• Analytical Science and Technology
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• 제17권5호
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• pp.375-380
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• 2004

Kinetics have been studied by high vacuum and high pressure apparatus under various temperatures and pressures for the nucleophilic substitution reaction. Rate constants, activated parameters and Hammett ${\rho}$-values are determined. The values of ${\Delta}V^{\ddag}$, ${\Delta}{\beta}^{\ddag}$ and ${\Delta}S^{\ddag}$ are all negative. The Hammett ${\rho}$-values are negative for the nucleophile (${\rho}x$) over the pressure range studied. Consequently the rate constant increases as the pressure increases, and some decrease in vacuum. So these reactions proceed in typical $S_N2$ reaction mechanism.

• Journal of the Korean Chemical Society
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• 제48권5호
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• pp.461-466
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• 2004

Kinetics for the nucleophiles have been studied under high vacuum and high pressures in various temperatures. Pseudo-first order rate constants, second order rate constants, thermodynamic parameters and Hammett ${\rho}$-values are determined. The values of ${\Delta}V^{\neq},\;{\Delta}{\beta}^{\neq}\;and\;{\Delta}S^{\neq}$are all negative. The Hammett r-values are negative for the nucleophile (${\rho}$x) over the pressure range studied. The results of kinetic studies for pressure and nucleophilet show that these reactions proceed in typical $S_N2$ reaction mechanism and change of mechanism.

• Journal of the Korean Vacuum Society
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• 제2권2호
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• pp.131-138
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• 1993

The Project of a superconducting asymmetric multipole wiggler in the 1.5GeV electron storage ring DELTA is in progress. In this work, the influences of nonlinear effects due to the this insertion device are investigated. The standard lattice is tolerable on the beam dynamics problems for all errors which are considered in our work.

• Journal of The Korean Astronomical Society
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• 제16권2호
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• pp.55-63
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• 1983

From UBVRI photometry and space motion data of 232 late type dwarf stars, it is found that for the stars of (R-I)<0.5, $\Delta$(U-B) and $\Delta$(B-V) color excesses are correlated with their orbital eccentricities. Therefore, $\Delta$(U-B) and $\Delta$(B-V) color excesses can be used as possible photometric abundance indicators for the stars of (R-I)<0.5. For the stars of (R-I)${\geq}$0.5, the correlation between color excess and orbital eccentricity is not clear. However, it is interesting to note that the high orbital eccentricity stars show some blue deficiencies and these blue deficiencies seem to be correlated with orbital eccentricity.

• Journal of applied mathematics & informatics
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• 제27권5_6호
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• pp.1119-1132
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• 2009

In this paper, we consider the quasilinear elliptic system $\\div(|{\nabla}u|^{p-2}{\nabla}u)=u(a_1u^{m1}+b_1(x)u^m+{\delta}_1v^n),\;\\div(|{\nabla}_v|^{q-2}{\nabla}v)=v(a_2v^{r1}+b_2(x)v^r+{\delta}_2u^s)$, in $\Omega$ where m > $m_1$ > p-2, r > $r_1$ > q-, p, q $\geq$ 2, and ${\Omega}{\subset}R^N$ is a smooth bounded domain. By constructing certain super and subsolutions, we show the existence of positive blow-up solutions and give a global estimate.

• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1118-1120
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• 1997

This paper presents a simple method for evaluating of voltage stability using the line flow equation. Line flow equations ($P_{ij}$, $Q_{ij}$) are comprised of state variable, $V_i$, ${\delta}_i$, $V_j$ and ${\delta}_j$, and line parameter, r and x. Using the feature of polar coordinate, these becomes one equation with two variables, $V_i$ and $V_j$. Moreover, if bus j is slack or generater bus, which is specified voltage magnitude, it becomes one equation with one variable $V_i$, that is, may be formulated with the second-order equation for $V_i^2$. Therefore, multiple load flow solutions may be obtained with simple computation, and the formulated equation used for approximately evaluating of voltage stability limit considering line flow sensitivity. The proposed method was validated to 2-bus and IEEE 6-bus system.

• Journal of Astronomy and Space Sciences
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• 제19권4호
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• pp.263-272
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• 2002

A total of 616 observations (308 in B, 308 in V) to. V523 Cas was made on three nights from October 19 to 21 in 1999 using the 1.8m telescope with 2K CCD camera of the Bohyunsan Optical Astronomy Observatory of KAO. With our data we constructed the BV light curves and determined 4 times of minimum light. We also obtained physical parameters of the system by combined analysis of both light and radial velocity curves using the Wilson-Devinney code.

• Journal of IKEEE
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• 제17권3호
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• pp.234-240
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• 2013

This paper presents an incremental delta-sigma analog-to-digital converter (ADC) for a single-electrode capacitive touch sensor. The second-order cascade of integrators with distributed feedback (CIFB) delta-sigma modulator with 1-bit quantization was fabricated by a $0.18-{\mu}m$ CMOS process. In order to achieve a wide input range in this incremental delta-sigma analog-to-digital converter, the shielding signal and the digitally controlled offset capacitors are used in front of a converter. This circuit operated at a supply voltage of 2.6 V to 3.7 V, and is suitable for single-electrode capacitive touch sensor for ${\pm}10-pF$ input range with sub-fF resolution.

• Journal of IKEEE
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• 제22권3호
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• pp.786-792
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• 2018

A third-order sigma-delta modulator with the architecture of cascade of integrator feedback (CIFB) is proposed for an analog-digital converter used in low-power sensor interfaces. It consists of three switched-capacitor integrators using a gain-enhanced current-mirror-based amplifier, a single-bit comparator, and a non-overlapped clock generator. The proposed sigma-delta analog modulator with over-sampling ratio of 160 and maximum SNR of 90.45 dB is implemented using $0.11-{\mu}m$ CMOS process with 1.2-V supply voltage. The area and power consumption of the sigma-delta analog modulator are $0.145mm^2$ and $341{\mu}W$, respectively.

• Journal of the Institute of Electronics and Information Engineers
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• 제52권7호
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• pp.33-39
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• 2015

In this work, SU-8 passivated IZO thin-film transistors(TFTs) made by solution-processes was investigated for enhancing stability of indium zinc oxide(IZO) TFT. A very viscous negative photoresist SU-8, which has high mechanical and chemical stability, was deposited by spin coating and patterned on top of TFT by photo lithography. To investigate the enhanced electrical performances by using SU-8 passivation layer, the TFT devices were analyzed by X-ray phtoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FTIR). The TFTs with SU-8 passivation layer show good electrical characterestics, such as ${\mu}_{FE}=6.43cm^2/V{\cdot}s$, $V_{th}=7.1V$, $I_{on/off}=10^6$, SS=0.88V/dec, and especially 3.6V of ${\Delta}V_{th}$ under positive bias stress (PBS) for 3600s. On the other hand, without SU-8 passivation, ${\Delta}V_{th}$ was 7.7V. XPS and FTIR analyses results showed that SU-8 passivation layer prevents the oxygen desorption/adsorption processes significantly, and this feature makes the effectiveness of SU-8 passivation layer for PBS.