• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.441-452
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• 2011

This study was carried out to survey the residual characteristics of endocrine disruptor (ED)-suspected pesticides in greenhouse soils and assess their leachabilites to groundwater. Greenhouse soils were collected from 40 sites of greenhouse in 2008 in Korea. Sixteen ED-suspected pesticides which had been using in Korea, such as alachlor, benomyl, carbaryl, cypermethrin, 2,4-D, dicofol, endosulfan, fenvalerate, malathion, mancozeb, metribuzin, metiram, methomyl, parathion, trifluralin, and vinclozolin, in the soils, were analyzed by chromatographic methods using GLC-ECD and HPLC-DAD/FLD. Limits of detection (LODs) of the test pesticides ranged from 0.0004 to 0.005 mg/kg. Recoveries of the target pesticides from soil ranged from 72.69 to 115.28%. Four pesticides including cypermethrin were detected in the range of from 0.001 to 2.019 mg/kg, representing that their detection rate from greenhouse soils was 37.5%. The highest detection rate was observed from endosulfan which was detected from 16 site soils of the total samples, indicating that endosulfan is persistent in soil because of its very low mobility and high adsorption characteristics in soil. Based on the groundwater ubiquity scores (GUSs) of the pesticides detected from greenhouse soils, most of them have little possibilities of groundwater contamination except the fungicide vinclozolin with some leaching potential because of high water solubility and very low soil adsorption property.

• Korean Journal of Microbiology
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• v.54 no.2
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• pp.105-112
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• 2018

To compare the denitrification efficiency, this study used molasses and methanol were used as external carbon sources. Specific experimental conditions were classified according to C/N ratio conditions. The batch test showed that the denitrification efficiency increased as C/N ratios of molasses and methanol rose. The most suitable C/N ratio of molasses turned out 4:1 considering the concentration of the residue chemical oxygen demand (COD) and the denitrification efficiency, which was 91.4%. Specific denitrification rate (SDNR) drawn as a kinetic factor demonstrated that molasses and methanol showed similar SDNR values as C/N ratios of molasses and methanol increased. Under the condition of C/N ratio 4:1, 0.0292 g $NO_3{^-}-N$ removal/g mixed liquor volatile suspended solid (MLVSS)/day (molasses), 0.0299 g $NO_3{^-}-N$ removal/g MLVSS/day (methanol) were found. Sludge adapted to molasses showed that Bacterium Pseudomonas sp. and Bergeylla sp. dominated through an analysis of microbial community. In addition, some bacteria were high convergences than the variety of microbial community. Accordingly, it was assumed that molasses focus on growing microorganisms specialized in denitrification and applied as a replaceable external carbon source that can enhance denitrification performance.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.2
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• pp.104-108
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• 2016

The objective of this study was to determine how feeding forage and concentrate separately (SF) or as a total mixed ration (TMR) affects enteric methane production of cattle. Six Holstein steers ($203{\pm}22.5kg$) were used in a $2{\times}3$ changeover design experiment. Experimental diets (TMR and SF) consisted of compound feed, timothy hay and soybean curd residue in a ratio of 40:48:12, respectively, and diets were fed at 10% of metabolic body weight, on an as-fed basis. There were no differences in dry matter intake and enteric methane production (g/d) between SF and TMR but the methane conversion rate (methane energy/GE intake) of TMR was significantly higher (p=0.05) than that of SF. The mean methane emission factor (kg/head/year) and conversion rate of the two treatments were 21.4 and 0.05, respectively. There was a strong relationship between metabolic body weight and enteric methane production (p<0.001). At the present time, further studies may be necessary in order to establish the effects of TMR and SF on enteric methane production.

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.9-16
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• 2021

The monitoring of residual pesticides in dried chili peppers and chili powders, which are circulated in Seoul from 2018 to 2019, was conducted for safety evaluation. As a result of analyzing for 71 kinds of pesticide residues in 101 cases of samples, pesticides were detected in 87 samples; however, no samples exceeded the MRLs (Maximum Residue Limits). Detection rates of pesticides in dried chili peppers and chili powders were 73.3% and 91.5%, respectively. The detection rate of residual pesticides in chili powders was a little higher than that in dried chili peppers. Twelve types of pesticides were detected, however, those pesticides were acceptable to use on peppers, according to the Crop Protection Guidelines. The most frequently detected pesticide was pyraclostrobin followed by flubendiamide, azoxystrobin, and chlorantraniliprole. The risk for detected pesticides was estimated as the ratio of ADI (Acceptable Daily Intake) to food intake rate. The ADI value resulting by intake of dried chili peppers and chili powders was in the range of 5.66E-05 to 3.34E-02, which was within a safe level.

• Clean Technology
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• v.30 no.1
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• pp.28-36
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• 2024

As demand for electric vehicles increases, the market for lithium-ion batteries is also rapidly increasing. The battery life of lithium-ion batteries is limited, so waste lithium-ion batteries are inevitably generated. Accordingly, lithium was selectively preleached from waste lithium iron phosphate (LiFePO₄, hereafter referred to as the LFP) cathode material powder among lithium ion batteries, and iron phosphate (FePO₄) powder was recovered. The recovered iron phosphate powder was mixed with alkaline sodium carbonate (Na₂CO₃) powder and heat treated to confirm its crystalline phase. The heat treatment temperature was set as a variable, and then the leaching rate and powder characteristics of each ingredient were compared after water leaching using Di-water. In this study, lithium showed a leaching rate of approximately 100%, and in the case of powder heat-treated at 800 ℃, phosphorus was leached by approximately 99%, and the leaching residue was confirmed to be a single crystal phase of Fe₂O₃. Therefore, in this study, lithium, phosphorus, and iron components were individually separated and recovered from waste LFP powder.

