• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.15-19
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• 2009

A simple and sensitive method for erythromycin quantification by liquid chromatography electrospray mass spectrometry (LC-MS/MS) in fishery products was developed. Samples were extracted by liquid-liquid extraction using 70% acetonitrile. Lipids were removed by acetonitrile saturated hexane. LC separation was performed on a Shiseido UG C-18 column ($150\;mm{\times}2.0\;mm$ internal diameter.) with a gradient system of 0.2% acetic acid-acetonitrile containing 0.2% acetic acid as a mobile phase at flow rate of 0.2 mL/min. The mass spectrometer was operated in selected reaction monitoring with positive electro-spray interface. Transitions were monitored a m/z $734{\to}577$ and $734{\to}158$, with m/z $734{\to}577$ chosen for quantification. Recovery of erythromycin from fish and shrimp fortified at the 10 ng/mL, 50 ng/mL and 100 ng/mL were 91.6-109.4%, 84.4-111.2% and 98.8-109.6% with high precision, respectively. Limits of quantification and limits of detection of erythromycin in both fish and shrimp were 10.0 ng/mL and 1.0 ng/mL, respectively. This analysis method for erythromycin has been proposed for registration in the Korean Official Methods of Food Analysis and has been utilized for fishery products analysis by the Korea Food and Drug Adminstration and the National Fisheries Products Quality Inspection Service.

• Journal of Environmental Health Sciences
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• v.44 no.3
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• pp.244-249
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• 2018

Objectives: The purpose of this study was the investigation of bromide and bromate in drinking water of water supply plants, mineral springs and small water supply system located in northern area of Gyeonggi province. Methods: Analytical method was based on EPA 326.0 to use Postcolumn reaction (PCR). The instrument was 887 professional UV/VIS detector IC manufactured in Metrohm. Results: Bromate was detected at $0.5{\sim}2.4{\mu}g/L$ in tap water from 5 water supply plants. These plants were used as disinfection method for sodium hypochlorite and on-site chlorine that causes generate bromate as a by products even if not used ozone. Conclusions: The bromate was detected up to $2.5{\mu}g/Lin$ drinking water in northern Gyeonggi area that showed within $10{\mu}g/L$ for standard of tap water. However, the continuous monitoring of bromate is necessary in drinking water.

• Journal of the Korean Chemical Society
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• v.45 no.2
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• pp.111-115
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• 2001

The ignition of NH$_3$-NO-Ar mixtures was examined in the temperature renge of 1675-2391 K behind reflected shock waves. The ignition delay times were measured by monitoring pressure profiles and the OH emissions at 1.0 cm from the end wall. A correlation between ignition delay times and concentrations of gases could be summarized in the form of mass-action expression, To complement the experiment, computer modeling study of the ignition of NH$_3$-NO-Ar mixtures was carried out using various mechanisms reported previously. The sensitivity analysis shows the reaction of NH$_2$+NO${\rightarrow}$NNH+OH is the most important step in the ignition of NH$_3$-NO-Ar mixtures.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11a
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• pp.76-100
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• 2000

A brief general discussion of the nature and function of biosensors is presented. While the primary motivator for biosensor development has been the health-care industries, recent research efforts have spread to problems in agriculture and biological production systems. To illustrate some of the research from our laboratory, three example biosensors and their corresponding applications are presented. The first of these is an immunosensor for measurement of the hormone progesterone during milking as a method to improve reproductive management of dairy herds. The second example is an enzyme sensor for measurement of urea in milk as a menas to determine the efficiency of conversion of input protein to milk protein and, thus, improve nutritional management of dairy herds. The third example is a DNA sensor using polymerase chain reaction to detect pathogenic bacteria in the wash water of fresh and minimally processed fruits and vegetables. The potential for application of biosensors in agriculture, agrobiotechnology, food processing, and environmental monitoring has barely been realized.

