• Korean Journal of Microbiology
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• v.34 no.3
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• pp.96-100
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• 1998

The effects of electron acceptors and acclimation of inoculum on the anaerobic degradation of benzene, toluene, and m-xylene (BTX) were investigated to enhance the rate of degradation by estuarine sediment inoculum. With the fresh sediment inocula, degradation of BTX ensued after a 10-week acclimation period, and 37~61% of benzene and 57~61% of toluene were degraded after 16 weeks. Sediments from heavily contaminated sites showed higher degradation rates of BTX. After a 6-month of acclimation, degradation onset rapidly from the time of BTX addition and no difference was found among the sediment inocula. Single compound of BTX was slowly degraded in the methanogenic conditions, however, the degradation of BTX mixture was slow in the denitrifying conditions. Although the degradation rate of m-xylene was the fastest among the components of BTX mixture, longer acclimation enhanced the degradation rate of BTX, especially that of benzene. When the culture fluids were tested with Microtox, anaerobic degradation of BTX reduced the toxicity of BTX as well.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.4
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• pp.313-318
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• 1990

Forty-two outbred female Sprague-Dawley rats weighing 145 g were used to study the effects of a beta-agonist, cimaterol, on growth, body composition and urinary excretion of 3-methylhistidine (MH) at 3, 6 and 18 d. Cimaterol (CIM) was administered in the feed at 10 mg/kg. The growth promoting effect of CIM was most evident during the initial part of the feeding period, followed by a gradual decrease in the magnitude of the response with no significant effect at 18 d. The action of CIM was confined to skeletal and cardiac muscles with no stimulating effect on other organs. The amount of urine excretion and urinary MH excretion was reduced (p<.01) at 3 d in the CIM group. No difference was found at 6 d, followed by an increased urine excretion (p<.05) and MH excretion (p<.01) at 18 d. An inverse relationship between growth rate and urinary MH excretion suggested that the increased growth rate of CIM-fed rats during the initial part of the feeding period is primarily attributed to the decreased protein degradation rate. It was further suggested that both fractional synthesis rate and fractional degradation rate increased during the later part of the feeding period.

• Journal of Environmental Science International
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• v.25 no.3
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• pp.385-393
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• 2016

Oxidative and thermal degradation of alkanolamines for a promising $CO_2$ capture technology of absorption might cause decrease in $CO_2$ capture efficiency and formation of hazardous byproducts. In this study, characteristics of a representative absorbent of monoehtanolamine (MEA) were examined for a long term operation using a laboratory scale absorption system. An $CO_2$ absorption system with ID 56 mm and absorption zone height 100 cm was developed for the characterization. Absorption solution of 30 wt% MEA was circulated at 100 mL/min to treat air with 15% $CO_2$ and 1 ppm NO at 10 L/min. Temperatures of absorber and stripper were maintained at $40^{\circ}C$ and $120^{\circ}C$, respectively. For the course of 5 weeks continuous operation, MEA concentration was decreased approximately by 70% and $CO_2$ removal efficiency was dropped from 95% to 65%. Ionic byproducts of $NH_4{^+}$, $NO_2{^-}$, and $NO_3{^-}$ were accumulated up to 48 g/mL, 0.2 g/mL, and 1.5 g/mL, respectively, tracking the variation of MEA concentration. Formation of various organic byproducts were also observed.

• Journal of Conservation Science
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• v.33 no.3
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• pp.203-214
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• 2017

This study evaluated the degradation characteristics of FRP by ultraviolet (UV) rays and applied a UV-resistant coating to prevent the degradation of the surface of these sculptures. As a result of the degradation caused by UV rays, there were slight changes in the FRP surface and contact angle. The chromaticity sharply increased in the early phase of degradation. After applying the coating to the FRP, no significant surface changes were observed. However, it had lower changes in color as compared to the uncoated specimen, so it was verified that the control of discoloration could be possible. Some changes in the gloss and contact angle were observed depending on the extent of degradation, but the UV coating agent remained relatively stable. Analysis of the infrared light spectrum showed that there were almost no chemical changes, and it could be concluded that the coating treatment prevented degradation for a certain period. This study investigated the degradation of FRP used as materials in artwork exposed to UV rays, and it was found that there was a delay in the onset of degradation in the FRP with the UV-resistant coating when compared to the uncoated FRP.

• Journal of the Korean Ceramic Society
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• v.34 no.9
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• pp.915-920
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• 1997

Tetragonal ZrO2 polycrystal (TZP), consisted of 90.24 mol% ZrO2-5.31 mol% Y2O3-4.45 mol% Nb2O5, were prepared using hot-press and mechanical properties and high-temperature degradation were investigated. The specimen, hot-pressed for 1 h at 140$0^{\circ}C$ in Ar atmosphere, exhibited flexural strength of 1010 MPa and fracture toughness of 7.5 MPam1/2 and experienced no low-temperature degradation below 40$0^{\circ}C$. However, as aged for 100h at temperatures higher than 40$0^{\circ}C$, TZP was suffered by high-temperature degradation due to an extensive cavitation caused by the oxidation of carbon. XPS observation revealed that the carbon incorporated in TZPs during hot-pressing exists as either an ether-type CO or a carbonyl-type C=O. Despite of the high-temperature degradation of t-ZrO2 co-doped with Y2O3 and Nb2O5, its flexural strength and fracture toughness were superior to those of the commercial 3 mol% Y2O3-TZP hot-pressed under the identical condition as determined before and after the aging treatments.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.E2
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• pp.35-42
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• 2001

