• Korean Journal of Animal Reproduction
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• v.25 no.2
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• pp.113-118
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• 2001

The objective of this study was to investigate the effects of $\alpha$-tocopherol and selenium on the boar semen characteristics. Semen volume and pH values were not different among treatments. However sperm concerntration, total number of sperm and sperm mortility were significantly(P＜0.05) increased comparing to the control group and sperm abnormality was significantly(P＜0.05) decreased comparing to the control group. Also, sperm mortility by storage day was significantly(P＜0.05) increased comparing to the control group. The results from this experiment indicate that dietary $\alpha$-tocopherol and selenium can affect boar semen characteristics.

• Journal of the Speleological Society of Korea
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• no.62
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• pp.11-16
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• 2004

Uro cave is a livestone cave formed at the Cambrian period. Uro cave is situated in Urosil, HogyeMyen, Moonkyunssi, HyungBok province. The temperature of the Uro cave is about 12～$15^{\circ}C$, humidity 90～95%, pH 7～8, Water temperature 12～$15^{\circ}C$, Carbon dioxide 500～900ppmv, hardness 110mg/$\ell$ in Conclusion, Uro cave does not have values of topography, environment, and tourism resource.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.2
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• pp.168-174
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• 2006

We investigated field-effect ion-transport devices based on carbon nanotubes by using classical molecular dynamics simulations under applied external force fields, and we present model schematics that can be applied to the nanoscale data storage devices and unipolar ionic field-effect transistors. As the applied external force field is increased, potassium ions rapidly flow through the nanochannel. Under low external force fields, thermal fluctuations of the nanochannels affect tunneling of the potassium ions whereas the effects of thermal fluctuations are negligible under high external force fields. Since the electric current conductivity increases when potassium ions are inserted into fullerenes or carbon nanotubes, the field effect due to the gate, which can modify the position of the potassium ions, changes the tunneling current between the drain and the source.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.2
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• pp.1-10
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• 2021

Lithium-ion batteries with high energy density, long cycle life and other advantages, have been widely used to energy storage systems(ESS). But as ESS fires frequently occur, the safety concern has become the main obstacle that hinders the large-scale applications of lithium-ion batteries. Especially, thermal runaway is the key scientific problem in battery safety research. Therefore, in this study, we performed a numerical analysis on the thermal runaway phenomenon of NCM111, NCM523 and NCM622 batteries using a two-dimensional analysis model. The results show that the two-dimensional simulation results are generally matched with three-dimensional simulation. Also, In the case of NCM111 with a low Ni content in the temperature range used in this study, thermal runaway phenomenon does occurred very slowly, but as the Ni content is increased, the thermal runaway phenomenon occurs rapidly and the thermal stability tends to be decreased. And, in NCM523 and NCM622 batteries, chain reactions occur almost simultaneously, but in the case of NCM111 battery, it is found that after the SEI(Solid Electrolyte Interface) layer decomposition reaction, the cathode-electrolyte reaction is appeared sequentially. After that, the anodic decomposition reaction is increased and leads to the thermal runaway reaction.

• Food Science and Preservation
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• v.17 no.3
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• pp.328-333
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• 2010

The effects of green tea on the physicochemical properties of eggs were investigated. One-hundred-and-fifty Isa Brown hens (27 weeks of age) were studied over 10 weeks. Green tea was added to the diet at levels of 4% and 8% w/w. The contents of Ca, K, P, Fe and Mg in eggs increased upon dietary supplementation with green tea powder, and were higher in the yolk than in the white, with the exception of Mg. The increase was greatest for Ca, from 41.0 mg% to 119.8 mg%, in egg white. For Fe, an increase from 3.7 mg% to 12.6 mg% was apparent in egg yolk. When hens consumed the green tea-supplemented diets, average egg weight decreased from 68.8 g to 64.4 g, but the total cholesterol content of egg yolk did not significantly change (control value: 1,899.1 mg% test value: 2,011.3 mg%). In sensory evaluation tests, egg white was similar in terms of astringency and grayness regardless of diet, and egg yolk was yellow-to-orange in color, and rated as fishy or slightly fishy, when green tea diets were administered. Such diets reduced pH values in all of the white, yolk, and white/yolk combination groups. The major fatty acids of egg yolk, constituting more than 90% of total fatty acids, were palmitic, stearic, oleic, and linoleic acid. Green tea diets reduced the saturated fatty acid level from 32.0% to 27.4% of total fatty acids, and unsaturated fatty acid levels increased from 68.0% to 72.6% in egg yolk.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.585-593
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• 2020

