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Tsuda Y.,Kurume National College of Technology
Journal of Photopolymer Science and Technology | Year: 2013

The soluble polyimides were synthesized from the several types of diamine monomers having multiple long-chain alkyl groups, tetracarboxylic dianhydrides such as Cyclohexene-DA, 3,4'-ODPA (a-ODPA), DSDA, and DDE as a diamine co-monomer. The thin films of obtained polyimides were irradiated by UV light (λmax; 254 nm), and the contact angles for the water decreased from near 100° (hydrophobicity) to near 20° (hydrophilicity) in proportion to irradiated UV light energy. From the result of contact angle measurements and the result of the ATR and XPS analysis, it is recognized that the hydrophobic long-chain alkyl groups on the polyimide surface decrease and the hydrophilic groups such as a carboxyl group and a hydroxyl group generate on their surface. Thus, the surface wettability of polyimides bearing long-chain alkyl groups can be controlled by UV light irradiation, and these methods are expected to be applied in the field of printed electronics. © 2013SPST.


Osada Y.,Kurume National College of Technology
IEEJ Transactions on Electronics, Information and Systems | Year: 2011

Leading-edge Monte Carlo simulation has been researched and developed for semiconductor with complicated calculation under advanced computational circumstances. On the other hand, Monte Carlo simulation based on an analytic band model was reported for electron transport in silicon from the view point of simplicity and speed of calculation on a desktop workstation(1). This simulation included scatterings by non-polar optical phonon and acoustic phonon in X valley in the conduction band. However, this simulator did not contain impact ionization or donor concentration. Therefore, it might be difficult to simulate at high electric fields and with donor concentrations. In the present study, Ensemble Monte Carlo simulation based on analytic band model has been developed for electron transport in silicon in order to extend the ranges of electric fields and donor concentrations at practical temperatures. For these purposes, the present simulator includes L valley, in addition to X valley, impact ionization and donor ionization rate. Furthermore, the simulation is executed on a personal computer. © 2011 The Institute of Electrical Engineers of Japan.


Ishi-I T.,Kurume National College of Technology | Sakai M.,Kurume National College of Technology | Shinoda C.,Kurume National College of Technology
Tetrahedron | Year: 2013

In this paper, we report the preparation and red-light-emitting behavior of benzothiadiazole-tris(alkyloxy)phenylethene dyes. In solution, we observed an efficient red light emission with high fluorescence quantum yields (up to 0.78). With increase in solvent polarity, the emission bands shifted to longer wavelengths accompanied by a large Stokes shift of up to 152 nm. A moderate fluorescence quantum yield of 0.52 could be achieved even in the polar solvent dimethylformamide. Red light emission with good fluorescence quantum yields (up to 0.50) was also observed in the bulk solid, liquid, and film state. © 2013 Elsevier Ltd. All rights reserved.


Tanaka H.,Kurume National College of Technology
Desalination | Year: 2011

A basin type solar still with a flat plate external bottom reflector extending from the front wall of the still in addition to the internal (two sides and back walls) reflector is presented and analyzed theoretically on three days (the spring equinox and summer and winter solstices) at 30°N latitude. We proposed a geometrical model to calculate the direct solar radiation reflected by the external bottom reflector and then absorbed onto the basin liner. We also performed a numerical analysis of heat and mass transfer in the still. We found that the external reflector can reflect the sunrays to the basin liner and increase distillate productivity. The daily amount of distillate of the still with internal and external bottom reflector is predicted to be 41%, 25% and 62% greater than that of a conventional basin type still on the spring equinox and summer and winter solstices, respectively, by setting the external reflector's inclination to the proper values according to the seasons when the glass cover's inclination angle is fixed at 20° from horizontal and the length of the external reflector is the same as the length of the basin liner. © 2011 Elsevier B.V.


Tanaka H.,Kurume National College of Technology
Energy Reports | Year: 2015

Augmentation of solar radiation absorbed on a flat plate solar thermal collector by a flat plate bottom reflector was numerically determined when there was a gap between the collector and reflector. The inclination of both the collector and reflector was assumed to be adjustable according to the season. A mirror-symmetric plane of the collector to the reflector was introduced, and a graphical model was proposed to calculate the amount of solar radiation reflected by the reflector and then absorbed on the collector. The performance was analyzed for three typical days at a latitude of 30°N. Solar radiation absorbed on the collector can be increased by the bottom reflector even if there is a gap between the collector and reflector. The optimum inclinations of both the collector and reflector are almost the same while the gap length is less than the lengths of the collector and reflector. However, the range of inclination of the reflector that can increase the solar radiation absorbed on the collector decreases with an increase in gap length, and the solar radiation absorbed on the collector rapidly decreased with an increase in the gap length when the reflector and/or collector were not set at a proper angle. © 2014 The Author.


