• 한국전자현미경학회:학술대회논문집
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• 1999.05a
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• pp.84-84
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• 1999

• Applied Microscopy
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• v.20 no.2
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• pp.1-11
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• 1990

The ultrastructure of freeze-substituted Malpighian tubule cells of German cockroach after rapid freezing was compared to that fixed with conventional chemical fixation. As results, freeze-substitution proved to be the superior technique revealing much more structural details of the tissue cells. Especially, all kinds of membrane structures including infoldings, microfilament, microtubules and ribosomes were best preserved in this material.

• The Korean Journal of Food And Nutrition
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• v.27 no.6
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• pp.1067-1077
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• 2014

A study was undertaken to examine the effect of adding freeze dried maquiberry powder on the quality of pound cakes. Freeze dried maquiberry was added to the flour at a ratio of 0.5, 1, 1.5 and 2.5%. The antioxidant activity was estimated by DPPH free radical scavenging activity, the total phenolic compounds content, and flavonoid content in freeze dried maquiberry powder of pounds cakes. Antioxidative activity was highly correlated with the total phenolic and total flavonoids contents of freeze dried maquiberry powder of pound cakes (r=0.9126, p<0.001, r=0.8366, p<0.001, respectively). The quality characteristics of freeze dried maquiberry powder of poundcakes were estimated. The specific volume decreased significantly with increased substitution level of freeze dried maquiberry powder (p<0.01). The lightness significantly decreased with increased freeze-dried maquiberry powder of pound cake crust and crumb (p<0.01, p<0.01). The hardness and adhesiveness increased, while gumminess tended to reduce with increased maquiberry powder. The consumer acceptability score of 0.5~2.5% freeze dried maquiberry powder of pound cakes ranked significantly (p<0.01) higher than those of the other groups in overall preference. These results showed that freeze dried maquiberry powder is a good ingredient to increase consumer acceptability and health.

• 한국전자현미경학회:학술대회논문집
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• 1999.11a
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• pp.70-71
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• 1999

• 한국전자현미경학회:학술대회논문집
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• 1998.05a
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• pp.63-63
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• 1998

• Journal of Microbiology
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• v.34 no.3
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• pp.220-224
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• 1996

Ultrastructural organization of encysting zoospores of Allomyces macrogynus was examined using the methods of cryofixation and freeze substitution. During enxcystment, obvious changes were observed at the surface of the plasma membrane and in the structure of gamma particles. Many multivesicular bodies associated with the plasma membrane were observed at early stages of encystment. After induction of encystment, vesicles were found within the gamma particles. These vesicles appeared to leave gamma particles after forming multivesicular bodies. This study suggests that the cell wall formation during encystment is mediated by the fusion of multivesicular bodies with the plasma membrane.

• 한국전자현미경학회:학술대회논문집
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• 2005.05a
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• pp.47-48
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• 2005

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.419-424
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• 2000

The primary objectives of this study are to investigate the properties of strength and durability of recycled aggregate concrete was added polypropylene as variables and to fabricate fine concrete in some conditions. The variables are substitution ratios of recycled aggregate(0, 30, 50, 100%) and additions of polypropylene(0, 0.2, 0.5, 1.0%). Compressive strength test to investigate strength properties and freeze-thawing test and drying shrinkage test to durability properties were done. As the result of this study, When variables are substitution ratio(30%) of recycled aggregated and addition(0.5%) of polypropylene, fine concrete was fabricated.

• Advances in concrete construction
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• v.6 no.2
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• pp.159-175
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• 2018

The main aim of this study is to investigate the possible effects of metakaolin on strength and durability properties of concrete. For this purpose, concrete mixtures are produced by substituting cement with metakaolin 0, 5, 10 and 20% by weight. The amount of binder for the concrete mixtures are 300 and $400kg/m^3$ with a constant water to cement ratio of 0.6. Compressive and bending strengths, freeze-thaw and high-temperature resistances, capillary coefficients and rapid chloride permeability properties were determined and compared each other. Because of all the experiments conducted, it has been found that the use of metakaolin as a pozzolanic additive in concrete have positive effects especially on compressive and bending strengths, capillary, rapid chloride permeability, freeze-thaw resistance, and high temperatures, up to $800^{\circ}C$. The results indicated that the performance of concrete can be enhanced by metakaolin. Particularly, compressive strength and durability properties have found to be improved with increasing metakaolin content which is attributed to pozzolanic activity and filler effect. Furthermore, metakaolin has relatively positive impacts under elevated temperatures and freeze-thaw effects. However, almost all the strengths of entire concrete specimens are lost at $800^{\circ}C$. Consequently, the optimum metakaolin substitution ratio can be suggested to be 20% as per this study.

• 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.