• 한국환경농학회지
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• 제28권4호
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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.

• 한국환경과학회지
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• 제16권12호
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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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• 제48권3호
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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.

• 한국식품위생안전성학회지
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• 제23권2호
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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.

• 한국식품위생안전성학회지
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• 제14권1호
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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%.

• 산업경영시스템학회지
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• 제44권4호
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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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• 제26권3호
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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.

• 한국임상약학회지
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• 제1권1호
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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).

• 정보관리학회지
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• 제26권2호
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• pp.211-222
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• 2009

전자출판은 정보검색, 이용패턴, 인용행태 등 학술 커뮤니케이션 전반에 많은 영향을 주었고 변화를 초래하였다. 이 연구는 전자출판 특히 전자학술지의 보급이 학술 커뮤니케이션에 어떠한 영향을 미치고 있는지를 규명하기 위하여 학술지의 수명을 간접적으로 보여주는 지표라 할 수 있는 인용반감기 데이터를 JCR 사회과학 편으로부터 수집한 후 전자학술지 도입 이전과 이후를 비교하고 분석하였다. 모두 여덟 부문의 주제영역에 관하여 데이터를 분석한 결과 인구통계학을 제외한 일곱 부문에서 1994년에 비해 2007년의 인용반감기가 증가한 것으로 나타났다. 특히 경제학, 교육학, 재정학, 사회학 등의 네 주제영역에서는 인용반감기의 평균이 통계적으로 유의미하게 증가하였다. 이 결과는 과거와 같이 핵심 학술지 및 최신호에 이용이 집중되던 현상이 완화되고 비핵심 학술지 및 오래된 학술지의 이용이 상대적으로 증가하는 '학술지 인용의 분산화(탈집중화) 현상'이 나타나기 시작했다는 것을 보여주는 것으로 간주할 수 있을 것이다. 디지털 환경에서는 오래된 자료라도 여러 가지 미디어에 힘입어 원활하게 접근이 가능하기 때문에 이의 이용과 인용이 증가할 가능성이 있고, 따라서 인용반감기의 증가로 이어질 수 있는 가능성도 충분하기 때문이다. 그러나 이러한 현상이 일시적으로 나타난 것인지 아니면 매우 다양한 분야에서 지속적으로 나타날 것인지는 시간을 두고 더 관찰해야 할 것으로 보인다.

• 한국환경농학회지
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• 제28권3호
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• pp.281-288
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• 2009

Azoxystrobin과 kresoxim-methyl의 참외 중 반감기와 잔류양상을 조사하였다. Azoxystrobin의 참외 중 0일차 잔류량은 기준량 및 배량 처리구에서 각각 0.09 및 0.14 mg/kg으로 나타났으며 농약의 반감기 소실곡선식은 y=0.0766e$^{-0.138x}$ ($r^2$=0.9424) 및 y=0.1143e$^{-0.0890x}$ ($r^2$=0.9310) 이었으며 생물학적 반감기는 각각 5.0일 및 7.8일 이었다. Kresoxim-methyl의 참외 중 0일차 잔류량은 기준량 및 배량 처리구에서 각각 0.10 및 0.23 mg/kg으로 나타났으며 농약의 소실곡선식은 y=0.0896e$^{-0.1672x}$ ($r^2$=0.9428) 및 y=0.1504e$^{-0.1446x}$ ($r^2$=0.9040) 이었고 생물학적인 반감기는 각각 4.1일 및 4.8일 이었다. 재배기간 중 참외의 무게증가에 농약희석효과를 배제한 절대잔류농도는 약제 살포 후 14일 경과시 azoxystrobin은 기준량 및 배량에서 0.01 및 0.05 mg/kg으로서 각각 83.6 및 67%의 농약이 분해되었다. Kresoxim-methyl은 각각 0.01 및 0.03 mg/kg 으로서 86.2 및 87.8% 정도의 농약 분해율을 보였다.