• Korean Journal of Environmental Agriculture
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• v.28 no.4
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• pp.419-426
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• 2009

This study was conducted to know the biological half-lives and dissipation patterns of fungicides, pyrimethanil, chlorothalonil and tetraconazole in Korean melon under green house condition. The instrument for analyzing pyrimethanil and chlorothalonil was HPLC equipped with UV detector. Initial residue amounts of pyrimethanil were 0.16 mg/kg at recommended rate and 0.28 mg/kg at double recommended rate in Korean melon. The biological half-lives of pyrimethanil were 11.2 days at recommended rate and 10.1 days at double recommended rate in Korean melon. In case of chlorothalonil, initial residue amounts of chlorothalonil were 0.06 mg/kg at recommended and 0.11 mg/kg at double recommended rate in Korean melon. The biological half-lives of chlorothalonil in Korean melon were 3.4 days at recommended rate and 6.6 days at double recommended rate. The instrument for analyzing tetraconazole was GLC equipped with electron capture detector. Initial residue amounts of tetraconazole were 0.14 mg/kg at recommended and 0.22 mg/kg at double recommended rate in Korean melon, respectively. The biological half-lives of tetraconazole were 9.6 days at recommended rate and 18.5 days at double recommended rate in Korean melon.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1463-1468
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• 2007

Emission of methyl bromide(MeBr) of soil fumigant was implicated in stratospheric ozone depletion. To determine the environmental fate for 1,3-dichloropene(1,3-D) of alternatives fumigants for MeBr, this paper researched the transformation for 1,3-D in water and soil. Half lives of cis-1,3-D in water with first-order kinetics are 9.9day and 1.7day at $25^{\circ}C\;and\;40^{\circ}C$, half lives of trans-1,3-D are 8.6day and 1.5day at $25^{\circ}C\;and\;40^{\circ}C$, respectively. Transformation for 1,3-D in water at high temperature faster then at low temperature. Hydrolysis for 1,3-D in water are unaffected at $pH\;2.5{\sim}pH\;10.0$, but hydrolysis for 1,3-D at pH 11.5 higher then at $pH\;2.5{\sim}pH\;10.0$. Half lives of cis-1,3-D in soil are 11.5day and 7.7day at 3% and 10% of soil moisture, half lives of trans-1,3-D are 9.9day and 6.9day at 3% and 10% of soil moisture, respectively. Transformation for 1,3-D in water increased with increasing soil moisture. Transformation for trans-1,3-D isomer are more rapid then cis-1,3-D isomer in water and soil. This research has identified that transformation for 1,3-dichloropropene are affected by temperature, pH, soil moisture, and isomer of cis and trans in water and soil.

• Journal of Radiation Protection and Research
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• v.48 no.3
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• pp.153-161
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• 2023

Background: Fukushima Medical University (FMU) is located 57 km northwest of the Fukushima Daiichi Nuclear Power Plant. Our laboratory has been conducting environmental radiation measurements continuously before and after the nuclear accident. We aimed to report the observed behavior of radiation originating from the released radioactive materials due to the accident, predict future trends, and disseminate the results to the local residents. Materials and Methods: Measurements of the counting rate by a diameter of 76 mm and a length of 76 mm thallium-doped sodium iodide (NaI[Tl]) scintillation detector (S-1211-T; Teledyne Brown Engineering Environmental Services) in the central part of the laboratory, and the dose rate outward at the window by NaI(Tl) scintillation detector and digital processor (EMF211; EMF Japan Co. Ltd.) were conducted. Results and Discussion: Measurements by Teledyne S-1211-T showed that in the early stages, radiation from radioactive isotopes with short half-lives was dominant, while radiation from radioactive isotopes with longer half-lives became dominant as the measurement period became longer. Through nonlinear least squares regression, both short and long half-lives were successfully determined. It was also possible to predict how the radiation dose would decrease. The environmental radiation trends around FMU were measured by the EMF211. Both measurements were affected by rainfall and snow accumulation. Decontamination work on the FMU campus impacted measurements by the EMF211 especially. Conclusion: The results of two types of measurements, one at the center and the other at the window side of the laboratory, were presented. By applying a simplified model, radiation from radioactive isotopes with short and long half-lives was identified. Based on these results, future trends were predicted, and the information was used for public communication with the local residents.

• Journal of Food Hygiene and Safety
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• v.23 no.2
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• pp.129-136
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• 2008

Three benzimidazole pesticides commonly used in korean lettuce were subjected to a field residue trial to ensure safety of terminal residue in the harvest. The residual patterns of three benzimidazole pesticides, which were carbendazim, benomyl and thiophanate-methyl were examined after applying with the recommended dose in two types of korean lettuce (Chima and Chuckmeon) and their DT50 were calculated. In Chima lettuce, biological half-lives of carbendazim, benomyl and thiophanate-methyl were 2.56, 1.37 and 2.54 days, respectively and their required time under MRL(5.0 mg/kg as carbendazim) were 4.5, 2.2 and 1.0days. In Chuckmeon lettuce, biological half-lives of them were 3.41, 1.70 and 4.20 days, respectively and their required time under MRL were 5.4, 1.9 and 0.5days.

