• Analytical Science and Technology
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• v.15 no.1
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• pp.36-42
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• 2002

The dissolved organic carbon extracted from groundwater is separated into humic acid and fulvic acid. They are characterized for their chemical composition, spectroscopic characteristics using UV/VIS, IR and solid state $^{13}C-NMR$ spectroscopy, proton exchange capacity and molecular size distribution. The results are comparable with the literature data. The study explains that the aquatic humic and fulvic acid in this experiment are site-specipic and polydisperse natural organic matter with considerable proton exchange capacity.

• Elastomers and Composites
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• v.48 no.4
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• pp.256-262
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• 2013

We synthesized thermoplastic polyurethane elastomer (TPU) with different contents of sulfuric acid group, and characterized their physical properties such as mechanical, thermal and grip properties. And the results were compared with carboxylic acid-introduced TPU. Wet slip, tensile strength and abrasion properties were increased by the introduction of acid group. Mechanical properties increased with increasing the acid content up to 0.3 wt%. However, wet slip was continually increased as the acid content increased due to increase of hydrophilicity of TPU.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1252-1256
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• 2004

Radiolytic characteristics of phytic acid by gamma irradiation were investigated, and the antioxidative activity between irradiated phytic acid and commonly used antioxidants including ascorbic acid, tocopherol and butylated hydroxyl anisole (BHA) was evaluated. Phytic acid sodium salt dissolved in a deionized distilled water was irradiated at 0, 5, 10, 15 and 20 kGy. It was found that the level of irradiation had an effects on the degree of degradation. After irradiation, stable DPPH radical scavenging capacity of phytic acid was newly observed, and it was significantly increased by dose-dependent manners (p<0.05). Antioxidant activity of phytic acid in the oil models was higher than that of the other antioxidant during storage, and phytic acid (400 $\mu\textrm{g}$/mL) irradiated at 20 kGy especially showed the highest antioxidative ability among the antioxidants tested during 3 weeks. Results indicated that irradiation induced the radiolysis of phytic acid in an aqueous model system, and the antiradical and antioxidative activities of irradiated phytic acid increased.

• Journal of Adhesion and Interface
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• v.16 no.2
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• pp.63-68
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• 2015

We synthesized thermoplastic polyurethane elastomer containing carboxylic acid group and TPV (thermoplastic vulcanizate). We measured the mechanical, grip, debris, contact angle and adhesion properties according to introducing acid group in elastomer structure. Mechanical and wet slip properties were improved because of the hydrogen bonding by introduction of acid group. Also adhesion strength was increased as increasing of surface polarity by carboxylic acid group. The debris property of TPV made from TPU containing carboxylic acid group was improved.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.284-290
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• 2007

Biodiesel and its blend fuels from soybean oil were characterized for their oxidation to apply automobile fuel from the analysis of FAME (fatty acid methyl ester) and chemical properties. Biodiesel produced from soybean oil contained unsaturated fatty acids (> 85 wt%) such as oleic acid, linoleic acid, and linolenic acid. Especially, polyunsaturated fatty acids such as linoleic acid and linolenic acid containing active methyl radical were over 60 wt%. It is believed that linoleic acid and linolenic acid cause oxidation. Linoleic acid and linolenic acid during oxidation were major reactants, and compounds with the carbon number having around 36 (boiling point of about $500^{\circ}C$) were produced from those of radical autoxidation.

• Korean journal of food and cookery science
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• v.18 no.5
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• pp.476-481
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• 2002

The Physical and sensory characteristics of muffins prepared with flavonoids such as ferulic acid and p-hydroxybenzoic acid were evaluated for the development of functional foods using these flavonoids. The solubilities of ferulic acid and p-hydroxybenzoic acid were over 1% in water and the solutions showed a good thermal stability. However, 1% ferulic acid and p-hydroxybenzoic acid solution showed a color change during heating. The volume and maximum height of the control muffin were the greatest among the muffin groups. The volume of the muffins decreased with the increase of flavonoid concentration. The volumes of muffins with p-hydroxybenzoic acid were smaller than those of muffins with ferulic acid. The L, a and b values on crust and crumb of the muffin groups were not significantly different. The chemical flavor, bitterness and after taste of the muffins prepared with ferulic acid were stronger than those of the control muffins. Savory flavor and sweetness of the muffins with ferulic acid were weaker than those of the control muffins. The muffins with p-hydroxybenzoic acid were not significantly different from the control muffins in the appearance, flavor, taste, texture and overall acceptability. These results demonstrated that p-hydroxybenzoic acid may be useful as an additive to muffin.

