• Journal of Food Hygiene and Safety
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• v.8 no.1
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• pp.9-15
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• 1993

In an attempt to quantitate and qualitate residual antibiotics and antibacterial agents in meat simultaneously, we studied a gas chromatography-mass spectrometry(GC/M8) analysis. For a simultaneous analysis of penicillin G, chloramphenicol and thiamphenicol in meat, a simple and rapid clean-up procedure including extraction with 0.01 M EDTA-2Na Mcilvaine buffer (pH 4.0), defatting with n-hexane, and elution with 0.01M-methanolic oxalic acid from Bond Elute $C_{18}$ cartridge, and quantitation by selected ion monitoring (SIM) mode after derivatization was performed. The recoveries (%) of penicillin G, chloramphenicol and thiamphenicol (CV, %) at 1 ppm fortification level were 63.5 (7.6), 76.3 (8.1) and 84.7 (2.0), and the detection limits of those were 0.6, 0.085 and $0.084\;\mu\textrm{g}$ beef, respectively. This method using 81M mode allows excellent detection and quantitation of residual antibiotics and antibacterial agents in meat. Moreover, confirmation by a full scan electron impact mass spectrum is possible if residual level in the sample in above 1 ppm.

• Journal of Life Science
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• v.29 no.2
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• pp.198-201
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• 2019

Recently, it has been reported that Bacillus mojavensis possesses antifungal properties and plant growth-promoting activities, which are similar to the characteristics of siderophore. In this study, the siderophore produced by B. mojavensis was assessed using a solid phase extraction (SPE) cartridge and liquid chromatography quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS). After B. mojavensis was incubated in phenol medium for 16 hr and lyophilized, the sample was dissolved in water and loaded to an SPE cartridge to remove interferences. The cartridge was washed with 5% methanol in water and eluted with 2% formic acid in methanol sequentially. The eluted solution was evaporated under a stream of nitrogen gas and reconstituted in methanol. The reconstituted sample was filtered, and $1{\mu}l$ of the sample was assessed using Q-TOF MS/MS. The mass spectrometer was operated using the positive electrospray ionization mode. Based on the mass spectrum and tandem mass spectrum, the siderophore produced by B. mojavensis was bacillibactin, one of the catechol types of siderophore with a molecular weight of 882.2556. This siderophore analysis could provide a justification for the study of B. mojavensis as a functional food and for pharmaceutical applications.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.98-103
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• 1995

During the screening of antifungal antibiotics from microbial metabolites, we selected Pseudomonas aeruginosa KGM-100 showing powerful antagonistic activity against various phytopathogenic fungi. Antibiotics KGM-100A and KGM-100B were purified from the culture broth of Pseudomonas aeruginosa KGM-100 by diaion HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, preparative TLC and recrystallization. KGM-100A which was recrystallized in MeOH showed antimicrobial activities against a broad spectrum of fungi and bacteria. Physico-chemical properties of KGM-100A were determined and identified to be phenazine-l-carboxylic acid by UV, IR, $^{1}$H-NMR, $^{13}$C-NMR, mass spectrum, and elemental analyses.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.34-40
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• 1997

Intervalence subband absroption of normally incident infrared radiation in p-type InGaAs-InAlAs coupled quantum well (CQW) is theoretically investigated by the multiband effective mass formalism. By solving a 4*4 luttinger-kohn hamitonian, we calculate valence subband structures, intervalence subband transition matrix elements, and absorption coefficient spectrum in the CQW which consists of a wider well, a thinner well and a barreir between them. Using the flexible design parameters given to the valence band CQW structure, we show that the absorption coefficient profile can be tailored. For a carefully designed CQW, theabsorption coefficient cn be made to maintain a large value over a wider wavelength range of incident infrared radiation compared with that shown in intersubband absorption in usual single quantum well.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.191-200
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• 1997

This paper discusses prediction of the sound pressure level produced by simple engine exhaust systems(plain pipe, plain expansion chamber pipe, plain expansion chamber with internally extended inlet and outlet pipe, perforated pipe enclosed in a plain expansion chamber) and a computer program has been developed which predicts the sound pressure level and the frequency spectrum. The program utilizes unsteady flow gas dynamic theory and acoustic theory to predict the pressure-time history in the exhaust system and the mass flow rate-time history at the open end of the system and the sound pressure levels(1/3 Octave band levels) and the frequency spectrum in semi-anechoic room. The predictions are compared with measured levels and show a high degree of correlation.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1333-1346
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• 2009