• Journal of Food Hygiene and Safety
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• v.14 no.1
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• pp.9-16
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• 1999

Effect of storage temperature, washing, and cooking on postharvest-treated pesticide residues in polished rice was investigated. After being treated with each 500 mg/kg of captan, carbaryl, phenthoate, fenthion, fenitrothion, chlorpyriphos-methyl, pirimiphos-methyl, the polished rice was stored for 8 weeks at 4 and 3$0^{\circ}C$, respectively. The penetation rate of carbaryl was the highest as 27.5% and the others, 13 to 18%. The half lives of pesticide residues were estimated as 30 to 230 weeks at 4$^{\circ}C$, but 1 to 12 weeks at 3$0^{\circ}C$. The residues were reduced faster at 3$0^{\circ}C$ than at 4$^{\circ}C$. The half lives of pesticide residues by water washing were estimated as 0.7 to 4.6 trials and the removed with the washing trials. The residues of captan and carbaryl in cooked rice were removed 100 and 98%, respectively, comparing to initial residues concentration in treated rice but those of other 5 pesticides were removed 80%.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.98-105
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• 2021

Using the frequency-based decomposition, I decompose the consumption growth to explain well-known patterns of stock returns in the Korean market. To be more specific, the consumption growth is decomposed by its half-life of shocks. The component over four years of half-life is called the business-cycle consumption component, and the components with half-lives under four years are short-run components. I compute the long-run and short-run components of stock excess returns as well and use component-by-component sensitivities to price stock portfolios. As a result, the business-cycle consumption risk with half-life of over four years is useful in explaining the cross-section of size-book-to-market portfolios and size-momentum portfolios in the Korean stock market. The short-run components have their own pricing abilities with mixed direction, so that the restricted one short-term factor model is rejected. The explanatory power with short- and long-run components is comparable to that of the Fama-French three-factor model. The components with one- to four-year half-lives are also helpful in explaining the returns. The results about the long-run components emphasize the importance of long-run component in consumption growth to explain the asset returns.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.139-142
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• 2001

The one of important parameter involved in the calculation of internal radiation dose to the human body is the biological half-life of the radionuclide. The biological half-life is population specific and may differ from one population group to another. So the effective half-life of tritium exposure based on urinal bioassay measurement of Wolsong Nuclear Power Plants was investigated and studied.

• Korean Journal of Clinical Pharmacy
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• v.1 no.1
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• pp.31-36
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• 1991

Tobramycin is one of the most frequently selected agents for pharmacokinetic drug monitoring because of its narrow therapeutic index and essential role for the management of serious infections, especially gram-negative infections. Its pharmacokinetic parameters are dependent on race, sex, age, ideal body weight. disease states, and etc. Therefore, to schedule the dosing of tobramycin, the individual pharmacokinetic parameters such as half-life and volume of distribution are needed. However, these pharmacokinetic parameters have never been reported in Koreans. The purposes of this study were to evaluate the volume of distribution of tobramycin in cancer patients who had normal renal function, to compare the mean values of Vd reported in the literature, and to compare the measured half-life with the expected half-life based on ABW, LBW, and IBW, respectively. Venous blood samples were collected just before and thirty minutes after dosing during steady state. Serum tobramycin concentrations were determined by $TD_x$ (fluorescence immunoassay). IBW were measured by the method of Devine: and LBW were measured by the method of Hallynck. Creatinine clearances (CLcr) of the patients were estimated using the Cockcroft and Gault equation. Elimination rate constants (kel) were determined using the Welling and Craig equation. Infusion rate (ko), volume of distribution (Vd), and half-life $(t_{1/2})$ were determined using the Saw chuk and Zaske equation. The volume of distribution Was $27\%$ greater than the Schentag's study (0.26 vs 0.33 l/kg), but the half-life was similar to the Levy's study. The predicted half-lives based on IBW were the closest to actual half-lives (1.85 vs 2.01 hr).

• Journal of the Korean Society for information Management
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• v.26 no.2
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• pp.211-222
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• 2009

Electronic publishing has influenced, and in some ways changed, information seeking, reading patterns and citation behaviours. This study collected the Cited Half-Lives, the indicator implies the life-span of scholarly journals, from JCR Social Science edition the before and after of the prevalence of electronic journals, and observed if there are some changes in these two periods. The analysis results of eight disciplines show that the average Cited Half-Lives increased in 2007 than in 1994 for seven disciplines except the demography. Especially in the four disciplines of economics, education, finance and sociology, the average Cited Half-Lives increased significantly. This results show that the concentration, researchers cite more recent articles and concentrate their citations on fewer ones, is lightening and the dispersion of citations is actually increasing. With the online availability of articles and journals the old online materials can be often accessed, used and cited more frequently, the more growth potential of Cited Half-Lives are made in a digital environment. Further research needs to investigate if the phenomenon will become more obvious in various disciplines after a few years.

• Korean Journal of Environmental Agriculture
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• v.28 no.3
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• pp.281-288
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• 2009

The strobilurin fungicides, azoxystrobin and kresoxim-methyl, were investigated to know the biological half-lives and dissipation patterns in Korean melon under plastic film house condition. Used pesticides for field application were 20% azoxystrobin of suspension concentrate and 47% kresoxim-methyl of water dispersible granule. Two pesticides were sprayed at recommended and double dose rate. Pesticide residues in Korean melon were analyzed until 14 days after application. The azoxystrobin was analyzed by HPLC equipped with UV detector after cleanup with florisil glass column. Initial residue concentrations of azoxystrobin in Korean melon at recommended and double dose rate were 0.09 mg/kg and 0.14 mg/kg, respectively. Those were less than 0.2 mg/kg maximum residue limit of Korean melon established by KFDA. The biological half-lives of azoxystrobin in Korean melon were 4.7 days at recommended dose rate and 7.8 days at double dose rate. Initial concentrations of kresoxim-methyl which was analyzed by GLC-ECD in Korean melon at recommended and double dose rate were 0.10 mg/kg and 0.23 mg/kg, respectively. Those were less than 1.0 mg/kg, MRL. The biological half-lives of kresoxim-methyl in Korean melon were 4.1 days at recommended dose rate and 4.8 days at double dose rate. The residue amounts of both pesticide was lower than MRL and biological half-lives were not so long. Because the weight of Korean melon under plastic film house condition was fast increased during cultivation.