• Elastomers and Composites
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• v.44 no.2
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• pp.175-181
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• 2009

The solution polymerization was conducted to synthesize pressure sensitive adhesive for polarizer film using acrylic monomers. 2-Ethylhexyl acrylate, butyl acrylate, acrylic acid were used as acrylic monomers, benzoyl peroxide as initiator, ethyl acetate as solvent. The ratio of monomers was 2-ethylhexyl acrylate: butyl acrylate: acrylic acid = 25:50:3.6 reflecting $-40^{\circ}C$ of glass transition temperature in the pressure sensitive adhesive. The amount of initiator was determined as 0.09% to monomer considering wetting power and initial tackiness. The ratio of monomer to solvent was determined as 1:1.7 considering wetting power and transmissivity. The transmissivity of pressure sensitive adhesive increased with decreasing both viscosity and molecular weight due to reducing of refractive index by low entanglement between molecules. In the measurement of pot life, it was found that the storage stability was good at 1:1.7 of monomer: solvent without large change of viscosity during 200 min.

• Natural Product Sciences
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• v.24 no.3
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• pp.189-193
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• 2018

Chemical investigation of the ethyl acetate extract of Gibberella moniliformis JS1055 endophytic fungus derived from a halophyte, Vitex rotundifolia, led to the isolation of nine compounds including 7-butyl-6,8-dihydroxy-3(R)-pent-11-enylisochroman-1-one (1), 7-butyl-6,8-dihydroxy-3(R)-pentylisochroman-1-one (2), 7-butyl6,8-dihydroxy-3(R)-pentylisochroman-1-one (3), $5{\alpha},8{\alpha}$-epidioxyergosta-6,9(11),22-trien-3-ol (4), ergosterol peroxide (5), tetradecanoic acid (6), 8-O-methylfusarubin (7), nicotinic acid (8) and adenosine (9). They were identified by extensive spectroscopic data analysis including 1D, 2D ($^1H-^1H$ COSY, HSQC, HMBC) NMR, and ESIMS. All the isolates (1-9) are reported for the first time from this endophytic fungus.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.105-114
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• 1998

In this study, 108 thinners were analyzed to identify their composition. The purposes of this study were to provide the data for MSDS and worker exposure levels. Thinners were collected from manufacturing industries, distributors and users. Wide ranges of thinner components were found ; Toluene, xylene, and ethyl benzene were most often found. Next, MIBK, cellosolve acetate, butyl cellosolve, and butyl acetate were found in 20-40 thinners. Others, such as acetone, n-hexane, cyclohexane, heptane, methylcyciohexane, octane and nonane were also found. There were about 5-6 components in each thinner. In the view point of Industrial Hygiene, Benzene was the most important component of thinners, which procures leukemia. Benzene was found from 8 kinds of thinners out of the total 108 surveyed. Thus, Content of benzene in thinners must be evaluated when industrial hygiene surveys are performed. Aromatic hydrocarbons were identified from 71 kinds of thinners out of total 108 and their contents were 10-87%. Alkanes were not contained in automobile painting, spraying, degreasing, urethane and epoxy thinners but lacquer, enamel and coating thinners.

• The Journal of the Korea Contents Association
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• v.6 no.12
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• pp.163-168
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• 2006

Hg-free fluorescent lamps were fabricated and electro-optical characterization were measured for using LCD backlight. PDP phosphors, nitro-cellulose and n-butyl acetate were mixed and coated uniformly in glass tube without stain. The glass tubes were sintered at $550^{\circ}C$ for 20 minutes, vacuumed to $10^{-6}$ torr and supplied discharge gas by using a gas mixture. After various experiment about phosphors thickness and inner diameter of glass tube, the appropriate phosphors thickness and inner diameter of glass tube were obtained. The luminance and luminous efficiency of manufactured fluorescent lamps with Ne+Xe discharge gas were $6,270cd/m^2$, 13 lm/W under 75 kHz sinusoidal wave voltage, respectively.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.588-594
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• 1992

