• Polymer(Korea)
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• v.26 no.5
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• pp.575-581
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• 2002

Heterogeneous ion exchange membranes were prepared by mixing polyethylene as matrix with bead and fibrous anionic ion exchangers at different mixing ratio. Generally, ion exchange capacities were increased with increasing the ratio of the fibrous ion exchanger content. The highest ion exchange capacity of the membrane was 1.86 meq/g at 30wt% IXF (ion exchange fiber) in the membrane. The water uptake, fixed ion concentration, and ion transport number of the membrane increased with increasing the content of the fibrous ion exchanger. However, the electrical resistivity of the membrane was decreased with increasing the content of the fibrous ion exchanger. The lowest electrical resistivity of 5$\Omega$/$\textrm{cm}^2$ was observed at 30 wt%of IXF.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.117-122
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• 1999

The antiwashout concrete which is a type of specific concrete is manufactured by using a plenty of superplasticizer with the non-dispersible underwater concrete admixture, and the application of it on construction site is being increased. But when we measure choride ion content by using the potentiographic tester, because it is over total chloride ion content(0.3kg/㎥ under) of Korean Concrete Specification, the claim of construction site is being presented on the quality of antiwashout concrete. Accordingly, hte aim of this study is to verify actual chloride ion content of antiwashout concrete by chloride ion analysis due to chemical admixtures by performance of antiwashout concrete. In conclusion the actual chloride ion content of antiwashout concrete is overestimated by anion($OH^-, SO4^{-2}, S^{-2}, etc) of chemical admixtures, and is proved to be as low as that of ordinary concrete.

• Journal of Bio-Environment Control
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• v.6 no.4
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• pp.264-269
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• 1997

This study was conducted to evaluate appropriate selenate ion concentration for the production of high functional vegetables. Sodium selenate was treated 0, 2, 4, 6 and 8mg/$\ell$ using herb nutrient solution developed by European R & D Vegetable Center in Belgium. Low level of Na2se04 concentration increased the growth of wormwood, but high selenate concentration decreased the growth. Total chlorophyll content was increased by sodium selenate. The higher selenate ion concentration in the nutrient solution, the more total chlorophyll content was. The vitamin C content in wormwood was high at 2 and 4mg/$\ell$ treatment, showing good growth, at higher concentration, however, the vitamin C content decreased. At 4mg/$\ell$ selenate ion concentration, essential oil content of wormwood was best. But higher selenate ion concentration decreased essential oil content. The uptake of Se by the plant increased with the increase of selenate ion concentration.

• Journal of Bio-Environment Control
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• v.7 no.1
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• pp.55-61
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• 1998

This experiment was conducted to evaluate the effects of sulfate ion concentration in nutrient solution on the growth and qualify of Mongolian wormwood (Artemisia mongolica var. tenuifolia). Sulfate ion concentration was treated 0, 0.5, 1, 2 and 3mM using the modified nutrient solution composition for herb plants developed by European Vegetable R & D Center in Belgium. The growth of Mongolian wormwood was good at 3mM treatment and dry weight was best at 3mM treatment, Chlorophyll content increased with sulfate ion concentration. Mineral content did not show any significant difference among treatments. But Ca content in tissue markedly decreased at 3mM treatment. Sulfate ion uptake increased in proportion to sulfate ion concentration in nutreint solution, the higher sulfate ion concentration, the more uptake of sulfate ion by plant. At 1mM sulfate ion treatment, essential oil content was best, but the higher sulfate ion concentration resulted in decrease of essential oil content.

• Journal of the korean Society of Automotive Engineers
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• v.4 no.2
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• pp.35-46
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• 1982

This paper deals with residual stress characteristics of ion-nitrided metal which is primarilly concerned with the effects of added carbon content in gas atmosphere. A small optimal amount of carbon content in gas atmosphere increase compound layer thickness, as well as to increase diffusion layer thickness and hardness. The residual stress and deflection of the specimens was measured in various elevated temperature at the surface of ion-nitrided metal and the internal stress distribution was calculated. It is found that compressive residual stress at the compound layer is largest at the compound layer, and decreases as the depth from the surface increases.

• International Journal of Concrete Structures and Materials
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• v.10 no.2
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• pp.249-256
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• 2016

This paper deals with the effects of silica fume content and polymer-binder ratio on the properties of ultrarapid-hardening polymer-modified mortar using silica fume and ethylene-vinyl acetate redispersible polymer powder instead of styrene-butadiene rubber latex to shorten the hardening time. The ultrarapid-hardening polymer-modified mortar was prepared with various silica fume contents and polymer-binder ratios, and tested flexural strength, compressive strength, water absorption, carbonation depth and chloride ion penetration depth. As results, the flexural, compressive and adhesion strengths of the ultrarapid-hardening polymer-modified mortar tended to increase as increasing polymer-binder ratio, and reached the maximums at 4 % of silica fume content. The water absorption, carbonation and chloride ion penetration resistance were improved according to silica fume content and polymer-binder ratio.

