• Journal of Radiation Industry
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• v.12 no.4
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• pp.277-285
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• 2018

Patients administered radioisotope for medical purposes are regulated by each country to quarantine them until their body's radioactivity contents decrease below release criteria. To predict the quarantine period and provide it to medical staffs and patients, it is necessary to approach the assessment of the exposure dose of persons due to patients in a realistic manner. For this purpose, a whole-body effective half-life should be applied to the dose assessment equation instead of the physical half-life. In this study, we constructed a bio-kinetic model for each nuclear species based on the ICRP publication to obtain a whole-body effective half-life of 10 unsealed gamma-ray emitting nuclei from the notification of Nuclear Safety and Security Commission, and calculated the effective half-life mathematically by simulating the distribution of the radioisotope administered in the whole body as well as each organ scale. The whole-body effective half-life of $^{198}Au$, $^{67}Ga$, $^{123}I$, $^{111}In$, $^{186}Re$, $^{99m}Tc$, and $^{201}TI$ were 1,93, 2.57, 0.295, 2.805, 1.561, 0.245, and 2.397 days respectively. However, it was found to be undesirable to offer a single value of the effective half-life of $^{125}I$, $^{131}I$, and $^{169}Yb$ because the changes in the effective half-life show no linearity. A bio-kinetic model created for the internal exposure assessment has been shown to be possible to calculate the effective half-life of radioisotopes administered in the patient's body, but subsequent studies of radiolabeled compounds are required as well.

• Journal of Applied Biological Chemistry
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• v.62 no.4
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• pp.407-415
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• 2019

The biological half-life of pesticides applied on crops is the key indicator for ensuring the safety of agricultural products. The biological half-life is affected by the several factors like growing conditions of the crop, climate, application method, and physicochemical properties of pesticides. In this study, the biological half-life was calculated and the degradation rates of six triazole fungicides sprayed on perilla leaves were evaluated. Moreover, the statistical analysis confirmed the correlation between the biological half-life and physicochemical properties of six triazole pesticides. The recoveries of the six pesticides were between 84.8-104.9%, which satisfied the residual pesticide analysis criteria. The biological half-life of six pesticides sprayed on perilla leaves, calculated using the first-order kinetics model, ranged between 6.4-15.1 days. When the biological half-life and the physicochemical properties were correlated using the principal component analysis: pKa and Log P, the biological half-life was found to be affected by PC1. The correlation coefficient between biological half-life and physicochemical properties (pKa), calculated by Spearman rank-order correlation, was R² = -0.928 (p <0.01). Biological half-life has been shown to correlate with pKa. In conclusion, it can be used as a database for the relationship between biological half-life and physicochemical properties and will contribute to ensure safe supply of agricultural products.

• BMB Reports
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• v.42 no.4
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• pp.212-216
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• 2009

The short in vivo half-life of GLP-1 prevents it from being used clinically. This short half-life occurs because GLP-1 is rapidly degraded by dipeptidyl peptidases such as DPP-IV. To overcome this obstacle, a GLP-1/Fc was constructed and evaluated to determine if it was degraded by DPP-IV and in serum. When the degradation of GLP-1/Fc by human DPP-IV and rabbit serum was compared with that of GLP-1 it was found to be reduced by approximately 5- and 4-fold, respectively. Furthermore, GLP-1/Fc showed a potent activity for human GLP-1 receptor activation ($EC_{50}$ approximately 6 nM). Taken together, these results indicate that GLP-1/Fc may have an extended half-life in vivo that occurs as a result of inhibition of degradation by human DPP-IV. Due to the extended half life, GLP-1/Fc may be useful for clinical treatments.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.1 no.1
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• pp.1-8
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• 2015

It is essential use of long term half life radioisotopes for positron emission tomography (PET) imaging study of biopharmaceuticals because most of biopharmaceuticals have long biological half-life. Some representative isotopes are $^{124}I$, $^{64}Cu$, $^{89}Zr$ and so on. These PET radioisotopes and their radiopharmaceuticals have recently received growing interest because of long half life and good imaging properties. Furthermore, $^{64}Cu$ and $^{89}Zr$ can be used in a number of radiopharmaceuticals due to its ease of conjugation to peptides and antibodies using the proper chelator. In recent years, since $^{124}I$ was first developed in 2005, we have been studied to develop an efficient method and procedure for producing these radioisotopes, and we have made considerable progress in production of long term half life radioisotopes. This review introduces the general production system, purification procedure, and several advances on targeting method for $^{124}I$ and $^{64}Cu$ in KIRAMS.

