• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.1008-1013
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• 2003

We have studied the effect of black matrix (BM) according to the dielectric anisotropy of liquid crystals (LCs) for a homogeneously aligned LC cell driven by fringe-electric field. The results show that for a LC with positive dielectric anisotropy (+LC) there is a large transmittance change when using a conductive BM, whereas the transmittance change is low for a LC with negative dielectric anisotropy (-LC). The conductive BM existing on top substrate produces vertical electric field, which makes the LC molecules be tilt upward from the substrate and have small twist angle for the +LC. However, for the -LC the conductive BM affects the LC distribution only slightly due to characteristic of the -LC orienting perpendicular to the field. Therefore, for the +LC the electro-optic characteristics are strongly dependent on conductivity of the BM on top substrate in a homogeneous liquid crystal cell driven by fringe-electric field.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.24-25
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• 2015

To secure fundamental materials for the performance change in concrete structure damaged by fire, this study analyzed SEM and XRD of hardened cement depending on high temperature conditions. As a result, at more than 200℃, SEM and XRD were not observed because of dehydration of Ettringite; at more than 500℃, calcium hydroxide was rapidly decomposed; at more than 700℃, calcium oxide was found; at 1000℃, the highest peak point appeared.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.87-90
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• 1990

We compare the reflectivity spectrum and phase change of Bragg reflectors obtained by the matrix method and the coupled wave method. We show that the results obtained by the two methods agree well generally and the discrepancy between the results obtained by the two methods increases as the fractional refractive index difference between adjacent layers increases and/or the absorption loss increases, due to the approximations inherent in the coupled wave method for the analysis of multiple dielectric layers.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.1
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• pp.1-7
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• 2006

In this paper, a novel power management structure for an energy harvesting pervasive system is proposed. The system considers the power state of each subsystem to assign proper power sources. The switch matrix structure utilizes each power source to reduce the peak current of the battery. The power management structure can be interfaced to an embedded system power supply without significant design change.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.826-830
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• 2004

Fault tolerant control method for 6-pole homopolar magnetic bearings are presented. If some of the coils or power amplifiers suddenly fail, the remaining coil currents change via a novel distribution matrix such that the same magnetic forces are maintained before and after failure. Lagrange multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrix that maximizes the load capacity of the failed bearing. Some numerical examples of distribution matrices are provided to illustrate this control method.

• KSBB Journal
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• v.5 no.4
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• pp.377-382
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• 1990

The characteristics controlled drug release have been studied for biodegradable polymer matrix. Polymer matrix was prepared from glycerine, prednisolone and dextran. Mathematical analysis of the data showed that the release behavior actually conformed to the Higuchi's diffusion controlled model. The release time was increased as drug loading doses increased, whereas decreased as glycerine concentration increased. The release rate did not change by varying molecular weight of dextran.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.387-392
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• 2006

This paper predicts the modified mass and stiffness of structure using the sensitivity coefficients with the iterative method. The sensitivity coefficients are obtained by the change of the eigenvectors according to structural modification. The method is applied to an examples of a 3 degree of freedom system by modifying mass and stiffness. The predicted mass and stiffness are in good agreement with these from the structural reanalysis using the modified mass and stiffness.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.83-92
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• 2008

This paper develops the theory for a fault-tolerant, permanent magnet biased, homopolar magnetic bearing. If some of the coils or power amplifiers suddenly fail, the remaining coil currents change via a novel distribution matrix such that the same magnetic forces are maintained before and after failure. Lagrange multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrix that maximizes the load capacity of the failed bearing. Some numerical examples of distribution matrices are provided to illustrate the theory. Simulations show that very much the same dynamic responses (orbits or displacements) are maintained throughout failure events (up to any combination of 3 coils failed for the 6 pole magnetic bearing) while currents and fluxes change significantly. The overall load capacity of the bearing actuator is reduced as coils fail. The same magnetic forces are then preserved up to the load capacity of the failed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.11
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• pp.1102-1111
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• 2007

The theory for a fault-tolerant control of homopolar magnetic bearings is developed. New coil winding law is utilized such that control fluxes are isolated for an 8-pole homopolar magnetic bearing. Decoupling chokes are not required for the fault tolerant magnetic bearing since C-core fluxes are isolated. If some of the coils or power amplifiers suddenly fail, the remaining coil currents change via a distribution matrix such that the same magnetic forces are maintained before and after failure. Lagrange multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrix that maximizes the load capacity of the failed bearing. Some numerical examples of distribution matrices are provided to illustrate the theory. Simulations show that very much the same dynamic responses (orbits or displacements) are maintained throughout failure events while currents and fluxes change significantly.

• Architectural research
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• v.17 no.3
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• pp.83-91
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• 2015

A comprehensive understanding of functions and performances enables a selection of appropriate alternatives to the existing design and can prevent defective design. A performance-based design quality management can ensure successful project completion. This study proposes a new model for design quality management in order to prevent defective design and to minimize design change. The new quality management model defines the requirement about function and performance based on technical characteristic, and assesses suitability for design alternatives. This study attempts to propose a quality matrix assessment method that can compare the alternative design and requirements defined with the new quality management model. This method can judge conformity and suitability of design quality in accordance with the requirements configured.