Tanaka H.,Kurume National College of Technology
Desalination | Year: 2011

This paper presents a theoretical analysis of a tilted wick solar still with a flat plate bottom reflector extending from the lower edge of the still on four days (the spring and autumn equinox and summer and winter solstices) at 30°N latitude when the still's inclination is fixed at 30° and the reflector's length is the same as the still's length. We propose a geometrical model to calculate the solar radiation reflected by the bottom reflector and then absorbed on the evaporating wick. We also performed a numerical analysis of heat and mass transfer in the still. We found that the bottom reflector can reflect the sunrays to the evaporating wick and increase distillate productivity of the tilted wick still when the reflector's inclination is larger than about 15° on the spring and autumn equinox and winter solstice, and 25° on the summer solstice, and the average distillate value for four days is greatest when the reflector's inclination is about 35° and would be about 13% greater than that of a conventional tilted wick still. © 2011 Elsevier B.V.


Tanaka H.,Kurume National College of Technology
Applied Energy | Year: 2011

In this report we present a theoretical analysis of a solar thermal collector with a flat plate top reflector. The top reflector extends from the upper edge of the collector, and can be inclined forwards or backwards from vertical according to the seasons. We theoretically predicted the daily solar radiation absorbed on an absorbing plate of the collector throughout the year, which varies considerably with the inclination of both the collector and reflector, and is slightly affected by the ratio of the reflector and collector length. We found the optimum inclination of the collector and reflector for each month at 30°N latitude. An increase in the daily solar radiation absorbed on the absorbing plate over a conventional solar thermal collector would average about 19%, 26% and 33% throughout the year by using the flat plate reflector when the ratio of reflector and collector length is 0.5, 1.0 and 2.0 and both the collector and reflector are adjusted to the proper inclination. © 2010 Elsevier Ltd.


In this report, we present a theoretical analysis of a basin type solar still with internal and external reflectors. The external reflector is a flat plate that extends from the back wall of the still, and can presumably be inclined forwards or backwards according to the month. We have theoretically predicted the daily amount of distillate produced by the still throughout the year, which varies according to the inclination angle of both the glass cover and the external reflector, at 30°N latitude. We found the optimum external reflector inclination for each month for a still with a glass cover inclination of 10-50°. The increase in the average daily amount of distillate throughout the year of a still with inclined external reflector with optimum inclination in addition to an internal reflector, compared to a conventional basin type still was predicted to be 29%, 43% or 67% when the glass cover inclination is 10°, 30° or 50° and the length of external reflector is half the still's length. © 2010 Elsevier Ltd.


Yasuda T.,Japan National Institute of Materials Science | Shinohara Y.,Kurume National College of Technology | Matsuda T.,Kurume National College of Technology | Han L.,Japan National Institute of Materials Science | Ishi-I T.,Kurume National College of Technology
Journal of Materials Chemistry | Year: 2012

A comparative study of the properties of bulk-heterojunction organic photovoltaic cells (OPVs) using a benzothiadiazole (BTD)-triphenylamine (TPA) small molecule and its polymerized molecule (poly(BTD-TPA)) is presented. OPVs using BTD-TPA or poly(BTD-TPA):PC 60BM at a 1:2 mixing weight ratio were fabricated. The power conversion efficiency (PCE) of the poly(BTD-TPA)-based OPV was twice that of the BTD-TPA-based OPV. The field-effect hole mobility of poly(BTD-TPA) is two orders of magnitude higher than that of BTD-TPA and the absorption peak of poly(BTD-TPA) is at a longer wavelength than that of BTD-TPA. Accordingly, the improved hole mobility and enhanced absorption of AM1.5 solar-simulated light led to a high short-circuit current (J sc) and PCE in OPVs based on poly(BTD-TPA). Using OPVs with poly(BTD-TPA):PC 70BM (1:4), the device performance exhibited a J sc value of 7.45 mA cm -2, an open-circuit voltage of 0.92 V, a PCE of 2.65%, and incident photon to current conversion efficiencies of around 50% at wavelengths ranging from 360 to 560 nm. The experimental results for the OPVs with BTD-TPA-based materials indicate that the polymer is effective for obtaining high-performance OPVs. © 2012 The Royal Society of Chemistry.


Yasuda T.,Japan National Institute of Materials Science | Shinohara Y.,Kurume National College of Technology | Ishi-I T.,Kurume National College of Technology | Han L.,Japan National Institute of Materials Science
Organic Electronics: physics, materials, applications | Year: 2012

An amorphous polymer, poly(BTD-TPA), which consists of benzothiadiazole and triarylamine units, can be successfully utilized to fabricate bulk heterojunction (BHJ) organic photovoltaics (OPVs), and the OPV performance can be demonstrated to be independent of the casting solvent or thermal annealing temperature. The OPV based on poly(BTD-TPA):PC 70BM (1:4) that was fabricated using chloroform (boiling point of 61 °C) and annealed at 60 °C for 10 min exhibited a power conversion efficiency (PCE) of 2.81% under simulated solar irradiation through an air mass of 1.5 at 100 mW cm -2. On the other hand, the OPV fabricated using o-dichlorobenzene (boiling point of 181 °C) and annealed at 110 °C for 10 min exhibited a PCE of 2.65%. Almost the same PCEs and incident photon to current conversion efficiencies (IPCEs) were obtained in both OPVs. The use of an amorphous film of poly(BTD-TPA) in the fabrication of OPVs offers great advantages over the use of a polycrystalline film of regioregular poly(3-hexylthiophene) (P3HT) in terms of high reproducibility of the OPV performance. © 2012 Elsevier B.V. All rights reserved.

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