• Nuclear Medicine and Molecular Imaging
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• v.41 no.3
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• pp.194-200
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• 2007

Purpose: $^{13}N$-ammonia is a well known radiopharmaceutical for the measurement of a myocardial blood flow (MBF) non-invasively using PET-CT. In this study, we investigated a correlation between MBF obtained from dynamic imaging and myocardial perfusion score (MPS) obtained from static imaging for usefulness of cardiac PET study. Methods: Twelve patients (11 males, 1 female, $57.9{\pm}8.6$ years old) with suspicious coronary artery disease underwent PET-CT scan. Dynamic scans (6 min: $5\;sec\;{\times}\;12,\;10\;sec\;{\times}\;6,\;20\;sec\;{\times}\;3,\;and\;30\;sec\;{\times}\;6$) were initiated simultaneously with bolus injection of 11 MBq/kg $^{13}N-ammonia$ to acquire rest and stress image. Gating image was acquired during 13 minutes continuously. Nine-segment model (4 basal walls, 4 mid walls, and apex) was used for a measurement of MBF. Time activity curve of input function and myocardium was extracted from ROI methods in 9 regions for quantification. The MPS were evaluated using quantitative analysis software. To compare between 20-segment model and 9-segment model, 6 basal segments were excluded and averaged segmental scores were used. Results: There are weak correlation between MBF (rest, 0.18-2.38 ml/min/g; stress, 0.40-4.95 ml/min/g) and MPS (rest 22-91%, stress, 14-90%), however the correlation coefficient between corrected MBF and MPS in rest state was higher than stress state (rest r=0.59; stress r=0.80). As a thickening increased, correlation between MBF and MPS also showed good correlation at each segments. Conclusions: Corrected and translated MPS as its characteristics using $^{13}N$-ammonia showed good correlation with absolute MBF measured by dynamic image in this study. Therefore, we showed MPS is one of good indices which reflect MBF. We anticipate PET-CT could be used as useful tool for evaluation of myocardial function in nuclear cardiac study.

• Journal of Food Hygiene and Safety
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• v.20 no.3
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• pp.141-146
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• 2005

A simple and sensitive analysis method based on reverse phase (RP) HPLC with UV detector was developed for simultaneous determination of chlorophyll a and b, pheophorbide a and $\beta-Carotene$ in Chlorella and Spirulina products. For added concentration $(50\;\mug/ml)$ of chlorophyll a and b, pheophorbide a and $\beta-Carotene$, recoveries of those were 70.3, 71.6, 60.1 and $90.5\%$, respectively, with relative standard deviations of 2.8,6.0, 10.6 and $10.4\%$. Limit of detection and quantification had ranges of $0.1\sim1.0\;\mug/ml$ and $0.2\sim2.0\;\mug/ml$, respectively. Calibration curve was linear with correlation coefficient of 0.995 for chlorophyll a and b, pheophorbide a and $\beta-Carotene$. Results of simultaneous determination in Chlorella and Spirulina products were showed ranges of $121.g\sim543.0\;\mug/ml$ for chlorophyll a,$0.6\sim160.0\;\mug/ml$ for chlorophyll b, $19.2\sim60.3\;\mug/ml$ for pheophorbide a and $383.6\sim1713.7\;\mug/ml$ for $\beta-Carotene$, respectively. Chlorophyll b contents in Chlorella products were detected above 30 times level to those in Spirulina products. $\beta-Carotene$ contents in Spirulina products were detected 2.7 times level to those in Chlorella products.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.86-90
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• 2012

