• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.11
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• pp.1701-1708
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• 2014

Phenolic compounds, physiological properties, and digestive enzyme inhibitory effect of 70% ethanol extracts from Aster scaber with different extraction methods (stirrer extraction, SE; reflux extraction, RE; autoclave extraction, AE; low temperature high pressure extraction, LTPE; ultrasonification extraction, USE) were investigated. Total polyphenols and flavonoids contents in LTPE were significantly higher than those of other extracts. The amount of substances related to cynarin (1,3-O-dicaffeoylquinic acid) was highest in USE (34.34 mg/g), followed by LTPE (33.83 mg/g), RE (32.27 mg/g), AE (25.40 mg/g), and SE (18.17 mg/g). Chlorogenic acid (5-O-caffeoylquinic acid) and astragalin (kaempferol-3-O-glucopyranoside) were highest in AE and LTPE, respectively. Xanthine oxidase, angiotensin- I converting enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase and acetylcholin esterase inhibitory activities of LTPE and USE at a concentration of 50 mg% (w/v) were somewhat higher than those of other extracts. The ${\alpha}$-amylase, ${\alpha}$-glucosidase, trypsin and lipase activities showed the same tendency as physiological properties (concentration of 500 mg%, w/v). Additionally, there was significantly higher or slightly lower inhibitory activity compared to the control group. These results suggest that extracts from Aster scaber have potential to act as functional materials, and LTPE and USE are superior for the enhancement of biological activity.

• The Korean Journal of Nuclear Medicine
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• v.25 no.2
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• pp.286-293
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• 1991

$^{123}I$, which is applied for the thyroid and other in vivo kinetic study, has a special role in life sciences. The 159 KeV $\gamma-ray$ from $^{123}I$ is almost ideally appropriate for the current imaging instrumentation. Its decay mode (electron capture) and short half-life (13.3 hr) reduced the burden of radiation dose to the patients, and its chemical property makes it easy to synthesize the labelling compounds. In this experiment, the production of $^{123}I$ via the nuclear reaction $^{124}Te(p,2n)^{123}I$ with 28 MeV protons was sutdied. $TeO_2$ is used as a target material, because it has good physical properties. The target was prepared with $TeO_2$ powder and was molten into a ellipsoidal cavity (a=14 mm, b=10 mm, $270.8mg/cm^2$ thick) of pure platinum. The irradiation was carried out in the external proton beam with incident energies range from 28 MeV to 22 MeV, and current was $30{\mu}A$. The loss of $TeO_2$ target was significantly reduced by using $4\pi-cooling$ system in irradiation. The dry distillation method was adopted for the separation of $^{123}I$ from irradiated target, and when it was kept 5 minutes at $780^{\circ}C$, its result was quantitative. The loss of the target material $(TeO_2)$ was below 0.2% for each production run and $^{123}I$ from the dry distillation apparatus was captured with 0.01 N NaOH in $Na^{123}I$ form, then the pH of the solution was adjusted to $7.5\sim9.0$ with HC1/NaOH. The $Na^{123}I$ solution was passed through $0.2{\mu}m$ membrane filter, and sterilized under high pressure and temperature for 30 minutes. The production of $^{123}I$ is acceptable for clinical application based on the quality of USP XXI.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.10-15
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• 1999

White emission thin film electroluminescent device was fabricated using ZnS for phosphor layer and BST ferroelectric thin film for insulating layer. For fabrication conditions of BST thin film, stoichiometry of target was $Ba_{0.5}Sr_{0.5}TiO_3$, substrate temperature was $400^{\circ}C$, working pressure was 30 mTorr, and A:$O_2$ ratio was 9:1. At this time, dielectric constant was 209 at 1kHz frequency. For phosphor layer ZnS:Mn, ZnS:Tb, and ZnS:Ag were used. Mixing rates of activators were respectively 0.8, 0.8, and 1 wt%. Total thickness of phosphor tapers was 500 nm, thickness of lower insulating layer was 200 nm, and thickness of upper insulating layer was 400 nm. In this conditions, luminescence threshold voltage of thin film electroluminescent device was $95\;V_{rms}$, maximum brightness was $3,000\;cd/m^2$ at $150\;V_{rms}$. Luminescence spectrum peak was observed at region of blue(450 nm), green(550 nm), and red(600 nm).

