• Journal of Environmental Health Sciences
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• v.36 no.1
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• pp.52-60
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• 2010

High performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC/MS) have been widely used to quantify aflatoxins in food, but these methods are expensive, time-consuming, unsuitable for analysis of the routine screening of large sample numbers and require derivatization and high level techniques to perform. The objective of this study is to detect aflatoxins in a large number of foods by a high efficient analytical system of combined enzyme linked immunosorbent assay (ELISA) for screening and LC/MS/MS for confirmation. The samples spiked individually with aflatoxin $B_1$ (0.5 and 1.0 ng/g) and total aflatoxins (10 ng/g) were analyzed by ELISA and LC/MS/ MS, and the recoveries for ELISA and LC/MS/MS were 71.8~119.2% and 70.8~135.3%, respectively. A total of 378 samples (grains, nuts, soybean and fermented soybean foods, pepper and fermented pepper foods) were purchased from the six major cities in Korea and analyzed by ELISA-LC/MS/MS system. Twenty two (5.8%; peanut: 11, pistachio: 2, walnut: 6, almond: 1, pepper powder: 1, pepper paste: 1) out of 378 samples were screened as aflatoxin B1 positive by ELISA, but, 4 (1.1%; peanut: 2, pistachio:1, pepper powder: 1) out of the 22 samples screened were confirmed as aflatoxins positive at levels of 1.02~52.79 ng/g by LC/MS/MS. ELISA-LC/MS/MS system provides a more rapid, accurate and cost-effective method for the detection of aflatoxins in large number of samples.

• Journal of Environmental Health Sciences
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• v.44 no.3
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• pp.238-243
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• 2018

Objectives: The purpose of this study was to determine skin adhesion rate of children's modeling clay for exposure assessment. Methods: Children's modeling clays were classified into 10 categories as PVA clay, PVA soft clay, starch-based clay, foam clay, rubber clay, oil clay, muddy clay, terra clay, paper clay and slime. A total of 26 children's clay goods was selected. Moisture content (%) and hardness of clays were measured. Five adults aged 20 to 25were recruited for experiment. Gravimetric difference of modeling clay was determined after 3 minutes playing time. Skin adhesion rate ($g/min/cm^2$) was estimated bythe amount of skin adhesion per minute (g/min) and each individual's palm surface area ($cm^2$). Results: Twenty four of the 26 children's modeling clay products were adhesive to skins. Two products of foam and rubber clay were not adhered to skin. For the 24 products, the average skin adhesion rate was $5.5{\times}10^{-4}{\pm}4.0{\times}10^{-4}g/min/cm^2$. The highest skin adhesion rate was $1.3{\times}10^{-3}{\pm}4.4{\times}10^{-4}g/min/cm^2$ for paper clay. The lowest skin adhesion rate was $4.6{\times}10^{-5}{\pm}1.1{\times}10^{-4}g/min/cm^2$ for oil clay. The skin adhesion rate was increased with increase of moisture content. Adhesion rates of some clays were varied by person and testing trials. Conclusion: The study determined skin adhesion rate of children's modeling clay. The adhesion rate is useful for exposure and risk assessments and setting safety guideline to protect children's health.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.2
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• pp.260-267
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• 2015

We investigated the applicability of polyethylene glycol (PEG) as a plasticizer in enteric-coated soft capsules based on determination of quality characteristics according to molecular weight and concentration of enteric-coating PEG solution. There was no difference according to molecular weight of PEG, whereas a low PEG concentration in the enteric-coating solution was associated with higher whiteness index and slower disintegration time in pH 6.8 media. Brittleness was observed in the coating film at seam areas in 5% PEG enteric-coating solution after 2 weeks of storage at room temperature. The enteric-coating properties of PEG were compared with those of acetylated monoglyceride (AMG) and triacetin, which are enteric-coating plasticizers. Enteric-coated soft capsule containing PEG as a plasticizer showed a lower whiteness index and faster dissolution profile than AMG and triacetin. Moreover, enteric-coated soft capsule containing AMG and triacetin as plasticizers showed coating film brittleness at seam areas after 2 months of accelerated storage [$40^{\circ}C$, relative humidity (RH) 75%] but no difference at room temperature storage ($25^{\circ}C$, RH 60%). The present study suggests that concentration of PEG is important to determine enteric-coating quality, regardless of the molecular weight of PEG. In conclusion, PEG has potential as a plasticizer due to its transparency and storage stability in enteric-coated soft capsules.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.23-31
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• 1988

