• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.15 no.3
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• pp.93-98
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• 2009

Migration levels of plasticizers, di-n-butyl phthalate (DBP), benzyl-butyl phthalate (BBP), di-n-octyl phthalate(DNOP), di-iso-decyl phthalate (DIDP) and di-iso-nonyl phthalate (DINP), di-(2-ethylhexyl) adipate (DEHA), from 46 poly(vinyl chloride) (PVC) wrap films and 54 PVC gaskets into food simulants were determined using gas chromatography/mass spectrometry (GC/MS). The method was validated with limit of detection (LOD) of $0.01{\sim}0.02\;{\mu}g/mL$ for DBP, BBP, DNOP and DEHA, and $2\;{\mu}g/mL$ for DIDP and DINP. The linearity were found to be > 0.99 for all the compounds in concentration range of $0.1{\sim}81.4\;{\mu}g/mL$, and overall recoveries were ranged from 90.4 ~ 99.6%. DBP, BBP, DNOP, DEHA, DIDP and DINP were not detected in food simulants, except 1 wrap sample from which 0.28 and $0.99\;{\mu}g/mL$ of DEHA were detected respectively when tested with 20% ethanol and n-heptane as food simulants. These values were below the regulatory limitation in European Union (EU).

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2206-2213
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• 2016

Recently, several studies have revealed that commercial microbial identification systems do not accurately identify the uncommon causative species of candidiasis, including Candida famata, Meyerozyma guilliermondii, and C. auris. We investigated the accuracy of species-level identification in a collection of clinical isolates previously identified as C. famata (N = 38), C. lusitaniae (N = 1 2), and M. guilliermondii (N = 5) by the Vitek 2 system. All 55 isolates were re-analyzed by the Phoenix system (Becton Dickinson Diagnostics), two matrix-assisted laser desorption ionization-time of flight mass spectrometry analyzers (a Vitek MS and a Bruker Biotyper), and by sequencing of internal transcribed spacer (ITS) regions or 26S rRNA gene D1/D2 domains. Among 38 isolates previously identified as C. famata by the Vitek 2 system, the majority (27/38 isolates, 71.1%) were identified as C. tropicalis (20 isolates) or C. albicans (7 isolates) by ITS sequencing, and none was identified as C. famata. Among 20 isolates that were identified as C. tropicalis, 17 (85%) were isolated from urine. The two isolates that were identified as C. auris by ITS sequencing originated from ear discharge. The Phoenix system did not accurately identify C. lusitaniae, C. krusei, or C. auris. The correct identification rate for 55 isolates was 92.7% (51/55 isolates) for the Vitek MS and 94.6% (52/55 isolates) for the Bruker Biotyper, as compared with results from ITS sequencing. These results suggest that C. famata is very rare in Korea, and that the possibility of misidentification should be noted when an uncommon Candida species is identified.

• Analytical Science and Technology
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• v.13 no.5
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• pp.636-645
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• 2000

A method is described for the determination of organotins in water samples by GC/MS. Optimized derivatization methods for ethylation and hydrogenation of organotins were surveyed according to various reaction conditions such as time, pH and concentration of reagents. The organotins were extracted with n-hexane in presence of 0.1% tropolone and hydrogenated with sodium borohydride. Extraction recoveries of organotins with hydrogenation were in the range of 61-112%. After ethylation, organotins in water samples were extracted by liquid-liquid extraction (LLE) and solid-phase extraction (SPE). Using LLE, extraction recoveries were in the range of 74-113%. The recoveries ranged from 61-97% in the case of SPE with styrene-divinylbenzene copolymers. Method detection limits of hydrogenated and ethylated organotins ranged from 0.05 to 0.5 ng/ml and from 0.02 to 0.05 ng/ml, respectively.