• Korean Journal of Food Science and Technology
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• v.40 no.5
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• pp.551-557
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• 2008

In order to investigate the effect of different ingredients on the quality of Korean rice wines, 30% of rice were substituted by malt, corn, potato, soybean, glutinous millet, unpolished rice, glutinous rice, or non-glutinous rice, when rice wines were prepared. Physicochemical and sensory characteristics of the rice wines from the varying ingredients were evaluated. Sample rice wines were analyzed for ethanol, pH, total acid, amino acid, soluble solid, coloring degree, UV absorbance, reducing sugar, organic acids, and free sugars. After fermentation for 16 days, the ethanol contents ranged from 13.28 to 16.23%, while the total acid levels were within the range of 0.27 to 0.32%. The amino acid contents in eight samples ranged from 0.18 to 0.36%, while the soluble solid contents were within the range of 8.35 to $11.1^{\circ}$Bx. Among the eight samples tested, rice wine prepared with malt showed the highest level of coloring degree, UV absorbance, and reducing sugar levels, while rice wine prepared with potato showed the lowest value. Organic acid contents of rice wines prepared with soybean, glutinous rice, and non-glutinous rice showed the highest levels of succinic acid followed by acetic acid, citric acid, malic acid, and pyroglutamic acid. Free sugar contents of all rice wines showed the higher levels of glucose followed by fructose and maltose. Rice wines prepared with unpolished rice and corn showed the same highest overall sensory preference. By descriptive analysis, the overall mean sensory intensities of samples prepared with glutinous rice and non-glutinous rice, showed similar levels of 'sweetness', 'fruitiness', and 'freshness of aroma', while those samples prepared with soybean, glutinous millet, and potato showed stronger intensities of 'nuruk', 'grain aroma', and 'yellowness'. Rice wine prepared with corn showed middle ranges in all sensory attributes tested.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.9
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• pp.1405-1409
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• 2010

The compositions of fatty acid and amino acid of specialty rice which includes colored rice (Heugjinju, Jeugjinju, Josangheugchalbyeo), flavored rice (Heughyangmi, Hyangmi1), and giant embryo rice (Keunnun) were determined and compared to those of regular rice (Ilpumbyeo, Whaseonchalbyeo). Major fatty acids were linoleic acid (C18:2) and oleic acid (C18:1), which were composed of 75~80% of total fatty acids. Major amino acids were glutamic acid and aspartic acid in most cultivars but Jeugjinju in which cysteine (169.61 nmol) and GABA (129.32 nmol) were the most abundant amino acids. Thermal properties measured by differential scanning calorimeter (DSC) revealed that the enthalpy (${\Delta}H$) for starch gelatinization was the highest in Josangheugchalbyeo and Whaseonchalbyeo. It suggests that the starch structure of waxy rice could be more crystallized compared to non-waxy rice, and also that amylopectin could have more impact on starch gelatinization than amylose. The on-set and complete temperature for starch gelatinization were higher in colored rice of Heugjinju and Jeugjinju, and regular rice of Whateonchalbyeo.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.455-460
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• 2003

Effects of 0.25 and 0.5% citric and phytic acids on color and quality properties of doenjang during fermentation at $30^{\circ}C$ for 80 days were evaluated. As concentration of organic acid and fermentation time of acid-added doenjang increased, acidity, lightness, and antibrowning rate increased, whereas pH, amino nitrogen, and enzyme activity decreased compared to nonacid-added control. Microbial populations of total bacteria, yeast, and lactic acid bacteria were not affected by decrease in pH. Although degree of brown color (p<0.05) could be differentiated, flavor, palatability, acid taste, and overall preference were not significantly different. Browning of doenjang added with 0.25% of either organic acid was inhibited, while quality properties and sensory characteristics were similar to those of the control.

• Journal of Adhesion and Interface
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• v.14 no.2
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• pp.68-74
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• 2013

We synthesized polyurethane elastomer containing acid groups. We measured the adhesion, grip, tensile strength and mechanical properties. Casting polyurethane elastomers were prepared with the contents of acid. The adhesive strength and the wet slip were increased. Also, the tensile strength and abrasion properties were increased. We measured the properties with different acid contents. Increasing the acid content, the mechanical properties were increased. But the mechanical properties were decreased above 0.20 wt% of acid content. The wet slip was increased and the contact angle was decreased as the acid content increased.