• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.162-177
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• 2001

The hydrolysis rates of seven kinds of polyol ester base oils 〔POEs〕 of different branch shape were investigated by using a simple apparatus under mild acidic condition. Seven polyol ester base oils were made of poly hydric alcohols of two-four valence, normal or branched fatty acids of different carbon number. p-Toluene sulfonic acid was used as acid catalyst to accelerate the rate of hydrolysis. Partial esters and fatty acid produced by sequential hydrolysis of POEs were identified and their concentrations were determined by calibrated-internal standard method using Gas Chromatography. The rate constants of each step in sequential hydrolysis were determined by the least square method from rate equation and the concentration of each component, were compared with one another. It was shown that the rate of hydrolysis of POEs was strongly affected by whether molecular structure of fatty acid was straight chain or branch chain and which position was branched. The hydrolysis stability for all the POEs can be reasonably explained by using a steric hindrance effect anticipated fi:om their molecular structures affecting as water molecule makes an attack on the carbonyl carbon of POEs.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.1
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• pp.59-69
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• 2017

Objectives: The objective of this study is to evaluate the exposure of VOCs and effects of the chemicals on the nail technicians whose works in a nail shop. Methods: For four month from May to August in 2016, we measured twenty-two kinds of VOCs in ten nail shops and carried out health examinations on thirty-four workers in there. Results: The TVOC concentration in indoor air of nail shops is $0.487mg/m^3$ at a minimum and $33.236mg/m^3$ at a maximum where it consists of 70.5% of Ketones, 25.4% of Alcohols, 2.6% of Esters, 0.8% of Aldehydes and 0.7% of Aromatics. The VOCs concentration during nail art works shows an increase in average ratio 1.8 compared to the concentration of indoor air quality and also the concentration of Isopropanol rose with 3.2 of the highest ratio. The results of Spearman correlation between TVOC concentration in indoor air and environmental factor was like that has significance level of correlation(${\rho}$<0.05, r=0.682) in case of number of customers per day, but the other factors were not meaningful in correlation. Correlation between VOCs and medical check-up items was like that has positive significance level(${\rho}$<0.01, r=0.638) between isopropanol and GPT, but the others have not meaningful. The exposure level of VOCs was not exceed the criteria exposure level 1 of working environment measuring method which announced by labor ministry in all ten nail shop indoor air quality. Conclusions: In this study although it was not significant correlation between harmful substances and medical check-up items in the nail shop indoor air quality, it is necessary to do more ventilation and to install exhaust facilities because of existing high VOCs concentration in the nail shop indoor air.

• Toxicological Research
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• v.21 no.3
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• pp.187-193
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• 2005

The rodent Hershberger assay is considered as a potential short term in vivo screening method for the detection of androgenic or anti-androgenic compounds. The objective of this study was to evaluate the anti-androgenic activities of di(2-ethylhexyl) phthalate (DEHP), di(n-butyl) phthalate (DBP), and butylbenzyl phthalate (BBP). A 10-day Hershberger assay was performed using immature Sprague-Dawley male rats castrated at 6 weeks of age. Tastosterone propionate (TP, 0.4 mg/kg/day) was administered s.c. to castrated male rats and followed by flutamide (1, 5, 10, or 20 mg/kg/day) treatment for 10 days by oral gavage. Similarly, DEHP, DBP, or BBP were also administered by oral gavage at 250, 500, or 1000 mg/kg/day after TP (0.4 mg/kg/day) administration. As expected, flutamide significantly inhibited the TP-induced re-growth of seminal vesicles, ventral prostate, and Levator ani plus bulbocavernosus muscles (LABC) at 1 mg/kg/day and above, and Cowper's glands and glans penis at 5 mg/kg/day and above. DEHP significantly (p<0.05) decreased the seminal vesicles, ventral prostate, LABC and Cowper's glands weights at 1000 mg/kg/day. BBP at 1000 mg/kg/day significantly inhibited TP-induced re-growth of the LABC in the immature castrated male rats, whereas ventral prostate, seminal vesicles, and Cowper's glands weights were unaffected. In contrast to DEHP, DBP did not affect accessory sex organ weights at any concentration. Body weights, combined adrenal glands, and kidney weights were not affected, but liver weights were significantly increased at high dosages in the DEHP, DBP, and BBP treatment groups. Our observations strongly suggest that DEHP acts as an androgen antagonist at the high dose (i.e., 1000 mg/kg/day).