• Membrane Journal
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• v.13 no.3
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• pp.191-199
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• 2003

Cation exchange polymer electrolyte membrane for the application of direct methanol fuel cell (DMFC) was studied. Poly(vinyl alcohol)(PVA) well known as a methanol barrier in pervaporation separation was used fur the base materials and poly(acrylic acid)(PAA) was used for the crosslinking agent with various concentration. Methanol permeability, ion conductivity, ion exchange capacity, water contents and fixed ion concentration of the membranes were investigated to evaluate the performance of the fuel cell electrolyte membrane. Methanol permeability and ion conductivity of the membranes were decreased with increasing PAA content and were increased over 15% of PAA content. These phenomena would be explained with the introduction of hydrophilic crosslinking agent. The membranes with 15% content of PAA showed methanol permeability of $6.49{\times}10^{-8}/cm^2/s,\; 2.85{\times}10^{-7}CM^2/s$ at $25^{\circ}C,\; 50^{\circ}C$ of operating temperatures, respectively. ion conductivities of the membrane were $2.66{\times}10^{-3}\;S/cm,$ $9.16{\times}10^{-3}\;S/cm$ at $25^{\circ}C,\; 50^{\circ}C$ of operating temperatures, respectively. ion exchange capacity, water content and fixed ion concentration of the membrane were revealed 1.32 meq/g membrane,0.25 g $H_2$O/g membrane and 5.25 meq/g $H_2O$, respectively.

• Journal of the Korean Home Economics Association
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• v.17 no.1
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• pp.22-28
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• 1979

The phyio-chemical properties of Ion exchange salt, crude salt, particaly refined salt, and Isoized salt were determined. The basic amount of salt used in cooking were standardized . Acceptabilities as to the taste and saltiness of food prepared with the standard amounts of various kinds of salt were compared. Whereupon, the following conclusion was obtained. 1) Crude salt showed 12.23 per cent water content, the highest among the kinds of salt examined, while particaly refined salt had 2.53% water content. Refined salt, Ion exchange salt, and Iodized salt showed 0.36%, and 0.28%, respectively. 2) Where the same amount of salt was dissolved in the same amount of water, crude salt and partialy refined salt were dissolved twice as Ion exchange salt of fine-grain form, refined salt, and Iodized salt. In actual cooking, Ion exchanges salt and refined salt are used only half as much as raw salt, and it can be said that the time required for dissolving salt is the same. 3) The comparison between content and weight of various kinds of salt showed that the weights of Ion exchange salt, Iodized salt, and refined salt were two times as heavy as crude salt and partialy refined condition of same content. 40 The threshold concentration of salt is the sensed degree of saltiness. Different concentrations were recorded for various for various kinds of salt, the threshold concentration of Ion exchanges salt showed the lowest degree of 0.05, while that of partialy refined salt was 0.09 equivalent to 1.8 times that of the former. 5) Experimental cooking involving various kinds of salt indicated that where salt was used accurately, soup, vegetables, kimchi, and soybean sauce which were prepared with Ion exchanges salt showed the best acceptability , but no statistical differences could be noted among sarious kinds of salt used in preparing those foods.

• Journal of the Korean Ceramic Society
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• v.34 no.4
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• pp.351-356
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• 1997

The origin of the variation of initial permeability in manganese-zinc ferrite polycrystals with a content of hematite was investigated. Initial permeability showed maximum with hematite content while there was no significant change in microstructure. Saturation magnetization increased with hematite content. So the variation of initial permeability was not explained on the basis of microstructural change or saturation magnetization. Temperature dependence of initial permeability revealed magnetocrystalline anisotropy was the origin of the variation of initial permeability. The change in magnetocrystalline anisotropy was ascribed to the variation in ferrous ion concentration. Therefore the variation of initial permeability in manganese-zinc ferrite polycrystals with a content of hematite was due to ferrous ion concentration via magnetocrystalline anisotropy.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.691-694
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• 2004

The effects of polymer-cement ratio and antifoamer content on the setting time and durability of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As a result, the setting time of the polymer-modified mortars using redispersible polymer powder tend to delayed with increasing polymer-cement ratio, regardless of the antifoamer content. The water absorption and chloride ion penetration depth of the high-fluidity polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and antifoamer content. The water absorption and chloride ion penetration improvement is attributed to the improved bond between cement hydrates and aggregates because of the incorporation of redispersible polymer powder.