Polyisocyanurate has been obtained from toluene diisocyanate(TDI) in the presence of potassium octoate catalyst and the effects of water and butanol in solvent were studied for the determination of the change of viscosity, the reaction time (length of time required for 5 poise of viscosity of product), molecular dispersity of product, and TDI conversion. When butyl acetate contains 0.1% of water by weight, uretidione was formed and a higher conversion was obtained at the condition. The uretidione was not formed by adding butanol to the solvent. At a higher concentration of butanol, a higher TDI conversion and a wider molecular dispersity were obtained.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.358-364
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• 2009

본 연구에서는 우리나라 주요 침엽수종인 소나무(Pinus densiflora)와 활엽수종인 굴참나무(Quercus variabilis)의 낙엽에 대해 FTIR(Fourier Transform Infrared) 분광계를 이용하여 배출 연소가스 종류 및 농도를 측정하였다. 실험결과 소나무와 굴참나무 낙엽에서 Carbon monoxide, Carbon dioxide, Acetic acid, Butyl acetate, Ethylene, Methane, Methanol, Nitrogen dioxide, Ammonia, Hydrogen Fluoride, Sulfur dioxide, Hydrogen bromide 등 13개 연소가스가 검출되었고 굴참나무 낙엽에서는 Nitrogen monoxide가 추가로 검출되었다. 방출된 연소가스의 전체 농도는 소나무 낙엽이 굴참나무 낙엽에 비해 4.5배 많이 검출되었다. 특히, 시간가중평균가스농도(TWA : Time-weighted average, ppm) 기준을 초과하는 연소가스는 Carbon monoxide, Carbon dioxide, Butyl acetate가 검출되었고 단시간노출기준(STEL : Short Term Exposure Limit, ppm) 기준을 초과하는 연소가스는 Carbon monoxide, Carbon dioxide로 소나무 및 굴참나무 모두에서 나타났다. 이에 산불에서의 낙엽층 지표화 연소시 전체 가스 방출량의 99% 이상을 차지하고 있는 Carbon monoxide, Carbon dioxide의 건강 위험성이 높은 것으로 나타났다. 하지만, 검출된 다른 건강 위험성 가스의 경우에도 연소물질의 양이 증가할수록 연소가스의 농도가 높아져 건강안정성에 해가 있을 것으로 판단되며 또한 검출된 연소가스 중 나무의 주요구성 원소가 아닌 Bromide, Fluoride 화합물에 대해서는 토양으로부터의 오염 또는 분석과정에서의 노이즈로 인한 검출 등에 대한 보다 면밀한 검토가 필요할 것으로 판단된다.

• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.570-576
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• 2011

The effect of nuruks and crude amylolytic enzyme on free amino acid and volatile components of brown rice vinegar prepared by static cultures was investigated. Five groups consisted of AV (100% nuruk without crude amylolytic enzyme), BV (75% nuruk; 25% crude amylolytic enzyme), CV (50% nuruk; 50% crude amylolytic enzyme), DV (25% nuruk; 75% crude amylolytic enzyme) and EV (100% crude amylolytic enzyme without nuruk). Free amino acid content in AV vinegar (132.06 mg%) was lower than the others (184.56-191.22 mg%). Acetic acid, 3-methyl butyl acetate, acetoin and isoamyl alcohol were major volatile components as analyzed using gas chromatography-mass spectrometry after headspace solid-phase microextraction. Acetic acid in AV and EV samples represented 67.56% and 55.53% of total GC peak area, respectively. E-nose provided different patterns in each case showing variation in sensory properties.

