• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.64-70
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• 2013

We investigated an electrochemical properties for Langmuir-Blodgett (LB) monolayer films of sphingomyelin and polyamic acid(1:1 molar ratio) mixture. LB monolayer films of mixture was deposited by the LB method on the indium tin oxide(ITO) glass. The electrochemical properties measured by cyclic voltammetry with three-electrode system in $KClO_4$ solution. The current of reduction and oxidation range was measured from 1650 mV to -1350 mV, continuously. The scan rates were 50, 100, 150, 200 and 250 mV/s, respectively. As a result, LB monolayer films of sphingomyelin and polyamic acid mixture was appeared on irreversible process caused by the reduction current from the cyclic voltammogram. Diffusion coefficient (D) in the sphingomyelin and polyamic acid mixture was calculated $2.67cm^2s^{-1}{\times}10^5$, $5.23cm^2s^{-1}{\times}10^6$ at 0.1 N and 0.2 N $KClO_4$ solutions, respectively.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.220-225
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• 2008

In this research, the P(VDF-TrFE) copolymer thin films were prepared by the physical vapor deposition and studied to their piezoelectric properties. In the case of a specimen produced by varying the deposition temperature from $260^{\circ}C$ to $300^{\circ}C$, its piezoelectric coefficient($d_{33}$) increased from 32.3pC/N to 36.28pC/N, and piezoelectric voltage coefficient($g_{33}$) from $793{\times}10^{-3}V{\cdot}m/N$ to $910.5{\times}10^{-3}V{\cdot}m/N$. On the basis of these experimental results, we concluded that the P(VDF-TrFE) copolymer thin film prepared at $300^{\circ}C$ showed the optimum piezoelectric properties. At the deposition temperature of $320^{\circ}C$, its piezoelectric coefficient(d33) decreased 25.3 pC/N and piezoelectric voltage coefficient($g_{33}$) $680{\times}10^{-3}V{\cdot}m/N$.

• Journal of IKEEE
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• v.14 no.2
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• pp.82-89
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• 2010

In this paper, a buck-boost converter using three DTMOS(Dynamic Threshold Voltage MOSFET) switching devices is presented. The efficiency of the proposed converter is higher than that of conventional buck-boost converter. DTMOS with low on-resistance is designed to decrease conduction loss. The threshold voltage of DTMOS drops as the gate voltage increases, resulting in a much higher current handling capability than standard MOSFET. In order to improve the power efficiency at the high current level, the proposed converter is controlled with PWM(pulse width modulation) method. The converter has maximum output current 300mA, input voltage 3.3V, output voltage from 700mV to 12V, 1.2MHz oscillation frequency, and maximum efficiency 90%. Moreover, the LDO(low drop-out) is designed to increase the converting efficiency at the standby mode below 1mA.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.352-358
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• 2014

We were investigated the stability through the electrochemical characteristics of saturated fatty acid(C12, C14, C16, C18) monolayer LB films by cyclic voltammetry. Saturated fatty acid monolayer LB films was deposited on the indium tin oxide(ITO) glass by the LB method. The electrochemical properties were measured by cyclic voltammetry with a three-electrode system in 0.1 N $NaClO_4$ solution. The measuring range was continuously oxidized to 1650 mV, with an initial potential of -1350 mV was reduced. Scanning rates of 50, 100, 150, 200, and 250 mV/s were set. As a result, LB monolayer films of saturated fatty acid were appeared on irreversible processes by the oxidation current from the cyclic voltammogram. Diffusion coefficient(D) of saturated fatty acid(C12, C14, C16, and C18) was calculated 22.231, 2.461, 7.114 and 2.371 ($cm^2s^{-1}{\times}10^{-4}$) in 0.1 N $NaClO_4$ solution, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.194-198
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• 2012

This paper describes flying inspection apparatus for 22.9kV distribution line. This apparatus is composed of multi-copter(more than 4 propellers), camcorder and remote controller. The existing inspections, such as hot-line inspection job and optical inspection method and distribution Line Checking Robot, have many restrictions. A electric working vehicle and hot-line job license are essential in hot-line inspection job. Besides its high cost, it can't be applied to the electric pole over 18m and road-blocked area. Optical method can't inspect upper side of electric facilities mounted on the electric pole. Robot method can't be applied to the corroded overhead earth wire and nothing of overhead earth wire. To solve the problems, in Korea Electric Power Co., we have applied flying inspection apparatus to the 22.9kV distribution line. The results of trial application show that this paper is practical and effective for the inspection technical method in 22.9kV distribution line

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.1012-1016
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• 2008

[ $TiO_2-V_2O_5$ ] sol was fabricated using sol-gel method and $TiO_2-V_2O_5$ thin films were fabricated using dip-coating method. $V_2O_5$ sol was added 0.01mole, 0.03mole, 0.05mole into $TiO_2$ sol. As a results of crystalline properties, $V_2O_5$ peaks were not found in spite of $V_2O_5$ additive. Thickness of thin films increased $0.1{\sim}0.25{\mu}m$ every a dipping. Capacitance of thin films increased with increasing heat treatment temperature and it increased largest at $700^{\circ}C$. Capacitance of thin films decreased with increasing $V_2O_5$ additive and it increased largest at 0.01mole. Because adsorption time and desorption time of thin films was about 2 minutes 40 seconds and about 3 minutes 40 seconds respectively, adsorption time was faster about 1 minutes than desorption time.