To assure the reliability of cylinders or shells with fluid-filled annulus, it is necessary to investigate the modal characteristics considering fluid-structure interaction effect. In this study, theoretical background and several finite element models are developed for cylindrical shells with fluid-filled annulus considering fluid-structure interaction. The effect of the inclusion of the fluid-filled annulus on the natural frequencies is investigated, which frequencies are used for typical dynamic analyses such as responses spectrum, power spectral density and unit load excitation. Their response characteristics are addressed with respect to the various representations of the fluid-structure interaction effect.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.57.2-57.2
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• 2014

Protostellar jets and outflows are signatures of star formation and promising mechanisms for driving supersonic turbulence in molecular clouds. We quantify outflow-driven turbulence through three-dimensional numerical simulations using an isothermal version of the total variation diminishing code. We drive turbulence in real space using a simplified spherical outflow model, analyze the data through density probability distribution functions (PDFs), and investigate density and velocity power spectra. The real-space turbulence-driving method produces a negatively skewed density PDF possessing an enhanced tail on the low-density side. It deviates from the log-normal distributions typically obtained from Fourier-space turbulence driving at low densities, but can provide a good fit at high densities, particularly in terms of mass-weighted rather than volume-weighted density PDF. We find shallow density power-spectra of -1.2. It is attributed to spherical shocks of outflows themselves or shocks formed by the interaction of outflows. The total velocity power-spectrum is found to be -2.0, representative of the shock dominated Burger's turbulence model. Our density weighted velocity power spectrum is measured as -1.6, slightly less that the Kolmogorov scaling values found in previous works.

• Journal of Radiation Protection and Research
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• v.34 no.2
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• pp.65-68
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• 2009

Metal-semiconductor contact is very important for the operating property of semiconductor detector. $Cd_{0.96}$ $Zn_{0.04}$ Te semiconductor crystal was grown with Bridgman method, and the crystal was cut and polished. EPMA (Electron Probe Micro Analyzer) and ICP-MS (Inductively Coupled Plasma Mass Spectrometry) analysis were done to obtain the chemical composition and impurity of the crystal. Metal contact was deposited with thermal evaporator on both sides of the crystal. Detectors with Au/CZT/Au and In/CZT/Au structure were made, and I-V curve and the energy spectrum were measured with the detectors. It could be seen that the detector with the In/CZT/Au structure has superior property than the detector with Au/CZT/Au structure when the crystal resistivity was low. However, the metal contact structure effect becomes low when the crystal resistivity was high.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.428-429
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• 2005

Novel fluoroionophore of dibenzothiazolyl-dibenzo-crown ethers were synthesized from diformal-dibenzo 18-crown-6 (24-crown-8) with 2-aminothiophenol, and they were characterizated by $^1H$-NMR, $^{13}C$-NMR, IR spectrum, Mass spectrum, elemental analyses, respectively. The fluorescent properties of the newly synthesized crown ether were examined with $Li^+$, $Na^+$, $K^+$, $Rb^+$, $Cs^+$, $NH_4^+$ and $CF_3COOH$, respectively. With protonation using $CF_3COOH$, the absorption bands of the new crown ethers are further blue shifted, the maximum emission wavelengths further red shifted.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.525-525
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• 2005

This study is for the seismic analysis and the structural integrity evaluation of the box beam for supporting nuclear fuel-transfer-basket of the HANARO reactor pool. For performing the seismic analysis and evaluating the structural integrity in air or submerged condition, the finite element model of the fuel-transfer-basket and its supporting box beam(the coupled model) was developed. The hydrodynamic effect is also considered by using added mass concept. The seismic response spectrum analyses of the coupled model under the design floor response spectrum loads of Safe Shutdown Earthquake(SSE) were performed. Through the numerical experiments, the analysis results show that the stress values of the coupled model lot the structural integrity are within the ASME Code limits.