• Journal of the Korean Society of Tobacco Science
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• v.37 no.1
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• pp.18-24
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• 2015

Urinary mutagenicity is widely recognized as a useful biomarker for the assessment of mutagen exposure level in human. In this study, we optimized the several parameters affecting the activity of Urinary mutagenicity using highly sensitive mutation test(microsuspension assay) instead of the conventional Ames test. First of all, we chose YG1024 as a highly sensitive strain from three str ains of Salmonella typhimurium(TA98, TA100, YG1024) using r epr esentative mutation substances, such as Benzo[a]pyrene, 2-Aminonaphthalene, 2-amino-3-methyl-9H-pyrido[2,3-b]indole($MeA{\alpha}C$) and cigarette total particulate matter(TPM). And we established the several kinds of test conditions such as number of bacter ia, concentr ation of metabolic activation system and incubation time for the most sensitive reaction. Also, we optimized efficient pre-treatment method using commercial C18 column. As a r esults, this method was shown a aver age of 94 % recovery value and 13 % relative standard deviation. When we compared the Urinary mutagenicity between several participants, we confirmed that compar ative measurements were possible for different levels of urine mutagenicity. In conclusion, the optimized highly sensitive mutation test to measure the Urinary mutagenicity may be useful in biological monitoring of mutagen exposure level.

• Korean Journal of Veterinary Research
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• v.40 no.3
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• pp.611-625
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• 2000

For the improvement of quality control of laboratory mouse, we investigated the environmental condition, histopathological findings and serological test using ELISA to mouse hepatitis virus(MHV), Mycoplasma pulmonis(MP), Clostridium piliforme(TZ) and Sendai virus (HVJ) of ICR, C57BL/6, CBA and C3H/He mice that were supplied from conventional laboratory animal facility. 1. The ammonia concentration of facility was below the recommended concentration, 15ppm, by the KNIH, and the room temperature($21{\sim}23^{\circ}C$) and relative humidity(40~60%) was optimum range recommend by the Ministry of Health and Welfare, respectively. 2. The incidence rate of inapparent disease was 86.6% and the major findings in the liver were vacuolar degeneration with nucleic pleomorphism. The lung was shown the thickening of alveolar wall and interstitial pneumonia with congestion. The kidney and spleen were observed the mild congestion and extramedullary hematopoiesis, respectively. 3. The positive reaction rates against MHV and MP in serological test was 97.9% and 37.5%, respectively but HVJ and TZ were negative. These results suggest that laboratory mice could be infected with MHV and MP under conventional environments. Therefore we recommend to select thoroughly inapparent infected mice and to convert conventional system into SPF facility as soon as possible.

• Polymer(Korea)
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• v.27 no.3
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• pp.249-254
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• 2003

The variation of chemical structure and physical properties of crosslinked polyethylene (XLPE) during thermal aging process was investigated. The formation of carbonyl functional group resulting from thermal oxidation reaction of XLPE was monitored using X-ray photoelectron spectroscopy and near infrared (NIR) spectroscopy. It was observed that the intensity of carbonyl peak observed at 1715 nm linearly increased with aging time in NIR spectroscopy. The linear relationship between NIR peak absorbance and aging time confirmed that NIR spectroscopy might be used as a proper tool for monitoring the aging process of polymeric materials. Also the formation of crosslinks during the aging process was monitored using thermal mechanical analysis, stress-strain test, and Shore hardness test. The change in the physical properties, such as the increase in the glass transition temperature from 110 to 132$^{\circ}C$, the decrease in the strain from 265 to 110%, as well as the increase in the shore D hardness from 32 to 50, was observed during the aging process.

