Hiroshima, Japan

Hiroshima Kokusai Gakuin University is a private university in Hiroshima, Hiroshima, Japan. The predecessor of the school was founded in 1927. It was chartered as a junior college in 1964 and became a four-year college in 1967. Wikipedia.


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Min S.,Wuhan Textile University | Nagamura K.,Hiroshima University | Nakagawa N.,Hiroshima Kokusai Gakuin University | Okamura M.,DaikyoNishikawa Coporation
Applied Acoustics | Year: 2013

Polycarbonate (PC) laminate is gradually substituted for the glass as window pane in automobile. Absorption performance of PC pane is poor using resin membrane between two folders of pane because of the low acoustic impedance of membrane. Micro-perforated absorbers can provide high absorption coefficients. However, the depths of air cavity were all over the 50 mm in past studies. In this paper, a compact and efficient micro-perforated membrane (MPM) absorber is designed as a combination of baffle-resonator and Helmholtz-resonator with sub-millimeter holes backed by an air space. Absorption coefficients of MPM absorbers are predicted by equivalent electric-acoustic circuit analysis method. This paper presents three different MPM materials of polypropylene, polyethylene, and carbon polyester respectively. The numerical results shows that absorption performance of PC pane can be improved using double layer MPM absorber and the whole thickness of MPM absorber is not exceed 10 mm to meet the structural requirement of PC pane application in automobile. Crown Copyright © 2012 Published by Elsevier Ltd. All rights reserved.


Yasuda T.,Hirotec Corporation | Yasuda T.,Hiroshima University | Wu C.,Wuhan University of Technology | Nakagawa N.,Hiroshima Kokusai Gakuin University | Nagamura K.,Hiroshima University
Applied Acoustics | Year: 2013

Tail pipe is a most common structure in mufflers to silence low frequency noise from an engine for its acoustic performance of low-pass filter. Based on the typical structure, a muffler with an interconnecting hole on the tail pipe was proposed to improve its acoustic performance in the present research. Acoustic performances of the proposed muffler were studied experimentally and theoretically in frequency and time domain. It was found that the interconnecting hole enabled the proposed muffler to have a noise attenuation performance of Helmholtz resonator. So the proposed muffler can attenuate the noise of low frequency and middle frequency at the same time. The frequency equation of this structure was derived using the acoustic-electronic analogy. It is useful for estimating the attenuation performance at the stages of predesign or tuning. The influence of structure parameters of the proposed muffler on its acoustic performance was studied. According to the results, the design guideline of this muffler was concluded in the present research. © 2012 Elsevier Ltd. All rights reserved.


Pomogaeva A.,Kyushu University | Gu F.L.,Kyushu University | Imamura A.,Hiroshima Kokusai Gakuin University | Aoki Y.,Kyushu University | Aoki Y.,Japan Science and Technology Agency
Theoretical Chemistry Accounts | Year: 2010

The investigations of one-dimensional periodic associations of benzo-2,1,3-chalcogendiazoles have been carried out by the elongation method. S, Se and Te chalcogens have been in use. For the polymers, band structures and local densities of states were extracted from ab initio calculations of electronic structure of the 15 units' oligomers. Static electric (hyper)polarizabilities were studied by the elongation finite-field method. © Springer-Verlag 2009.


Imamura A.,Hiroshima Kokusai Gakuin University | Aoki Y.,Kyushu University
Chemical Physics Letters | Year: 2013

Polyyne oligomers (H2CnH2), with CH 2 group at each end of the oligomer, have been found to give helical molecular orbitals for the HOMO and LUMO and other molecular orbitals around the HOMO and LUMO when the two CH2 groups are tilted from their equilibrium positions. This can be explained by the changes in the symmetry of H2C2m+1H2 from D 2d to D2, the former having degenerate molecular orbitals but the latter having non-degenerate orbitals. These helical molecular orbitals have been pointed out as being a kind of molecular device through which electrons pass. © 2013 Elsevier B.V. All rights reserved.


