• Geophysics and Geophysical Exploration
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• v.10 no.3
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• pp.183-190
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• 2007

The site effects of seismic stations were evaluated by conducting a simultaneous inversion of the stochastic point-source ground-motion model (STGM model; Boore, 2003) parameters based on the accumulated dataset of horizontal shear-wave Fourier spectra. A model parameter $K_0$ and frequency-dependent site amplification function A(f) were used to express the site effects. Once after a H/V ratio of the Fourier spectra was used as an initial estimate of A(f) for the inversion, the final A(f) which is considered to be the result of combined effect of the crustal amplification and loca lsite effects was calculated by averaging the log residuals at the site from the inversion and adding the mean log residual to the H/V ratio. The seismic stations were classified into five classes according to $logA_{1-10}^{max}$(f), the maximum level of the site amplification function in the range of 1 Hz < f < 10 Hz, i.e., A: $logA_{1-10}^{max}$(f) < 0.2, B: 0.2 $\leq$ $logA_{1-10}^{max}$(f) < 0.4, C: 0.4 $\leq$ $logA_{1-10}^{max}$(f) < 0.6, D: 0.6 $\leq$ $logA_{1-10}^{max}$(f) < 0.8, E: 0.8 $\leq$ $logA_{1-10}^{max}$(f). Implication of the classified result was supported by observing a shift of the dominant frequency of average A(f) for each classified stations as the class changes. Change of site classes after moving seismic stations to a better site condition was successfully described by the result of the station classification. In addition, the observed PGA (Peak Ground Acceleration)-values for two recent moderate earthquakes were well classified according to the proposed station classes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.3
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• pp.51-57
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• 2010

A dual-mode direct conversion receiver is developed in $0.13\;{\mu}m$ RF CMOS process for IEEE 802.11n based wireless LAN and IEEE 802.16e based mobile WiMAX application. The RF receiver covers the frequency band between 2.3 and 2.7 GHz. Three-step gain control is realized in LNA by using current steering technique. Current bleeding technique is applied to the down-conversion mixer in order to lower the flicker noise. A frequency divide-by-2 circuit is included in the receiver for LO I/Q differential signal generation. The receiver consumes 56 mA at 1.4 V supply voltage including all LO buffers. Measured results show a power gain of 32 dB, a noise figure of 4.8 dB, a output $P_{1dB}$ of +6 dBm over the entire band.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.127-133
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• 2005

An f-coloring of a graph G = (V, E) is a coloring of edge set E such that each color appears at each vertex v $\in$ V at most f(v) times. The minimum number of colors needed to f-color G is called the f-chromatic index $\chi'_f(G)$ of G. Any graph G has f-chromatic index equal to ${\Delta}_f(G)\;or\;{\Delta}_f(G)+1,\;where\;{\Delta}_f(G)\;=\;max\{{\lceil}\frac{d(v)}{f(v)}{\rceil}\}$. If $\chi'_f(G)$= ${\Delta}$f(G), then G is of $C_f$ 1 ; otherwise G is of $C_f$ 2. In this paper, the classification problem of complete graphs on f-coloring is solved completely.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.539-545
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• 2012

3-(2-benzotriazolovinyl)thiophene (BVT) was synthesized by the connection of the thiophene with the electron-withdrawing group, benzotriazole, through the vinylene. Its structure was confirmed by FT-IR, $^1H$-NMR, $^{13}C$-NMR and 2D hetero-cosy spectroscopy. Both BVT and 3-octylthiophene (OT) were copolymerized and showed an average molecular weight of 12000 (PDI 2.67) and 15000 (PDI 2.55), respectively. The copolymers were dissolved in the organic solvent such as chloroform, THF, TCE, etc. The mole ratios of BVT and OT in the synthesized copolymers were confirmed as 1 : 1.8 and 1 : 2.8 from $^1H$-NMR spectra. The UV-vis maximum absorption of copolymers appeared at the wavelength of 470 nm and 465 nm and the photoluminescence at ${\lambda}_{max}$ = 662 nm and 641 nm correspond to red-orange light. The band gaps of copolymers at 1.96 eV and 2.02 eV were found to be higher than those of poly(3-octylthiophene). The HOMO energy levels of the copolymers decreased overall in comparison with those of poly(3-octylthiophene), but the overall LUMO energy level increased.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.442-447
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• 1998

