• Journal of Food Hygiene and Safety
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• v.22 no.1
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• pp.23-28
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• 2007

The residue depletion of streptomycin was investigated in the olive flounder (Paralichthys olivaceus), rockfish (Sebastes schlegeli), and red sea bream (Pagrus major) after consecutive three days treatment with dipping water at a dose of 20 g/ton water. Fishes were sampled for muscle on 1st, 2nd, 3rd, 4th, and 5th day after treatment. Streptomycin concentrations were determined by high performance liquid chromatography with tandem mass spectrometry. The recovery rates of streptomycin in muscle samples ranged from 87.2 to 102.3% and from 80.4 to 94.1% for the concentration of 0.05 mg/kg and 0.1 mg/kg, respectively. Streptomycin concentrations detected on the 1st day after treatment were 0.066, 0.058, and 0.073 mg/kg in muscles of olive flounder, rockfish, and red sea bream, respectively. At day 2, residue concentrations of all samples were believed to decrease to lower than 0.05 mg/kg, the detection limit. From results of the present study, a withdrawal period of streptomycin is proposed on 3 days after consecutive three days treatment with dipping administration at a dose of 20 g/ton water to avoid the presence of excessive residues of the edible muscles of olive flounder, rockfish, and red sea bream. The present study showed that residue concentrations of streptomycin decreased to below 0.05 mg/kg after treatment 2nd day.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.570-577
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• 2000

A method was presented for determination of bisphenol F(BPF), bisphenol A(BPA), bisphenol F diglycidyl ether(BFDGE) and bisphenol A diglycidyl ether(BADGE) in 3 aqueous-based food simulants (water, 4% acetic acid, 20% ethanol) by reverse-phase high performance liquid chromatography(RP-HPLC)with fluorescence detection and gas chromatography with mass selective detection(GC/MSD). All the calibration lines in the range of $5{\sim}800\;{\mu}g/L$ had correlation coefficients greater than 0.9998 and detection limits of less than $1.2\;{\mu}g$ bisphenols/L. Precision at $200\;{\mu}g/L$ was under 3.1%. Recoveries of bisphenols simultaneously spiked to aqueous food simulants exceeded 95% for BPF and BPA but about 80% for BFDGE and BADGE. However, recoveris of BFDGE and BPADGE respectively spiked increased upto 95%. Detection limits in recovery test were less than $0.40\;{\mu}g$ bisphenols/L. In migration test bisphenols were determined by RP-HPLC coupled with confirmation by GC/MSD. Can coatings of epoxy phenol, modified epoxy, epoxy ester phenol and thermoset vinyl were exposed to the 3 aqueous food simulants. BPF, BFDGE and BADGE were not detected in all the can coatings but BPA was detected in 4% acetic acid and 20% ethanol in all the can coatings except modified epoxy.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.181-192
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• 2015

The aim of this study is to obtain optimum process condition for using two tower distribution to recycle the waste Propylene Glycol Monomethyl Ether Acetate (PGMEA) that is formed after washing LCD. The optimum process condition for the content of PGMEA, which is dependent variable, at 1st distillation was calculated according to Bottom temperature (BTM temperature), Reflux amount, Feed amount, Feed temperatures, and the optimum process conditions and optimum factors for the content of PGMEA at 2nd distillation according to Bottom temperature (BTM temperature), Reflux amount, Feed amount, Feed temperatures. At 1st distillation, Reflux amount, Feed amount, and Feed temperature are significant variables. However, it is found that the BTM temperature range is not significant in the range of process condition used in this study. The optimum process conditions are based on $5700{\ell}$ of Feed amount, $2500{\ell}$ of Reflux amount, $165^{\circ}C$ of BTM temperature, and $130^{\circ}C$ of Feed temperature. For the this condition, the predicted content of PGMEA was calculated as 92.12~94.62%. Significant factors at 2nd distillation are Reflux amount, Feed amount, and BTM temperature. Multicollinearity is between Reflux amount and BTM temperature. BTM was omitted in the multiple regression equation because there is a strong positive correlation between Reflux amount and BTM temperature. Base on $199^{\circ}C$ of BTM temperature, The optimum process conditions are based on $4275{\ell}$ of Feed amount, $6200{\ell}$ of Reflux amount and $130^{\circ}C$ of Feed temperature. In this condition, the predicted content of PGMEA was calculated as 99.0~99.5%.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.1
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• pp.96-103
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• 2014