Imamura A.,Hiroshima Kokusai Gakuin University | Aoki Y.,Kyushu University
International Journal of Quantum Chemistry | Year: 2013

Recently, many interesting materials made from carbon atoms have been discovered such as carbon nanotubes, fullerenes, and graphenes. In this article, we studied electronic structures and molecular structures of polyynes with sp2 carbons on both ends. Polyynes calculated were H 2CCnCH2 with various number of n. These molecules have two π systems which are perpendicular to each other and these π systems have their tendency to make double bond nature by Peierls instability but for different alternating bonds. In other words, these two π systems are competing to form the double bond formations. The calculations were performed at Hartree-Fock level geometry optimization with 6-31G, 6-311G, and 6-31G* basis sets. For CH2(C)2mCH2, we have found that there are two metastable structures, one of which is the bond-alternating structure and another is nearly equi-bond structure. The former has small highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap while the latter has relatively large gap although it is smaller in comparison with the value of polyyne with sp carbon atoms on both ends: H(C)2mH. The small highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap in bond-alternating structure is due to the fact that HOMO and MO's near to HOMO have relatively localized electronic distribution in both end regions, and thus, the weak interaction between the both regions leads to the small HOMO-LUMO gap. The stability is larger for the former especially in long polyynes. For CH 2(C)2m+1CH2, we have found only one stable structure, that is, equi-bond structure. This type of polyyne oligomers has two terminal CH2 groups which are perpendicular with each other. It is found that the longer the length of oligomer is, the smaller the HOMO-LUMO gap is as is usually expected. By summarizing these results, we proposed a design for a single-chain electronically conductive polymers. © 2012 Wiley Periodicals, Inc.


Murayama K.,Nihon University | Monji K.,Nihon University | Deki H.,Hiroshima Kokusai Gakuin University
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2010

The similarity of the excitation energy dependence of the luminescence peak energy in a-Si:H to that of Si nanoparticles in porous Si is indicated. The 2 ms life time of the slow luminescence component in a-Si:H almost agrees with that of the luminescence from the Si nanoparticles in the porous Si. It is explained from the similarity that the luminescence in a-Si:H is due to the radiative recombination of a trapped hole and a quantum-confined electron in hydrogen-free Si nanostructures. The observation of the luminescence accompanying with the phonon emission in the hydrogen-free Si nanostructure has been tried. A weak structure expected to be due to one optical phonon emission has been observed with the exciting light of the energy less than the hopping gap. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.


Nakasa K.,Hiroshima Kokusai Gakuin University | Yamamoto A.,Asahi Surface Tec LLC | Sumomogi T.,Hiroshima Kokusai Gakuin University
Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan | Year: 2014

Argon ion sputter etching was applied to three kinds of martensitic stainless steels (SUS410, SUS420J2 and SUS440C) and a ferritic stainless steel (SUS430) at a radio frequency power of 250 W for 0.6 ks to 21.6 ks. When the sputter etching time is 0.6 or 0.9 ks, the pillar-shaped protrusions with diameters smaller than 1 μm are formed on the surface of the SUS420J2 steel. With increasing sputter etching time, the cone-shaped protrusions are formed around the base of the pillars, and the size of the conical protrusions increases to more than 10 μm with further increase in the sputter etching time. When the sputter etching time is 21.6 ks, the size of the protrusion becomes more than 20 μm and the surface of the protrusions is heavily damaged. According to an EDX analysis, the Cr content of the surface of a cone is larger than that of the inside and the matrix surrounding the cone. Other steels show a similar protrusion formation process to the SUS420J2 steel, but the formation speed and the density of the cones are smaller for the SUS410 or SUS430 steels with smaller carbon content than the SUS420J2 steel, whereas they are a little larger for the SUS440C steel with larger carbon content. For the martensitic stainless steels, the quenching increases the hardness of protrusions, which is convenient for a traction roll and a transcription roll to imprint many holes to sheets.


Fujiyama H.,Fukuoka Institute of Technology | Sumomogi T.,Hiroshima Kokusai Gakuin University | Nakamura M.,Hiroshima Kokusai Gakuin University
Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films | Year: 2012

