• Journal of Food Hygiene and Safety
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• v.39 no.2
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• pp.72-82
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• 2024

This study aimed to develop a scientifically and systematically standardized xylooligosaccharide analytical method that can be applied to products with various formulations. The analysis method was conducted using HPLC with Cadenza C₁₈ column, involving pre-column derivatization with 1-phenyl-3-methyl-5-pyrazoline (PMP) and UV detection at 254 nm. The xylooligosaccharide content was analyzed by converting xylooligosaccharide into xylose through acid hydrolysis. The pre-treated methods were compared and evaluated by varying sonication time, acid hydrolysis time, and concentration. Optimal equipment conditions were achieved with a mobile phase consisting of 20 mM potassium phosphate buffer (pH 6)-acetonitrile (78:22, v/v) through isocratic elution at a flow rate of 0.5 mL/min (254 nm). Furthermore, we validated the advanced standardized analysis method to support the suitability of the proposed analytical procedure such as specificity, linearity, detection limits (LOD), quantitative limits (LOQ), accuracy, and precision. The standardized analysis method is now in use for monitoring relevant health-functional food products available in the market. Our results have demonstrated that the standardized analysis method is expected to enhance the reliability of quality control for healthy functional foods containing xylooligosaccharide.

• Journal of Food Hygiene and Safety
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• v.39 no.3
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• pp.221-230
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• 2024

Pesticide residues were monitored in dried red pepper and pepper powder samples purchased in Northern Gyeonggi-do and from domestic online markets. The QuEChERS method was used to prepare 88 samples. GC-MS/MS and LC-MS/MS were used to analyze 338 pesticide residues. In the study, pesticide residues were detected in 70 samples (79.5%), with residues exceeding the maximum residue limits (MRL) in 4 samples (4.5%). Pesticide levels exceeded the MRL in imported samples, with two samples of dried red pepper and two samples of pepper powder showing elevated levels. Among the 61 pesticides detected, tebuconazole, a fungicide was most frequently detected (52 times). Tricyclazole, which is used to control the main disease affecting rice, exceeding the MRL in 3 of 12 Vietnam-origin samples. Ethion exceeded the MRL in one Indian-origin sample. Both tricyclazole and ethion are banned for use in pepper products in Korea and are regulated under the positive list system (PLS). Conversely, pesticides detected in domestic samples were within the MRLs. Therefore, authorities should monitor pesticide residues in imported red pepper products.

• Journal of Food Hygiene and Safety
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• v.39 no.3
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• pp.250-259
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• 2024

In this study, we investigated in pesticide residues and heavy metals in fermented liquor products (wine, beer, makgeolli). Targeted analysis of 400 pesticide residues in the sample was performed using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method, followed by gas chromatography-tandem mass spectrometry (MS/MS) and LC-MS/MS. The contents of heavy metals (Pb, Cd) were determined by ICP-MS using the microwave method. The mercury was measured using a mercury analyzer. From the analysis of 150 cases, 102 (68.0%) cases of fermented liquor were detected, and 35 pesticide residues (including metalaxyl, mandipropamid, azoxystrobin, and fenhexamid) were detected among the 400 pesticide residues tested. Pb, Cd, and Hg were tested in 150 samples. Lead was detected in 73 samples (48.7%), cadmium in 9 samples (6.0%), and mercury in 36 samples (24.0%). Exposure assessment was conducted to determine the safety of the detected pesticide residues and heavy metals. According to this assessment, the pesticide residues and heavy metals showed very low %ADI values (less than 1%).

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.95-103
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• 2010

Fomesafen is a selective herbicide, and used to control annual and perennial broad-leaf grass on soybean and fruit fields in USA and China, but not introduced in Korea yet. So, MRL (Maximum Residue Level), and analytical method of fomesafen were not establishment in Korea. Therefore, this experiment was conducted to establish a determination method for fomesafen residue in crops using HPLC-UVD/MS. Fomesafen residue was extracted with acetone from representative samples of five raw products which comprised hulled rice, soybean, apple, green pepper, and Chinese cabbage. The extract was diluted with saline water, and dichloromethane partition was followed to recover fomesafen from the aqueous phase. Florisil column chromatography was additionally employed for final clean up of the extract. The fomesafen was quantitated by HPLC with UVD, using a Shiseido CAPCELL-PAK UG C18 column. The crops were fortified with fomesafen at 3 levels per crop. Mean recovery ratio were ranged from 87.5% for a 0.4 ppm in hulled rice to 102.5% for a 0.4 ppm in apple. The coefficients of variation were ranged from 0.6% for a 2.0 ppm in hulled rice to 7.7% for a 0.04 ppm in green pepper. Quantitative limit of fomesafen was 0.04 mg/kg in representative 5 crop samples. A LC/MS with selected-ion monitoring was also provided to confirm the suspected residue. Therefore, this analytical method was reproducible and sensitive enough to determine the residue of fomesafen in agricultural commodities.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.7 no.2
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• pp.228-238
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• 2004

