• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.715-721
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• 2021

In radiation brachytherapy, the wrong source location may cause excessive dose to normal tissue. Therefore, research on digital dosimeters is being made to replace the analog detection method. Therefore, in this study, a lead (II) oxide (PbO) dosimeter applied with a passive layer (PL) was fabricated as a basic study to improve the dosimeter performance. Afterwards, reproducibility, linearity, and distance dependence were evaluated to analyze the performance of the Ir-192 source under irradiation conditions. The reproducibility of the PL-PbO dosimeter was 0.40%, which satisfies the evaluation criteria of 1.5%, and showed improved results compared to the PbO dosimeter. Linear function R2 showed excellent results as 0.9995, and slope analysis through regression analysis of the linear function was excellent in PL-PbO. The distance dependence of the PL-PbO dosimeter was +0.599 higher than that of PbO when the slope obtained through regression analysis of the power function was compared with the inverse square value. This study presents the effects and measurement variables according to the measurement configuration of the solid-state dosimeter, and can be used in various radiation detection fields.

• Journal of Food Hygiene and Safety
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• v.36 no.6
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• pp.474-480
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• 2021

Sodium alginate is the sodium salt of alginic acid, commonly used as a food additive for stabilizing, thickening, and emulsifying properties. A relatively simple and universal analysis method is used to study sodium alginate due to the complex pretreatment process and extended analysis time required during the quantitative method. As for the equipment, HPLC-UVD and Unison US-Phenyl column were used for analysis. For the pretreatment condition, a shaking apparatus was used for extraction at 150 rpm for 180 minutes at room temperature. The calibration curve made from the standard sodium alginate solution in 5 concentration ranges showed that the linearity (R²) is 0.9999 on average. LOD and LOQ showed 3.96 mg/kg and 12.0 mg/kg, respectively. Furthermore, the average intraday and inter-day accuracy (%) and precision (RSD%) were 98.47-103.74% and 1.69-3.08% for seaweed jelly noodle samples and 99.95-105.76% and 0.59-3.63% for sherbet samples, respectively. The relative uncertainty value was appropriate for the CODEX standard with 1.5-7.9%. To evaluate the applicability of the method developed in this study, the sodium alginate concentrations of 103 products were quantified. The result showed that the detection rate is highest from starch vermicelli and instant fried noodles to sugar processed products.

• Journal of Food Hygiene and Safety
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• v.31 no.2
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• pp.94-98
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• 2016

This study was conducted to establish the simultaneous analysis method for veterinary drug residues in honey by high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS). The eleven targeting veterinary drugs with honey test method in Korean Food Standards Codex were divided into Group 1 (streptomycine dihydrostreptomycine, neomycine) and Group 2 (oxytetracycline, enrofloxacin, ciprofloxacin, cymiazole, chloramphenicol, amitraz, coumaphos, fluvalinate) to be analyzed simultaneously. From the results, the retention time (RT) of the targeting drugs was within 15 min, the range of detection limits was 0.0056 to $0.0643{\mu}g/g$ and the range of quantification limits was 0.0169 to $0.1948{\mu}g/g$. The coefficients of determination ($R^2$) for Group 1 ($0.05{\sim}1.0{\mu}g/mL$) and Group 2 ($0.01{\sim}1.0{\mu}g/mL$) were 0.9917~0.9987 and 0.9923~1.000 respectively, and showed the good linearity. The recovery rates for Group 1 (final conc. $0.25{\mu}g/g$) and Group 2 (final conc. $1.0{\mu}g/g$) were 65.1~80.6% and 64.2~90.3% respectively. Also, the analysis results of inter day (n = 3) and intra day (n = 6) RSD (%) for area and retention time showed that the RSD (%) for area and retention time was below 10.92% and 1.57%. Therefore, the simultaneous analysis method of this study is evaluated to be a good test method for veterinary drug residues in honey.

