• Polymer(Korea)
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• v.39 no.1
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• pp.169-173
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• 2015

Metallocene was supported on the silica, which was functionalized with aminosilanes such as aminopropyltrimethoxysilane (1NS) or N-[3-(trimethoxysilyl)propyl]ethylenediamine (2NS), and ionic liquids such as 1-butyl-4-methylpyridinium chloride (Cl), tributylmethylammonium chloride (Amm), benzyldimethyltetradecylammonium chloride (Ben), 1-butyl-1-methylpyrrolidinium chloride (Pyr), and then ethylene polymerizations were performed. The Zr contents of $SiO_2/1NS/IL/(n-BuCp)_2ZrCl_2$ and $SiO_2/2NS/IL/(n-BuCp)_2ZrCl_2$ were lower than those of only aminosilane-treated silicas. However, the polymerization activity of $SiO_2/1NS/IL/(n-BuCp)_2ZrCl_2$ was higher than that of $SiO_2/1NS/(n-BuCp)_2ZrCl_2$. The polymerization activity of $SiO_2/2NS/IL/(n-BuCp)_2ZrCl_2$ was lower than that of $SiO_2/2NS/(n-BuCp)_2ZrCl_2$ due to much lower Zr content.

• Corrosion Science and Technology
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• v.12 no.1
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• pp.50-55
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• 2013

The purpose of this study was to investigate corrosion characteristics of Ti-xTa alloys with Ta contents. Ti-xTa alloys used as samples (x=30, 40%) were arc-melted under argon atmosphere of 99.9% purity. Ti-xTa alloys were homogenized for 12hr at $1000^{\circ}C$ and then water quenched. The surface characteristics of Ti-xTa alloys were investigated using optical microscopy (OM) and X-ray diffractometer (XRD). The anodic corrosion behaviors of the specimens were examined through potentiodynamic, potentiostatic and galvanostatic test in 0.9 % NaCl solution at $36.5{\pm}1^{\circ}C$. After corrosion test, the surface characteristics of Ti-xTa alloys were investigated using OM. The microstructure of Ti-Ta alloy showed the beta structure with Ta content. The corrosion resistance of Ti alloy was improved by increasing Ta content and the corrosion morphology of Ti-Ta alloy showed that the site attacked by chloride ion decreased from the active to passive region with Ta content. Potential of Ti-40Ta alloy increased as time increased, whereas, current density of Ti-40Ta alloy decreased as time increased compared to Ti-30 alloy.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.503-512
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• 2020

Using Na₂CO₃ versus NaCl as chemical activator, we compared the quality of activated carbon produced from oil palm fronds as raw material. These activators were selected for comparison because both are readily available and are environmentally friendly. In the manufacturing, we used Indonesian National Standard (SNI 06-3730-1995) parameters. For the quality comparison, we determined activated-carbon yield, moisture, ash, volatiles, and fixed-carbon contents; and adsorption capacity of iodine. The best characteristics, assessed by morphological surface analysis and Fourier transform infrared (FTIR) spectral analysis, were observed in the carbon activated by Na₂CO₃ at an activator concentration of 10% and carbonization temperature of 400 ℃. The results were as follows: activated-carbon yield, 84%; water content, 8.80%; ash content, 2.20%; volatiles content, 14.80%; fixed-carbon content, 68.60%; and adsorption capacity of iodine, 888.51 mg/g. Identification using the FTIR spectrophotometer showed the presence of the functional groups O-H, C=O, C=C, C-C, and C-H in the Na₂CO₃-activated carbon.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.69-76
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• 1998

This study was investigated to determine the effect of additives and ionic strength on the functionality of extracted proteins in preblends in order to use less additive in restructured meat products. Preblends contained the combinations of sodium chloride (NaCl; 0, 4.5, 9.0%), sodium tripolyphosphate (STPP; 0, 2.5, 5.0%), and tetrasodium pyrophosphate (PP; 0, 2.44, 4.88%). The pH values increased linearly with increasing STPP and PP concentrations (p<0.01). In the equivalent ionic strengths, PP was more effective than STPP in increasing pH. Phosphate ions were more effective on total extractable protein (used 1 M NaCl buffer) than chloride ion at equivalent ionic strengths. Solubility was decreased by adding NaCl and increasing total extractable proteins. Meat sulfhydryl contents were high with increasing total extractable proteins. When protein extracts were heated at $65^{\circ}C$, 7 min, meat sulfhydryl contents decreased and surface hydrophobicity increased (p<0.01). However, all protein extracts showed no differences in SDS-PAGE pattern. In conclusion, PP is more effective than STPP in order to use less additive but there was no linear relationship between functionnal improvement and ionic strength.