A total of 320 Larix leptocepzs Trees growing in Kyonggi and Kangwon Province were examined to estimate tree volume and height with DBH and age. The criteria of selecting the "best" regression equation were based on coefficient of determination, $R^2$, adjusted standard error, I, and the ease of application. From the results obtained in this study, the method of estimating tree volume and height with DBH and age showed the following advantages ; 1. Since no measurement of tree height is needed, it saves time and labor in forest survey. 2. It has the ease of application because age is determined directly in artificial forests. 3. Volume and height can be estimated more easily and accurately with DBH and age than other methods.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.381-387
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• 2013

In compiling flood hazard maps for the case of dam-failure, a scenario-based numerical modeling approach is commonly used, involving the modeling of important parameters that capture peak discharge, such as breach formation and progress. In this study, an earth-dam-break model is constructed assuming an identical mechanism and hydraulic process for all dam-break processes. A focus of the analysis is estimation of the hydrograph at the outlet as a function of time. The constructed hydrograph then serves as an upper boundary condition in running the flood routing model downstream, although flood routing is not considered here. Validation was performed using the record of the Tangjishan dam-break in China. The results were satisfactory, with a coefficient of determination of 0.974, Nash-Sutcliffe Coefficient of Efficiency (NSC) of 0.94, and Root Mean Square Error (RMSE) of $610m^3/sec$. The proposed model will contribute to assessments of potential flood hazards caused by dam-break.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.202-208
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• 2001

Under the constant daylength of 13 hours and growth temperatures of 15$^{\circ}C$ to 27$^{\circ}C$, the final number of loaves (FNL) on the main culm was constant as 15 regardless of temperature in rice variety 'Kwanganbyeo'. Leaf appearance rate (LAR) increased with rising temperature and decreased with phenological development. Threshold temperature (T$_{o}$) was not constant across growth stages, but increased with phenological development. Effective accumulated temperature (EAT), which is calculated by the summation of values subtracting T0 from daily mean temperature, is closely related with number of leaves appeared (LA). LA was fitted to bilinear, quadratic, power and logistic function of EAT. Among the functions, logistic function had the best fitness of which coefficient of determination was $R^2$=0.995. Therefore, LAR prediction model was established by differentiating this function in terms of time: (equation omitted). where dL/dt is LAR, T$_1$ is daily mean temperature, L is the number of leaves appeared, and a, b, and c are constants that were estimated as 41.8, 1098.38, and -0.9273, respectively. When predictions of LA were made by LAR prediction model using data independent of model establishment, the observed and predicted LA showed good agreement of $R^2$$\geq$0.99.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.210-217
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• 2009

Pollen flow is one of the essential components in the ecological risk assessment of transgenic crops, because pollen can act as a vehicle to disseminate transferred alien genes. Pollen flow pattern of a cultivated rice variety and Living modified (LM) rice was studied at diurnal and distance changes under field. We measured airborne pollen density at the distances of -1, 0.5, 0, 1, 2, 3, 4, 5, 7, 9, 11 and 13 m from rice cultivation and recorded the direction and speed of wind using weather station in the conventional rice paddy field during the flowering period of rice. Diurnal changes in pollen density were observed as a peak between 10:00 to 13:00 hr. The density of airborne rice pollen geometrically decreased with the increase of distance from pollen sources. It is therefore necessary to carry out a detailed investigation of pollen flow of a particular species, where ecological risk assessment requires an accurate estimation of pollen flow including both distance and intensity of pollen dispersal. The rice pollen flow was significantly influenced by weather conditions, particularly by wind direction and speed. The precise determination of the local wind conditions at flowering time therefore appears to be of primary importance for setting up suitable isolation distance from transgenic rice in the field.

