• Transactions of the Korean hydrogen and new energy society
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• v.2 no.1
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• pp.77-82
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• 1990

To investigate the effect of strains heat effect and thermal energy on the intrinsic degradation of $LaNi_5$, the changes of P-C-Isotherm curves under the condition of mainly applied one of the above factors were investigated. The revesible hydrogen storage capacity decreased by means of the hydrogenation at high temperature without cyclings or pressure induced cyclings with low thermal energy. The degree of degradation was more severe as the heat of hydrogenation reaction increased. Thus the intrinsic degradation of $LaNi_5$ depended upon lattice strain as well as thermal energy.

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1139-1144
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• 2004

We studied a extraction and degradation of alginate from seaweed-stems using microorganism DS-02. DS-02 has a maximum growth rate at $30^{\circ}C$ and the enzyme has a maximum activity of alginate extraction at $35^{\circ}C.$ The yield of alginate extraction using DS-02 is about $16.0{\%}$ for 3.0 hour and molecular weight of the alginate decreased to about 1/8 of initial value after 24 hour extraction. Alginate extraction method by DS-02, compared with general alkali-extraction method, has an advantage of decreasing the molecular weight of alginate during extraction.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.2
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• pp.55-61
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• 2002

In this paper, 'lifetime-temperature rise model' based on the 'lifetime-resistance model' is theoretically Proposed, in order to find out the evaluation method of degradation and the residual lifetime by use of infrared image camera for electric connections/contacts. Two assumptions have been builded up for the 'lifetime-temperature rise model': one is associated with the linear relationship between the temperature ism ΔK and contact resistance, and the other the functional relationship between the temperature of electric connections/contacts and the operating time presenting in the 'lifetime-resistance model'. To prove the proposed model, experiments have been performed for various electric connections/contacts. From the experimental results, measured values were quite similar to the calculated values, which proved the above-mentioned two assumptions. Therefore, by use of 'lifetime-temperature rise model', it is possible to estimate the trend of degradation and the residual lifetime for electric connections/contacts through the temperature measurements .

• Journal of the Korean Society for Heat Treatment
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• v.11 no.2
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• pp.92-98
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• 1998

Degradation and recovery of damping capacity in a Cu-65%Mn alloy have been studied. When the alloy was isothermally aged at $400^{\circ}C$, the highest damping capacity was observed after aging for 4 hours. In case when the alloy aged at $400^{\circ}C$ for 4 hours was maintained at $100^{\circ}C$, the damping capacity gradually decreased with time. The microstructural observations showed that the formation of subdomains and ${\alpha}$-Mn precipitates are responsible for the degradation of damping capacity. When the degraded specimen was reheated at $250^{\circ}C$ for 30 minutes, the damping capacity was recovered considerably owing to the redistribution of impurity atoms, the extinction of subdomains and the release of damping sources from ${\alpha}$-Mn precipitates during the repeated transformation, fcc${\leftrightarrow}$fct.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.57-65
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• 2002

The photocatalytic degradation of TCE using solar energy in POFR was studied. The use of solar energy was investigated in plastic optica fiber photocatalytic reactor (POFR). In POFR, the main parameters of photocatalytic degradation of TCE were lihgt intensity, thickness of $TiO_2$-coated film on plastic fiber core, the same of total $TiO_2$-coated surface area with changed length. We studied the apparent photonic efficiency and photocatalytic degradation rate of TCE in POFR. The apparent photonic efficiency of various light intensities was decreased by an incresed intensities. The photocatalytic activities of $TiO_2$-coated optical fiber reactor system depended on the coating thickness, and total clad-stripped surface area of POF. Photocatalytic degradation of trichloroethylene ($C_2HCl_3$, TCE) in the gas-phase was elucidated by using $TiO_2$-coated plastic optical fiber reactor. In TCE degradation, in-situ FTIR measurement resulted in mineralization into $CO_2$.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.685-694
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• 2016