Purpose: Quantification of myocardial blood flow (MBF) using dynamic PET imaging has the potential to assess coronary artery disease. Rb-82 plays a key role in the clinical assessment of myocardial perfusion using PET. However, MBF could be overestimated due to the underestimation of left ventricular input function in the beginning of the acquisition when the scanner has non-linearity between count rate and activity concentration due to the scanner dead-time. Therefore, in this study, we evaluated the count rate linearity as a function of the activity concentration in PET data acquired in list mode. Materials & methods: A cylindrical phantom (diameter, 12 cm length, 10.5 cm) filled with 296 MBq F-18 solution and 800 mL of water was used to estimate the linearity of the Biograph 40 True Point PET/CT scanner. PET data was acquired with 10 min per frame of 1 bed duration in list mode for different activity concentration levels in 7 half-lives. The images were reconstructed by OSEM and FBP algorithms. Prompt, net true and random counts of PET data according to the activity concentration were measured. Total and background counts were measured by drawing ROI on the phantom images and linearity was measured using background correction. Results: The prompt count rates in list mode were linearly increased proportionally to the activity concentration. At a low activity concentration (<30 kBq/mL), the prompt net true and random count rates were increased with the activity concentration. At a high activity concentration (>30 kBq/mL), the increasing rate of the prompt net true rates was slightly decreased while the increasing rate of random counts was increased. There was no difference in the image intensity linearity between OSEM and FBP algorithms. Conclusion: The Biograph 40 True Point PET/CT scanner showed good linearity of count rate even at a high activity concentration (~370 kBq/mL).The result indicates that the scanner is useful for the quantitative analysis of data in heart dynamic studies using Rb-82, N-13, O-15 and F-18.

• Journal of Korea Water Resources Association
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• v.50 no.7
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• pp.475-488
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• 2017

To simulate accurate drought, a drought index is needed to reflect the hydrometeorological phenomenon. Several studies have been conducted in Korea using the Modified Surface Water Supply Index (MSWSI) to simulate hydrological drought. This study analyzed the limitations of MSWSI and quantified the uncertainties of MSWSI. The influence of hydrometeorological components selected as the MSWSI components was analyzed. Although the previous MSWSI dealt with only one observation for each input component such as streamflow, ground water level, precipitation, and dam inflow, this study included dam storage level and dam release as suitable characteristics of the sub-basins, and used the areal-average precipitation obtained from several observations. From the MSWSI simulations of 2001 and 2006 drought events, MSWSI of this study successfully simulated drought because MSWSI of this study followed the trend of observing the hydrometeorological data and then the accuracy of the drought simulation results was affected by the selection of the input component on the MSWSI. The influence of the selection of the probability distributions to input components on the MSWSI was analyzed, including various criteria: the Gumbel and Generalized Extreme Value (GEV) distributions for precipitation data; normal and Gumbel distributions for streamflow data; 2-parameter log-normal and Gumbel distributions for dam inflow, storage level, and release discharge data; and 3-parameter log-normal distribution for groundwater. Then, the maximum 36 MSWSIs were calculated for each sub-basin, and the ranges of MSWSI differed significantly according to the selection of probability distributions. Therefore, it was confirmed that the MSWSI results may differ depending on the probability distribution. The uncertainty occurred due to the selection of MSWSI input components and the probability distributions were quantified using the maximum entropy. The uncertainty thus increased as the number of input components increased and the uncertainty of MSWSI also increased with the application of probability distributions of input components during the flood season.

• Journal of Food Hygiene and Safety
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• v.26 no.1
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• pp.16-24
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• 2011

A method was established for the simultaneous determination of sugar alcohols, erythritol, xylitol, sorbitol, inositol, mannitol, maltitiol, lactitol and isomalt by High Performance Liquid Chromatography (HPLC). The sugar alcohols were converted into strong ultraviolet (UV)-absorbing derivatives with p-nitrobenzoyl chloride (PNBC). HPLC was performed on Imtakt Unison US-$C_18$ column, using acetonitrile: water (77:23) as a mobile phase and UV detection (260 nm). The calibration curves for all sugar alcohols tested were linear in the 10~200 mg/L range. The average recoveries of the sugar alcohols from three confectioneries spiked at 100 ppm of eight sugar alcohol standards ranged from 81.2 to 123.1% with relative standard deviations ranging fromo 0.2 to 4.9%. The limits of detection (LODs) were $0.5{\sim}8\;{\mu}g/L$ and the limits of quantification (LOQs) were $2{\sim}17\;{\mu}g/L$. Reproducibility of 8 sugar alcohols was 0.28~1.97 %RSD. The results of the analysis of confectioneries showed that 89 samples of 130 were detected and the sugar alcohols content of samples investigated varied between 0.4 and 693.7 g/kg. A method for the simultaneous determination of eight sugar alcohols will be used as basic data for control of sugar alcohols in confectioneries, and quality control in food manufacturing.