• Journal of the East Asian Society of Dietary Life
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• v.16 no.1
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• pp.37-45
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• 2006

The purpose of this study was to provide basic information need to promote early childhood's growth with balanced diet and preferable dietary attitude by observing the provision of food service management in kindergarten in Daejeon. We researched the dietary life of full- and half-day program children and their mothers. A questionnaire survey was conducted with 392 children attending kindergarten and their mothers. The questionnaire items examined general characteristics, dietary life, dietary behavior, frequency food intake etc. The results of the survey were as follows. The frequency of breakfast intake of the half-day program children and their mothers was higher than that of the full-day program children and their mothers. Most of the children had an unbalanced diet about soybean, kimchi, and vegetables, whereas their mothers had an unbalanced diet about processed food In general, the half-day program children showed higher scores than full-day children for the items of the dietary behavior of kindergarten. The dietary attitude and nutrition attitude scores of the half-day program children and their mothers were higher than those of the full-day program children and their mothers.

• 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.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.98-103
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• 2014

Purpose: The effective half life of I-131 is useful to calculate radiation dose, period of hospitalization, and exposure dose of surrounding people from patient. However, it is difficult to measure. This study estimates the effective half life in whole body and thyroid in using of value of residual radioactivity obtained from the early and delay images of Dual time I-131 whole body scan. Also, the correlations between the effective half life and serum creatinine, GFR, and administration dose were investigated in this study. Materials and Methods: The targets were 50 patients administration high dose of I-131 from February to August in 2013, having normal range of serum creatinine and over $30{\mu}IU/mL$ of TSH levels. After administration radioactive I-131, the early scan in the 3rd day and the delay scan in the 5-6th days were performed. To measure the residual radioactivity in the whole body and thyroid, ROI was set and then background radioactivity was corrected to estimate. The effective half life was estimated by calculating the ratio of measured values between the early and delay images. To compare the effective half lives of the whole body and thyroid, it was analyzed by Independent t-test, and each correlation of the effective half life, GFR, serum creatinine, and the dose of administration were analyzed by calculating the pearson's correlation coefficient. All of the analysis were determined to be statistically significant when P<0.05. Results: The effective half life of the whole body was $17.06{\pm}5.50$ hours and of the thyroid was $17.22{\pm}5.41$ hours. The two effective half life did not show significant difference (P=0.887). As the value of GFR was increased, the effective half life of whole body (r=-0.407, P=0.003) and of thyroid (r=-0.473, P=0.001) were significantly decreased; as the value of serum creatinine was increased, the effective half life of whole body (r=0.309, P=0.029) and of thyroid (r=0.371, P=0.008) were significantly increased. In the administration dose, effective half life did not have correlations. Conclusion: The effective half life of I-131 of patients treated for their thyroids were estimated only by using the images of Dual time I-131 whole body scan. Also, the correlations with the effective life, GFR, and serum creatinine were examined. This study might be utilized for a study on optimization for the period of hospitalization of patients treated by high dose of I-131 and on evaluation for internal absorbed dose of MIRD schema in application of the effective half life.

• 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.

• 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).

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.2
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• pp.78-86
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• 2002

In general, X-ray diffraction method detects the changes of crystal lattice under material surface using the angle of diffraction 2$\theta$. This technique which deals with in the presented paper can be applied to a behavior on the slipped band or the micro crack cause to material degradation. The relation between half-value breadth and cycle numbers shows three stages, which consist of rapid decrease in the initial cycle, slight decrease in the middle cycle, and then rapid decrease in the final cycle. The ratio of half-value breadth has a constant value on B/B$\_$0/ - N diagram under the loading condition except early part of fatigue life. The ratio of half-value breadth B/B$\_$0/ - log N$\_$f/ with respect to number of cycle to failure N$\_$f/ has linear behavior on B/B$\_$0/ - log N$\_$f/ diagram. Therefore, the evaluation of fatigue life by the average gradient has much less mean error than the estimation of fatigue life by log B/B$\_$0/ - log N/N$\_$f/ relation.