• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.237-241
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• 1998

In this study, PLZT stock solutions around x/65/35 (x=6~11) ferroelectric region were prepared by Sol-Gel method and deposited on ITO-glass by spin-coating method. The thin films were annealed by RTA(rapid thermal annealing). The variations of crystallographic structure of the thin films were observed using XRD and hysteresis curves, dielectric characteristics, and optical transmittances were measured in order to investigate the characteristics of the thin films. The thin films were crystallized at $750^{\circ}C$ for 5 min by RTA. Relative dielectric constant and optical transmittance increased with increasing La content, Ec and Pr were higher for thin films than for bulk materials.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.82-84
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• 1993

A method for simulating general characteristics and temperature characteristics of magnetizing fixture coil of the capacitor discharge impulse magnetizer-magnetizing fixture system using SPICE is presented. This method has been developed which can aid the design, understanding and inexpensive, time-saving of magnetizing circuit. As the detailed characteristics of magnetizing circuit can be obtained, the efficient design of the magnetizing circuit which produce desired magnet will be possible using our SPICE modeling. Especially, The knowledge of the temperature of the magnetizing fixture is very important to forecast the characteristics of the magnetizing circuits tinder different conditions. The capacitor voltage was not raised above 810[V] to protect the magnetizing fixture from excessive heating. The temperature estimation method uses multi-lumped model with equivalent thermal resistance and thermal capacitance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.80-83
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• 2008

Because of its advantages of simple structure, fast response speed, strong anti-pollution ability and good stability, high-speed solenoid valve has been widely used in aeroengine control systems, and some performances of the aeroengine control systems were affected directly by the response speed of high-speed solenoid valve. For some two-position two-way highspeed solenoid cone-valve, the paper discusses the establishment of its mathematical model and analyses its response characteristics by simulation model which is run in simulink of Matlab. Further more, a backstepping and segmentation method is used in the research of response characteristics, and the method is proved to be an accurate, fast and new method to get the influences of parameters on the valve s response characteristics.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.4
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• pp.318-324
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• 1999

In this paper. a control method based on finite element analysis is presented to improve the control characteristics of t the permanent magnet linear synchronous motor (PMLSM). In the control method. additional compensation current is a added to the conventional control current according to the position of mover. The characteristics of thrust ripple a according to the position of mover and the current are analyzed by using finite element method (FEM). And. the value of current to compensate the thrust ripple due to the cog밍ng force is calculated from the analysis results. The c characteristics according to control method are compared in case of speed control. and to conform the validity of the p presented method, a test set is built and experiments are performed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.9
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• pp.40-46
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• 2012

The single-phase switched reluctance motor(SRM) has only one inductance variation and the positive torque is generated in the restricted section. So, it cannot be started by itself. To solve this problem, many researchers have addressed the several starting method for the single-phase SRM. This paper is focused on the torque characteristics of the single-phase SRM according to starting method. The four major starting method - permanent magnet, saturable stator pole, to grade the rotor, stepped rotor pole - is selected to analyze the torque characteristics. The analysis model of each starting method is designed to changed the pole shape or inserting other material in the basic model. The torque characteristics of each analysis model is obtained by using FEM analysis. The FEM analysis is performed at incremental rotor positions over half inductance cycle in any one pole with 250AT, 500AT, 750AT. The distortion factor of each analysis model is analyzed through the FFT to compare the distortion between basic model and four analysis model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.9 s.240
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• pp.1175-1182
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• 2005

General systems have many substructures assembled at joints. The bolted joint is generally used in assembling the mechanical parts. However, there are no effective modeling methods to analyze the dynamic characteristics of bolt jointed structure using the finite element (FE) analysis, especially in case of large area contact. Moreover, the design methods for the appropriate bolt locations and the number of bolts considering the dynamic characteristics are not guided properly. In this study, a proper modeling method is developed to simulate the dynamic characteristics of a structure with the large interfaced area using the cone frusta method and spring elements. The natural frequencies are also controlled by adjusting the bolt-joint location and the number of bolts considering relative distances in mode shapes at the interface of bolt-jointed plates. The Modeling method and the optimized design method are verified based on the experimental and the FE analysis results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.393-399
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• 2006