• Food Science of Animal Resources
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• v.38 no.5
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• pp.1109-1119
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• 2018

In this paper, we report the development of a nondestructive prediction model for lean meat percentage (LMP) in Korean pig carcasses and in the major cuts using a machine vision technique. A popular vision system in the meat industry, the VCS2000 was installed in a modern Korean slaughterhouse, and the images of half carcasses were captured using three cameras from 175 selected pork carcasses (86 castrated males and 89 females). The imaged carcasses were divided into calibration (n=135) and validation (n=39) sets and a multilinear regression (MLR) analysis was utilized to develop the prediction equation from the calibration set. The efficiency of the prediction equation was then evaluated by an independent validation set. We found that the prediction equation - developed to estimate LMP in whole carcasses based on six variables - was characterized by a coefficient of determination ($R^2_v$) value of 0.77 (root-mean square error [RMSEV] of 2.12%). In addition, the predicted LMP values for the major cuts: ham, belly, and shoulder exhibited $R^2_v$ values${\geq}0.8$ (0.73 for loin parts) with low RMSEV values. However, lower accuracy ($R^2_v=0.67$) was achieved for tenderloin cuts. These results indicate that the LMP in Korean pig carcasses and major cuts can be predicted successfully using the VCS2000-based prediction equation developed here. The ultimate advantages of this technique are compatibility and speed, as the VCS2000 imaging system can be installed in any slaughterhouse with minor modifications to facilitate the on-line and real-time prediction of LMP in pig carcasses.

• Korean Journal of Food Science and Technology
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• v.17 no.1
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• pp.37-40
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• 1985

The reactor performance of a coimmobilized glucose oxidase and catalase enzyme system was investigated. In the determination of efficiencies of glucose oxidase and catalase of dual, mixed and soluble systems, the dual type immobilized one was superior to either the soluble or to the mixed system. In the continuous plugflow bed reactor system of glucose oxidase and catalase, $k-d$, deactivation rare constant of glucose oxidase only and catalase/glucose oxidase = 10 were $1.12\;{\times}\;10^{-2}\;and\;2.17\;{\times}10^{-3}\;hr^{-1}$, respectively. In the effect of ${\tau}$, space time, the point of $O_2$ limitation is $5.5\;g{\cdot}hr/l$ in both catalase/glucose oxidase = 1 and 10. In the effect of $O_2$ concentration to reduce the $O_2$ diffusion limitation, it appeared that ${\tau}\;=\;8.3g{\cdot}r/l$ is the maximum point of $O_2$ concentration in both catalase/glucose oxidase = 1 and 10.

• Korean Journal of Environmental Agriculture
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• v.9 no.1
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• pp.15-22
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• 1990

The efects of application time on the persistence of chlorothalonil in sesame plants and its persistence in soil were studied in the field. A procedure was used which permited the analysis of residues of Chlorothalonil (DACONIL 2787) in sesame(Sesamum indicum L.)and soil. The procedure was based on the multiresidue analytical method using an polarized acetonitrile solution or acidified acetone as the extracting solvent. The DACONIL 2787 is separated from the fat in the extracts by using an activated alumina and Florisil chromatogaphic column. Residues of DACONIL 2787 were determined by subjecting the alternate eluate from the Florisil column to gas chromatographic analysis(ECD). Residue of chlorothalonil in sesame are proved to 0.06 ppm for six sprays, 3rd day before harvest The half-life of chlorothalonil in soil proved to be 8.9 days and residues of chlorothalonil was only 0.03 ppm 100 days after application of 15 ppm.