Visible photoluminescence (PL) has been observed generally in the blue and green spectral region from anodically etched porous Ge as well as spark processed Ge. Porous Ge which is prepared by anodic etching without UV light illumination displays the PL peak max of 52 nm (2.38 eV), while porous Ge with UV light illumination exhibits PL peak blue shift to a 470 nm (2.63 eV). Spark processed Ge shows a PL peak max of 520 nm with shoulder peaks at 420 nm and 610nm. The values of energy shift as a function of decreasing temperature between 300 K and 20 K is 0.53 and $1.89\;meVK^{-1}$ for anodic etched Ge without UV illumination and with UV illumination, respectively. On the contrary, no continuous blue shift of PL peak as a function of decreasing temperature is observed for the green luminescing spark processed Ge. From the results of PL as a function of temperature the origin of blue and green luminescing anodically etched Ge as well as spark processed Ge is discussed.

• Journal of the Korean Mathematical Society
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• v.38 no.1
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• pp.177-191
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• 2001

We consider a linear differential game described by the delay-differential equation in a Hilbert space H; (※Equations, See Full-text) U and V are Hilbert spaces, and B(t) and C(t) are families of bounded operators on U and V to H, respectively. A(sub)0 generates an analytic semigroup T(t) = e(sup)tA(sub)0 in H. The control variables g, and u and v are supposed to be restricted in the norm bounded sets (※Equations, See Full-text). For given x(sup)0 ∈ H and a given time t > 0, we study $\xi$-approximate controllability to determine x($.$) for a given g and v($.$) such that the corresponding solution x(t) satisfies ∥x(t) - x(sup)0∥ $\leq$ $\xi$($\xi$ > 0 : a given error).

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.795-801
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• 2005

New PPV derivatives which contain electron-withdrawing trifluoromethyl ($CF_3$) group, poly[2-(2-ethylhexyloxy)-5-(4-trifluoro methylphenyl)-1,4-phenylenevinylene] (EH$CF_3$P-PPV), and poly[2-(2-ethylhexyloxy)-5-(3,5-bis(trifluoromethyl)-phenyl)-1,4-phenylenevinylene] (EHB$CF_3$P-PPV), have been synthesized by GILCH polymerization. As the result of the introduction of the electron-withdrawing $CF_3$ group to the phenyl substituent, the LUMO and HOMO energy levels of EH$CF_3$P-PPV (2.8, 5.1 eV) and EHB$CF_3$P-PPV (3.0, 5.3 eV) were lower than those of known poly[2-(2-ethylhexyloxy)-5-phenyl-1,4-phenylenevinylene] (EHP-PPV) (2.6, 4.9 eV). These polymers have been used as the electroluminescent (EL) layers in double layer lightemitting diodes (LEDs) (ITO/PEDOT/polymer/Al). EH$CF_3$P-PPV, and EHB$CF_3$P-PPV show maximum photoluminescence (PL) peaks at ${\lambda}_{max}$ = 550, 539 nm, and maximum EL peak at ${\lambda}_{max}$ = 545, 540 nm, respectively. The current-voltage-luminance (I-V-L) characteristics of the polymers show that turn-on voltages of EH$CF_3$P-PPV and EHB$CF_3$P-PPV are around 4.0 and 3.5 V, respectively.

• ALGAE
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• v.32 no.2
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• pp.139-153
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• 2017

The ability of a red tide species to take up nutrients is a critical factor affecting its red tide dynamics and species competition. Nutrient uptake by red tide species has been conventionally measured by incubating nutrient-depleted cells for a short period at 1 or 2 light intensities. This method may be applicable to certain conditions under which cells remain in oligotrophic water for a long time and high nutrients are suddenly introduced. Thus, a new method should be developed that can be applicable to the conditions under which cells are maintained in eutrophicated waters in healthy conditions and experience light and dark cycles and different light intensities during vertical migration. In this study, a new repletion method reflecting these conditions was developed. The nitrate uptake rates of the red tide dinoflagellate Prorocentrum micans originally maintained in nitrate repletion and depletion conditions as a function of nitrate concentration were measured. With increasing light intensity from 10 to $100{\mu}E\;m^{-2}s^{-1}$, the maximum nitrate uptake rate ($V_{max}$) of P. micans increased from 3.6 to $10.8 pM\;cell^{-1}d^{-1}$ and the half saturation constant ($K_{s-NO3}$) increased from 4.1 to $6.9{\mu}M$. At $20{\mu}E\;m^{-2}s^{-1}$, the $V_{max}$ and $K_{s-NO3}$ of P. micans originally maintained in a nitrate repletion condition were similar to those maintained in a nitrate depletion condition. Thus, differences in cells under nutrient repletion and depletion conditions may not affect $K_{s-NO3}$ and $V_{max}$. Moreover, different light intensities may cause differences in the nitrate uptake of migratory phototrophic dinoflagellates.