• Korean Journal of Pharmacognosy
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• v.30 no.4
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• pp.397-403
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• 1999

Tyrosinase plays an important role in the process of melanin polymer biosynthesis. Therefore, the enzyme inhibitors have been of great concern as cosmetics to have skin-whitening effects on the local hyperpigmentation. During the search for new inhibitory compounds on melanin polymer biosynthesis from natural sources, MeOH extracts of 589 higher plants were tested for the inhibitory effect on tyrosinase activity by the muschroom tyrosinase assay in vitro. Among plants tested, the leaves of Cercis chinensis exhibited potent inhibitory effect on mushroom tyrosinase activity. Subsequently seven active compounds were isolated from the ethyl acetate soluble part of acetone extract of the leaves of C. chinensis by the activity guided fractionation monitoring the inhibitory effect on tyrosinase activity. Their chemical structures were identified as $kaempferol-3-0-{\alpha}-L-rhamnoside$, quercitrin, $myricetin-3-0-{\alpha}-L-rhamnoside$, myricetin-3-0-(2'-O-galloyl)- ${\alpha}$ -L-rhamopyranoside (desmanthin), (-)-epicatechin-3-0-gallate, (-)-epigallocatechin-3-0-gallate, and methyl gallate on the basis of the speculation of spectral data and chemical reaction. Among the flavonol rhamnosides, myricetin-3-0-(2'-O-galloyl)- -L-rhamnoside(desmanthin) showed most potent inhibitory effect on tyrosinase activity and the structure of B-ring in flavonol moiety was related to the activity. (-)-Epigallocatechin-3-O-gallate having pyrogallol group in flavan-3-ol moiety exhibited more potent inhibitory effect than (-)-epicatechin-3-0-gallate having catechol group in flavan-3-ol moiety on mushroom tyrosinase activity.

• Journal of Environmental Health Sciences
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• v.30 no.5 s.81
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• pp.417-426
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• 2004

We investigate changing characteristics and concentration distribution of ambient air quality using data from which obtained local ambient air monitoring network and local meterological measuring sites in Gwangju area from January to December in 2003. Sulfur dioxide ($SO_2$) showed that increase from 8 AM and decrease in 6 PM but, it was not drastically changed concentration. it also 0.010 ppm in 1995 from at this time it's decrease step by step and than some constant in year 2001 to 2003. Nitrogen dioxide ($NO_2$) concentration was showed highest peak in 10 AM and increase again at 6 PM. And also it showed peak concentration (0.026 ppm) in 2001 and decreased from after that times. Ozone was showed peak concentration in 1 PM and Nitrogen dioxide was ditto in 10 AM from this data, we can conclude that this two article ws showed chemical reaction by 3 to 5 hours. There was no case of Ozone alarm in Gwangju area since 1995, but it showed highest ozone concentration (over 0.070 ppm) in May and June of the year and 2 to 4 PM of the day and sometimes it showed increase at the dawn. Ozone product optimum condition was that air temperature is over $25^{\circ}C$, no rain and increase solar radiation (over $20MJ/m^2$) and no wind or below 2.0 m/s wind speed.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.117-126
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• 2006

The purpose of this study is to develop a badge-type passive sampler for the measurement of short-term nitrogen dioxide and to evaluate its performance. The principle of the method is a colorimetric reaction of nitrogen dioxide with sulfanilic acid, N-1-naphthylethylendiamine, and phosphoric acid. First, it has been shown that the filter paper should be rinsed with ultrapure water and ultrasound, and then dried in a vacuumed desiccator. The concentration and volume of absorption reagent (triethanolamine) were $20\%$ and 100 ${\mu}L$, respectively. The extraction time was determined as 60 min. Second, duplicate measurements (n= 116) were carried out for evaluating the precision of the passive sampler. The relative error and the correlation coefficient between duplicates are $3.4\pm 3.0\%$ and 0.994, respectively. In addition, the $95\%$ confidence interval of intraclass correlation coefficient and the estimated value are 0.992$\sim$0.996 and 0.994, respectively. Third, a paired t-test was carried out for evaluating the accuracy of the passive sampler (n=40). In the result of the test, the $95\%$ confidence interval of the difference was -1.710 ppb <$\gamma$< 0.788 ppb. Finally, the average concentration of blanks, measurement detection limit, limit of detection, and limit of quantification are $2.4\pm 0.4$ ppb, 104 ppb, 3.8 ppb, and 7.0 ppb, respectively.