• Analytical Science and Technology
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• v.31 no.6
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• pp.225-231
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• 2018

Benzoic acid, methyl paraben, and butyl paraben are preservatives that have been used in pharmaceutical, cosmetic, and food products. However, as their toxicities for human have been reported, many nations and organizations including Korea have established a regulation limit for thier usage of these preservatives in food products. The present study developed the isotope dilution liquid chromatography mass spectrometry method for accurate determination of three target preseratives in soysauce. In this study, the isotope dilution liquid chromatography mass spectrometry method was developed for accurate determination of three target preservatives in soy sauce. LC separation was optimized considering the pKa of benzoic acid which is lower than those of methyl and butyl parabens. A C18 column was used with 5 mM ammonium acetate and methanol as mobile phases. Mass spectrometry was operated in negative mode and selected reaction monitoring mode (SRM). Soy sauce sample was cleaned-up with C18 SPE cartridge for removing matrix inferences and color material. Optimized conditions and the method were validated with soy sauce reference materials for the analysis of food preservatives from Health Science Authority in Singapore. The measured values of benzoic acid, methyl and butyl paraben agreed well with reference values within their uncertainties.

• Safety and Health at Work
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• v.2 no.1
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• pp.39-51
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• 2011

Objectives: This study was designed to evaluate exposure levels of various chemicals used in wafer fabrication product lines in the semiconductor industry where work-related leukemia has occurred. Methods: The research focused on 9 representative wafer fabrication bays among a total of 25 bays in a semiconductor product line. We monitored the chemical substances categorized as human carcinogens with respect to leukemia as well as harmful chemicals used in the bays and substances with hematologic and reproductive toxicities to evaluate the overall health effect for semiconductor industry workers. With respect to monitoring, active and passive sampling techniques were introduced. Eight-hour long-term and 15-minute short-term sampling was conducted for the area as well as on personal samples. Results: The results of the measurements for each substance showed that benzene, toluene, xylene, n-butyl acetate, 2-methoxy-ethanol, 2-heptanone, ethylene glycol, sulfuric acid, and phosphoric acid were non-detectable (ND) in all samples. Arsine was either "ND" or it existed only in trace form in the bay air. The maximum exposure concentration of fluorides was approximately 0.17% of the Korea occupational exposure limits, with hydrofluoric acid at about 0.2%, hydrochloric acid 0.06%, nitric acid 0.05%, isopropyl alcohol 0.4%, and phosphine at about 2%. The maximum exposure concentration of propylene glycol monomethyl ether acetate (PGMEA) was 0.0870 ppm, representing only 0.1% or less than the American Industrial Hygiene Association recommended standard (100 ppm). Conclusion: Benzene, a known human carcinogen for leukemia, and arsine, a hematologic toxin, were not detected in wafer fabrication sites in this study. Among reproductive toxic substances, n-butyl acetate was not detected, but fluorides and PGMEA existed in small amounts in the air. This investigation was focused on the air-borne chemical concentrations only in regular working conditions. Unconditional exposures during spills and/or maintenance tasks and by-product chemicals were not included. Supplementary studies might be required.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.4
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• pp.452-463
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• 2019

Objectives: The purpose of this study is to evaluate airborne concentrations of volatile organic compounds(VOCs) during nail art practice by college students. Methods: Personal samples for students were measured using passive samplers(OVM 3500) during three kinds of practice, including polish nail, gel nail and acrylic French sculpture at two universities located in Gyeongsangbuk-do Province. We also monitored area concentrations using active samplers and real-time total VOC monitors(ppbRAE 3000). All samples were analyzed with a gas chromatography flame ionized detector. Statistical analysis for monitored data were conducted using a web-based Bayesian toolkit, EXPOSTATS(www.expostats.ca). Results: Twenty-four personal samples and ten area samples were collected and five chemicals(acetone, butyl acetate, ethyl acetate, ethyl methacrylate(EMA) and methyl methacrylate(MMA)) were detected. Acetone was detected in all personal samples and ranged from 2.58 ppm to 50.3 ppm. EMA was detected in all personal and area samples with a maximum concentration of 9.78 ppm during acrylic French sculpture. Personal exposure levels to acetone, butyl acetate and mixtures were significantly higher with high occupant density (p<0.05). Geometric mean (GM) concentrations of 3.61 ppm for EMA personal samples were significantly higher than that of area samples, 1.5 ppm (p<0.05). Since there was no local ventilation, total VOC concentration continued to increase as the practice progressed. Conclusions: In order to minimize VOCs exposure for trainees, it is necessary to introduce a local ventilation system and maintain adequate occupant density.