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.13-19
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• 1998

Copolyimide membranes of different chemical structure based on pyromellitic dianhydride (PMDA)/methylendianiline(MDA) were prepared by varying their chemical compositions with adding meta-phenylendiamine (MPD), para- phenylendiamine (PPD), 2,4,6- trimethyl-1,3-phenylenediamine(TriMeMPD) as a co-monomer. The $N_2$ and $O_2$ permeation properties are qualitatively correlated to specific free volume and intersegmental distance of membrane. The partial replacement of MDA with MPD or PPD caused in the PMDA/MDA based membranes increase in density, and decrease in free volume, d-spacing, consequently resulted in decreased permeability coefficient. In the case of TriMeMPD, opposite results were observed. In all membranes, the permeability coefficients were pressure independent, and membranes which have high permeability coefficient showed low $N_2/O_2$ ideal separation factor as an usual manner. The permeability coefficient also increased with temperature and $N_2/O_2$ ideal separation factor decreased. The increase ratio of the $N_2$ permeability coefficient was larger than that of $O_2$.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.3
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• pp.156-161
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• 2011

Objectives: Tetrahydrofuran (THF) is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. THF has been used as a solvent and a precursor for various syntheses of polymers. However, THF is known to irritate to the eyes, skin and mucus membranes. Overexposure by inhalation, ingestion or skin contact may produce nausea, dizziness, headaches, respiratory irritation and possible skin burns. The purpose of this study is to evaluate of the worker exposure and characteristics of workers in the workplaces that use or manufacture THF. Methods: Sixteen factories in Korea, which manufacture or use THF, were selected for this study and a total of 130 air samples including 104 time-weighted average (TWA) samples and 26 short-term exposure limit (STEL) samples, were collected. Air samples were collected with charcoal tube (100mg/50mg) and analyzed by gas chromatograph/flame ionization detector(GC/FID). Results: The TWA concentration of THF was 16.05ppm (GM) at PS script printing, 2.32ppm (GM) at PVC stabilizer, 1.03ppm (GM) at Lithium triethylborohydride, 0.63ppm (GM) at Polytetramethylene ether glycol(PTMEG), 0.42ppm (GM) at Manufacturing THF, 0.13ppm (GM) at Glue and 0.12ppm (GM) at synthetic rubber/resins. Two out of sampes for PS script printing exceeded 50ppm as 8-hour exposure limit of MOEL. The short term exposure to THF was 54.77ppm (GM) at PS script printing, 17.10ppm (GM) at PTMEG, 13.76ppm (GM) at Manufacturing THF, 2.86ppm (GM) at Lithium triethylborohydride, 0.87ppm (GM) at synthetic rubber/resins and 0.13ppm (GM) Glue. We found that the highest exposure process for both the TWA and STEL samples was PS script process. Two samples exceeded 100ppm as short term exposure limit of Ministry of Employment and Labor(MOEL). Conclusions: Characteristic of STEL concentration for THF is considerably different from TWA concentration in workplaces because workers could exposure high concentration of THF in a moment when they work irregularly schedule. So exposure controls for momentary works have to be prepared, and considered the skin absorption and inhale of THF.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.1027-1033
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• 2010

A two-phase (gas-liquid) flow is a common phenomenon in fluidic systems, e.g., fluidic systems in the electro-magnetic or nuclear power generation industry and in the steel industry. The measurement of a two-phase flow is important for guaranteeing the safety of the system and for achieving the desired performance. The measurement of the void fraction, which is one of the parameters of the two-phase flow that determines the pressure drop and heat transfer coefficient, is very important. The time resolution achieved by employing the impedance method that can be used to calculate the void fraction from the impedance of the fluid is high because the electric characteristics are taken into account. Therefore, this method can be employed to accurately measure the void fraction without distortion of flow in real time by placing electrodes on the walls of the tubes. Coney analytically studied a ring-type impedance meter, which can be employed in a circular tube. The aim of this study is to experimentally verify the robustness of a three-ring impedance meter to variations in the electric conductivity of the fluid; this robustness was suggested by Coney but was not experimentally verified.