• Korean Journal of Clinical Pharmacy
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• v.13 no.1
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• pp.13-17
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• 2003

This study was carried out to compare the bioavailability of $Ceclex^{(R)}$ SR TAB (test drug, cefaclor 375 mg/Tablet) with that of Ceclor $MR^{(R)}$ SR IAB (reference drug) and to estimate the pharmacokinetic parameters of cefaclor in healthy Korean volunteers. The bioavailability was examined on 24 healthy volunteers who received a single dose (375 mg) of each drug in the fasting state in a randomized balanced 2-way crossover design. After dosing, blood samples were collected for a period of 7 hours. Plasma concentrations of cefaclor were determined using HPLC with UV detection. The pharmacokinetic parameters $(AUC_{0-7h},\;C_{max},\;T_{max},\;AUC_{inf},\;K_e,\;t_{1/2},\;V_d/F,\;and\;CL/F)$ were calculated with non-compartmental pharmacokinetic analysis. The ANOVA test was utilized for the statistical analysis of the $T_{max}$, log-transformed $AUC_{0-7h$}$, log-transformed $C_{max},\;t_{1/2},\;V_d/F$, and $CL/F$. The ratios of geometric means of $AUC_{0-7h}\;and\;C_{max}$ between test drug End reference drug were $95.67\%\;(8.55\;vs\;8.18{\mu}g{\cdot}hr/ml)\;and\;103.86\%\;(2.85\;vs\;2.96{\mu}g/ml)$, respectively. The $T_{max}$ of test drug and reference drug was $2.56\pm0.15\;and\;2.23\pm0.13\;hrs,\;respectively.\;The\;90\%$ confidence intervals of mean difference of logarithmic transformed $AUC_{0-7h}\;and\;C_{max}$ were log0.90-log1.04 and log0.91-log1.13, respectively. It shows that the bioavailability of test drug is equivalent with that of reference drug.

• Physical Therapy Korea
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• v.6 no.2
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• pp.56-66
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• 1999

The purpose of this study focused how to show physiological responses comparing exercise group and non exercise group for progressive maximal wheelchair ergometer exercise loading in complete paraplegia. It also examined the various factors which would be influenced physiological responses. Sixteen subjects have been investigated in this study, and the subjects are divided into two groups as follows: 1) exercise group (7 subjects) 2) non exercise group (9 subjects). Each test was terminated by physical exhaustion and/or an inability to maintain a flywheel velocity. The results were as follows: 1) No difference was noted in pulmonary function test between two groups. 2) $\dot{v}$ Emax value during maximal exercise was significantly different between the groups (p<0.05). The mean $\dot{v}$ Emax of exercise group was $69.67{\ell}/min$, non exercise group was $41.47{\ell}/min$. 3) $\dot{v}$ $O_2max$(${\ell}/min$) value during maximal exercise was significantly different between the groups (p<0.05). The mean $\dot{v}$ $O_2max$(${\ell}/min$) of exercise group was $1.72{\ell}/min$, non exercise group was $1.15{\ell}/min$. 4) $\dot{v}$ $O_2$ max(ml/kg/min) value during maximal exercise was significantly different between the groups (p<0.05). The mean $\dot{v}$ $O_2max$($ml/kg{\cdot}min$) of exercise group was $25.99ml/kg{\cdot}min$, non exercise group was $18.61{\ell}/min$. 5) Maximal heart rate(HRmax) value during maximal exercise was significantly different between the groups (p<0.05). The mean HRmax of exercise group was 180.43 beats/min, non exercise group was 175.00 beats/min. 6) $\dot{v}\;E/\dot{v}\;O_2$ value during maximal exercise was not significantly different between the groups (p>0.05). The mean $\dot{v}\;E/\dot{v}\;O_2$ of exercise group was $36.36{\ell}/{\ell}\;O_2$, non exercise group was $45.46{\ell}/{\ell}\;O_2$. Considering the results which explore the exercise group with paraplegia has shown the maximal aerobic power compared with non exercise group, regular and consistent physical training is highly assumed as a main factor to improve cardiopulmonary fitness.