• Korean Journal of Food Science and Technology
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• v.42 no.3
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• pp.287-291
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• 2010

In this study, a simple and rapid pre-treatment method based on liquid extraction was applied for the simultaneous determination of three macrolides (spiramycin, tylosin, and tilmicosin) residues. In these studies, the stock farm products was used as a matrix sample. When the liquid extraction method was compared with the solid phase extraction (SPE) method, the former showed higher recovery percentages and simpler steps than the latter. The macrolids were separated using a reverse-phase C18 ($250\;mm{\times}4.6\;mm$, $5\;{\mu}m$) column and a gradient elution with mobile phases consisting of phosphate buffer (pH 2.5) and acetonitrile. Tylosin and tilmicosin were detected at 288 nm and spiramycin was detected at 232 nm. The average recovery percentage ranged between 83.0-90.2% for samples spiked with the three macrolids at 50 and 100 ng/g The validation results showed that the limit of detection (7 (spiramycin), 12 (tilmiconsin), 12 (tylosin) ng/g)) was under the regulatory tolerances and the linearity from calibration curves was satisfactory for determining the multi-residue of three macrolids in farm products. Monitoring samples were collected at the main cities in Korea as Seoul, Busan, Deajeon, Incheon, Deagu, and Gwangju. Microlide antibiotics were not detected in most samples.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.157-163
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• 2012

BACKGROUND: For the safety of imported agricultural products, the study was conducted to develop the analytical method of unregistered pesticides in domestic. The analytical method of 6 pesticides, chlorthal-dimethyl, clomeprop, diflufenican, hexachlorobenzene, picolinafen, and propyzamide, for a fast multi-residue analysis were established for two different type crops, orange and brown rice by GC-ECD and confirmed by mass spectrometry. METHODS AND RESULTS: The analytical method was evaluated to limit of quantification, linearity and recoveries. The crop samples were extracted with acetonitrile and performed cleanup by liquid-liquid partition and Florisil SPE to remove co-extracted matrix. The extracted samples were analyzed by GC-ECD with good sensitivity and selectivity of the method. The limits of quantification (LOQ) range of the method with S/N ratio of 10 was 0.02~0.05 mg/kg for orange and brown rice. The linearity for targeted pesticides were $R^2$ >0.999 at the levels ranged from 0.05 to 10.0 mg/kg. The average recoveries ranged from 74.4% to 110.3% with the percentage of coefficient variation in the range 0.2~8.8% at two different spiking levels (0.02 mg/kg and 0.2 mg/kg, 0.05 mg/kg and 0.5 mg/kg) in brown rice. And the average recoveries ranged from 77.8% to 118.4% with the percentage of coefficient variation in the range 0.2~6.6% at two different spiking levels (0.02 mg/kg and 0.2 mg/kg, 0.05 mg/kg and 0.5 mg/kg) in orange. Final determination was by gas chromatography/mass spectrometry/selected ion monitoring (GC/MS/SIM) to identify the targeted pesticides. CONCLUSION: As a result, this developed analytical method can be used as an official method for imported agricultural products.

• ANNALS OF ANIMAL RESOURCE SCIENCES
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• v.29 no.4
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• pp.150-157
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• 2018

The Zygote arrest 1 (ZAR1) gene is known to affect early embryonic development in various vertebrates. In this study, we performed the association analysis to check whether there is any significant relationship between semen kinematic characteristics and the ZAR1 gene. To determine semen kinematic characteristics, we measured motility (MOT), straight-line velocity (VSL), curvilinear velocity (VCL), average path velocity (VAP), linearity (LIN), straightness (STR), amplitude of lateral head displacement (ALH), and beat cross frequency (BCF) of spermatozoa in boars. In order to detect single nucleotide polymorphisms (SNPs), we extracted genomic DNA from multiple Duroc boars, and then subsequently used them in sequencing reactions. As a result, three SNPs were detected in the intronic region of ZAR1 gene (g.2435T>C in intron 2, g.2605G>A and g.4633A>C in intron 3 ). SNPs g.2435T>C and g.2605G>A were significantly associated with MOT (p<0.01) and VSL (p<0.05), and g.4633A

• Journal of Soil and Groundwater Environment
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• v.12 no.4
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• pp.86-93
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• 2007

