• Journal of the Korean Chemical Society
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• v.45 no.6
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• pp.524-531
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• 2001

Micro-HPLC/IS/MS after solid phase extraction has been employed to enhance the accu-racy in the determination of toxic microcystins, such as microcystin-LR, -YR and -RR. The absorbance at 238 nm in HPLC/UV and characteristic spectra of 135 m/z and $[M+H]^+$ m/z in MS have been widely monitored to identify those microcystin-LR, -YR and -RR. In this study, new lines at 507 m/z for LR, 520 m/z for RR and 532 m/z for YR have been additionally detected in the micro-HPLC/IS/MS spectrum, corresponding to double charge. The micro-HPLC/IS/MS methodology has been applied to investigate the presence of the toxic microcystins in Taecheong lake.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3C
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• pp.271-280
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• 2008

M channel near-perfect-reconstruction(NPR) pseudo-QMF banks are a hybrid of conventional pseudo-QMF design and spectral factorization approach where the analysis and synthesis filters are cosine-modulated versions of the prototype-lowpass filter(p-LPF). However, p-LPF H(z) does not have linear-phase symmetry as well as magnitude-distortion optimization since it is obtained by spectral factorization of $2M^{-th}$ band filter $G(z)=z^{-(N-1)}H(z^{-1})H(z)$. A fair amount of attention, therefore, has been focused on the design of filter banks for reducing only alias-cancellation distortion without reconstructed-amplitude distortion. In this paper, we propose a new method for designing linear-phase p-LPF in NPR pseudo-QMF banks, which is based on Maxflat(maximally flat) FIR filters with closed-form transfer function. In addition, p-LPF H(z) is optimized in this approach so that the 2M-channel overall distortion response represented with $G(z)=H^2(z)$ approximately becomes an unit magnitude response. Through several examples of NPR pseudo-QMF banks, it is shown that the peek ripple of the overall magnitude distortion is less than $3.5{\times}10^{-4}\;({\simeq}-70dB)$ and analysis/synthesis filters have the sharp monotone-stopband attenuation exceeding 100 dB.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.79-84
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• 1998

Tandem HPLC and atmospheric pressure chemical ionization(APcI) LC/MS method was used for the determination and confirmation of carbendazim residues in soybean sprout. Fluorescence(FL) detector was connected in tandem with the ultraviolet(UV) detector for dual detection of the carbendazim residue at the excitation and emission wavelength of 280 nm and 310 nm, respectively. The limit of detection for carbendazim was $0.1{\mu}g/kg$ sample. Recoveries of carbendazim from fortified soybean sprout at 0.5, 1.0 and 2.0 ppm were averaged 89.1%. Mass spectrometry using a APcI source confirmed the carbendazim residue in the soybean sprout sample. Fragmentation pattern on the APcI LC/MS spectrum of carbendazim was simpler than that from electron impact(EI) mass spectrum. Carbendazim produced 3 major ions including m/z 133, m/z 159 and m/z 191($M^{+}$). This method was sensitive enough to provide reliable and reproducible results for practical applications.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.47-60
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• 1975