• Analytical Science and Technology
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• v.13 no.5
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• pp.616-623
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• 2000

The most common phthalate acid esters (8 compounds) and adipate were determined from water and sediment simultaneously. After liquid-liquid extraction with n-hexane for water and sonication extraction with dichloromethane for sediment, these were determined by the GC/MS with SIM mode. There were good linearities (above $R^2=0.993$) on the range of the 0.1-20 ng/ml (water) and 10-500 ng/g (sediment), and the detection limits of method were below 0.1 ng/ml and 10 ng/g for water samples and sediment samples, respectively. The method shows a good precision and accuracy for measurement of phthalates and adipate.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.363-368
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• 2021

The fruits of tomato (Lycopersicon esculentum) were extracted with 70% aqueous methanol (MeOH) and the concentrates were partitioned into ethyl acetate (EtOAc), n-butanol (n-BuOH), and water (H₂O) fractions. The repeated silica gel (SiO₂) and octadecyl silica gel column chromatographies for the EtOAc fraction, whose activity was confirmed, led to isolation of one flavone compound. Nuclear magnetic resornance, infrarad spectroscopy, and mass spectroscopy (MS) revealed the chemical structure of the isolated compound, 5,7,3'-trihydroxy-6,4',5'-trimethoxyflavone (1). LC-MS/MS analysis determined the content level of compounds 1 in the MeOH extract to be 4.02±0.12 ㎍/mg and in the TME-10 fraction to be 0.96±0.03 ㎍/mg. Through this study, the antioxidantive capacity was confirmed by demonstrating that the L. esculentum extract and their fractions showing an increase in glutathione mean and a decrease in glutathione heterogeneity uniformly raises the intracellular glutathione level.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.3
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• pp.285-291
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• 2022

In order to use the liquid rocket fuel, 1,5-diamino-4-methyltetrazolium azide, [DMT]⁺[N₃]^- and 1,5-diamino-4-methyltetrazolium cyanide, [DMT]⁺[CN]^- were synthesized and prepared the ionic liquid rocket fuel after dissolving the synthesized solid-type energetic chemicals in hydrazine, respectively. The thermal decomposition temperatures(T_d) and densities(d) of the prepared ionic liquid rocket fuels were about 200 ℃ and above 1.0 g/cm³ respectively. The ignition delay times(I_dt) of the ionic liqud rock fuels with [DMT]⁺[N₃]^- and [DMT]⁺[CN]^- were in a range of 26.6 - 82.5 ms and the 44.0 - 98.5 ms, respectively. These results mean that the synthesized tetrazolium salts could be used as an ionic liquid rocket fuels. The viscosities of the ionic liqud rock fuels with [DMT]⁺[N₃]^- and [DMT]⁺[CN]^-, which were dissolved in mixture solution of hydrazine/2-hydroxyethylhydrazine were to be 1.34 - 101 cP, and 1.29 - 80.5 cP, respectively. The synthesized ionic liquid rocket fuels in this study could be used as rocket fuel because the [I_dt(100 ms or less), T_d(150 ℃ or more), d(1.00 g/cm³ or more), and η(40.0~ 100 cP)] were achieved to satisfy the range of the used liquid rocket fuels.

• Journal of Environmental Science International
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• v.33 no.9
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• pp.645-665
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• 2024

