• The Korean Journal of Pesticide Science
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• v.15 no.1
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• pp.36-47
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• 2011

This study was performed to investigate the contaminated status of endocrine disruptor-suspected pesticides in agricultural products distributed in northern Seoul in 20l0. We analyzed 33 kinds of pesticides by multiresidue analysis method in 3,081 samples. Twelve pesticidcs were detected 600 times and violated 22 times from the agricultural products. The highest frequency of detection was procymidone and that of violation was endosulfan. The highest rates of detection divided violation times as diazinon. In agricultural products, 466 samples had pesticide residues and 22 samples violated the maximum residue limits (MRLs). Agricultural products were also classified by type and red pepper powder belonged to the others was the highest detection rate at 70.7%, fruiting vegetables 35.3%, tea leaves 23.6%, stalk and stem vegetables 21.2%, fruits 14.6% and leafy vegetables 11.2%. The rates of violation sample were stalk and stem vegetables 1.1%, leafy vegetables 1.0% and roots and tubers 0.4%. Leek was to be managed primarily because it had the high detection and violation ratio and was detected together several pesticides.

• Journal of the Korean Wood Science and Technology
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• v.36 no.3
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• pp.30-38
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• 2008

Petroleum-based resin adhesives have extensively been used for the production of wood panels. However, with the increase of manufacturing cost and the environmental issue, such as the emission of volatile organic compounds, of the adhesive resins, it is necessary to be developed new adhesive systems. In this study, the potential of okara, which is a residue wasted from the production of tofu, for the development of bio-based adhesives was investigated. At first, the physical and chemical properties of okara were examined. After okara was hydrolyzed in acidic and/or alkaline solutions, okara-based adhesive resins were formulated with the mixtures of the okara hydrolyzates and phenol formaldehyde (PF) prepolymer. The adhesive resins were used for the fabrication of plywood panels, and then the adhesive strength and formaldehyde emission of the plywood panels were measured to examine the applicability of the resin adhesives for the production of plywood panels. The solids content and pH of the okara used in this study were around 20% and weak acidic state, respectively. In the analysis of its chemical composition, the content of carbohydrate was the highest, and followed by protein. The shear strengths of plywood fabricated with okara-based resin adhesives exceeded a minimum requirement of KS standard for ordinary plywood, but its wood failure did not reach the minimum requirement. In addition, the formaldehyde emissions of all plywood panels were higher than that of E1 specified in the KS standard. Based on these results, okara has the potential to be used as a raw material of environmentally friendly adhesive resin systems for the production of wood panels, but further researches - biological hydrolysis of okara and various formulations of PF prepolymer - are required to improve the adhesive strength and formaldehyde emission of okara-based resin adhesives.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.1
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• pp.38-46
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• 2002

Chrysanthemum boreale M. (hereafter, C. boreale M.), a perennial flower, has been historically used as a natural medicine in Korea. With increasing concerns for health-improving foods, the demand for C. boreale M. has become higher than ever. Howevr, the amount of wild C. boreale M. collected from mountainous areas is not enough to cover all demands. The cultivation system and fertilization strategy are required to meet increasing demand on C. boreale M. with a good quality. We investigated the effects of nitrogen application on plant growth and effective components of C. boreale M. to suggest optimum rate of nitrogen fertilization. C. boreale M. was cultivated in a pot scale (1/2000a scale), and nitrogen applied with rate of 0(N0), 50(N50), 100(N100), 150(N150), 200(N200), and $250(N250)kg\;ha^{-1}$. Phosphate and potassium were applied at the same level ($P_2O_5-K_2O=80-80kg\;ha^{-1}$) in all treatments. Maximum yield achieved in 246 and $226kg\;ha^{-1}$ N treatment on the whole plant and the flower part, a valuable part as a herbal medicine, respectively. Proline was the most abundant amino acid in the flower of C boreal M. and the contents of amino acids increased with increasing nitrogen application rate in flower. Nitrogen recovery efficiency was high more than 41% in all nitrogen treatments and increased to 61.8% in nitrogen N100 treatment. From the nitrogen content, the high nitrogen uptake, the low residue of mineral N and the reasonably good apparent fertilizer recovery, it can be inferred that C. boreale M. made efficient use of the available nitrogen. In flower, contents of Cumambrin A. which is a sesquiterpene compound and has the effect of blood-pressure reduction, decreased with increasing nitrogen application. However, the amount of Cumambrin A in flower increased as nitrogen rate increased, because of increasing flower yield. Conclusively, nitrogen fertilization could increase yields and enhance quality. The optimum nitrogen application rate might be on the range of $225{\sim}250kg\;ha^{-1}$ in a mountainous soil.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.123-128
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• 2008