Purpose: Obesity is rapidly increasing in Korean children. Obesity is a risk factor for cardiovascular morbidity and is frequently associated with hypertension, diabetes mellitus and coronary artery disease. This study was designed to evaluate risk factors of the metabolic syndrome in obese children. Methods: From February 2000 to June 2004, eighty eight obese (body mass index ${\geq}95th$ percentile) children aged 4 to 15 years were included. We measured serum lipid levels (total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol), fasting sugar levels and insulin levels. Insulin resistance was determined by homeostasis model assessment, fasting insulin/glucose ratio and quantitative insulin sensitivity check index. Results: Clustering of risk factors for the metabolic syndrome in obese children demonstrated that 60.2% had more than one risk factors. Hypertension (14.8%), hypertriglyceridemia (14.8%), HDL-hypocholesterolemia (14.8%), LDL-hypercholesterolemia (12.5%) and hyperinsulinemia (12.5%) were observed. As BMI increased, there was statistically significant increase in systolic blood pressure, insulin and insulin resistance values. Insulin resistance was correlated to systolic blood pressure, serum lipid and insulin levels. The more risk factors for the metabolic syndrome obese children had, the higher was their insulin resistance. Conclusion: The increase in insulin resistance and clustering of risk factors for the metabolic syndrome are already apparent in obese children. Monitoring these risk factors for the metabolic syndrome should become a part of routine medical care for obese children.

• Journal of Korea Water Resources Association
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• v.53 no.1
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• pp.15-27
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• 2020

Streamflow discharge as a fundamental riverine quantity plays a crucial role in water resources management, thereby requiring accurate in-situ measurement. Recent advances in instrumentations for the streamflow discharge measurement has complemented or substituted classical devices and methods. Among various potential methods, surface current meter using microwave has increasingly begun to be applied not only for flood but also normal flow discharge measurement, remotely and safely enabling practitioners to measure flow velocity postulating indirect contact. With minimized field preparedness, this method facilitated and eased flood discharge measurement in the difficult in-situ conditions such as extreme flood in active ways emitting 24.125 GHz microwave without relying on natural lights. In South Korea, a rectangular shaped instrument named with Microwave Water Surface Current Meter (MWSCM) has been developed and commercially released around 2010, in which domestic agencies charging on streamflow observation shed lights on this approach regarding it as a potential substitute. Considering this brand-new device highlighted for efficient flow measurement, however, there has been few noticeable efforts in systematic and comprehensive evaluation of its performance in various measurement and riverine conditions that lead to lack in imminent and widely spreading usages in practices. This study attempted to evaluate the MWSCM in terms of instrumen's monitoring configuration particularly regarding tilt and yaw angle. In the middle of pointing the measurement spot in a given cross-section, the observation campaign inevitably poses accuracy issues related with different tilt and yaw angles of the instrument, which can be a conventionally major source of errors for this type of instrument. Focusing on the perspective of instrument configuration, the instrument was tested in a controlled outdoor river channel located in KICT River Experiment Center with a fixed flow condition of around 1 m/s flow speed with steady flow supply, 6 m of channel width, and less than 1 m of shallow flow depth, where the detailed velocity measurements with SonTek micro-ADV was used for validation. As results, less than 15 degree in tilting angle generated much higher deviation, and higher yawing angle proportionally increased coefficient of variance. Yaw angles affected accuracy in terms of measurement area.

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.27-37
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• 2012

To investigate the effect of aquifer disturbance on hydraulic properties while well drilling at unconsolidated aquifer, the following tests were conducted: the surge block and air-surging methods, which are well development methods used after well drilling; and step-drawdown tests and constant-rate pumping tests, which are used to assess changes in the aquifer after well drilling and development. The result of step-drawdown tests indicated that drawdown for a pumping-rate of $700m^3/day$ was 21.62 m after well development, decreasing 4.39 m from 26.01 m after well drilling. The skin factor used to identify the well properties decreased from 7.92 after well drilling to 5.04 after well development, respectively, which shows the improvement of well. Constant-rate pumping tests revealed a small increase in aquifer transmissivity after well development at MW-2, -3, and -4, centering around pumping well, from $1.684{\times}10^{-3}{\sim}4.490{\times}10^{-3}m^2/sec$ to $4.002{\times}10^{-3}{\sim}4.939{\times}10^{-3}m^2/sec$. MW-1, however, showed decline in hydraulic conductivity from $1.018{\times}10^{-2}m^2/sec$ to $6.988{\times}10^{-3}m^2/sec$, which was caused by a small decrease of aquifer permeability around monitoring well MW-1 due to latent factor of air interception and clogging in aquifer during surging. This finding indicates that fine particles have an effect on hydraulic properties at unconsolidated aquifers during well drilling; therefore, we consider that well drilling and development have an effect on hydraulic properties.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.3
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• pp.127-133
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• 2005