• Journal of Food Hygiene and Safety
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• v.20 no.4
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• pp.277-283
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• 2005

A plasticizer is a substance which is added to a material to improve its processability, flexibility and stratchability. Phthalates and adipates are the most frequently used plasticizers of poly(vinyl chloride) (PVC). However, they can migtate into food from PVC food packaging, and some of them are especially suspected as endocrine disruptors. In this study, Simultaneous analysis of 13 phthalates and 9 adipates were carried out by dual-column gas chromatography system equipped wi two FID detectors for rapid confirmation and quantification. The Proposed method was validated with > 0.993 of linearity in the ranges of 10-500 mg/l, < $3.5\%$ RSD of reproducability in 10 inter-days sample preparations, and > $98.1\%$ of recoveries for all the plasticizers. DEHA was detected in all the 3 PVC wraps at levels of 176.9-198.5mg/g. Among the 51 samples of PVC gaskets, the targeted plasticizers were detected in 41 samples. Of these plasticizer detected samples,40 contained DIDP at the levels of 157.3-374.7 mg/g and one contained DMP at the levels of 165.6 mg/g. Also, some plasticizers were detected in other packaging materials such as PET, PP, PE, Pulp. But it might be attributed to contamination in manufacturing.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.354-360
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• 2015

In recent years, Allium victorialis has been extensively used as a pharmacological agent for various diseases in the form of anti-arteriosclerotic, anti-diabetic and anti-cancer. Allium victorialis is severely affected by various fungal diseases since it naturally grow in the shady and humid environments in Korea. In this case, different types of fungicides are applied to control the fungal diseases in Allium victorialis. The present study was aimed to determine the residual characteristics of two fungicides namely tebuconazole and fludioxonil on Allium victorialis. For this study, the fungicides were drenched soil on Allium victorialis in the cultivation area Pyeongchang by the standard (two thousand fold) and double (thousand fold) dilutions. At the end of $15^{th}$, $30^{th}$ and $40^{th}$ days samples were collected for residue analysis. Residues of tebuconazole and fludioxonil were analyzed using GC/NPD (Gas Chromatography/Nitrogen Phosphorus Detector) and their recovery were found to be 108.8~119.5% and 91.3~104.8%, respectively. The method of limits of quantification for both fungicides was $0.01mg\;kg^{-1}$. Further, the results of this study shows that the residue levels of both fungicides on Allium victorialis were <$0.01{\sim}0.12mg\;kg^{-1}$ and $0.01{\sim}0.09mg\;kg^{-1}$ and their % ADI (% Acceptable Daily Intake) were 17.44% and 25.75%, respectively. Based on the results obtained in this study, we suggest that the residue levels of both of the fungicides on Allium victorialis are safe and these fungicides can also be used to control fungal diseases in Allium victorialis.

• Journal of Food Hygiene and Safety
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• v.14 no.4
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• pp.319-326
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• 1999