Until now, 29 fire accidents have occurred; 22 of them were caused by the interconnection of renewable energy sources that occurred during the rest period after the lithium-ion battery had been fully charged regardless of the seasons. The fire accidents of ESS were attributed to thermal runaway due to the overcharging of a few cells with the phenomenon of self-energy balancing, which is unintentional current flow from cells with a high SOC to the low cells if the SOC condition of each cell connected in parallel is different. Therefore, this paper proposes a novel configuration and operation algorithm of the BMS to prevent the self-energy balancing of ESS and presents a hybrid SOC estimation algorithm. From the test results of the self-energy balancing phenomenon between aging and normal cells based on the proposed algorithm and BMS, it was confirmed the possibility of self-energy balancing, which is unintentional current flow from cells with a high SOC to cells with a low SOC. In addition, the proposed configuration of the BMS is useful and practical to improve the safety of lithium-ion batteries because the BMS can reliably disconnect a parallel connection of the cells if the self-energy balancing current becomes excessively high.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.28-33
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• 1999

Introducing boric acid to the polyviny alcohol(PVA) solutions has a profound effect on the rheological properties through crosslinking between hydroxyl groups of PVA. This study investigates the effect of boric acid on the rheological properties of polyvinyl alcohol(PVA)/dimethyl sulfoxide(DMSO)/water systems in the absence of cations. The viscosity of PVA/ DMSO/water systems containing 1 wt.% boric acid was decreased with increasing water content. PVA/DMSO systems containing 1 wt.% boric acid exhibited rheological properties similar to elastic gels by forming crosslinked structures. On the other hand, PVA/water systems containing 1 wt.% boric acid exhibited rheological properties typical of viscous materials. In-corporation of boric acid into PVA/DMSO system caused a notable change in the viscosity of the system, whereas boric acid had little effect on the viscosity of PVA/water system. PVA/DMSO/boric acid system gave the greatest storage modulus among the PVA solution systems. Increasing water level in the mixed solvent of DMSO and water diminished the storage modulus of the systems.

• Journal of Life Science
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• v.10 no.3
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• pp.241-246
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• 2000

This study was carried out to investigate the antioxidant activity of the water extract from Coptis chinensis Franch. Coptis chinensis Franch. exhibited antioxidative activity at all concentration tested. The extract was as good as antioxidative action of the synthetic antioxidant, butylated hydroxytoluene and ascorbic acid; Also, the one was superior to that of natural antioxidant, $\alpha$ -tocopherol. With heavy metal ions (Fe3+, Zn2+) present, Coptis chinensis Franch. showed strong antioxidative effect.

• Polymer(Korea)
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• v.24 no.2
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• pp.259-267
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• 2000

Gel polymer electrolytes were prepared from poly(vinylidene fluoride-co-hexafluoro propylene)[P(VdF-co-HFP)] that had higher mechanical properties as well as higher dielectric constant ($\varepsilon$=8~13) than other polymeric matrix. Mechanical properties and ionic conductivities have been investigated as a function of blend ratio of electrolyte solution and polymer matrix. Ethylene carbonate (EC)/${\gamma}$-butyrolactone (${\gamma}$-BL) and lithium triflate (LiCF$_3$SO$_3$) were used as solvent and salt, respectively. The mechanical properties such as tensile strength, tensile modulus, compression modulus, and dynamic shear modulus were evaluated. The highest ionic conductivity was 1.09$\times$10$^{-3}$ S/cm for PVH40 containing 28.6 wt% of P(VdF-co-HFP) at $25^{\circ}C$. Tensile strength, tensile modulus and compression modulus were increased with P(VdF-co-HFP) content and abruptly changed between PVH70 and PVH80. Dynamic shear moduli showed a typical gel behavior and changed with shear strain.

• Polymer(Korea)
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• v.25 no.2
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• pp.168-176
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• 2001

The effect of novel N-crotyl-N,N-dimethyl-4-methylanilinium hexafluoroantimonate (CMH) curing agent as a thermal latent initiator on thermal behaviors, rheological properties, and thermal stability of diglycidylether of bisphenol A (DGEBA) epoxy cationic system was investigated. From DSC measurements of DGEBA/CMH system, it was shown that this system exhibits an excellent thermal latent characteristic at a given temperature. The conversion and conversion rate of DGEBA/CMH system increased with increasing the concentration of initiator, due to high activity of CMH. Rheological properties of the system were investigated under isothermal condition using a rheometer The gelation time was obtained from the analysis of storage modulus (G'), loss modulus (G"), and damping factor (tan $\delta$). As a result, the reduction of gelation time was affected by high curing temperature and concentration of CMH, resulting in high degree of network formation in cationic polymerization, due to difference of activity. The thermal stability of the cured epoxy resin was discussed in terms of the activation energy for decomposition and thermal factors determined from TGA measurements.ents.