In recent tests using tracer have been frequently conducted by fluorescent tracers. In this study, granular activated charcoal (GAC) as a detector for the fluorescent tracers (rhodamine WT and uranine) was investigated through laboratory and field tests. In the laboratory tests, tracer concentrations of rhodamine WT and uranine determined by the GAC were slightly different from those of standard solutions but they were excellent in linearity. Results show that GAC is excellent as tracer detector when concentration of the fluorescent tracers is greater than 10 & micro; g/L whileas no obvious differences in mixed solutions of the two tracers due to interferences. Compared to conventional methods of water sampling, field results shows a high potential of GAC as a tracer in the field. Our results also show that wet analysis is better for the lower concentrations of tracers whileas dry analysis is good for high concentrations of tracers. This study demonstrates that fluorescent tracer detection using the GAC is very useful and economical for a hydraulic connection between target areas and very longer period of the tracer test.

• Journal of the Korea Society of Computer and Information
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• v.17 no.8
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• pp.107-114
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• 2012

We have developed a textile capacitive pressure sensor for smart gait analysis. The proposed system can convert sensor signal into step counts and pressure levels by different posture. To evaluate the performance of insole type textile capacitive sensor, we measured capacitance change by increment of weights from 10 kg to 100 kg with 10 kg increment using M1 class rectangular weights (four 20 kg weights and two 10 kg weights) which have ${\pm}10%$ tolerance. The result showed non-linearity characteristic of a general capacitive pressure sensor. The test was performed according to a test protocol for four different postures (sitting, standing, standing on a left leg and standing on a right leg) and different walking speeds (1 km/h and 4 km/h). Five healthy male subjects were participated in each test. As we expected, the pressure level was changed by pressure distribution according to posture. Also, developed textile pressure sensor showed higher recognition rate (average 98.06 %) than commercial pedometer at all walking speed. Therefore, the proposed step counts and posture monitoring system using conductive textile capacitive pressure sensor proved to be a reliable and useful tool for monitoring gait parameters.

• Tunnel and Underground Space
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• v.22 no.2
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• pp.86-92
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• 2012

Point estimate method has a less accuracy than Monte Carlo simulation that is usually considered as an exact probabilistic method, but this method still remains popular in probability-based reliability assessment in geotechnical and rock engineering, because it significantly reduce the number of sampling points and produces the statistical moments of a performance function in a reasonable accuracy. In the present study, we investigated the accuracy and applicability of point estimate methods proposed by Rosenblueth and Zhou & Nowak by comparing the results of these two methods with those of Monte Carlo simulations. The comparison was carried out for the problem of a lined circular tunnel in an elastic medium where an closed-form analytical solution is given. The comparison results showed that despite the non-linearity of the analytical solution, the statistical moments calculated by the point estimate methods and the Monte Carlo simulations agreed well with an average error of roughly 1-2%. This average error demonstrates the applicability of the two point estimate methods for the probabilistic reliability assessment of underground structures in combination with numerical analysis.

• Journal of the Korean Chemical Society
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• v.60 no.2
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• pp.118-124
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• 2016

Parabens were commonly used for preventing the growth of microorganisms as preservatives in the pharmaceutical, cosmetic and food industry. Also, parabens are known endocrine disruptors because of their estrogenic effects on human. Parabens affect the endocrine system and show adverse effect such as, genital malformations, precocious puberty and testicular cancer in young children, infants and fetuses. In this study, we developed analytical method for four parabens (methyl paraben, ethyl paraben, propyl paraben, butyl paraben) in human breast milk which frequently consumed by newborn baby. The analytes were extracted using liquid-liquid extraction (LLE) after enzyme hydrolysis with protease and lipase, then quantitative analysis was performed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The method validation results were as follows; the linearity of calibration curves were excellent with coefficient of determinations (r²) higher than 0.999, the limit of detections (LODs) were 0.019~0.044 ng/mL, the accuracies were 85.3~105.9% and the precisions were lower than 10%. The average concentration ± standard deviation of parabens in ten human breast milk sample were MP 0.660 ± 0.519 ng/mL, EP 1.631 ± 2.081 ng/mL and PP 0.326 ± 0.320 ng/mL, and BP was not detected.