A liquefied natural gas(LNG) in cryogenic liquid is converted back into gaseous form for distribution to residential and industrial consumers. In this re-gasification process, LNG supplies a plenty of cold thermal energy about $83.7{\times}10^4kJ/kg$. The LNG cold thermal energy is utilized for the re-liquefaction process of cryogenic fluids such as Nitrogen, Hydrogen and Helium, and ice manufacturing process and air-conditioning system in some advanced countries. Therefore, it is also necessary to establish the recovery systems of the LNG cold thermal energy around Incheon, Pyungtaek and Tongyung LNG import terminals in our country. Methane is used as working fluid in this paper, which is the major component of LNG over 85 % by volume, in order to investigate the flow behavior characteristics of LNG with phase change at low heat flux. This paper presents the effects of pipe diameters, pipe inclinations and saturation pressures on the flow boundaries of methane flowing in a cryogenic heat exchanger tube, together with those of nitrogen, propane, R11 and R134a. The outcomes obtained from this theoretical researches are also compared with previous experimental data. It was also found that the effect of pipe inclination on the methane flow boundaries was significant.

• Clean Technology
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• v.17 no.3
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• pp.259-265
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• 2011

The textile industry is suffered from air pollution problems which must be resolved. In particular, white smoke and odor after the tenter process require abatement. The major air pollution problem in the textile industry occurs during the finishing stages, where various chemicals are used for coating the fabrics. Lubricating oils, plasticizers, and water repellent chemicals are the fabric treatment chemicals. The coated fabrics are cured by heating in tenter facility. In this process, most of air pollutants emitted into the air. White smoke is basically made up of tiny solid or liquid particles of VOCs less than one micron in size. The oil mist can be carried over long distance from their point of origin. The most effective method of removing odor from tenter process is to get rid of tiny oil mist at the emitted gas. For this reason, the full-scale EFC (Electric Fume Collector) of 700 CMM was tested for removing odorous substances emitted from tenter facility. As a result of this study, odor and white smoke can be eliminated effectively and quite large amounts of oil can be recovered.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1137-1143
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• 1999

Microstructure and mechanical properties of Mod.9Cr-1Mo and W added 9Cr-0.5Mo2W steels were investigated for liquid metal reactor (LMR) heat exchange tube. The tempering temperatures at which cell structure was formed were $700^{\circ}C$ for Mod.9Cr-1Mo steel and $750^{\circ}C$ for W added 9Cr0.5Mo-2W steel. indicating the recovery of dislocation was delayed by the addition of W. 9Cr-0.5Mo-2W steel had the same kinds of precipitates with Mod.9Cr-1Mo steel, but the W was included in the precipitates in 9Cr-0.5Mo-2W steel. Micro-hardness and ultimate tensile strength of 9Cr-0.5Mo-2W steel were higher than those of Mod.9Cr-1Mo steel. The impact property of Mod.9Cr-1Mo steel was superior to that of 9Cr-0.5Mo-2W steel.

• Polymer(Korea)
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• v.31 no.3
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• pp.215-220
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• 2007

The control of the surface energy by electrohydrodynamic force provides electrospraying with various potential advantages such as simple particle size control, mono-dispersity, high recovery, and mild processing conditions. The advantages are quite helpful to improve the stability of protein drug and control its release. Herein, the nano-encapsulation of protein drugs using electrospraying was investigated. Albumin as a model protein was processed using uniaxial and co-axial electrospraying, and chitosan, polycaporlactone (PCL), and poly (ethylene glycol) (PEG) were used as encapsulation materials. The major processing parameters such as the conductivity of spraying liquids, flow rate, the distance of electrical potential gradient, etc were measured to obtain the maximum efficiency. In the chitosan systems, mean particles size decreases as flow rate and the distance between nozzle and the collecting part decreases. In the uniaxial technique of the PCL systems, mean particles size decreases as flow rate decreases. In the coaxial technique of the PCL systems, it was found that the particles size gets larger under the application of the higher ratio of inner-to-outer liquid flow rates. The primary particles formed out of an electrospraying nozzle showed narrow particle size distribution, but once they arrived to the collecting part, aggregation behavior was observed obviously. Efficient nano-encapsulation of albumin with PCL, PEG, and chitosan was conveniently achieved using electrospraying at above 12 kV.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.11
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• pp.626-633
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• 2017