The MRLs (maximum residue limits) of DDT (DDD and DDE) in fresh ginseng, dried ginseng, and steamed red ginseng are set as low as 0.01 mg/kg, 0.05 mg/kg, and 0.05 mg/kg, respectively. Therefore, this study was undertaken to develop a simple and highly sensitive analysis method, as well as to reduce interfering ginseng matrix peaks, for the determination of DDT isomers (o,p'-DDE, p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT, and p,p'-DDT) in fresh ginseng, dried ginseng, and steamed red ginseng at the 0.01 mg/kg level. The method used acetonitrile extraction according to simultaneous analysis, followed by normal-phase Florisil solid-phase extraction column clean-up. The purification method entailed the following steps: (1) dissolve the concentrated sample extract in 7 mL hexane; (2) add 3 mL of $H_2SO_4$; (3) vigorously shake on avortex mixer; (4) cetrifuge at 2000 rpm for 5 min; (5) transfer 3.5 mL of the supernatant to the Florisil-SPE (500 mg/6 mL);and (6) elute the SPE column with 1.5 mL of hexane and 10 mL of ether/hexane (6:94). The determination of DDT isomers was carried out by a gas chromatography-electron capture detector (GC-${\mu}$ECD). The hexane and ether/hexane (6:94) eluate significantly removed chromatographic interferences, and the addition of 30% $H_2SO_4$ to the acetonitrile extract effectively reduced many interfering ginseng matrix peaks, to allow for the determination of the DDT isomers at the 0.01 mg/kg level. The recoveries of the 6 fortified (most at 0.01 mg/kg) DDT isomers from fresh ginseng, dried ginseng, and steamed red ginseng ranged from 87.9 to 99.6%. The MDLs (method detection limits) ranged from 0.003 to 0.009 mg/kg. Finally, the application of this method for the determination of DDT isomers is sensitive, rapid, simple, and inexpensive.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.28-36
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• 2018

Studies on suspected endocrine disrupting pesticide (EDP) residues in agricultural products were carried out in 2016 in Busan, Korea. Twelve different EDPs, ranging in concentration between 0.003-2.049 mg/kg, were detected in 19.5% of 462 samples. About 0.2% of agricultural product samples exceeded the maximum residue limits (MRLs). Risk indices of all of the EDPs were less than 10% of the acceptable daily intake (ADI). The outcomes indicated that the risk groups at highest risk of exposure to diazinon (found in Korean cabbages) and carbendazim (found in apples) were females aged 40 to 49 and young males less than 10 years old, respectively. Based on the stochastic assessment at $95^{th}$ percentile (P95), risk index in these risk groups accounted for 8.38 and 2.98% of ADIs. The results showed that the occurrence of EDP residues in agricultural products could not be considered a public health problem.

• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.131-140
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• 2014

The objective of this study was to develop a simultaneous method of 8 penicillin antibiotics including amoxicillin, ampicillin, cloxacillin, dicloxacillin, nafcillin, oxacillin, penicillin G and penicillin V in meat using LC-MS/MS. The procedure involves solid phase extraction with HLB cartridge and subsequent analysis by LC-MS/MS. To optimize MS analytical condition of 8 compounds, each parameter was established by multiple reaction monitoring in positive ion mode. The chromatographic separation was achieved on a $C_{18}$ column with a mobile phase of 0.05% formic acid and 0.05% formic acid in acetonitrile at a flow rate of 0.2 mL/min for 20 min with a gradient elution. The developed method was validated for specificity, linearity, accuracy and precision in beef, pork and chicken. The recoveries were 71.0~106%, and relative standard deviations (RSD) were 4.0~11.2%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.003~0.008 mg/kg and 0.01~0.03 mg/kg, respectively, that are below maximum residue limit (MRL) of the penicillins. This study also performed survey of residual penicillin antibiotics for 193 samples of beef, pork and chicken collected from 9 cities in Korea. Penicillins were not found in all the samples except a sample of pork which contained cloxacillin (concentration of 0.08 mg/kg) below the MRL (0.3 mg/kg).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.1-7
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• 2017