• 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.39 no.2
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• pp.114-121
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• 2007

The purpose of this study was to investigate 253 kinds of pesticide residues in 58 commercial dried agricultural products in Seoul. The determinations of the pesticide residues were performed using multiresidue methods and were carried out by a gas chromatography-nitrogen phosphorus detector (GC-NPD), an electron capture detector ($GC-{\mu}ECD$), a mass spectrometry detector (GC-MSD) and high performance liquid chromatography-ultraviolet detector (HPLC-UV), and a fluorescence detector (HPLC-FLD). The pesticide residue detection rate in the commercial dried agricultural products was 24.1% (14 of 58 samples). Twelve pesticide residues without maximum residue limits (MRLs) were detected. In the vegetable groups, the frequency of pesticide residues was found to be in the increasing order of dried fruiting vegetables > dried leafy vegetables > dried stalk and stem vegetables. The pesticides used on dried red pepper in the dried fruiting vegetables were varied (7 kinds) and numerous (4 of 8 samples). The pesticide types detected in the commercial dried agricultural products were in the order of pyrethroid > organochloride > organophosphorus and insecticide > fungicide > herbicide ${\cdot}$ nematicide. The primary pyrethroid pesticide detected was cypermethrin. According to the producing areas of products, large numbers of pesticide residues were found in the order of Korea, China, North Korea, USA, and Vietnam.

• Analytical Science and Technology
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• v.29 no.2
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• pp.57-64
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• 2016

Many phthalic acid esters (PAEs), including DMP, DEP, DBP, BBP, and DEHP, as well as DEHA are widely used as plasticizers in plastics. An analytical method was developed and used to analyze these compounds at 41 industrial facilities. The coefficient of determination (R²) for each constructed curve was higher than 0.98. The method detection limit (MDL) values were 0.4–0.7 μg/L for PAEs and 0.6 μg/L for DEHA. In addition, the recovery rate was shown to be 77.0–92.3%, while the relative standard deviation was shown to be in the range of 5.8-10.5%. DMP (n = 3), DEP (n = 2), DBP (n = 2), BBP (n = 2), and DEHA (n = 3) were detected in the range of 2.2-11.1% in the influent. DEHP was a predominant compound and was detected at > MDL in both the influent (n = 16, 35.6%) and the effluent (n = 4, 10.0%) at a high removal efficiency (92–100%). The highest levels of residue in industrial wastewater influent were 137.4 μg/L of DEHP at plastic products manufacturing facility, 12.5 μg/L of DEHA at a chemical manufacturing facility, and 14.0 μg/L of DEP at an electronics facility. The highest concentration of effluent was 12.5 μg/L of DEHP at a chemical manufacturing facility, which indicated that the effluent was below the allowable concentration (800 μg/L). Therefore, the levels of PAEs and DEHA that are discharged into nearby streams could not influence the health of the ecosystem.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.9
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• pp.63-73
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• 2015

This work proposes a 2-channel time-interleaved (T-I) 10b 120MS/s pipeline SAR ADC minimizing offset mismatch between channels without any calibration scheme. The proposed ADC employs a 2-channel SAR and T-I topology based on a 2-step pipeline ADC with 4b and 7b in the first and second stage for high conversion rate and low power consumption. Analog circuits such as comparator and residue amplifier are shared between channels to minimize power consumption, chip area, and offset mismatch which limits the ADC linearity in the conventional T-I architecture, without any calibration scheme. The TSPC D flip-flop with a short propagation delay and a small number of transistors is used in the SAR logic instead of the conventional static D flip-flop to achieve high-speed SAR operation as well as low power consumption and chip area. Three separate reference voltage drivers for 4b SAR, 7b SAR circuits and a single residue amplifier prevent undesirable disturbance among the reference voltages due to each different switching operation and minimize gain mismatch between channels. High-frequency clocks with a controllable duty cycle are generated on chip to eliminate the need of external complicated high-frequency clocks for SAR operation. The prototype ADC in a 45nm CMOS technology demonstrates a measured DNL and INL within 0.69LSB and 0.77LSB, with a maximum SNDR and SFDR of 50.9dB and 59.7dB at 120MS/s, respectively. The proposed ADC occupies an active die area of 0.36mm2 and consumes 8.8mW at a 1.1V supply voltage.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.463-470
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• 2011

This study was carried out to survey the residual characteristic of chlorpyrifos and estimate their residues in squash before harvest. The pesticide was sprayed onto the crop at the recommended and its double rates 10 days before the prearranged harvest and sampling was done at 0, 2, 3, 5, 6, 7 and 10 days after spraying. The amounts of the chlorpyrifos residue in the crop was analyzed by chromatographic method. Limit of detection (LOD) of chlorpyrifos was 0.005 mg/kg and its recovery ranged from 95.21 to 102.69%. The initial concentration of chlorpyrifos sprayed with recommended dose exceeded its MRL of 0.1 mg/kg but its concentration was less than its MRL 10 days after application. However its concentration in case of the double dose was over its MRL both immediately and 10 days after application. Biological half-lives of chlorpyrifos sprayed onto squash was 2.5 and 2.9 days at the recommended and double doses, respectively. Ten days later, the residual concentration of chlorpyrifos in squash was decreased substantially. The concentration of chlorpyrifos was estimated in squash at the given day using its regression equations. The estimated concentration of chlorpyrifos in case of application with recommended dose was below its MRL at 10 days after application but its concentration in case of application with double dose was over its MRL at 10 days of the prearranged harvest. The rate of the estimated daily intake (EDI) of chlorpyrifos to its acceptable daily intake (ADI) was 282% right after application but it decreased to less than 18% at 10 days of the prearranged harvest.