• The Korean Journal of Physiology
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• v.17 no.1
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• pp.1-11
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• 1983

1) The two microelectrode method was used to voltage clamp small preparations of rabbit sinoatrial node. The kinetics of hyperpolarization activated inward current, $i_f$ were analysed. 2) The hrperpolarization pulses activated $i_f$ current in the presence of $10^{-7}g/ml$ TTX and 2 mM $Mn^{2+}$. The activation range was in between -45 mV to -75 mV. The current magnitude was increased and time course was faster by strong hyperpolarization pulses. 3) Standard envelope tests indicated that this current is exponentially controlled by single gate. 4) Semilogarithmic plot of $i_f$ activation versus time was found to be linear in the activation range. The decrease in current magnitude and the shifts in activation curve and rate constants curve to the hyperpolarizing direction were obtained with $Ba^{2+}$, indicating that $Ba^{2+}$ shifts the voltage dependence of the gating kinetics, were partially reversed by 24 mM $K^+$.

• Biomolecules & Therapeutics
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• v.14 no.1
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• pp.40-44
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• 2006

Mirtazapine is an antidepressant agent with dual action on both the noradrenergic and serotonergic neurotransmitter systems. A simple high performance liquid chromatographic method has been developed and validated for the quantitative determination of mirtazapine in human plasma. A reversed-phase Cl8 column was used for the determination of mirtazapine with a mobile phase composed of 0.01M ammonium acetate solution (pH 4.2) and acetonitrile (75:25, v/v%) at a flow rate of 1.2 mL/min. Terazosin hydrochloride was used as an internal standard. The fluorescence detector was set at excitation and emission wavelengths of 290 and 350 nm, respectively. Intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification of 3 ng/mL. Mirtazapine was stable in human plasma under various storage conditions. This method was used successfully for a pharmacokinetic study using plasma samples after oral administration of a single 30 mg dose as mirtazapine base to 8 healthy volunteers. The maximum plasma concentration of mirtazapine was $64.1{\pm}28.0ng/mL$ at 1.8 h, and the area under the curve and elimination half-life were calculated to be $674.1{\pm}218.5ng\;h/mL\;and\;23.4{\pm}3.8h$, respectively.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.568-573
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• 2013

A selective and sensitive method for simultaneous determination of copper in blood by adsorptive differential pulse cathodic stripping voltammetry is presented. The procedure involves an adsorptive accumulation of Cu(II)-ETSC (4- ethyl-3-thiosemicarbazide) on a hanging mercury drop electrode, followed by a stripping voltammetry measurement of reduction current of adsorbed complex at about -715 mV. The optimum conditions for the analysis of copper (II) ion are : pH 10.3, concentration of 4-ethyl-3-thiosemicarbazide $3.25{\times}10^{-6}$ M and an accumulation potential of -100 mV. The peak current is proportional to the concentration of copper over the range 0.003-125 ng/mL with a detection limit of 0.001 ng/mL and an accumulation time of 60 s. Moreover, with the use of the proposed method, there is a considerable improvement in the detection limit, the linear dynamic range and the deposition time, compared with the methods of adsorptive stripping voltammetry for the determination of copper. The developed method was validated by analysis of whole blood certified reference materials.

• BMB Reports
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• v.37 no.2
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• pp.167-176
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• 2004

Although efficient antiviral lamivudine is used for HBV-infected patients, a prolonged treatment with nucleoside analogs often results in lamivudine-resistant variants. In this study, we evaluated the fidelity of the lamivudine-resistant variants. The FLAG-tagged wild-type (FPolE) and Met550 variants (FPolE/M550A, M550V, and M550I) of HBV DNA polymerases were expressed in insect cells then purified. Like many other reverse transcriptases, no $3'{\rightarrow}5'$ exonuclease activity was detected in the HBV DNA polymerase. Since there is no proofreading activity, then the use of the site-specific nucleotide misincorporation method is beneficial. From the $f_{ins}$ value analysis, it is evident that M550I and M550V exhibit higher fidelity values than the wild-type HBV DNA polymerase, while M550A exhibits similar fidelity values. It is therefore suggested that lamivudine resistance comes from the stringency to dNTP binding and the discrimination of dCTP and lamivudine in M550V and M550I.