• Journal of the Korean Chemical Society
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• v.62 no.4
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• pp.265-268
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• 2018

The solvolyses of anthraquinone-2-carbonyl chloride (1) were studied kinetically in 27 pure and various mixed solvents. The analysis using the extended Grunwald-Winstein equation in the solvolyses of anthraquinone-2-carbonyl chloride (1) obtained the l value of $2.11{\pm}0.11$, the m value of $0.54{\pm}0.06$, and the correlation coefficient of 0.955. The solvolysis reaction of 1 might proceed via an associative $S_N2$ mechanism enhancing bond making than bond breaking in the transition state (TS). This interpretation is further supported by a relatively large solvent kinetic isotope effect (SKIE, 2.27).

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.357-368
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• 2003

II-A isotherms and phase behaviors of 'tocomide', a newly synthesized 1,3-bis(N-(2-hydroxyethyl)-tocopherol succinylamino)-2-hydroxypropane, mixed with cholesterol and linoleic acid, was studied for its monolayer miscibility and a stable delivery formulation for antioxidant applications. The monolayer of tocomide and cholesterol was formed in a homogeneously mixed state at air-water interface. The ternary mixtures with linoleic acid showed various bulk structures, including a stable and transparent solution of thermodynamically stable lamellar phase. The lamellar structure was confirmed by the X-ray diffraction (XRD) patterns and polarized microscopy such that pure tocomide formed a liquid crystal at room temperature with a lamellar periodicity of 36.7 $\AA$(2$\theta$=2.41$^{\circ}$).

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.09a
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• pp.73-77
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• 1998

Langasite(La3Ga5SiO14) is a new piezoelectric material which is similar to quartz, LN(LiNbO3) and LT(LiTaO3) in its acoustic behavior. In this study, pure Langasite and Langasite family groups were synthesized by the solid state reactions in air. For the synthesis process, diffusion species were investigated and sintered body of synthesized powders were studied on dielectric property according to surface microstructures.

• Structural Engineering and Mechanics
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• v.58 no.4
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• pp.641-659
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• 2016

This paper deals with the pure bending of incompressible elastic perfectly plastic two-layer sheets under plane strain conditions at large strains. Each layer is classified by its yield stress, shear modulus of elasticity and its initial percentage thickness in relation to the whole sheet. The solution found is semi-analytic. In particular, a numerical technique is only necessary to solve transcendental equations. The general solution is cumbersome because different analytic expressions for the radial and circumferential stresses should be adopted in different regions of the whole sheet. In particular, there are several alternative ways a plastic region (or plastic regions) can propagate. However, for any given set of material and process parameters the solution to the problem consists of a sequence of rather simple analytic expressions connected by transcendental equations. The general solution is illustrated by a simple example.

• Kyungpook Mathematical Journal
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• v.28 no.1
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• pp.23-34
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• 1988

A version of Ascoli's Theorem (equating compact and equicontinuous sets) is presented in the context of convergence spaces. This theorem and another, (involving equicontinuity) are applied to characterize compact subsets of quasi-multipliers of a $C^*$-algebra B, and to characterize the compact subsets of the state space of B. The classical Ascoli Theorem states that, for pointwise pre-compact families F of continuous functions from a locally compact space Y to a complete Hausdorff uniform space Z, equicontinuity of F is equivalent to relative compactness in the compact-open topology([4] 7.17). Though this is one of the most important theorems of modern analysis, there are some applications of the ideas inherent in this theorem which arc not readily accessible by direct appeal to the theorem. When one passes to so-called "non-commutative analysis", analysis of non-commutative $C^*$-algebras, the analogue of Y may not be relatively compact, while the conclusion of Ascoli's Theorem still holds. Consequently it seems plausible to establish a more general Ascoli Theorem which will directly apply to these examples.

• International Journal of Knowledge Content Development & Technology
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• v.6 no.2
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• pp.67-92
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• 2016

Employing a newly developed conceptual framework of the tasks and activities that comprise today's digital scholarly undertaking and their potentially reputation building, maintaining and enhancing components, the efforts of ResearchGate in supporting scholars' reputation building endeavours were put under the microscope. Not unexpectedly, RG performs well in regard to basic research activities. Clearly, too, with ten metrics at its disposal, RG is in a league of its own when it comes to monitoring individual research reputation. Where RG falls down is regarding scholarly activities that do not concern pure research and so especially teaching. Its claim to have created a new way of measuring reputation is only partially true because if it wants to do so genuinely then it needs to extend the range of scholarly activities covered. RG also falls short in informing members as to the nature and changes to its service and of embracing new actors, such as citizen scientists and amateur experts.

• Journal of Power Electronics
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• v.14 no.4
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• pp.796-805
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• 2014

A digital controller with a low-power approach for point-of-load synchronous buck converters is discussed and compared with its analog counterpart to confirm its feasibility for system integration. The tri-mode digital controller IC in $0.35{\mu}m$ CMOS process is presented to demonstrate solutions that include a PID, quarter PID, and robust RST compensators. These compensators address the steady-state, stand-by, and transient modes according to the system operating point. An idle-tone free condition for ${\Sigma}-{\Delta}$ DPWM reduces the inherent tone noise under DC-excitation. Compared with that of the traditional approach, this condition generates a quasi-pure modulation signal. Experimental results verify the closed-loop performances and confirm the power-saving mechanism of the proposed controller.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.237-239
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• 1995

The inverter for UPS system is required to satisfy pure sinusoidal output voltage with very low THD(Total Harmonic distortion). This paper proposes a TMS320c31 digital signal processor based predictive instantaneous control scheme of inverter. The proposed scheme is able to satisfy the conditions; high capability, high efficiency, low audible noise and robustness of inverter. The transient state characteristics of proposed inverter has been improved. in case of power failure or recovery, nonlinear load, sudden load change or parameters variations. Finally, the performance of the proposed inverter is shown and discussed by simulation and experiment.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.580-583
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• 2003

The general time optimal control law provides the optimal solution for a minimum time control problem. But in most real systems with disturbances and model uncertainties, the time optimal control law leads to chattering effect. This chattering effect can cause the system to be unstable. Therefore, we propose a robust optimal control algorithm for the nonlinear second order systems with model uncertainty. The proposed algorithm is combined with bang-bang control and sliding mode control. Thus the proposed algorithm has two state space regions to implement to control algorithm. In each region, the appropriate linear or nonlinear feedback control law is used satisfying the dynamic system equations. Simulation results show the superiority of the proposed controller in comparison with pure time optimal control(bang-bang control).

• Macromolecular Research
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• v.10 no.6
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• pp.297-303
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• 2002

We have investigated the microstructural properties of a weakly charged polyelectrolyte modeled with both Hookean spring and Debye-Huckel potential, by employing a novel hybrid scheme of molecular dynamics (MD) and Monte Carlo (MC) simulations. Although the off-lattice pivot step facilitates the earlier computations stage, it gives rise to oscillations and hinders the stable equilibrium state. In order to overcome this problem, we adopt the MC off-lattice pivot step in early stage only, and then switch the computation to a pure MD step. The result shows that the computational speed-up compared to the previous method is entirely above 10 to 50, without loss of the accuracy. We examined the conformations of polyelectrolyte in solvents in terms of the end-to-end distance, radius of gyration, and structure factor with variations of the screening effects of solvent and the monomer charges. The emphasis can favorably be given on the elongation behavior of a polyelectrolyte chain, with observing the simultaneous snapshots.