• Journal of Applied Reliability
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• v.5 no.4
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• pp.413-425
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• 2005

As an alternative to traditional life testing, degradation tests can be effective in assessing product reliability when measurements of degradation leading to failure can be observed. This article presents an accelerated degradation testing for vacuum fluorescent displays (VFDs). The accelerated degradation model is based on Arrhenius-lifetime relationship for cathode temperatures. We compare the results between accelerated degradation test and test at normal use condition. Accelerated degradation test for display devices is observed as an efficient method to warrantee product reliability to customers, as well as a tool to save time and costs.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.47-51
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• 2007

The present paper reports the life time prediction of Acrylonitrile-Butadiene rubber (NBR) fuel cell gasket materials as a function of operational variables like acid concentration, ageing time and temperature. Both material and accelerated acid-heat aging tests were carried out to predict the useful life of the NBR rubber gasket for use as a fuel cell stack. The acid ageing of the gasket compounds has been investigated at 120, 140 and $160^{\circ}C$, with aging times from 3 to 600 h and increasing acid ($H_2SO_4$) concentrations of 5, 6, 7 and 10 vol%. Material characteristics the gas compound such as cross-link density, tensile strength and elongation at break were studied. The hardness of the NBR rubber was found to decrease with decreasing acid concentration at both 120 and $140^{\circ}C$, but at $160^{\circ}C$ interestingly the hardness of the NBR rubber increased abruptly in a very short time at different acid concentrations. The tensile strength and elongation at break were found to decrease with increase in both the acid concentrate ion & temperature. The life time of the compounds were evaluated using the Arrhenius equation.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.947-952
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• 1996

The effect of fluctuating temperature on the respiration of vegetables has been investigated. Spinach was selected as the experimental material because of its high respiratory activity and kept under the condition that temperature changed alternately at low and high levels every 4 hours. The low-high level temperature combination was set in $1-10^{\circ}C,{\;}1-20^{\circ}C{\;}and{\;}1-30^{\circ}C$. Respiration was evaluated in terms of quantity of $CO_2$ evolved from spinach. The evolution rate of $CO_2$ was determined by a change in its concentration. The evaluation rate of $CO_2$ followed closely the temperature change. In the temperature combinations at $1-10^{\circ}C{\;}and{\;}1-20^{\circ}C$, the relationship between $CO_2$ evolution rate and temperature was found to be able to express by Arrhenius law, while at $1-30^{\circ}C$, it did not obey the law.

• Elastomers and Composites
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• v.50 no.4
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• pp.292-296
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• 2015

Biomimetic artificial basilar membrane being a core part of artificial cochlear requires performance evaluation through aging test. To evaluate the aging properties of PVDF piezoelectric membrane used for artificial basilar membrane, its mechanical properties such as tensile strength and elastic modulus and piezoelectric property such as piezoelectric constant were measured. The aging test conditions and acceleration constants were calculated based on Arrhenius model. The changes in tensile strengths and elastic moduli measured were less than 10~20% after aging test equivalent for 10 years. The piezoelectric constants were decreased drastically to 80% of its initial value in the early stage of the aging test and expected to decrease slowly down to 65% over 10 years. The experimental results show the reliability of totally implantable novel artificial cochlear and will contribute its commercialization.

• Preventive Nutrition and Food Science
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• v.12 no.2
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• pp.111-114
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• 2007

Water vapor adsorption kinetics of Inonotus mushroom powders were investigated in temperature and water activity ranges of 20 to 40$^{\circ}C$ and 0.30 to 0.81, respectively. Initial water vapor adsorption rate of mushroom powders increased with increases in temperature and water activity. The temperature dependency of water activity followed the Clausius-Clapeyron equation. The net isosteric heat of sorption increased with an increase in water activity. Water vapor adsorption kinetics of the mushroom powders can be well described by a simple empirical model. Temperature dependency of the reaction rate constant followed the Arrhenius relationship. The activation energy ranged from 56.86 to 91.35 kJ/mol depending on water activity. Kinetic compensation relationship was observed between k$_o$ and E$_a$ with the isokinetic temperature of 790.27 K.