In this paper we applied a ray tracing method to estimate the scattering characteristics from large scale random rough surfaces. For the electromagnetic field evaluation, we have used the diffracted coefficient of the knife edge diffraction for the diffracted rays and Fresnel's reflection coefficients in connection with reflected rays. In addition, we examine to search for the traced rays using the imaging method which can be obtained all rays to arrived at receivers accurately and the diffracted field from rough surfaces is considered. Numerical examples have been carried out for the scattering characteristics of an ocean wave-like rough surface and delay spread characteristics of a building-like surface. In the present work we have demonstrated that the ray tracing method is effective to numerical analysis of a rough surface scattering.

• Structural Engineering and Mechanics
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• v.52 no.5
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• pp.997-1017
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• 2014

According to the structure characteristics of the non-uniform beam bridge, a practical model for calculating the vibration equation of the non-uniform beam bridge is given and the application scope of the model includes not only the beam bridge structure but also the non-uniform beam with added masses and elastic supports. Based on the Bernoulli-Euler beam theory, extending the application of the modal perturbation method and establishment of a semi-analytical method for solving the vibration equation of the non-uniform beam with added masses and elastic supports based is able to be made. In the modal subspace of the uniform beam with the elastic supports, the variable coefficient differential equation that describes the dynamic behavior of the non-uniform beam is converted to nonlinear algebraic equations. Extending the application of the modal perturbation method is suitable for solving the vibration equation of the simply supported and continuous non-uniform beam with its arbitrary added masses and elastic supports. The examples, that are analyzed, demonstrate the high precision and fast convergence speed of the method. Further study of the timesaving method for the dynamic characteristics of symmetrical beam and the symmetry of mode shape should be developed. Eventually, the effects of elastic supports and added masses on dynamic characteristics of the three-span non-uniform beam bridge are reported.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.193-196
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• 1998

A new excitation method of switched reluctance motor drive is described in this paper. This excitation method produces reluctance torque by mutual action between two phases as well as conventional self reluctance torque due to two phase excitation at a time. In other words, the change of self inductance and mutual inductance are used to produce torque. This paper suggests the operational principle, the mechanism of torque product of switched reluctance motor with two phase excitation. The acoustic noise characteristics of two phase excitation method are described against that of conventional excitation method.

• Journal of Fashion Business
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• v.9 no.2
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• pp.1-19
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• 2005

The purpose of this study is to investigate the practice d social marketing of fashion business in Korea. A questionnaire was designed by the researcher and consisted of items of 30 items of social marketing practice in fashion business. Responsers are administrators and merchandisers who work in fashion business. Data were analyged using SPSS by frequency, mean, standard deviation, $x^2$-test, ANOVA and Duncan's multiple range test. The results of this study were as follows : 1. In decision-making method of social marketing, degrees of practice were shown comparatively high. And, three practice factors (consumerism, humanism, and environmentalism) showed indifference in six business characteristics (store type, staff number, annual budget, annual education method, education frequency, and the location). 2. In feedforward method of social marketing, degrees of practice were shown comparatively high. And, two practice factors (business strategy, and product strategy) showed indifference in seven business characteristics (date of establishment, store type, staff number, annual budget, education method, annual education frequency, and the location). 3. In administrative method of social marketing, degrees d practice were shown comparatively high. And, four practice factors (product development, price decision, distribution management, and advertisement and promotion) showed indifference in eight business characteristics (date d establishment, store type, staff number, annual budget, education method, annual education frequency, the location, and distribution structure). 4. In total system method of social marketing, degrees of practice were shown comparatively high. And, two practice factors (marketing planning, and self-audits system) showed indifference in six business characteristics (business size, store type, annual budget, education method, annual education frequency, and distribution structure). The present findings provide that social marketing of fashion business in korea has been practiced comparatively high.