For volatile organic compounds (VOCs) emanating from workplaces within the Noksan national industrial complex, the emission characteristics of pollutants were identified through zone-based measurements using vehicles equipped with selective ion flow tube mass spectrometry(SIFT-MS). The average concentration of total VOCs was higher in zones 2, 4, and 5 than in zones 1, 3, and 6, and was 2.1 to 4.2 times higher than background concentrations. The average concentrations of pollutants investigated were (from highest to lowest) methyl ethyl ketone, formaldehyde, methanol, and n-hexane. However, the pollutants that should be prioritized for reduction to decrease ozone generation were (from highest to lowest) methyl ethyl ketone, n-hexane, for maldehyde, and ethylbenzene+xylene. Benzene, a substance governed by atmospheric environmental standards, exhibited a frequency distribution exceeding the stipulated limits, and concentrations exceeding 100 ppb were identified for methyl ethyl ketone, methanol, toluene, and n-hexane. In certain class 4 and 5 workplace facilities, VOC emissions and emission prevention installations were inadequately managed, necessitating the formulation of management measures for small enterprises. Also, workplaces that emit large amounts of VOCs need to upgrade to VOC-prevention installations with higher processing efficiencies. To efficiently monitor VOCs in a wide range of areas, such as the Noksan national industrial complex, it is considered appropriate to monitor workplaces that emit high concentrations of VOCs using mobile SIFT-MS in real time rather than relying on fixed monitoring methods. A specialized method targeting approximately 10 VOCs is necessary to quickly track emission sources.Furthermore, it is essential to phase in a system for the intensive management of suspected workplaces based on accumulated data from SIFT-MS in areas where high VOC concentrations are measured and to establish a cooperative system for sharing data between relevant institutions.

• Microbiology and Biotechnology Letters
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• v.45 no.2
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• pp.143-148
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• 2017

Ten Bacillus strains possessing amine oxidase activity were selected from 126 Bacillus isolates from meju and doenjang (two traditional Korean soybean foods). Among the isolates, two B. licheniformis strains (8MI05 and 8MS03) harbored the amine oxidase gene yobN. By conducting a gene search against published B. licheniformis genomes, the possession of yobN was proved to be a strain-specific property. Both strains degraded four types of biogenic amines (cadaverine, histamine, putrescine, and tyramine) supplemented in tryptic soy broth during their culture. A recombinant harboring yobN also degraded the four types of biogenic amines during cultivation. Both Bacillus strains could grow at a NaCl concentration of 14% and exhibited strain-specific protease and lipase activities.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.1-7
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• 2000

The SNOSFET memory devices with ultrathin ONO(tunnel oxide-nitride-blocking oxide) gate dielectric were fabricated using n-well CMOS process and investigated its characteristics. The thicknesses of tunnel oxide, nitride and blocking oxide were $23{\AA},\; 53{\AA}\; and\; 33{\AA}$, respectively. Auger analysis shows that the ONO layer is made up of $SiO_2(upper layer of blocking oxide)/O-rich\; SiO_x\N\_y$. It clearly shows that the converting layer with $SiO_x\N\_y(lower layer of blocking oxide)/N-rich SiO_x\N\_y(nitride)/O-rich SiO_x\N\_y(tunnel oxide)$. It clearly shows that the converting layer with $SiO_x\N\_y$ phase exists near the interface between the blocking oxide and nitride. The programming condition of +8 V, 20 ms, -8 V, 50 ms is determined and data retention over 10 years is obtained. Under the condition of 8 V programming, it was confirmed that the modified Fowler-Nordheim tunneling id dominant charge transport mechanism. The programmed threshold voltage is distributed less than 0.1 V so that the reading error of memory stated can be minimized. An $8\times8$ NAND type flash EEPROM with SONOSFET memory cell was designed and simulated with the extracted SPICE parameters. The sufficient read cell current was obtained and the upper limit of $V_{TH}$ for write state was over 2V.

• Journal of the Korean Magnetics Society
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• v.26 no.4
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• pp.129-132
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• 2016

The effect of thermal-nitrification on L1o transfomation in nano-sized FePt particles was studied. As-synthesized FePt nanoparticles by thermal decomposition method have fcc structured phase and their Hc and Ms were 247.34 Oe and 27.308 emu/g, respectively. According to the XRD analysis, phase transformation from fcc (face centered cubic) to fct (face centered tetragonal) structure was revealed by heating under $NH_3+H_2$ mixed-gas atmosphere. Also a slight shift of each (111) peak indicated phase transformation from fcc to fct structure. Hc and Ms of fct FePtN were 1058.2 Oe and 32.718 emu/g, respectively. The nano-sized FePtN magnetic particles synthesized by thermal decomposition method and mixed-gas nitrification are expected for advanced applications such as high density magnetic recording media and biomedical materials.