For the calculation of population parameter and estimation of recruitment of a fish population, an application of multiple regression method was used with some statistical inferences. Then, the differences between the calculated values and the true parameters were discussed. In addition, this method criticized by applying it to the statistical data of a population of bigeye tuna, Thunnus obesus of the Indian Ocean. The method was also applied to the available data of a population of Pacific saury, Cololabis saira, to estimate its recuitments. A stock at t year and t+1 year is, $N_{0,\;t+1}=N_{0,\;t}(1-m_t)-C_t+R_{t+1}$ where $N_0$ is the initial number of fish in a given year; C, number o: fish caught; R, number of recruitment; and M, rate of natural mortality. The foregoing equation is $$\phi_{t+1}=\frac{(1-\varrho^{-z}{t+1})Z_t}{(1-\varrho^{-z}t)Z_{t+1}}-\frac{1-\varrho^{-z}t+1}{Z_{t+1}}\phi_t-a'\frac{1-\varrho^{-z}t+1}{Z_{t+1}}C_t+a'\frac{1-\varrho^{-z}t+1}{Z_{t+1}}R_{t+1}......(1)$$ where $\phi$ is CPUE; a', CPUE $(\phi)$ to average stock $(\bar{N})$ in number; Z, total mortality coefficient; and M, natural mortality coefficient. In the equation (1) , the term $(1-\varrho^{-z}t+1)/Z_{t+1}$s almost constant to the variation of effort (X) there fore coefficients $\phi$ and $C_t$, can be calculated, when R is a constant, by applying the method of multiple regression, where $\phi_{t+1}$ is a dependent variable; $\phi_t$ and $C_t$ are independent variables. The values of Mand a' are calculated from the coefficients of $\phi_t$ and $C_t$; and total mortality coefficient (Z), where Z is a'X+M. By substituting M, a', $Z_t$, and $Z_{t+1}$ to the equation (1) recruitment $(R_{t+1})$ can be calculated. In this precess $\phi$ can be substituted by index of stock in number (N'). This operational procedures of the method of multiple regression can be applicable to the data which satisfy the above assumptions, even though the data were collected from any chosen year with similar recruitments, though it were not collected from the consecutive years. Under the condition of varying effort the data with such variation can be treated effectively by this method. The calculated values of M and a' include some deviation from the population parameters. Therefore, the estimated recruitment (R) is a relative value instead of all absolute one. This method of multiple regression is also applicable to the stock density and yield in weight instead of in number. For the data of the bigeye tuna of the Indian Ocean, the values of estimated recruitment (R) calculated from the parameter which is obtained by the present multiple regression method is proportional with an identical fluctuation pattern to the values of those derived from the parameters M and a', which were calculated by Suda (1970) for the same data. Estimated recruitments of Pacific saury of the eastern coast of Korea were calculated by the present multiple regression method. Not only spring recruitment $(1965\~1974)$ but also fall recruitment $(1964\~1973)$ was found to fluctuate in accordance with the fluctuations of stock densities (CPUE) of the same spring and fall, respectively.

• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.138-146
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• 2011

This study was carried out to select salt tolerant zoysiagrass breeding lines. Eighty two native zoysiagrasses collected from S. Korea were used in this study. Saline water were prepared by mixing sea water and tap water. ECw levels of saline water treated ranged from 2 to $3dS{\cdot}m^{-1}$. Zoysiagrass planted in pot by sprigging were soaked into the plastic box containing saline water. Winter injury was investigated under the pot condition. Most of Z. japonica types did not show winter injury. But Z. tenuifolia type, Z. matrella type, and Z. sinica type showed winter injury under the pot condition at Cheonan area. NaCl level in soil was increased from 0% to 0.51% by treatment of saline water. Soil ECe measurement showed upto $170dS{\cdot}m^{-1}$. Z. tenuifolia type (Z5034), Z. matrella type ('Konhee', Z4109, 'Semill'), Z. japonica type (Z1055, Z1040, Z1008, 'Zenith', 'Millock') and medium leaf type zoysiagrass (Z6096, Z6118, Z6021, Z6074) resulted in below 30% leaf firing under the saline condition. This approach might be useful for selecting salt tolerant breeding lines.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.49-56
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• 2011

Purpose: The aim of this study was to evaluate the effect of mechanical, chemical surface treatments on the zirconia-to-resin cement shear bond strength (SBS). Materials and methods: Eighty zirconia discs (Lava, 3M ESPE) and eighty zirconia/alumina composite (Zirace, Acucera) were embedded in an epoxy resin base. Zirconia discs were randomly divided in to four treatment groups(10 for each manufacturer): $50\;{\mu}m$ $Al_2O_3$ sandblasting (S50), $110\;{\mu}m$ $Al_2O_3$ sandblasting (S110), $50\;{\mu}m$ $Al_2O_3$ and primer (Z-Prime Plus, Bisco Inc) (S50z) and $110\;{\mu}m$ $Al_2O_3$ and primer (Z-Prime Plus) (S110z). Two resin-based luting cements (Calibra, Panavia F) were used to build 2 mm diameter cylinders onto the zirconia. After 24 h of storage in water, SBS testing was evaluate using a universal testing machine. Bond strength data were analyzed with one-way ANOVA, two-way ANOVA test and post hoc comparison was done using Tukey test (${\alpha}$ = .05). Results: Groups using primer showed the high shear bond strength. The groups that did not use primer presented lower shear bond strengths. Conclusion: The use of primer (Z-Prime Plus, Bisco) had significantly higher shear bond strengths.