• Elastomers and Composites
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• v.31 no.1
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• pp.33-42
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• 1996

NR, NBR, and CR rubber were prepared by mixing filler in various ratios. Their vulcanization characteristics and thermal properties were studied. Vulcanization characteristics were investigated using cure curve that had been obtained from oscillating disk rheometer study. The Arrhenius law is known to describe the relationship between cure time and temperature of most elastomers. Curing could be done by the addition of sulfur, peroxides, and proper acceleratores. The optimum cure time that affects desirable values of modulus and tensile strength of the vulcanizate is taken as t90 as measured by a rheometer. Rubbers were cured in the rheometer at temperatures ranging from $130^{\circ}C\;to\;180^{\circ}C$ in order to check the validity of the curing system used. A linear relationship between ln(ts2) and ln(t90) was found for all elastomers. The term sensitivity has been used to describe the relationship between a change of ts2 to the corresponding change of t90 due to an increment of temperature. This is related to the formula of the compound.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.7
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• pp.1048-1052
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• 2011

This study examined the flow properties, paste clarity, freeze-thaw stability and gel strength of acetylated sweet potato starch (ASPS) pastes and gels as a function of degree of substitution (DS). ASPS showed high shear-thinning flow behaviors with high Casson yield stress ($\sigma_{oc}$). Consistency index (K), apparent viscosity ($\eta_{a,100}$) and $\sigma_{oc}$ values of ASPS increased with an increase in DS. In the temperature range of $25{\sim}70^{\circ}C$, ASPS followed an Arrhenius temperature relationship. The activation energies (Ea=13.2~14.3 kJ/mol) of the ASPS samples were much lower than that (18.1 kJ/mol) of the native sweet potato starch (SPS). ASPS gels showed better freeze-thaw stability with a significant decrease in syneresis (%) compared to SPS gel. The gel strength values of ASPS were much lower than that of SPS, and significantly decreased with an increase in DS. The clarity of native SPS paste increased after acetylation.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.509-515
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• 2017

Quartz is the most abundant mineral in the Earth's continental crust. Therefore, understanding of quartz dissolution and precipitation is very important to know about weathering processes and interactions between rocks and water in hydrothermal and metamorphic environments. This paper presents a basic review on the research about quartz dissolution mechanism under various physico-chemical conditions. We rearranged the relationship between each physico-chemical factor and dissolution mechanism from the results of previous researchers in this paper. From this result, we understood that quartz dissolution and precipitation are affected by each factor such as temperature, pH, and applied stress conditions at contact point. In particular, we recognized that the high pH and temperature conditions have different anion concentrations on mineral's surface. As a result, high pH and temperature conditions have a better effect than applied stress condition to the quartz dissolution mechanism.

• Korean Journal of Food Science and Technology
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• v.33 no.2
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• pp.221-225
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• 2001

Flow properties of red flower cabbage pigment solutions were determined over a wide range of temperatures ($20-50^{\circ}C$) and soluble solid concentrations (1-65%) using a cone and plate rotational viscometer. Flow properties of the pigment solutions were adequately described by the simple power law model. Within the tested ranges of concentration, temperature and shear rate, the flow behavior index (n) and the consistency index (K) of the solutions were in the ranges of 0.841-0.998 and $0.008-31.525\;Pa{\cdot}s^n$, respectively. The effect of temperature on the apparent viscosity of the solutions followed an Arrhenius type relationship. Activation energy of flow varied from 9.36 to 52.48 kJ/mol depending on the solid concentration and shear rate. The combined effect of temperature and concentration on the apparent viscosity at the shear rate of $100\;s^{-1}$ could be represented by a single equation as ${\ln}\;{\eta}_a\;=\;6.11\;-\;3103.94(1/T)\;-\;0.03C$.

• Elastomers and Composites
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• v.47 no.3
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• pp.254-258
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• 2012

Material characteristics and the prediction of life time of polyacrylic rubber (ACM) for automotive engine gasket were studied. Two kinds of ACM rubber compounds, having chlorine cure-site and carboxyl cure-site, were made with optimum formulations and the properties of each materials were examined. As a test results for the thermal properties and compression set, which are very important in the application for the automotive engine gasket, the compound using ACM with carboxyl cure-site was evaluated as having a better characteristics than that of ACM with chlorine cure-site. Arrhenius relationship based on time-temperature superposition principle (TTSP) was obtained through the accelerated heat aging test to predict the useful life-time for the compound using ACM with carboxyl cure-site.