• Journal of the Korean Solar Energy Society
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• v.27 no.1
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• pp.75-81
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• 2007

Steam reforming of methane using Xe-arc solar simulator was studied for the application of concentrated solar energy into chemical reaction. The reactor, a volumetric absorber, consisted of a porous ceramic foam disk coated with commercial reforming catalyst. Operating temperature was in the range of $450\;-\;550^{\circ}C$ and the excess steam ratio to methane was from 3.0 to 5.0. At the steady-state condition, the conversion of methane Increased with temperature in the range of 15 % - 30 % and the experimentally determined conversion was found to be close to theoretical equilibrium conversion. It was also found that the CO selectivity slightly decreased with excess steam ratio. Finally, the conversion of methane decreased significantly with space velocity of reactants.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.353-356
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• 2005

We developed a dynamic model of PEM fuel cell system which can analyze its transient response to dynamic load current. System components such as compressor, air cooler, humidifier, and stack were modeled based on their dynamic equations and performance maps by using Matlab Simulink platform. Through this simulation model, dynamic characteristics of fuel cell system including oxygen excess rat io, stack voltage, and system efficiency were shown. In addition to that, we briefly analyzed the humidity effect on cathode pressure and system efficiency, expecting that this model can be further used to optimize fuel cell system parameters just like operating pressure and temperature, humidity and oxygen excess ratio.

• Journal of the Korean Applied Science and Technology
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• v.13 no.3
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• pp.119-125
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• 1996

The excess volumes of mixing of benzyl alcohol, ethyl alcohol, halothane, and procaine in vesicle and suspensions of several lipids have been determined at $25^{\circ}C$ using a excess volume dilatometer. The potency of general anesthetics has long been known to be correlated with lipid solubility. Denaturations of the bacteriorhodopsin, which is a sole membrane protein in the purple membrane of Halobacteriun Halobium, were studied by UV/Vis absorption changes. The excess volumes of mixing of benzyl alcohol and procaine in egg lecithin were all found to be negative and this result was confirmed as Miller's supposition.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.60-66
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• 2001

Combustion using pure oxygen instead of air is an energy saving technology that can increase thermal efficiency by the improvement of burning rate and ultra high temperature flame, being used on the industrial spot. But information about it is not so enough yet. Flame figure, temperature distribution and emission concentration were measured with oxygen excess ratio and swirl number in a turbulent diffusion flame to investigate the combustion characteristics using pure oxygen. The results showed that flame figure became different as long as oxygen excess ratio varied and that concentration of NO and CO increased suddenly around ${\lambda}$=1.5.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.353-356
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• 2002

Planar laser induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Preliminary investigation was performed to measure quantitative air excess ratio distribution in an engine fueled with LPG. It is known that fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone was excited by KrF excimer laser (248nm) and its fluorescence image was acquired by ICCD camera with a cut-of filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile was suggested. Raw images were divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which was taken by a calibration process, were converted to air excess ratio distribution. This investigation showed instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1403-1407
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• 2004

Dielectric relaxation measurements on 3-nitrotoluene (3-NT) mixture of dimethylacetamide (DMA), dimethylformamide (DMF) and dimethysulphoxide (DMSO) have been carried out across the entire concentration range using Time domain reflectometry technique at 15, 25, 35 and $45^{\circ}C$ over the frequency range from 10 MHz to 20 GHz. For all the mixtures, only one dielectric loss peak was observed in this frequency range and the relaxation in these mixtures can be well described by a single relaxation time using Debye model. Bilinear calibration method is used to obtain complex permittivity ${\varepsilon}^{*}({\omega})$ from complex reflection coefficient ${\rho}^{*}({\omega})$ over frequency range 10 MHz to 20 GHz. The excess permittivity, excess inverse relaxation time, Kirkwood correlation factor, molar energy of activation are also calculated for these mixtures to study the solute-solvent interaction.

• Korean Journal of Metals and Materials
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• v.46 no.2
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• pp.53-57
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• 2008

This study examined the role of excess free volume on the corrosion resistance of an amorphous alloy. Corrosion behaviors were monitored on the amorphous alloys, of which amount of free volume was controlled via the isothermal annealing below the glass transition temperature, using immersion tests and potentiodynamic polarization tests in HCl aqueous solutions. It was found that the corrosion resistance of the amorphous alloy is improved by reducing the amount of excess free volume. The possible reason explaining the experimental result was discussed from the viewpoint of the internal energy associated with the annihilation of excess free volume.

• Journal of Ginseng Research
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• v.14 no.3
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• pp.416-420
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• 1990

Ultrastructural and anatomical features of the leaf were studied in Panax ginseng C.A. Meyer(ginseng). The ginseng leaf poorly developed palisade tissue and the size of mesophyll cell was larger and the chloroplast density was lower than that of Glycine max (soyben). Ginseng chloroplast was filled with highly stacked grana and condensely-arrayed thylakoid, so the stroma space was hardly absorbed. However, ginseng mesophyll tissue and chloroplast array did not reduce light energy entering the mesophyll chloroplast, and the high LHCP/CP ratio of ginseng thylakoid resulted in the absorption of excess photon. It is reasonable to assume that 1O1-photogenearation by excess light energy partially resulted from the anatomical and ultrastructural characteristics of the ginseng leaf.

• Journal of The Korean Astronomical Society
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• v.38 no.3
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• pp.339-344
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• 2005

We present analysis results of the energy spectra of MCG-2-58-22 associated with occasional flares which appear in a long-term X-ray light curve. We measure an intrinsic power-law slope of this object to be ${\Gamma}=1.74{\pm}0.02$ in the energy range of ${\sim}1-5keV$ and find that this slope is little affected by flares. We confirm that there exists a broad excess emission above 5 keV to the power-law continuum. The excess emission is less variable compared with a flux variation of flare and tends to be relatively weak during flares. A soft X-ray spectrum is also found to change, implying the presence of a variable soft component. We discuss the implications of these spectral variations.

• The Journal of the Acoustical Society of Korea
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• v.19 no.3E
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• pp.25-32
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• 2000

The main question addressed in this research was whether an adaptation of a standard exercise Physiology Procedure would be sensitive enough to record excess oxygen uptake associated with speech activity. Oxygen consumption was recorded for a single subject during 7-minute rest periods and an automatic speech task, also 7-minutes long and performed at three different vocal efforts. The data show measurable and systematic speech-induced modifications of breathing and oxygen uptake patterns. The subject was found to use less power for normal than for soft and loud speech. This result is similar to findings reported by experimental biologists on the energetics of locomotion. However, more comprehensive feasibility studies need to be undertaken on a larger population before solid and detailed conclusions about speech energy costs are possible. However, it appears clear that, for experimental tasks like the present one, i.e., variations in vocal effort, standard exercise physiology methods may indeed offer a viable approach to recording excess oxygen uptake associated with speech movements.