The measurement technique using laser distometer to estimate soil erosion on sloped upland was assessed for its possibility for application. This technique was practiced in lysimeter installed in Chuncheon and Pyeongchang in 2001. The lysimeter installed at Chuncheon has 12% slope, 10 m slope length, 2 m width, and soil texture was sandy loam, while the lysimeter installed at Pyeongchang showed 23% slope, 15 m slope length, 5 m width, and sandy loam soil. Change of surface soil height was monitored using laser distance meter before and after rainy season on same spots. The Investigated periods in Chuncheon and Pyeongchang were from 22 June to 22 September and from July to October, respectively. Precipitation in Chuncheon and Pyeongchang in this period was 892.2 and 931.9 mm, respectively. Rainfall over 60% of annual precipitation was concentrated on July and August in Chuncheon and September and October in Pyeongchang, respectively. By monitoring the change of surface soil height using laser distance meter before and after rainy season, eroded soil surface in up-down fallow field in Chuncheon was 0.874 cm, while eroded soil surface in slant furrow field in Pyeongchang was 1.127 cm, which correspond to 79.5 and $98.0MT\;ha^{-1}$. Soil erosion increased as furrow length increased. Amounts of estimated soil loss using laser distance meter was 0.98-1.18 times higher compared to the estimated values through Iysimeter experiment, which implies possibility for application to monitor soil loss particularly in up-down and slant furrowed field. However, in the lysimeter with contoured tillage, amount of estimated soil loss using laser distance meter was approximately a half compared to that from lysimeter experiment, which implies inadequacy of distance meter application in contour- tillage field. The great soil loss difference between distance meter and lysimeter might be caused by disruption of some of the contoured furrows in lysimeter. The measurement technique using distometer in this study could be useful to estimate soil loss especially in up-down and slant-tillage fields.

• Journal of Animal Science and Technology
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• v.50 no.5
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• pp.613-620
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• 2008

The genetic parameters used in National Hanwoo Genetic Evaluation(NHGE) were needed to be monitored and updated periodically for accounting any possible changes in population parameters due to selection and environmental changes. Genetic parameters were estimated with single and two-trait models with MTDFREML package using 2,791 carcass records of steers collected from Hanwoo Progeny Test Program(HPTP). Single and two-trait models gave similar parameter estimates for all traits. The heritability estimates from single and two-trait models for carcass weight(CW), dressing percentage(DP), eye muscle area(EMA), back fat thickness(BFT) and marbling score(MS) were 0.30, 0.30, 0.37, 0.44 and 0.44, respectively. The heritability estimates for all the traits except BFT were slightly lower than those used in NHGE but seemed to be within the acceptable ranges. However, further monitoring is needed because the data might not have fully reflected the changes such as carcass grading standards in performance testing program. In order to shift statistical model of NHGE from single trait model to multiple-trait model, the genetic correlations between carcass traits were estimated with pairwise two-trait models. The genetic correlation coefficients between CW and DP, between CW and EMA, between CW and BFT and between CW and MS were 0.44, 0.63, 0.17 and 0.06, respectively. Those between DP and EMA, between DP and BFT and between DP and MS were 0.29, 0.40 and 0.20. Those between EMA and BFT and between EMA and MS were －0.24 and 0.15, respectively. The genetic correlation coefficient between BFT and MS was 0.03.

• The Korean Journal of Pesticide Science
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• v.15 no.2
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• pp.114-124
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• 2011

The characteristics of pesticide residues by multiresidue analysis method using GC, HPLC and GC-MSD were examined for 18,069 numbers of 91 kinds of vegetables in Seoul from 2007 to 2009. Detection rates of pesticide residues were 11.2% in 2007, 8.5% in 2008 and 12.0% in 2009, respectively, and the excess rates of Maximum Residue Limits (MRLs) showed a declining tendency as 4.6% in 2007, 2.8% in 2008 and 2.1% in 2009, respectively. The pesticides exceeding MRLs were 43 ingredients in 2007, 30 ingredients in 2008 and 36 ingredients in 2009, respectively. The frequencies of pesticides exceeding MRLs were 71 of azoxystrobin in 2007, 29 of procymidone in 2008, 24 of endosulfan in 2009, respectively. The excess rate of mustard green for MRLs in comparison with sample numbers was the highest among vegetables analyzed more than 10 cases each year. As a result of comparing annually pesticide residues about pesticide ingredients showed high frequency rates for pesticide detection, there was a statistical significance for the detection quantities of diazinon, endosulfan, paclobutrazol and procymidone.