• Advances in materials Research
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• v.2 no.1
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• pp.1-13
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• 2013

Lead-free compound $(Na_{0.5}Bi_{0.5})(Zr_{0.75}Ti_{0.25})O_3$ was prepared using conventional ceramic technique at $1070^{\circ}C$/4h in air atmosphere. X-ray diffraction analysis showed the formation of single-phase orthorhombic structure. Permittivity data showed low temperature coefficient of capacitance ($T_{CC}{\approx}5%$) up to $100^{\circ}C$. Complex impedance studies indicated the presence of grain boundary effect, non-Debye type dielectric relaxation and evidences of a negative temperature coefficient of resistance. The ac conductivity data were used to evaluate the density of states at Fermi level and apparent activation energy of the compound.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.997-1008
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• 2012

This work provides an alternative derivation of third order response functions in four wave mixing spectroscopy of multichromophoric macromolecular systems considering only single exciton states. For the case of harmonic oscillator bath linearly and diagonally coupled to exciton states, closed form expressions showing all the explicit time dependences are derived. These expressions can provide more solid physical basis for understanding 2-dimensional electronic spectroscopy signals. For more general cases of system-bath coupling, the quantum master equation (QME) approach is employed for the derivation of multistep time evolution equations for Green function-like operators. Solution of these equations is feasible at the level of 2nd order non-Markovian QME, and the new approach can account for inter-exciton coupling, dephasing, relaxation, and non-Markovian effects in a consistent manner.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.159-169
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• 1981

The mixing length theory is extended to close the momentum queations for two-phase turbulent flow at a first-order closure level. It is assumed that the mass fraction of the particles is of the order of unity, that the particle size is so small that the particles are fully suspended is the primary fluid, and that the relaxation time scale of the particles is of the same order as the time scale of the energy containing eddies so that the suspended particles are responsive to the fluctuating turbulent field. The bulk motion of the particles is treated as a secondary fluid with its own coefficient of momentum transport. The proposed closure is uniformly destributed acress the pipe section. Predicted velocity profiles and the friction factors are in good agreement with avaiable experimental data.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.205-215
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• 2008

convergence networks (BcN). The problem seeks to minimize the total cost of switch and cable while satisfying the requirement of demand and quality of service (QoS). We develop mixed integer programming models to obtain the optimal switch location of the access network. We develop a Tabu Search (TS) heuristic algorithm for finding a good feasible solution within a reasonable time limit. We propose real networks with up to 25 nodes and 180 demands. In order to demonstrate the effectiveness of the proposed algorithm, we generate lower bounds from nonlinear QoS relaxation problem. Computational results show that the proposed heuristic algorithm provides upper bounds within 5% optimality gap in 10 seconds.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.127_128
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• 2009

A new technique using a search method which is based on fuzzy multi-criteria function is proposed for GMS(generator maintenance scheduling) in order to consider multi-objective function. Not only minimization of probabilistic production cost but also maximization of system reliability level are considered for fuzzy multi-criteria function. To obtain an optimal solution for generator maintenance scheduling under fuzzy environment, fuzzy multi-criteria relaxation method(fuzzy search method) is used. The practicality and effectiveness of the proposed approach are demonstrated by simulation studies for a real size power system model in Korea in 2010.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.2
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• pp.47-52
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• 2020

Liquid-liquid phase separation (LLPS) of biomolecules, a newly-found phase behavior of molecules in the liquid phase, has shown to its relationship to various biological function and misfolding diseases. Extensive studies have increasingly revealed a general mechanism of LLPS and characterized the liquid droplet; ho wever, intermolecular interactions of proteins and structural states of LLPS-inducing proteins inside of the droplet remain largely unknown. Solution NMR spectroscopy has emerged as a powerful approach as it provides invaluable information on protein intermolecular interactions and structures at the atomic and residue level. We herein comprehensively address useful techniques of solution NMR including the effect of paramagnetic relaxation enhancement for the study on the LLPS and droplet based on recent studies.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.12
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• pp.601-607
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• 2002

IPMC(Ionic Polymer Metal Composite)actuators were optimized for producing improved forces by changing multiple parameters including repetition of number of plating, surface electroding and additive(PVP)-treatment on reduction. The platinum electrode is deposited on the surface of the material where platinum particle stay in a dense form that appears to introduce a significant level of surface electrode resistance. Actuation tests were performed for such IPMC actuators under a low voltage. The test results show that the lower surface-electrode resistance generates higher actuation capability in the IPMC actuators. In order to investigate relaxation behavior of bending and repeatability in dry condition, the IPMC was coated by$rubber(KRATON^{TM})$to minimize the effect of water evaporation from IPMC. This actuator can be used in air with surface coating to avoid membrane drying.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1104-1107
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• 1999

A new technique using search method based on fuzzy multi-criteria function is proposed fur flexible generator maintenance scheduling. Minimization of probabilistic production cost, maximization of system reliability level and air pollution are considered fur fuzzy multi-criteria function. To obtain an optimal solution for generator maintenance scheduling under fuzzy environment fuzzy multi-criteria relaxation method(fuzzy search method) is used. The practicality and effectiveness of the proposed approach are demonstrated by the simulation results of the real size model system of KEPCO-1997 SYSTEM.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.81.2-81.2
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• 2017

Polarized mid-infrared emission from polycyclic aromatic hydrocarbons (PAHs) can provide a crucial test of basic physics of alignment of nanoparticles and opens a potential new window into studying magnetic fields. In this talk, I will present a new model of polarized PAH emission that takes into account the effect of PAH alignment with the magnetic field due to resonance paramagnetic relaxation. I will then present our predictions for the polarization level of the strong PAH emission features from the interstellar medium. I will present the first detection of polarization of PAH emission at 11.3micron which is consistent with our theoretical prediction. Finally, I will discuss important implications of this work for tracing magnetic fields via mid-IR PAH features and for constraining the polarization of anomalous microwave emission that is useful for the quest of CMB B-modes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.2
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• pp.35-43
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• 1984

The purpose of this paper is to develop a mathematical model which can be used to compute the position of the free surface due to water level fluctuations in the canal and the transient pressure distributions along the canal lining. The diagnostic equation has been solved by the point successive over-relaxation method, and the linearized prognostic equation has been solved by the implicit Lax-Wendroff scheme. Four different cases in the simulation conditions are presented for both permeable and impermeable canal lining to predict the transient seepage surface development.