• Journal of the Korean institute of surface engineering
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• v.49 no.4
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• pp.344-348
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• 2016

Stainless steel is widely applied in many industrial fields due to its excellent anti-corrosion and durability characteristics. However, stainless steel is very vulnerable to cavitation attack caused by high speed flow of fluid in the chloride environments such as marine environment. These conditions promote intergranular corrosion and cavitation-erosion, leading to degradation of the structural integrity and service life. In order to prevent these problems, the stabilized stainless steel is applied to the offshore and shipbuilding industries. In this study, Ti was added to 19%Cr-9%Ni as the stabilizer element with different concentrations (0.26%, 0.71%), and their durabilities were evaluated with cavitation-erosion experiment by a modified ASTM G32 method. The microstructural change was observed with the stabilizer element contents. The result of the observation indicated that the amount of carbide precipitation was decreased and its size became finer with increasing Ti content. In the cavitation-erosion experiment, both weight loss and surface damage depth represented an inverse proportional relationship with the amount of Ti element. Consequently, the stainless steel containing 0.71% of Ti had excellent durability characteristics.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.172-179
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• 2016

For an evaluation of service life in RC(Reinforced Concrete) structures, deterministic method and probabilistic method considering random variables of design parameters are usually adopted. In the work, surface chloride contents which vary with distance from sea shore and height are investigated from the previous research literature surveys, and they are considered for service life estimation. Through the analysis, the probabilistic method shows much lower results, which is due to variations of design parameters and very low intended durability failure. In the deterministic method, the structures within 250m and higher than 60m are evaluated to be free from chloride attack. In the probabilistic method, those higher than 60m in all the region and higher than 40m and 250m from sea shore are evaluated to satisfy the service life.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.2
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• pp.99-105
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• 1998

This research explored the feasibility of preparing and utilizing a preformed polymeric solution of Al(III) for coagulation in water treatment. Slow base(NaOH) injection into supersaturated aluminum chloride solutions did produce high yields of the type of Al polymers useful to water treatment applications. PACl's characteristic analysis showed that the quantity of polymeric Al produced at value of $r(OH_{added}/Al)=2.2$ was 83% of the total aluminum in solution, as showing maximum contents and precipitate was dramatically increased when r was increased above 2.35. And PACl was stable during sitoring period so aging effect was negligible. Results of the coagulation of Nakdong river waters with three PACls showed that the effectiveness of the three coagulants can be considered as r = 2.2 > r = 2.0 > r = 2.35 which are also the order of higher polymeric aluminum contents. Coagulation results for synthetic water exhibited optimum dose of 0.25mM Al, for three PACls, but above optimum dose, r = 2.0 and 2.2 PACl impaired the coagulation and sedimentation of turbidity and humic acid because of the restabilization of particulate. The effect of pH for on coagulation of Nak Dong River water showed that it had much effect turbidity and TOC removal, especially near pH 7. But pH effect was little for turbidity and TOC removal when r = 2.35 PACl was used for coagulation, that PACl had much more precipitates content.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1069-1075
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• 1999

The sterilization was attempted to improve the quality deterioration of soybean paste during its storage. For this experiment, soybean paste was sterilized at 80oC for 30 minutes and stored during 6 months at 15oC and 30oC, respectively. The total approximate composition contents were moisture 52.5%, crude protein 11.94%, crude fat 2.0%, amino nitrogen 413.3mg%, sodium chloride 11.61% and ash 15.5%. According to the increase of storage period, pH was decreased gradually because of the increase of organic acids by the metabolism of microorganisms and the acid accumulation by acid forming bacteria, but titratable acidity was increased during storage. Amino nitrogen was rapidly increased for the first one or two month storage period and maintained as the same level for the rest of them. Each amino acid contents of soybean paste, which were glutamic acid, tryptophan, proline, arginine, and aspartic acid, had much higher level than others. In color changes sterilized soybean paste(SSP) was much lower than that of raw ones(RSP). Hunter L and b values on the surface of soybean paste were decreased during storage, and the decreasing levels were higher at 30oC than at 15oC. Hunter a value, however, was increased a little in the initial storage, and thereafter it was decreased. Lactic acid bacteria, yeasts, and molds were disappeared completely by the sterilization. However, the bacteria of aerobes and anaerobes were not disappeared by this processing.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.128-135
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• 2016

In the current concrete structure of the highway is still the major problem most of concrete deterioration caused by the freeze-thaw and deicing salt, which is of issues that are not completely resolved. In particular, a single freezing event does not cause much harm, durability of concrete under multi-deterioration environment by repeated freeze-thaw and deicing salt is rapidly degraded and reduce its service life. In this study, the exposure environmental condition according the regional highway points were established. The damage condition and chloride content of the concrete at general and severe environmental exposure condition were also investigated. In addition, the experimental test of chloride ion permeability, scaling resistant and freeze-thaw resistance were carried out to improve the durability of the mechanical placing concrete of subsidiary structure. According to the results of this study, in observation of concrete surface condition, the concrete exposed by severe environmental condition showed broad ranges of damage with high chloride contents. Meanwhile, the water-binder(W/B) ratio and the less water content, and fly ash concrete than the specified existing mix proportion is significantly improved the durability. Also, the optimal mix proportion derived for test is satisfied the strength and air contents, water-binder ratio, and durability criteria of concrete specifications, as well as service life seems greatly improved.

• Food Science and Preservation
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• v.8 no.4
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• pp.456-461
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• 2001

To develop the use of natural pigment for food, carotenoids from wasted persimmon peel were extracted with seven organic solvents. Among the solvents, acetone was a high yielding solvent of carotenoids. Extraction trends depending on process variables(temperature, time, solvent ratio to persimmon peel) were explained through response surface which was made by central composite experimental design. Carotenoid contents were increased with the extraction time and solvent ratio but it decreaed in the higher experimental design. Carotenoid contents were increased with the extraction time and solvent ratio but it decreased in the higher extraction temperature. The optimum conditions of extraction process variables were predicted as 29$\^{C}$, 93min. at fixed solvent ratio(1:27).