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.232-240
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• 2012

Bio-diesel (BD) is the mono alkyl esters of long chain fatty acids derived from renewable feed stocks like vegetable oils or animal fats. Bio-diesel shows poorer fuel properties than that of diesel fuel in a cold condition. For the diesel fuel, many cold flow improvers have been developed; however, since primary ingredients of bio-diesel are different from those of the diesel fuel, there is a limit to the cold flow improvement when the same cold flow improvers are added to bio diesel. In this study, to improve low temperature properties of bio-diesel, we developed a cold flow improver using an alkyl methacrylate monomer, prepared via ester reaction, and maleic anhydride and also conducted a ring opening reaction using amine. We characterized the products using $^1H-NMR$, FT-IR and GPC methods. In addition, the cold flow improvements of the products in Soybean BD and Palm BD in the concentration rage of 1000~10000 ppm were investigated. It was found that the addition of LMA2SMA6MA2-C8A in Soybean BD improved the pour point by $12.5\;^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.430-436
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• 2016

Solid phase microextraction and gas chromatography-mass spectrometry (SPME/GC-MS), electronic nose, and electronic tongue were used to characterize the sensory profiles of cider vinegars from Korea (K1-2), China (C1-2), Japan (J1-2), and US (U1-2). SPME-GC/MS detected acetic acid as the common volatile compound in all vinegars, in addition to isovaleric acid, octanoic acid, and phenethyl acetate. Acids and acetic esters were the major components of Korean and US vinegar samples, respectively. Chinese vinegars had high ethyl acetate content, while Japanese samples were characterized by a low content of acetic acid. Principal component analysis (PCA) pattern provided a clear categorical discrimination of Chinese vinegars by E-nose and E-tongue analyses. The instrumental sensory scores and the taste attributes for flavor ($r^2=0.9431$), sourness ($r^2=0.9515$), and sweetness ($r^2=0.8325$) were highly correlated. Therefore, SPME/GC-MS, E-nose, and E-tongue analyses may be useful tools to discriminate the sensory profiles of cider vinegars of different origins.

• Korean Journal of Food Science and Technology
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• v.49 no.4
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• pp.369-376
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• 2017

Maturation of distilled spirit can generate diverse flavors and tastes. Rice Soju was matured in oak casks (MSO) and stainless steel containers (MSS) for one year at ambient temperature. Ipguk (Aspergillus luchuensis) and Saccharomyces cerevisiae Y88-4 were used, and reduced pressure ($110{\pm}20Torr$) distillation was applied to brew Soju. Acidity and conductivity were increased in both MSO and MSS. MSO reduced alcohol content (from 43 to 40%) and volume (from 18,000 to 12,730 mL), and significantly altered yellowness (from 0.2 to 30.2). Furthermore, MSO increased the isoamyl alcohol (from 276.7 to $339.2{\mu}g/mL$) and isobutyl alcohol (from 122.3 to $144.2{\mu}g/mL$) content. Gas chromatography-mass spectrometry was used to detect volatile compounds in Soju, which included 20 esters, 7 alcohols, 2 acids, and 5 miscellaneous compounds. Oak lactone was detected only in MSO and was considered as a specific flavor component associated with oak maturation. Thus, maturation materials contribute to the physicochemical property of distilled spirits.

• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1358-1364
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• 2000

A mixed culture of bacteriocin-producing lactic acid bacteria and yeast was used to prepare unique fermented fruit and vegetable beverage which contains bacteriocin. Fruit and vegetable broth fermented by Lactococcus lactis 11454 showed inhibitory activity against foodborne pathogens such as Listeria monocytogens and Staphylococcus aureus, and Streptococcus mutans which is a major causative agent for dental caries. Bacteriocin was detected at the end of fermentation of fruit and vegetables and its antimicrobial activity was stable for 5 weeks during storage at $4^{\circ}C$. These results suggest that the presence of bacteriocin in beverages during fermentation and storage will provide a safeguard against foodborne pathogens and spoilage bacteria. To improve flavor of the fermented broth, post-fermentation of the fermented broth was carried out at $4^{\circ}C$ by using yeast isolated from raw material mixture. Total acidity of the post-fermented broth was slightly decreased, but significant increase in the concentration of succinic acid was observed in the post-fermented broth. It was also observed that bitter and disagreeable taste compounds such as phthalates were decreased, and mild acidic and fruity flavor esters and alcohols were increased by the post-fermentation of the fermented broth with yeast.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.889-899
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• 2017