The effect of O 2 partial pressure on the mechanical properties of Al 2O 3 films is studied. Using films prepared by inductively coupled plasma-assisted radio frequency magnetron sputtering, the deposition rate of Al 2O 3 decreases rapidly when oxygen is added to the argon sputtering gas. The internal stresses in the films are compressive, with magnitude decreasing steeply from 1.6 GPa for films sputtered in pure argon gas to 0.5 GPa for films sputtered in argon gas at an O 2 partial pressure of 0.89 × 10 -2 Pa. Stress increases gradually with increasing O 2 partial pressure. Using a nanoindentation tester with a Berkovich indenter, film hardness was measured to be about 14 GPa for films sputtered in pure argon gas. Hardness decreases rapidly on the addition of O 2 gas, but increases when the O 2 partial pressure is increased. Adhesion, measured using a Vickers microhardness tester, increases with increasing O 2 partial pressure. Electron probe microanalyzer measurements reveal that the argon content of films decreases with increasing O 2 partial pressure, whereas the O to Al composition ratio increases from 1.15 for films sputtered in pure argon gas to 1.5 for films sputtered in argon gas at O 2 partial pressures over 2.4 × 10 -2 Pa. X-ray diffraction measurements reveal that films sputtered in pure argon gas have an amorphous crystal structure, whereas γ-Al 2O 3 is produced for films sputtered in argon gas with added O 2 gas. Atomic force microscopy observations reveal that the surface topography of sputtered Al 2O 3 films changes from spherical to needlelike as O 2 partial pressure is increased. Fracture cross sections of the films observed by scanning electron microscopy reveal that the film morphology exhibits no discernible features at all O 2 partial pressures. © 2012 American Vacuum Society.


Koseki Y.,Hiroshima Kokusai Gakuin University
Geographical Review of Japan | Year: 2016

With increased imports of agricultural products to Japan, concerns over safety and quality increased. The Ministry of Health, Labour and Welfare introduced "a positive list system" for agricultural chemical residues in food on May 29, 2006. Japan has been working hard to regulate residual agricultural chemicals. This paper examines how Taiwanese mangos are produced and exported to Japan. It also examines how Taiwan's market response to Japan focusing on safety and quality control has been influencing its mangoproducing region and agriculture in general. After Japan introduced the positive list system for agricultural chemical residues, the Executive Yuan Council of Agriculture established a production and exportation system conforming with Japanese safety standards. This mandatory registration system regulates mango exporters and cultivators under mango production contracts, and a pesticide residue inspection by cultivators must be carried out twice before mangos are shipped to Japan. In addition, the exporters and producers share information concerning safety and quality control for mangos. This information is disclosed to consumers through the traceability system of the Executive Yuan Council of Agriculture. In Taiwan's mango-producing region, most growers who sell to both the Japanese and domestic markets use the same production and exportation system along with Japanese safety standards to grow Irwin mangos. Some producers, who are able to add value to their mangos by utilizing the traceability system that ensures food safety, also sell their mangos on the domestic market. This suggests that the traceability system developed for exportation to Japan has resulted in quality assurance that gives high added value to mango producers in Taiwan. Producing and exporting mangos utilizing the Japanese safety standards have therefore been playing a role in enhancing agricultural standards in Taiwan. Changes in the system concerning food safety developed the traceability system and heightened the awareness of producers and exporters of the need for safety and cultivation management. Taiwan's response to Japan focusing heavily on safety has also increased the incomes of mango growers. If Taiwan wants to continue exporting mangos to Japan, it is important for it to see the advantage of spending on labor and costs to ensure safety after the system changes. Moreover, mangos cultivated based on the production and exportation system along with Japanese safety standards have created a new differentiated domestic market. Taiwan's efforts for exportation to Japan with a heavy focus on safety have become one of the reasons why the agriculture sector in Taiwan diversified the market for domestic mangos.


Nakasa K.,Hiroshima Kokusai Gakuin University | Yamamoto A.,Yamatomec Co.
Surface and Coatings Technology | Year: 2012

Argon ion sputter-etching was applied to W-Mo-Cr-V high speed steel, Cr-Mo-V die steel, and type 304 and 316 austenitic stainless steels. Vapor-deposition of the polyethylene (PE) or 1H, 1H, 2H, 2H, -Perfluorodecyltriethoxysilane (PFDS) was carried out on the sputter-etched surface. The hydrophobicity was evaluated by measuring the contact angle (CA) of a water droplet on the surface. The sputter-etching formed fine and dense pillar- or cone-shaped protrusions with a diameter of 100. nm to 1 μm on the tool steels and the type 316 steel but cone-shaped protrusions with a diameter of more than 1 μm on the type 304 steel. The surfaces of all the steels just after the sputter-etching revealed CAs smaller than 4.5°, or superhydrophilicity. On the other hand, all the steels that were sputter-etched and vapor-deposited with PE or PFDS produced CAs of more than 150°, or superhydrophobicity, except that the CA of the type 304 steel with micron-sized protrusions was 146° The adhesion of the PFDS layer to the protrusions is much stronger than the PE layer, i.e. it is difficult to remove the PFDS layer by heating at 473. K and ultrasonic cleaning in acetone. © 2012 Elsevier B.V.

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