• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.271-272
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• 2012

Bulk Metallic Glasses (BMGs or amorphous alloy) exhibit high strength and good corrosion resistance. Applications of thin films and micro parts of BMGs have been used a lot since its inception in the research of BMGs. However, Application and fabrication of BMGs are limited to make structural materials. Thin films of BMGs which is sputtered on the surface of structural materials by sputtering process is used to improve limits about application of BMGs. In order to investigate the difference of properties between designed alloys and thin films, we identified that thin films deposited on the surface that have the characteristic of the amorphous films and the composition of designed alloys. Zr-Cu (Cu=30, 35, 38, 40, 50 at.%) and Zr-Cu-Al (Al=10 at.% fixed, Cu=26, 30, 34, 38 at.%) alloys were fabricated with Zr (99.7% purity), Cu (99.997% purity), and Al (99.99% purity) as melting 5 times by arc melting method before rods 2mm in diameter was manufactured. In order to analyze GFA (Glass Forming Ability), rods were observed by Optical Microscopy and SEM and $T_g$, $T_x$, ($T_x$ is crystallization temperature and $T_g$ is the glass transition temperature) and Tm were measured by DTA and DSC. Powder was manufactured by Gas Atomizer and target was sintered using powder in large supercooled liquid region ($=T_x-T_g$) by SPS(Spark Plasma Sintering). Amorphous foil was prepared by RSP process with 5 gram alloy button. The composition of the foil and sputtered thin film was analyzed by EDS and EPMA. In the result of DSC curve, binary alloys ($Zr_{62}Cu_{38}$, $Zr_{60}Cu_{40}$, $Zr_{50}Cu_{50}$) and ternary alloys ($Zr_{64}Al_{10}Cu_{26}$, $Zr_{56}Al_{10}Cu_{34}$, $Zr_{52}Al_{10}Cu_{38}$) have $T_g$ except for $Zr_{70}Cu_{30}$ and $Zr_{60}Al_{10}Cu_{30}$. The compositions with $T_g$ made into powders. Figure shows XRD data of thin film showed similar hollow peak.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.665-671
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• 2007

In this study, the soil characteristics and the landslide probability are investigated in East Island of Dok-do. The distribution and depth of soil layer were investigated and the soil samples were taken from the soil layer in East Island. As the results of field investigation, the soil layer was partly distributed in specific location and the soil depth was ranged from 1cm to 50cm. Also, the soil depth was mainly ranged about 10cm in the large part of soil layer. The soils were classed as the weathered residual soils and involved many organic contents such as rotten roots and leaves. The average of water contents is 23.2%, and the average of liquid limits is 42.2%. Also, the soils is non-plastic condition. Also, the soils were mainly classed as the poor graded sand including loam contents. Meanwhile, the landslide probability was investigated through a survey of the soil layer distribution in East Island. The soil depth was very shallow in the large part of the soil layer, and the distribution area of soil layer was small. Therefore, it may predict that the landslide probability is very low due to the dissatisfaction of landslide occurrence condition.

• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.277-281
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• 2011

A rapid and very sensitive high-performance liquid chromatography/atmospheric-pressure chemical-ionization mass spectrometry method to detect ethylenethiourea (ETU) fungicide residues in fruits was developed. Methylene chloride was used as the surface extraction solvent for the target component. Recovery rates improved when cysteine hydrochloride and sodium carbonate were added to product prior to fortification. The limits of detection and quantification were approximately 0.006 and 0.02 mg/kg, respectively, from mandarin oranges. Recoveries from mandarin oranges, oranges, bananas, and pears, spiked in the range of 0.05-0.5 mg/kg, averaged 80-100%. The proposed method was used to monitor the presence of ETU in commercial fruits purchased from different markets in Seoul, Korea. ETU was found in four orange peels and in three mandarin orange peel samples. The highest ETU residue levels were $73.6{\mu}g/kg$ and $29.8{\mu}g/kg$.

