• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.206-210
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• 1996

In order to investigate the electrical properties for transformer oils which contains a Pure sodium chloride, the dielectric properties is made researches. To measure the dielectric loss of specimen, a coaxial cylindrical liquid electrode is used, and its geometric capacitance is confirmed to 16[pF]. And the dielectric dissipation factor, tan$\delta$, is measured by using the Video Bridge 2150. The thermal static oven with an automatically static temperature controller is used so as to support specific temperature to the specimen. This experiments for measuring the dielectric lass is performed at 20-120[$^{\circ}C$] in the temperature range, 30∼1.5x10$\^$5/[Hz] in the frequency range and 300∼1500[mV] in the voltage range. The result of experiment for the movement of carrier and the physical constants to contribute dielectric properties of specimen with a pure sodium chloride.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.2
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• pp.270-281
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• 1996

This study was carried to figure out the effect of bleaching on the cationic surfactant (DSDMAC) absorption by cotton fabrics. And physico-chemical change, static electricity, and fabric stiffness of bleached cotton fabrics were measured. Cotton fabrics bleached with sodium hypochlorite soluton and with sodium percarbonate solution were used to analyze the DADMAC absorption. The results were as follows: 1. As the number of bleaching cycles were increased, the degree of oxidation on cotton fabrics was increased. So their carboxyl content was increased and their tensile strength was decreased. 2. DSDMAC absorption by cotton fabrics was increased by bleaching and was in propor- tion to carboxyl content. Therefore, it was groved that DSDMAC absorption by cotton fabrics was motivated by ion exchange mechanism. 3. The static electricity of cotton fabrics almost no change when bleached and unbleached absorption had no effect on the static electricity of cotton fabrics. 4. DSDMAC which was absorbed by cotton fabrics acted as a lubricant. DSDMAC absorption reduced the friction coefficient of yarn, so stiffness of cotton fabric was decreased.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3517-3527
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• 2021

New 80-MW (electric) ultra-long-life sodium cooled fast reactor core having inherent safety characteristics is designed with heterogeneous fuel assemblies comprised of driver and blanket fuel rods. Several options using upper sodium plenum and SSFZ (Special Sodium Flowing Zone) for reducing sodium void reactivity are neutronically analyzed in this core concept in order to improve the inherent safety of the core. The SSFZ allowing the coolant flow from the peripheral fuel assemblies increases the neutron leakage under coolant expansion or voiding. The Monte Carlo calculations were used to design the cores and analyze their physics characteristics with heterogeneous models. The results of the design and analyses show that the final core design option has a small burnup reactivity swing of 618 pcm over ~54 EFPYs cycle length and a very small sodium void worth of ~35pcm at EOC (End of Cycle), which leads to the satisfaction of all the conditions for inherent safety with large margin based on the quasi-static reactivity balance analysis under ATWS (Anticipated Transient Without Scram).

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1468-1475
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• 2023

Enhancement of wear resistance of components used in fast reactors is necessary for long service life of the components. Plasma nitriding is a promising surface modification technology to impart high hardness and improved wear resistance of various steel components. This study discusses the characterization of chrome nitrided SS316L casing ring used in secondary sodium pump of fast breeder reactor and its stability under long term sodium exposure. Microstructural and hardness analysis showed that stress relieved component could be chrome nitrided successfully to a thickness of about 100 ㎛. Assessment of in-sodium performance of the chrome nitrided casing ring subjected to long term exposure up to 5000h at 550℃, showed retention of chrome nitrided layer with a case depth almost similar to that before sodium exposure. A slight decrease in the hardness was observed due to prolonged high temperature sodium exposure. Tribological studies indicate very low coefficient of friction indicating the retention of good wear resistance of the coating even after long term sodium exposure.

• Korean Journal of Food Science and Technology
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• v.11 no.2
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• pp.112-117
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• 1979

By using the existing caustic refining system with a minimum modification and by using a combination of various emulsifiers(0.2 % sodium hexametaphosphate. 0.05 % sodium lauryl sulfate and 0.001 % dioctyl sodium sulfosuccinate), a new economical dewaxing process for sunflower seed oil was developed in order to reduce the cost of the dewaxing process. The results indicate that the waxes can be removed satisfactorily from the sunflower seed oil by emulsifying. batchwise or continuously, the oil with the aqueous surfactant solution, followed by centrifugation at ambient temperatures $(16{\sim}27^{\circ}C)$. Dewaxing loss for the batch process was satisfactory for both low wax-and high wax-crude oil, whereas dewaxing loss for the continuous process needs to be improved. The results indicate that initial level of wax content (low wax vs. high wax) did not affect the loss for batch process (0.82 % vs. 0.62 %), but affected the loss for continuous processes, regardless of the type of mixing mode (2.28 % and 5.68 % for low wax-and high wax-oil, respectively). It was also noted that the type of mixing mode (centactor vs. static mixer) for the continuous process affected the loss, regardless of the wax content (5.2 % and 2.8 % for contactor and static mixer, respectively).