Recently, it is continuously rising to concern about the health risk being induced by microorganisms in food such as Escherichia coli O157:H7 and Listeria monocytogenes. Various organizations and regulatory agencies including U.S.FPA, U.S.DA and FAO/WHO are preparing the methodology building to apply microbial quantitative risk assessment to risk-based food safety program. Microbial risks are primarily the result of single exposure and its health impacts are immediate and serious. Therefore, the methodology of risk assessment differs from that of chemical risk assessment. Microbial quantitative risk assessment consists of tow steps; hazard identification, exposure assessment, dose-response assessment and risk characterization. Hazard identification is accomplished by observing and defining the types of adverse health effects in humans associated with exposure to foodborne agents. Epidemiological evidence which links the various disease with the particular exposure route is an important component of this identification. Exposure assessment includes the quantification of microbial exposure regarding the dynamics of microbial growth in food processing, transport, packaging and specific time-temperature conditions at various points from animal production to consumption. Dose-response assessment is the process characterizing dose-response correlation between microbial exposure and disease incidence. Unlike chemical carcinogens, the dose-response assessment for microbial pathogens has not focused on animal models for extrapolation to humans. Risk characterization links the exposure assessment and dose-response assessment and involve uncertainty analysis. The methodology of microbial dose-response assessment is classified as nonthreshold and thresh-old approach. The nonthreshold model have assumption that one organism is capable of producing an infection if it arrives at an appropriate site and organism have independence. Recently, the Exponential, Beta-poission, Gompertz, and Gamma-weibull models are using as nonthreshold model. The Log-normal and Log-logistic models are using as threshold model. The threshold has the assumption that a toxicant is produce by interaction of organisms. In this study, it was reviewed detailed process including risk value using model parameter and microbial exposure dose. Also this study suggested model application methodology in field of exposure assessment using assumed food microbial data(NaCl, water activity, temperature, pH, etc.) and the commercially used Food MicroModel. We recognized that human volunteer data to the healthy man are preferred rather than epidemiological data fur obtaining exact dose-response data. But, the foreign agencies are studying the characterization of correlation between human and animal. For the comparison of differences to the population sensitivity: it must be executed domestic study such as the establishment of dose-response data to the Korean volunteer by each microbial and microbial exposure assessment in food.

• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.544-552
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• 2011

The purpose of this study was to develop an analytical method for determining 15 polycyclic aromatic hydrocarbons (PAHs) of EU priority using gas chromatography (GC)-tandem mass spectrometry (MS). The PAHs in ground coffee were analyzed after being extracted using methods such as saponification-liquid-liquid extraction, Soxhlet extraction, and solid-liquid extraction. The solid-liquid extraction method showed the greatest repeatability and most efficient reduction of the matrix effect. GC-tandem MS for the quantification of the 15 PAHs showed better resolution and lower limit of detections (LODs) than GC-MS-selected ion monitoring (SIM) and high performance liquid chromatography with fluorescence detector. LODs of this method for the ground coffee types were 0.002-0.1 ${\mu}g/kg$ and limit of quantifications (LOQs) were 0.006-0.2 ${\mu}g/kg$ The recoveries ranged from 52.6 to 93.3%. Forty-six commercial types of ground coffee were analyzed to determine their PAHs contamination levels. PAHs concentration ranged from ND to 5.988 ${\mu}g/kg$. This study was conducted with toxicity equivalence factors, the U.S. EPA recommendation to identify dietary risks for PAHs in different types of coffee. The estimated average daily dose of PAHs was $5.24{\times}10^{-8}$ mg/kg body weight/day.

• Analytical Science and Technology
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• v.29 no.2
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• pp.94-103
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• 2016

An analytical method was developed to determine the amount of spinetoram (spinetoram J and spinetoram L) in livestock samples. The spinetoram was extracted with acetonitrile and purified through a primary secondary amine (PSA) sorbent. The spinetoram residues were then quantified and confirmed using a liquid chromatography–tandem mass spectrometer (LC-MS/MS) in the positive ion mode using multiple reactions monitoring (MRM). Matrix-matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/kg) into a blank extract with r² > 0.994. The limits of detection and quantification were 0.002 and 0.01 mg/kg, respectively. The recovery results of spinetram ranged between 81.9-106.4% at different concentration levels (LOQ, 10LOQ, 50LOQ, n=5) with relative standard deviations (RSDs) less than 10%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL40, 2003). An interlaboratory study was conducted to validate the method. The proposed analytical method proved to be accurate, effective, and sensitive for spinetoram determination. The method will be used as an official analytical method in Korea.