Recent development of photocatalytic degradation method that is mediated by TiO$_2$ is of interest in the treatment of volatile organic compounds(VOCs). In this study, trichloroethylene(TCE) and acetone were closely examined in a batch scale of photo-reactor as a function of water vapor, oxygen, and temperature. Water vapor inhibited the photocatalytic degradation of acetone, while there was an optimum concentration in TCE. A lower efficiency was found in nitrogen atmosphere than air, and the effect of oxygen on photocatalytic degradation of acetone was greater than on that of TCE. The optimum reaction temperature on photocatalytic degradation was about 45$^{\circ}C$ for both compounds. NO organic byproducts were detected for both compounds under the present experimental conditions. It was ascertained that the photocatalytic reaction in a batch scale of photo-reactor was very effective in removing VOCs such as TCE and acetone in the gaseous phase.

• Journal of Pharmaceutical Investigation
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• v.22 no.3
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• pp.173-183
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• 1992

To study the feasibility of transmucosal delivery of $[D-ala^2]-methionine$ enkephalinamide (YAGFM), its enzymatic degradation and stabilization in various rabbit mucosal extracts were investigated by HPLC method. The degradation of YAGFM was observed to follow the first-order kinetics and the half-lives of YAGFM in the nasal, rectal and vaginal mucosal extracts were found to be 25.7, 3.0 and 7.8 hr, respectively. However, there was no significant difference in degradation rates of YAGFM between the mucosal and serosal extracts obtained from the same mucosal membrane. This finding suggests that even a synthetic enkephalin analog, which is designed to be resistent to aminopeptidases, needs to be fully protected from the enzymatic degradation in mucosal sites for the delivery of the analog through mucosal routes. To inhibit the degradation of YAGFM in various mucosal extracts, effects of enzyme inhibitors such as bestatin (BS), amastatin (AM), thiorphan (TP), thimerosal (TM) and EDTA, alone or in combination, and modified cyclodextrins were observed by assaying YAGFM staying intact during 24 hr-incubation at $37^{\circ}C$. It was found from the results that mixed inhibitors such as TM (0.5 mM)/EDTA (5 mM) or AM $(50{\mu}M)/TM$ (0.5 mM)/EDTA (5 mM) provided very useful means for the stabilization in various mucosal extracts. The latter was found to protect YAGFM from the degradation in the nasal, rectal, and vaginal mucosal extracts by 90.9, 90.4 and 91.3%, respectively, after 24 hr-incubation, suggesting almost complete inhibition of YAGFM-degrading enzymes present in the incubation mixture. However, BS $(50{\mu}M)$, AM 50 $(50{\mu}M)$ or TP$(50{\mu}M)$ alone did not reveal sufficient inhibition except TM (0.5 mM) or EDTA (5 mM). The adddition of $2-hydroxylpropyl-{\beta}-cyclodextrin$(10%) to the nasal mucosal extract, and $dimethyl-{\beta}-cyclodextrin$(10%) to the rectal and vaginal mucosal extracts reduced the first-order rate constants for the degradation of YAGFM by 5.8, 17.3 and 8.9 times, respectively, compared to those with no additive.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.11
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• pp.693-698
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• 2017

In this study, the thermal degradation properties of polyethylene terephthalate film has been examined by the capacitance, Tan ${\delta}$, thermography, FTIR, and SEM results at temperatures of $90{\sim}170^{\circ}C$ and frequencies of 0.3~3,000 kHz. It was found that the capacitance decreased with increasing thermal imaging temperature, probably caused by weakening of chemical bond with increasing temperature. Tan ${\delta}$ decreased upon increasing temperature from $90^{\circ}C$ to $170^{\circ}C$, probably due to the molecular motion of COOH radical or OH radical. The FT-IR measurement reveals that no structural change of the material occurs upon thermal radiation. The SEM measurement shows that the material is stabilized by thermal decomposition with increasing temperature; however, excessive thermal degradation obstructs the stabilization of the material.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.12
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• pp.54-59
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• 2011

LED lightings typically do not fail catastrophically during use. However, over time the light output will gradually depreciate. Even if there are same LED lighting, they are so different at all. because of dissimilar the use and environment of each LED lighting. In this paper, we make a description of reliability analysis procedures for the degradation data using collected field data. Reliability analysis procedures are consisted of estimating degradation models and failure time, verification of distribution and parameters of the distribution, and reliability measures estimation. At some point in time, the light emitted from an LED lightings depreciates to a level where it is no longer considered adequate for a specific application.

• Journal of Applied Reliability
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• v.3 no.2
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• pp.93-101
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• 2003

Life time data analysis requires some time-to-failure data to an extent. Some life tests result in few or no failure. In such cases, it is difficult to access reliability with traditional life tests that record only time to failure. Furthermore, with short product development time, reliability tests must be conducted with severe time constraints. For some devices, it is possible to obtain degradation measurements over time, and these measurements may contain useful information about product reliability. This article describes degradation reliability analysis methods to do inferences and predictions about a failure-time distribution by using software. In addition, the possibility of extension to CBM (Condition Based Maintenance) is suggested as an example of applied degradation data analysis.