• Environmental Analysis Health and Toxicology
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• v.7 no.1_2
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• pp.67-87
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• 1992

Each detergent-solution in the concentration of 0.4% was prepared with four kinds of raw materials of detergents and two kinds of commercial surfactants for kitchen. LAS (Linear Alkyl Benzene Sulfonate), AOS ($\alpha$-O1effine Sulfonate), SLS (Sodium Lauryl Sulfonate) and SLE (Sodium Lauryl Ester Sulfonate) were used as the raw materials. Vegetables and fruits such as cucumber, crown daisy, lettuce, strawberry and tomatos were diped in each solution and washed 5 times in static or flow state. For the other experiments, tablewares such as porcelain, stainless bowls, glass and plastic cups were diped in each solution and washed also 5 times with cold and hot water in static or flow state. The residues of the detergents on the every steps of wash-conditions were measured. The results of this study were summarized as followings: 1. The residures of the detergents on the tested vegetables and fruits after 5 times washing were detected with the range from 0.450 to 7.120 ppm in static state and from 0.343 to 6.375 ppm in flow state. 2. The residures of the detergents on the tested tablewares after 5 times washing with cold water were observed with the range from 0.057 to 0.815 ppm in static state and from 0.066 to 0.905 ppm in flow state. 4. The residures of the detergents on the tested tablewares after 5 times washing with hot water were determined with the range from 0.061 to 0.424 ppm in static state and from 0.066 to 0.368 ppm in flow state. 4. Independent on detergent types, water temperatures and washing methods, the detergents were remained stablely on the porcelain; 0.057~0.815 ppm, on the stainless bowl; 0.061~0.905 ppm, on the glass cup; 0.0l4~0.592 ppm and on the plastic cup; 0.201~0.592 ppm.

• Computers and Concrete
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• v.20 no.2
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• pp.205-214
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• 2017

The Hydraulically driven test system and ${\Phi}100mm$ split Hopkinson pressure bar(SHPB) test device were employed to research the quasi-static and dynamic mechanical properties of concrete specimens which has been immersed for 60 days in sodium sulfate (group S1) and sodium chloride (group S2) solution, the evolution of their mass during corrosive period was explored at the same time, and the mechanism of performances lost was analyzed from the microscopic level by using scanning electron microscope. Results of the experimental indicated that: their law of mass both presents the trend of continuous rising during corrosive period, and it increases rapidly on the early days, the mass growth of group S1 and group S2 in first 7 days are 76.78% and 82.82% of their total increment respectively; during the corrosive period, the quasi-static compressive strength of specimens in two groups are significantly decreased, both of which present the trend of increase first and then decrease, the maximum growth rate of group S1 and group S2 are 7.52% and 12.71% respectively, but they are only 76.23% and 82.84% of specimens which under normal environment (group N) on day 60; after immersed for 60 days, there were different decrease to dynamic compressive strength and specific energy absorption, and so as their strain rate sensitivities. So the high salinity environment has a significant effect of weaken the quasi-static and dynamic mechanical performance of concrete.

• Bulletin of the Korean Chemical Society
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• v.2 no.1
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• pp.24-28
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• 1981

Theoretical studies of the sodium cation binding and the isotope hydration effects on the static model compound B-DNA have been qualitatively elucidated by using empirical potential energy functions. In the first place, the sodium cations bound to phosphate anions and their hydration scheme have been optimized and have given a reasonable agreement with other theoretical results and experimental studies. In the second stage, the isotope effect on the hydration through the substitution of $D_2O\;for\;H_2O$ has been carried out by the same procedure. The stabilization of B-DNA has been explained and compared in terms of the sodium cation binding to phosphate anions and its hydration in both cases of $H_2O\;and\;D_2O$.

• Journal of the Korean Applied Science and Technology
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• v.19 no.4
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• pp.327-334
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• 2002

Transesterfication of vegetable oils and methanol with alkaline catalyst was carried out to produce biodiesel fuel by continuous process. The process consists of two static mixers, one tubular reactor and two coolers and gave $96{\sim}99$% of methyl ester yield from soybean oil and rapeseed oil. Experimental variables were the molar ratios of methanol to vegetable oil, alkaline catalyst contents, flow rates, mixer element number. The optimum ranges of operating variables were as follows; reaction temperature of $70^{\circ}C$, l:6 of molar ratio of methanol to oil, O.4%(w/w) sodium hydroxide based on oil, static mixer elements number of 24 and 4 min. residence time.

• Steel and Composite Structures
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• v.29 no.2
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• pp.201-218
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• 2018

In this study, the effects of magnesium sulfate on the mechanical performance and the durability of confined and unconfined geopolymer concrete (GPC) specimens were investigated. The carbon and basalt fiber reinforced polymer (FRP) fabrics with 1-layer and 3-layers were used to evaluate the performances of the specimens under static and cyclic loading in the ambient and magnesium sulfate environments. In addition, the use of FRP materials as a rehabilitation technique was also studied. For the geopolymerization process of GPC specimens, the alkaline activator has selected a mixture of sodium silicate solution ($Na_2SiO_3$) and sodium hydroxide solution (NaOH) with a ratio ($Na_2SiO_3/NaOH$) of 2.5. In addition to GPC specimens, an ordinary concrete (NC) specimens were also produced as a reference specimens and some of the GPC and NC specimens were immersed in 5% magnesium sulfate solutions. The mechanical performance and the durability of the specimens were evaluated by visual appearance, weight change, static and cyclic loading, and failure modes of the specimens under magnesium sulfate and ambient environments. In addition, the microscopic changes of the specimens due to sulfate attack were also assessed by scanning electron microscopy (SEM) to understand the macroscale behavior of the specimens. Results indicated that geopolymer specimens produced with nano-silica and fly ash showed superior performance than the NC specimens in the sulfate environment. In addition, confined specimens with FRP fabrics significantly improved the compressive strength, ductility and durability resistance of the specimens and the improvement was found higher with the increased number of FRP layers. Specimens wrapped with carbon FRP fabrics showed better mechanical performance and durability properties than the specimens wrapped with basalt FRP fabrics. Both FRP materials can be used as a rehabilitation material in the sulfate environment.