• Analytical Science and Technology
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• v.15 no.5
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• pp.410-416
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• 2002

In this study, a new quantitative analytical method has been developed for the rapid determination of vancomycin in human plasma and urine using liquid chromatography/tandem mass spectrometry (LC - MS/MS). Chromatography was carried out on a $C_{18}$ XTerra MS column ($2.1{\times}30mm$) with a particle size of $3.5{\mu}m$. The mobile phase was 0.25% formic acid in 10% acetonitrile and the flow rate was $250{\mu}L/min$. Vancomycin and caffeine (internal standard) were detected by MS/MS using multiple reaction monitoring (MRM). Vancomycin gives a predominant doubly protonated precursor molecule ($[M+2H]^{2+}$) at m/z 725.0 and a corresponding product ion of m/z 100.0. Detection of vancomycin was good, accurate and precise, with a limit of detection of 1 nM in plasma. The calibration curves for vancomycin in human plasma was linear in a concentration range of $0.01{\mu}M$ - $100{\mu}M$ for plasma. This method has been successfully applied to determine the concentration of vancomycin in human plasma and urine from pharmacokinetic study and relative studies.

• Tuberculosis and Respiratory Diseases
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• v.39 no.3
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• pp.242-247
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• 1992

Background: The ability to precisely measure specific mRNA levels by hybridization to complementary DNA probes is an important tool for analyzing the regulation of gene expression. Surfactant proteins have important roles in regulating surfactant metabolism as well as in determing its physical properties. Method: The complete coding regions for rat surfactant protein complementary DNA of surfactant protein B were subcloned into pGem 3Z or 4Z such that either antisense or sense transcripts were obtained by using SP 6 RNA polymerase. Surfactant protein B mRNA was measured by filter hybridization. Results: Equation of standard curve between counts per minute (Y) and surfactant protein B mRNA transcript input (X) was Y=2034.9 X+159.1. Correlation coefficient was 1.0. Couclusions: Filter hybridization assay is suited to situation when rapid, accurate quantitation of multiple samples is required.

• Journal of the Korean Geotechnical Society
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• v.36 no.3
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• pp.15-23
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• 2020

Ground motion models predicting intensity measures on surface use a time-averaged shear wave velocity, V_S30, as a key variable simulating site effect. The V_S30 can be directly estimated from V_S profiles if the profile depth (z) is greater than or equal to 30 m. However, some sites have V_S profiles with z < 30 m. In this case V_S30 can be predicted using extension models. This study proposes new coefficient sets for existing prediction equations using 297 Korea V_S profiles. We have collected V_S profiles from KMA and Geoinfo database. Fitting six existing methods to data, we suggest new coefficients for each method and evaluate their performance. It turns out that if z ≥ 15 m, the standard deviation (σ) of residual in log₁₀ is 0.061, which indicates that the estimated V_S30 is nearly accurate. If z < 15 m, the σ keeps increasing up to 0.1 for z = 5 m, so we caution the use of models at very low z. Nonetheless, we recommend investigating up to 30 m depth for V_S30 calculation if possible.

• Journal of the Korean Magnetics Society
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• v.24 no.1
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• pp.1-10
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• 2014

$Co_2Z$-type barium ferrites ($Ba_3Co_2Fe_{24}O_{41}$) were synthesized using variation method. First, M-type, $Co_2Y$-type and $Co_2Z$-type synthesized by hydrothermal method. Second, M- and Y-type precursors for synthesis of $Co_2Z$ hexaferrite by hydrothermal and ball milling method. the morphology, structure and magnetic properties of the barium ferrite particles were characterized using XRD, FESEM, VSM, impedance. As a result, Single phase of M-type and $Co_2Y$-type were obtained. Manufactured powders of M+Y ball milling, M+Y hydrothermal were similar to single phase of $Co_2Z$-type hexaferrite, all powders were obtained theoretical magnetization (50 emu/g). The largest initial permeability were obtained $Co_2Z$ hexaferrite synthesized by reagent precusor, With increasing calcination temperature was lowered the initial permeability. In another synthesis didn't almost that little change could be found.