To investigate the quality characteristics of domestic $ros{\acute{e}}$ wines marketed in Korea, 11 kinds of wines were purchased at the Korea Wine Festival in 2016. The color, physiological activity, aroma component and sensory evaluations were conducted. The hue value of $ros{\acute{e}}$ wines ranged from 0.592 to 1.990, with the Ro7 of Delaware having the highest value. The brightness of $ros{\acute{e}}$ wines ranged from 42.96 to 94.99, the redness from 3.20 to 59.37, and the yellowness from 8.43 to 24.83. Of the 11 $ros{\acute{e}}$ wines evaluated, 1 was a dry wine and 10 were sweet wines. The average sugar content of the sweet wines was 73.89 mg/mL. Among the organic acid contents, malic acid ranged from 0.214 to 2.903 mg/mL, and lactic acid content ranged from 0 to 3.423 mg/mL. Malolactic fermentation differed, depending on the source. The total polyphenol content of $ros{\acute{e}}$ wines ranged from 50.55 to 99.55 mg%, the anthocyanin content was 2.12 to 213.30 mg/L, and the DPPH radical scavenging activity of $ros{\acute{e}}$ wines was between 73.75 to 90.41%. A total of 41 volatile components were detected, including 7 alcohols, 22 esters, 4 terpenes, 3 acids and 5 other compounds. Of these, 9 compounds had odor activity value(OAV) greater than 1; these were identified as 1-propanol (alcohol, pungent), 3-methyl-1-butanol (harsh, nail polish), ethyl butanoate (strawberry, lactic), isopentyl acetate (fresh, banana), ethyl hexanoate (green apple, fruity), ethyl octanoate (pineapple, pear, floral), ethyl decanoate (fruity, fatty, pleasant), linalool (flower, lavender) and limonene (lemone, orange). As a result of the sensory evaluation, the Ro5 wine made from Campbell Early grape, and having a good color, flavor and taste, was the most preferred.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.196-201
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• 1993

In order to investigate some chemical components, higher alcohols, ethyl acetate and volatile compounds of Vitis vinifera red wines were analyzed by HPLC, GC and GC-MS. During the process of ripening for the content of wine and acids were much changed, particurally the content of tartaric acid was decreased largely. Content of total phenolics and phenol flavonoid in wines which manufactured with Malbec varieties as 470mg/L and 245mg/L respectively, was higher than those in Cabernet sauvignon (310mg/L, 135mg/L) and Cabernet franc (425mg/L, 125mg/L) wines, and nonflavonoid was higher in Cabernet franc wine(300mg/L) than in others. Content of acetaldehyde was higher in Malbec wine (33mg/L) than in Cabernet sauvignon (26mg/L) and Cabernet franc (28mg/L) wines. Amount of methyl alcohol, propanol and isoamyl alcohol were higher in Cabernet sauvignon wine than in others, and isobutanol was more in Malbec wine(64mg/L), ethyl acetate was more in Cabernet franc wine as 35mg/L than in Malbec(28mg/L) and in Cabernet sauvignon (23mg/L) wines. Volatile compounds were isolated about 87~91 varieties from concentrates of three red wines by GC, and thirty-five compounds including terpine-4-ol were identified by GC-MS.

• Polymer(Korea)
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• v.36 no.1
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• pp.76-87
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• 2012

Three kinds of hydroxypropyl cellulose (HPC) derivatives, [6-{4-(4-cyanophenylazo)phenoxy}]hexyloxypropyl celluloses (CAHPCs) with degree of etherification (DET) ranging from 0.4 to 3, fully substituted acrylic acid esters of HPC (HPCA) and CAHPCs (CAHPCAs) were synthesized. The crosslinked HPCA (HPCAG) and CAHPCAs (CAHPCAGs) were also prepared by exposing thermotropic mesophases of HPCA and CAHPCAs to UV light. Both CAHPCs and CAHPCAs with DET ${\leq}$ 1.2, as well as HPC and HPCA, formed enantiotropic cholesteric phases whose optical pitches(${\lambda}_m$'s) increase with temperature, wheras both CAHPCs and CAHPCAs with DET ${\geq}$ 1.4 showed monotropic nematic phases. CAHPCAGs with DET ${\leq}$ 1.2, as well as CAHPCAs with DET ${\leq}$ 1.2, exhibited reflection colors in a wide temperature range. On the other hand, CAHPCAGs with DET ${\geq}$ 1.4, as well as CAHPCAs with DET ${\geq}$ 1.4, showed Schileren textures typical of nematic phase, indicating that the liquid crystalline structure is virtually locked upon photocrosslinking. The isotropization temperatures($T_i$'s) of both CAHPCAs and CAHPCAGs decreased with increasing DET. The $T_i$ of CAHPCAG, however, was higher than that of CAHPCA at the same DET. Moreover, the temperature dependence of ${\lambda}_m$ of CAHPCAGs was much weaker than that of CAHPCAs.