The present study investigated the effect of a water-washing process, which is part of the acid hydrometallurgical process for recovery of high purity of zinc, on the removal of alkali metals and chlorides (Na, K, Ca, Cl) from Electric arc furnace dust (EAFD). Two EAFD samples with different properties were characterized by particle size, XRD and element analysis, and their washing efficiencies (%) on alkali metals and chlorides were compared according to pH, washing time, liquid to solid (L/S) ratio and number of washings. The results show that the alkali metals and chlorides could be effectively removed by the washing (at L/S ration of 3 for more than 30 min., pH 10~11) while minimizing loss of zinc (<0.1%), in which the washing efficiency was Na-78%, K-76%, Cl >99%, respectively. Na and K could be removed up to 97% and 89% respectively by 3 times of repeated washings. With increased sample volume (10 times) of the mixed (1:1, w/w) sample with two types of EAFD, it was confirmed that the pH(10~11) can be used as the main process control parameter for the washing of the alkali metals regardless of EAFD properties.

• Journal of agricultural medicine and community health
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• v.36 no.4
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• pp.218-226
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• 2011

Objectives: Paraquat (PQ) is a widely used ionic pesticide that is fatal when ingested accidentally or for suicidal purposes. It is thought that chronic exposure of PQ is related with the development of Parkinson's disease, but epidemiological studies have not yet confirmed that theory. This study attempted to estimate the possibility of environmental PQ exposure through soil and water. Materials and Methods: We analyzed the amount of decomposed PQ solution in wet soil after exposure to ultraviolet light. An artificial rainfall condition was simulated over soil sprayed with PQ to measure the amount of eluted PQ. In addition, PQ was diluted in water from three differently rated rivers and the changes in PQ concentration were measured after ultraviolet exposure over one month. High performance liquid chromatography/ultra violet detection was used to analyze the concentrations of PQ. Results: In the method we used, the recovery rate of PQ showed a precision rate less than 5%, an accuracy greater than 88%, and the calibration equation was y=5538.8x-440.01($R^2$=0.9985). There were no significant differences in the concentrations of PQ obtained from the three specimens over a 1-week period. From the PQ-sprayed soil, the artificial rainfall conditions showed no PQ elution over a 1-month period, and there was no significant differences in PQ concentrations according to ultraviolet exposure among the three samples. Conclusions: PQ remains well adsorbed naturally in soil. However, it may still exist in an integrated state for a long time in the hydrosphere, so the possibility of PQ exposure through drinking water cannot be disqualified.

• Clean Technology
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• v.22 no.4
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• pp.274-280
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• 2016

In this study, it was to develop a chemical method that can recycle the cutting oil which accounts for about 25% of the cost of the process among containing materials of silicon waste sludge generated in the process for producing a solar cell wafer. The 7 types of reagents have been used, including acetone, HCl, NaOH, KOH, $Na_2CO_3$, HF, $CH_2Cl_2$, etc. for this experiment. And It was carried out at a speed of 3000 rpm for 60 minutes centrifugation after performing a reaction with a waste sludge at various concentrations. As a result, the best reagents and conditions for separating the solid such as a silicon powder and a metal powder and liquid cutting oil were identified as 0.3 N NaOH. It is found to be pH 6.05 in a post-processing recycled cutting oil with 0.3 N NaOH after reaction of waste sludge and 0.1 N HCl which is effective to remove metal powder in order to adjust the pH to suit the properties of the weak acid is a commercially available cutting oil and it showed excellent turbidity than when applied to sludge with 0.3 N NaOH alone. The results of FT-IR analysis which can compare the properties of the commercially available cutting oil shows it has a possibility of recycling oil. The cutting oil recovery rate obtained through the experiment was found to be 86.9%.