In this study, the thermal degradation behavior of biomass during torrefaction was studied by thermogravimetric and byproduct gas analysis. Torrefaction temperature, time, and heating rate were $220{\sim}300^{\circ}C$, 110 min, and $10{\sim}30^{\circ}C/min$, respectively. The degradation rate of yellow poplar was 8.01~8.81% at $220^{\circ}C$ and 71.86~77.38% at $300^{\circ}C$ depending on heating rate. The degradation rate significantly increased at temperature over $240^{\circ}C$. On the other hand, degradation rate of larch was relatively low as 49.58~54.15% at $300^{\circ}C$. The activation energy of yellow poplar was 87.32~91.24 kJ/mol; these values did not significantly change with heating rate. The activation energy of larch was 83.85~91.60 kJ/mol. The major components of the gas generated during torrefaction were derived from hemicellulose. The component types and concentrations increased with torrefaction severity. High concentrations of furfural and acetic acid were detected during torrefaction of yellow poplar.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.9
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• pp.628-633
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• 1999

Degradation diagnosis of XLPE insulated URD cables was accomplished through out new method, which was to be analyzed by non-electrical experiments and synthesized by degradation points. To supplement this method, It was also carried out using several electrical analyses. Tan$\delta$ had commonly a different tendency by means oftemperature and frequency and also appeared higher at the outer part rather than innerpart of insulator. PD-q increased generally in proportion to the applied voltage andshowed regular patterns in relation to the thickness of insulator. Breakdown voltageswere measured and breakdown lifetimes were predicted appling for Weibull distribution function. As a result, breakdown lifetime in failure cables was shorter up to$\fraction one-third$ times than that in general cables. It was very available to estimate cable degradation using above method, but it needs further study on XLPE insulated URD cables in order to improve reliability.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.6
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• pp.347-351
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• 2002

Benzoate produced from the degradative pathways of various aromatic chemicals is generally recognized as a pollutant compound. However, various bacterial strains isolated as benzoate degraders have exhibited certain limits to their functions, including a loss of viability and degradability when cultivated in a broth medium for a longer time. Accordingly, immobilization techniques have been utilized to overcome such problems, and the current study examined the use of alginate and polyurethane for immobilizing Klebsiella oxytoca C302 to extend its viability and degradability of benzoate. The organism was well encapsulated by both matrices and the immobilized cells showed a high stability as regards their viability and degradability of 2 mM benzoate in a MM2 broth medium during cultivation for longer than 60 h in a semicontinuous batch system.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.322.1-322.1
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• 2014

Many research groups have studied tandem or multi-junction cells to overcome this low efficiency and degradation. In multi-junction cells, band-gap engineering of each absorb layer is needed to absorb the light at various wavelengths efficiently. Various absorption layers can be formed using multi-junctions, such as hydrogenated amorphous silicon carbide (a-SiC:H), amorphous silicon germanium (a-SiGe:H) and microcrystalline silicon (${\mu}c$-Si:H), etc. Among them, ${\mu}c$-Si:H is the bottom absorber material because it has a low band-gap and does not exhibit light-induced degradation like amorphous silicon. Nevertheless, ${\mu}c$-Si:H requires a much thicker material (>2 mm) to absorb sufficient light due to its smaller light absorption coefficient, highlighting the need for a high growth rate for productivity. ${\mu}c$-SiGe:H has a much higher absorption coefficient than ${\mu}c$-Si:H at the low energy wavelength, meaning that the thickness of the absorption layer can be decreased to less than half that of ${\mu}c$-Si:H. ${\mu}c$-SiGe:H films were prepared using 40 MHz very high frequency PECVD method at 1 Torr. SiH4 and GeH4 were used as a reactive gas and H2 was used as a dilution gas. In this study, the ${\mu}c$-SiGe:H layer for triple solar cells applications was performed to optimize the film properties.

• Journal of the Korean Ceramic Society
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• v.46 no.3
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• pp.263-270
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• 2009

The effect of photoelectrocatalytic (PEC) degradation for different dyes with the CNT/$TiO_2$ electrode was studied. The prepared electrode was characterized with surface properties, structural crystallinity, elemental identification, and PEC activity. The $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine CNT. This indicated the blocking of micropores on the surface of CNT, which was further supported by observation via FESEM. XRD patterns of the composites showed that the CNT/$TiO_2$ composite contained a mixing anatase and rutile phase. EDX spectra showed the presence of C, O and Ti peaks for all samples. The decomposition efifciency of the prepared electrode was evaluated by the PEC degradation of three dyes (methylene blue (MB), rhodamine B (RH.B), methyl orange (MO)). The variations of the FT-IR spectra and pH value of dye solutions were measured during the PEC system; it was found that the CNT/$TiO_2$ electrode has better PEC degradation for MB solution than that of RH.B and MO. The proposed degradation mechanism was present.