Cobalt silicide was used as a counter electrode in order to confirm its reliability in dye-sensitized solar cell (DSSC) devices. 100 nm-Co/300 nm-Si/quartz was formed by an evaporator and cobalt silicide was formed by vacuum heat treatment at $700^{\circ}C$ for 60 min to form approximately 350 nm-CoSi. This process was followed by etching in $80^{\circ}C$-30% $H_2SO_4$ to remove the cobalt residue on the cobalt silicide surface. Also, for the comparison against Pt, we prepared a 100 nm-Pt/glass counter electrode. Cobalt silicide was used for the counter electrode in order to confirm its reliability in DSSC devices and maintained for 0, 168, 336, 504, 672, and 840 hours at $80^{\circ}C$. The photovoltaic properties of the DSSCs employing cobalt silicide were confirmed by using a simulator and potentiostat. Cyclic-voltammetry, field emission scanning electron microscopy, focused ion beam scanning electron microscopy, and energy dispersive spectrometry analyses were used to confirm the catalytic activity, microstructure, and composition, respectively. The energy conversion efficiency (ECE) as a function of time and ECE of the DSSC with Pt and CoSi counter electrodes were maintained for 504 hours. However, after 672 hours, the ECEs decreased to a half of their initial values. The results of the catalytic activity analysis showed that the catalytic activities of the Pt and CoSi counter electrodes decreased to 64% and 57% of their initial values, respectively(after 840 hours). The microstructure analysis showed that the CoSi layer improved the durability in the electrolyte, but because the stress concentrates on the contact surface between the lower quartz substrate and the CoSi layer, cracks are formed locally and flaking occurs. Thus, deterioration occurs due to the residual stress built up during the silicidation of the CoSi counter electrode, so it is necessary to take measures against these residual stresses, in order to ensure the reliability of the electrode.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.214-220
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• 1993

Browning of ascidian, Halocynthia roretzi, meat occurres very rapidly when skinned off or cut during processing and it resulted the quality loss of fresh frozen, dehydrated or fermented products. In this study, the causes of color development and prevention of browning were experimented. The browning of ascidian meat may be occurred enzymatically by a tyrosinase contained in meat and viscera which acted specifically on L-tyrosine as a substrate rather than on catechol. Activity of the enzyme in viscera was three times higher than in meat. The optimum pH and temperature on the tyrosinase activity of crude enzyme obtained from ascidian was 6.0 and $30{\sim}35^{\circ}C$, respectively. The enzyme was inactivated heating at $80^{\circ}C$ for 3 minutes or $90{\sim}100^{\circ}C$ for 1 minute and it was inhibited by $0.1{\sim}0.5mM$ solutions at ascorbic acid, sodium hydrogen sulfite, cystein, citric acid, cyanide but only sodium hydrogen sulfite treatment was effective to retard such a high content of enzyme as in case of viscera. In practical use for processing of ascidian meat browning was retarded by dipping the viscera removed ascidian meat in 0.2M citric acid for 5 minutes or $0.2\%$ sodium hydrogen sulfite solution for 1 minute resulting in sulfur dioxide residue less than 100 ppm.

• Journal of agriculture & life science
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• v.46 no.3
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• pp.97-108
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• 2012

Physical, chemical and biological hazards of strawberry farms at the cultivation stage were analyzed to establish the GAP(Good Agricultural Practice) system. Samples were collected from the plants, cultivation environments(water, soil and air), and personal hygiene (hand, glove, and clothes) of three strawberry farms(A, B, and C) and were tested to analyze physical, chemical (heavy metals and pesticide residues), and biological(sanitary indications and foodborne pathogens) hazards. Physical hazards such as insects and pieces of metal and glass were found in the strawberry farms and can be potential bow for strawberry products. Heavy metal and pesticide residue as chemical hazards were detected at levels lower than the regulation limit. In case of biological hazards, total bacteria and coliform were detected at the levels of 1.6~7.3 and 1.3~5.6 log CFU/g, leaf, mL, hand or $100cm^2$. However, Escherichia coli was not detected in all samples. Bacillus cereus and Staphylococuus aureus were detected at levels of ${\leq}$ 1.1~6.1 log CFU and 4.7~5.4 log CFU/g, mL, hand or $100cm^2$, whereas Listeria monocytogenes, E. coli O157 and Salmonella spp. were not detected in all samples. This study demonstrates that various harzards were in strawberry farms at the growing stage. Therefore proper management such as GAP is needed to prevent the occurrence of food poisoning associated with the hazards revealed in this study.

• Journal of Food Hygiene and Safety
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• v.34 no.5
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• pp.413-420
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• 2019

In this study, a sample preparation method and a simultaneous determination method by ultra-high performance liquid chromatography coupled with tandem mass spectrometry for 9 isomers of chlorogenic acid and arbutin in fruits were developed. The samples were extracted using 90% methanol (pH 3.0), with the solutions being shaken and then sonicated for 10 min each. After centrifugation at 4,000 rpm for 10 min, the extraction was concentrated under a vacuum at $40^{\circ}C$ using a vacuum evaporator. The residue was dissolved in 5 mL of 5% methanol and filtered through a $0.45{\mu}m$ membrane before UHPLC-MS/MS analysis. The separations were performed on a C18 column with gradient elution of water (containing 0.1% formic acid) and methanol (containing 0.1% formic acid). The specificity, linearity, limit of detection, limit of quantification, accuracy, and precision of the proposed methods were also evaluated.