• Analytical Science and Technology
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• v.18 no.3
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• pp.250-256
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• 2005

A selective method of high performance liquid chromatography with UV detector has been applied to determine 4 tetracycline antibiotics in the animal food, simultaneously. The targets were chlortetracycline (CTC), doxycycline (DC), oxytetracycline (OTC), and tetracycline (TC) that are used routinely in veterinary medicine for prevention and control of disease. Food samples were beef, pork, chicken, milk, whole egg, flatfish (Limanda yokohamae), jacopever (Sebastes hubbsi), seabream (Chrysophrys major), eel (Anguilla japonica) and lobster (Hommarus americanus). After extracting food samples with 20% trichloroacetic acid and McIlvaine buffer, they were purified by a $C_18$ SPE cartridge with 0.01M methanolic oxalic acid solution. The concentrated residue was re-dissolved in methanol, filtered, cleaned up and analyzed on a $C_18$ column. The mobile phase was a mixture of 0.01M oxalic acid and acetonitrile with a gradient ratio from 85:15 to 60:40. The UV wavelength was 365 nm. The overall recoveries were ranged from 71% to 98% and the limit of detections were 0.022 for CTC, 0.012 for DC and OTC and 0.009 mg/kg for TC at signal/noise > 3, respectively. As results, CTC, DC and TC were not detected in all selected food samples, however, OTC was detected in meat and fishes. The determined level of OTC was 0.04 ppm for pork, 0.17 ppm for flatfish and 0.05 and 0.08 ppm for jacopever, that were within the Maximum Residue Limits (MRLs) in the food.

• Journal of Food Hygiene and Safety
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• v.33 no.5
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• pp.354-360
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• 2018

This study presents a method validation for extraction and quantitative analysis of trichothecene mycotoxins in nuts based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach for extraction and enhanced matrix removal (EMR)-lipid-disperive-SPE (d-SPE) cleanup method, with detection and quantification by high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in positive- and negative-ion modes. Linearity, precision, and accuracy were validated for LC-MS/MS methods. Results obtained with LC-MS/MS were linear, with correlation coefficient ($R^2$) of 0.998. Limits of detection and quantification for mycotoxins were $0.41-3.57{\mu}g/kg$ and $1.23-10.82{\mu}g/kg$, respectively. Intra- and inter-day precisions (RSD, %) were 0.40-8.44% and 1.93-12.46%, respectively. Results indicated to be rapidly and accurately identifying trichothecene mycotoxins and may be used as a suitable safety management method for nuts and nuts related commodities.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.14-21
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• 1982

Analytical methods for residues of six N-methylcarbamate insecticides were investigated to compare the minimum detectability, recovery from several crops and feasibility of multiple residue analysis. Those methods studied in this work included spectrophotometry by diazotization and gas chromatography by N-trifluoroacetylation(TFA), pentafluorobenzylether(PFB) and dinitrophenylether (DNP) derivatization. Maximum absorbed wavelength of the diazotized MIPC, XMC, BPMC, propoxur and carbofu ran was around 460 ㎚, while that of carbaryl recorded 510 ㎚. Recovery from brown rice and apple by diazotization method ranged from 80 to 120% and minimum detectable limits were 0.03 to 0.05 ppm in 50 g of the sample. Minimum detectability of PFB derivatives by gas chromatography was superior to TFA and DNP derivatives. DNP derivatives showed the longest retention time among the given derivatives. Recovery from crops by gas chromatographic met hod ranged 74 to 94%, 78 to 93%, and 85 to 99% in brown rice, rice straw and apple, respectively. Limit of detection was 0.01 ppm for TFA, 0.005 ppm for PFB and 0.02 ppm for DNP derivatives in 50 g of the crop samples.

• Food Science and Preservation
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• v.21 no.1
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• pp.69-74
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• 2014

We tested for residual pesticide levels in school foodservice agricultural products in Seoul, Korea from 2010 to 2012. A total of 316 samples of 23 different types of agricultural products were analyzed via gas chromatography-nitrogen phosphate detector (GC-NPD), an electron capture detector (GC-${\mu}ECD$), a mass spectrometry detector (GC-MSD), and a high performance liquid chromatography-ultraviolet detector (HPLC-UV). We used multi-analysis methods to analyze 185 different pesticide types. Among the selected agricultural products, residual pesticides were detected in 26 samples (8.2%), of which 6 samples (1.9%) exceeded the Korea Maximum Residue limits (MRLs). We detected pesticide residue in more than 65% of the Chwinamul, while 6 among 9 analyzed samples contained pesticide residue, and 1 sample exceeded the Korea MRLs. Among the 185 kinds of pesticides that we have tested, 18 were detected, while 7 of them were detected more than twice. Data obtained were then used for estimating the potential health risks associated with the exposures to these pesticides. The most critical commodity is carbofuran in the perilla leaves, which has contributed 3.8% to the hazard index (HI). These results showed that the detected pesticides could not be considered as a serious public health problem. Nevertheless, constant supervision is recommended.