• Journal of Food Hygiene and Safety
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• v.27 no.2
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• pp.109-116
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• 2012

The study indicated that antimicrobial activity about gram positive and gram negative bacteria of ginger-oleoresin(GO) extract with the condition of ethanol and supercritical fluid extractions. As the concentration of extraction increases, the clear zone of GO ethanol extract also increased dependently. This led the antimicrobial activity of gram positive bacteria to take bigger place than gram negative bacteria especially in Listeria monocytogenes. There was a high antimicrobial activity in E-III treatment where the ratio of the ginger powder extract to ethanol extraction was 1:6. It was quite effective to treat the antimicrobial activity of GO ethanol extract under $80^{\circ}C$ and there was not big difference in the intervals which were the extraction time - 1 to 7 hours. The antimicrobial activity of supercritical fluid extract seemed to take the biggest place in Listeria monocytogenes. From the supercritical fluid extract, it was shown the strong ability of antimicrobial activity in the condition with 100 bar $35^{\circ}C$, 250 bar $35^{\circ}C$ and 250 bar $65^{\circ}C$. Furthermore, according to the case of solvent extract, there was not any significant difference in the antimicrobial activity with condition of extraction. However, there was significant antimicrobial activity in E-III treatment of 100 bar and 500 bar of extraction pressure, and $35^{\circ}C$ and $65^{\circ}C$ of extraction temperature.

• Journal of Food Hygiene and Safety
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• v.23 no.1
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• pp.73-79
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• 2008

The productions of beauvericin and enniatins H, I, and MK1688 by Fusarium oxysporum KFCC 11363P were investigated on rice substrate at four temperatures (15, 20, 25, and $30^{\circ}C$) and three moisture contents (10, 20, and 40%). The largest amount of beauvericin ($718.0\;{\mu}g/g$) was produced at $25^{\circ}C$, and maximum levels of enniatin H ($781.9\;{\mu}g/g$), I ($725.8\;{\mu}g/g$), and MK1688 ($425.8\;{\mu}g/g$) were measured by high pressure liquid chromatography (HPLC) at the same temperature. The optimal moisture content for the production of beauvericin and enniatins H, I, and MK1688 was 40%, and the trace amounts of these toxins were observed at 10% moisture content. Sixty five grain samples (n=65) were tested for the monitoring of beauvericin. This mycotoxin was detected in six grain samples including three maize, two barley, and one wheat samples. The highest contamination level of beauvericin was observed in maize sample ($0.23\;{\mu}g/g$).

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1300-1307
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• 1999

Supercritical fluid extraction was applied to recycling triglyceride from used shortening. Used shortening and its fractions were analyzed with high performance size exclusion chromatography for their composition in triglycerides, polymer and low molecular weight compounds. Conjugated diene value and color of the fractions were also measured with a UV spectrophotometer and a colorimeter, respectively. Pressure and temperature ranges employed were $15{\sim}30$ MPa and $40{\sim}60^{\circ}C$, respectively. Concentration of fat in supercritical (SC) $CO_2$ ranged from $0.3\;X\;10^{-3}{\sim}7.4\;X10^{-3}(g\;fat/g\;CO_2)$. An exponential relation between concentration of fat in SC $CO_2$ and density was observed. Color of the extracts was light yellow which was very close to that of the fresh shortening. Low molecular weight compounds were preferentially concentrated in the initial fraction, while polymer was extracted in the final fraction. Conjugated diene value of the initial fractions was clearly lower than that of feed. It increased sharply as the polymer content in the fraction became significantly large.

• Analytical Science and Technology
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• v.14 no.5
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• pp.451-457
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• 2001

Because liquids with high molecular weight such as mineral oil have low vapor pressure at room temperature, it is generally thought to be difficult to lose them to evaporation. However, when they are dispersed into air in small droplets during application in machining processes, their surface area becomes considerably higher. To determine the potential for metalworking fluids (MWF) filter losses, MWF mist was generated and collected on polyvinyl chloride (PVC) filters in test chamber. After collected MWF was exposed to clean air during designated period (range 10~240 minutes) and the filters were desiccated, losses were evaluated. As duration of clean air passing through PVC filter increased, loss of MWF gradually increased. MWF lost after 10 minutes ranged form 12.4 % to 21.8 % of the original loading mass, on average 53.3 % of the total loss. These results indicate that significant mass of MWF collected on PVC filters can be lost at the beginning of air sampling. Loss of MWF collected on PVC filter also occurred during desiccation without active airflow. In multiple regression to identify which factors influence the loss of MWF collected on PVC filter, both duration of air passing through PVC filter and MWF age (fresh vs. used) were significant predictor (p=0.0001). Therefore, workers' exposure to MWF measured method 0500, may underestimate true concentration. Further study is needed to develop a new method to quantify the workers' exposure to airborne MWF mist accurately.