is presented The proposed circuit is verified by the computer Simulation and the prototype experiment<br/>
Hong, S.,Lee, Y. M.,Cho, K. B.,Seo, M.,Song, D.,Yoon, J.,Garcia-Serres, R.,Clemancey, M.,Ogura, T.,Shin, W. THE ROYAL SOCIETY OF CHEMISTRY 2014 Chemical Science Vol.5 No.1
The mechanism of the alkylperoxo O-O bond cleavage of low-spin iron(III)-alkylperoxo species has been well established in nonheme iron models. In contrast, the alkylperoxo O-O bond cleavage in nonheme high-spin iron(III)-alkylperoxo species binding an axial ligand has yet to be elucidated. Herein, we report the synthesis and characterization of mononuclear nonheme high-spin iron(III)-alkylperoxo complexes each bearing an N-tetramethylated 13-membered macrocyclic ligand (13-TMC), [Fe-III(OOC(CH3)(3))-(13-TMC)](2+) and [Fe-III(OOC(CH3)(2)C6H5)(13-TMC)](2+). The high-spin iron(III)-alkylperoxo complexes were converted to an iron(IV)-oxo complex at a fast rate upon addition of thiocyanate (NCS ) via the formation of a short-lived intermediate. This intermediate was identified as a high-spin iron(III)alkylperoxo complex binding a thiocyanate ion as an axial ligand by characterizing it with various spectroscopic methods and density functional theory (DFT) calculations. We have also provided strong evidence that conversion of the high-spin iron(III)-alkylperoxo complex to its corresponding iron(IV)-oxo complex occurs via O-O bond homolysis. Thus, we have concluded that the role of the axial ligand binding to a high-spin iron(III)-alkylperoxo complex is to facilitate the alkylperoxo O-O bond cleavage via the ' push effect', which has been well established in heme enzymes. To the best of our knowledge, the present study reports the first clear example showing the O-O bond homolysis of a high-spin iron(III)-alkylperoxo complex and the axial ligand effect on the alkylperoxo O-O bond cleavage in nonheme iron models.
K. Fukutania,S. Ogura,K. Fukada,M. Matsumoto 한국진공학회 2014 Applied Science and Convergence Technology Vol.23 No.5
The influence of electron irradiation and hydrogen adsorption on the electronic structure of the SrTiO3 (001) surface was investigated by ultraviolet photoemission spectroscopy (UPS). Upon electron irradiation of the surface, UPS revealed an electronic state within the band gap (in-gap state: IGS) with the surface kept at 1×1. This is considered to originate from oxygen vacancies at the topmost surface formed by electron-stimulated desorption of oxygen. Electron irradiation also caused a downward shift of the valence band maximum indicating downward band-bending and formation of a conductive layer on the surface. With oxygen dosage on the electron-irradiated surface, on the other hand, the IGS intensity was decreased along with upward band-bending, which points to disappearance of the conductive layer. The results indicate that electron irradiation and oxygen dosage allow us to control the surface electronic structure between semiconducting (nearly-vacancy free: NVF) and metallic (oxygen de cient: OD) regimes by changing the density of the oxygen vacancy. When the NVF surface was exposed to atomic hydrogen, in-gap states were induced along with downward band bending. The hydrogen saturation coverage was evaluated to be 3.1±0.8×1014 cm−2 with nuclear reaction analysis. From the IGS intensity and H coverage, we argue that H is positively charged as H~0:3+ on the NVF surface. On the OD surface, on the other hand, the IGS intensity due to oxygen vacancies was found to decrease to half the initial value with molecular hydrogen dosage. H is expected to be negatively charged as H− on the OD surface by occupying the oxygen vacancy site.