• Journal of Pharmaceutical Investigation
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• v.41 no.3
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• pp.191-196
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• 2011

In this study simple and sensitive high performance liquid chromatographic method using a commercially available column, was developed and validated for the determination of zolpidem tartrate in human plasma. The developed method with suitable validation was applied to a bioequivalence study of two different kinds of zolpidem tartrate. Two different formulations containing 10 mg of zolpidem tartate (CAS : 99294-93-6) were compared in 24 healthy male volunteers in order to compare the bioavailability and prove the bioequivalence. The study was performed in an open, single dose randomized, 2-sequence, cross-over design in 24 healthy male volunteers with a one-week washout period. Blood samples for pharmacokinetic profiling were drawn at selected times during 12 h. The mean $AUC_{0-12h}$, $C_{max}$, $T_{max}$ and $T_{1/2}$ were $676.6{\pm}223.4$ $ng{\cdot}h{\cdot}mL^{-1}$, $177.4{\pm}34.2$ $ng{\cdot}mL^{-1}$, and $0.8{\pm}0.4$ and $3.5{\pm}2.1$, respectively, for the test formulations, and $640.7{\pm}186.6$ $ng{\cdot}h{\cdot}mL^{-1}$, $193.0{\pm}64.5$ $ng{\cdot}mL^{-1}$, and $0.9{\pm}0.4$ and $2.7{\pm}0.9$, respectively, for the reference formulation. Both primary target parameters $AUC_{0-12h}$ and $C_{max}$ were log-transformed and tested parametrically by analysis of variance (ANOVA). 90% confidence intervals of $AUC_{0-12h}$ and $C_{max}$ were in the range of acceptable limits of bioequivalence (80-125%). Based on these results, the two formulations of zolpidem tartate are considered to be bioequivalent.

• Journal of Applied Biological Chemistry
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• v.56 no.1
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• pp.29-35
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• 2013

This study was performed to analyze 48 kinds of pesticide residues using gas chromatography (GC)/nitrogen phosphorous detector, GC/micro electron capture detector, GC/mass selective detector, and high performance liquid chromatograph/diode array detector in 186 fresh ginseng samples collected in the Seoul area from 2010 to 2011. Fresh ginseng dietary intakes were estimated using the data from the 2009 Korea National Health and Nutrition examination survey. Residual pesticides were detected in 79 samples (42.5%) with eight different fungicides. Only 20 samples (10.8%) exceeded the maximum residue limits (MRLs) for pesticides registered by the Korea Food & Drug Administration. Among them, tolclofos-methyl residues (10.2%) exceeded the MRL for fresh ginseng in 18 ginseng seedlings and one of the two-year old fresh ginseng plants, and the residual level in just one ginseng seedling violated the MRL for pyrimethanil. The results showed that residual pesticides levels in marketable fresh ginseng around Seoul were relatively safe. The percent acceptable daily intake (%ADI) was calculated using pesticide residues in fresh ginseng and dietary intakes of fresh ginseng. The risk caused by pesticide residues in fresh ginseng was very low.

• Journal of the Korean Chemical Society
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• v.39 no.12
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• pp.918-924
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• 1995

THMs and PCBs were separated and analysed with elution on Novapak ODS or $\mu-Bondapak$ phenyl column by an eluent containing p-nitrophenol (p-NP). THMs studied were CHCl3, CHBrCl2, CHBr2Cl, and CHBr3, and PCBs used were Aroclor 1221, 1242, 1248, $\alpha-$ and $\beta-BHC.$ It was thought that the retention on the stationary phase and sensitivities of the samples are related to the interaction between the sample and stationary phase or p-NP. THMs were separated completely on the ODS column by elution with MeOH-water (30 : 70) containing $1.0{\times}10^{-4}$ M p-NP and some of PCBs were separated on the phenyl column by elution with $CH_3CN$-water(50 : 50) containing $1.0{\times}10^{-4}$ M p-NP. Detection limits of THMs were from $1.0{\times}10^{-4}$ g to $1.0{\times}10^{-6}$ g. Aroclors were $2{\times}10^{-6}$ g, and $\alpha-$ and $\beta-BHC$ were $2{\times}10^{-4}$ g and $1.0{\times}10^{-4}$ g respectively.