• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.42-49
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• 2014

Performance evaluation was carried out for the 70 N-class hydrazine thruster whose design performance had been already verified. The pulse-mode firing test was conducted for the development model thrusters with various thrust chamber diameters. Evaluation was made by the performance parameters such as specific impulse, impulse bit, and characteristic velocity, etc: specific impulse and characteristic velocity were deteriorated as the thrust chamber diameter deviates from a standard model. Consequently, it is revealed that the performance characteristics of standard model is most superior among the test models.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.32-33
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• 2009

We propose viewing angle switchable liquid crystal display(LCD) associated with fringe-field switching (FFS) mode with high aperture ratio characteristic. This device is composed of R(red), G(green), B(blue), pixel and W(white) pixel in which R,G,B pixel shows image and white pixel for both viewing angle control and image. Conventional viewing angle controllable liquid crystal display has not transmittance because the liquid crystal only tilts up without rotates in viewing angle control region. In this paper, we suggested that the device has high transmittance characteristic because the LC directors are rotated in which viewing angle control region are generated fringe electric field.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.122-129
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• 2001

A characterization procedure for analyzing symmetric coupled MIS(Metal-Insulator-Semiconductor) transmission line is used the same procedure as a general single layer symmetric coupled line with perfect dielectric substrate from the extraction of the characteristic impedance and propagation constant for even- and odd-mode. In this paper, an analysis for a new substrate shielding symmetric coupled MIS structure consisting of grounded crossbar at the interface between Si and SiO2 layer using the Finite- Difference Time-Domain(FDTD) method is presented. In order to reduce the substrate effects on the transmission line characteristics, a shielding structure consisting of grounded crossbar lines over time-domain signal has been examined. Symmetric coupled MIS transmission line parameters for even- and odd-mode are investigated as the functions of frequency, and the extracted distributed frequency- dependent transmission line parameters and corresponding equivalent circuit parameters as well as quality factor for the new MIS crossbar embedded structure are also presented. It is shown that the quality factor of the symmetric coupled transmission line can be improved without significant change in the characteristic impedance and effective dielectric constant.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.960-964
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• 2003

In this paper, the CMOS integrated circuit technique for implementing current-mode maximum and minimum operations scheme is described. The maximum and minimum operations are incorporated into the same scheme with parallel processing. Using this scheme as the basic unit, an analog three-input maximum, median, and minimum circuit is designed. The performance of the proposed circuit shows a very sharp transfer characteristic and high accuracy. The proposed circuit achieves a high-speed operation, which is suitable for real-time systems. The PSPICE simulation results demonstrating the characteristic of the proposed circuit are included.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.5
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• pp.425-429
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• 2007

A linear ultrasonic motor was designed by a combination of the longitudinal and bending mode. linear ultrasonic motors are based on an elliptical motion on the surface of elastic body, such as bar or plates. The corresponding eigen-mode of one resonance frequency can be excited twice at the same time with a phase shift of 90 degrees in space and time. That is excite symmetric and anti-symmetric modes. Then it determines the thrust and speed of the motor. Linear ultrasonic motors are investigated experimentally in according to be fabricated a general classification to motor structure and material characteristic. There was the first to simulate as use of finite element analysis ANSYS 9.0. The AL-T2W8-ARM14-LEG18-ANGLE80 motor has a maxim efficiency 18 % under the speed 0.14 m/s, thrust 345 gf and preload 280 gf, operating frequency is 57.6 kHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.267-270
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• 2000

This paper describes measurement of relative permittivity of illite found in young-dong area. A measurement of relative permittivity of illite used to cylindrical cavity resonators with moveable cap. A concentric dielectric-rod inserted cylindrical cavity resonator and an exact field representation of travelling wave mode are introduced for measurement of relative permittivity. The exact electromagnetic fields in cylindrical cavity with concentric dielectric rod is analysed. A relative permittivity of dielectric in cavity is calculated by analyzing the characteristic equation. The characteristic equation is solved by using the ContourPlot graph of Mathematica. We know that the field representation of travelling mode is exact. As a result, relative permittivity of dielectric materials were 7.820 at sample-1 and 7.894 at sample-2.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.729-731
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• 2003

This Paper describes for vibration characteristic analysis by mode variation of ring type ultrasonic motor. Design for piezoelectric ceramic and elastic body of stator was calculated by Atila using the finite element method(FEM) that considers the resonance frequency, vibration mode and coupling efficiency etc. The propriety of this paper was established through simulation and experiment results of ring type ultrasonic motor.

• Journal of electromagnetic engineering and science
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• v.19 no.1
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• pp.1-5
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• 2019

In this study, optimum locations for a loop-type ground radiation antenna are evaluated for C-shaped ground planes of two different sizes. To achieve good radiation performance, the antenna needs to be located such that it couples with the dominant current mode of the ground plane. Antenna locations are proposed using the characteristic mode analysis of the ground planes. The measured bandwidths of the antennas at the proposed locations have more than twice the bandwidths of the cases in which the antennas are coupled with non-dominant modes. The operating frequency of the antennas is 2.45 GHz.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.7
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• pp.23-29
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• 1995

A characteristic mode theory for longitudinal slot of arbitrary width in the outer conductor of coaxial waveguide is applied for calculating the characteristic magnetic currents, the characteristic fields, radiation patterns, and the fields evershere(inside and outside the guide, and in the aperture region). Numerical results of the equivalent magnetic currents and the radiation patterns are compared with those obtained by use of the method of moments.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1296-1302
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• 2008

This paper deals with modeling and dynamic characteristic analysis of a large-powered LNG electric ship propulsion system. Basically, we perform to verify the adequacy of system modeling on the sea going mode and LNG unloading mode based on load flow analysis. And then, we observe the dynamic characteristic of system to perform motor starting analysis and transient stability analysis. Particularly, this paper examine analysis results in comparison with the IEEE standard 141 and the class rule. Hence, this paper has evaluated stability of the electric ship propulsion system at static and dynamic conditions.