• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.629-635
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• 1997

The theory of characteristic modes for coaxial waveguide with periodic axial slots is used to derive the weighted eigenvalue equation for calculating the characteristic values and the characteristic currents. Once the characteristic values and the characteristic currents are obtained, the important quantities such as the equivalent magnetic current, radiation patterns, and RCS are determined. Numerical results of the equivalent magnetic currents, radiation patterns, and RCS are compared with those obtained by use of the method of moments. A fairly good correspondence is observed between them.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.79.1-84
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• 1995

The thermal analysis method containing micro drilling characteristic is proposed for the first time. There are such problems in thermal analysis of micro hole drilling as the thermal modeling complexity of drilling process and the undesirable micro drilling characteristic. Especially, the undesirable micro drilling characteristic prevents our using conventional thermal modeling. To model the thermal behavior of the micro drilling process, the finite different method, where heat source vectors are distributed by the measured rhrust and torque, is proposed. This method agrees with thermal behavior of the real system. And, it enable to predict the temperature field near the drill during. The validity of this method is verified in comparing with experimental results.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.381-384
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• 2003

Among digital halftoning methods, error diffusion is a procedure for generating high quality bilevel images from continuous-tone images but blurs the edge information in the bilevel images. To solve the problem, we propose the edge enhanced error diffusion using the edge information of the original images. The edge enchanted weights is computed by adding local characteristic weights and input pixels multiplied a constant. Also, we combined the edge enhanced method with the adaptive error diffusion using human spatial and frequency perception characteristic. The performance of the proposed method is compared with conventional method by measuring the edge correlation. The halftoned images applied the proposed method get more fine quality due to the enchanced edge and better quality in halftoned image. And the detailed edge is preserved in the halftoned images by the proposed method.

• Journal of KSNVE
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• v.7 no.5
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• pp.781-787
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• 1997

A new method is presented to determine two fundamental acoustic quantities of sound-absorbing materials such as characteristic impedance and propagation constant. In this study, the surface acoustic impedances of sound-absorbing materials are measured using the impedance tube and the anechoic chamber to determine the above acoustic quantities. The measured results are given for two typical sound-absorbing materials(glass wool and urethane foam) int the frequency range between 150 and 1, 600 Hz. The results are verified by other two known methods, which are Smith & Parrott method and Utsuno et al. method. The absorption coefficients calculated from the empirical models(Miki model for glass wool and Jung model for urethane foam) and two quantities by present method are in good agreement with the measured values.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.1
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• pp.67-73
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• 2000

The water quality of inland stream is polluting with industrialization and urbanization, and with that water quality of lake also deteriorated, to manage water quality pollution problem of lake, new water quality management method is needed. As a pilot study of the method that manage water quality of lake using GSIS(Geo-Spatial Information System), we study the method which automatically extract the hydraulic characteristic informations of lake in GSIS environment. Also, as an example of practical use of the extracted hydraulic characteristic information of lake, we carry out the characteristic analysis of waterbody flow using finite different method. With the automation the extraction procedure of hydraulics characteristic information needed in characteristic analysis of waterbody flow, we carried out the analysis efficiently. Particularly, with the extraction of section information on lake not in layout form, in analyzable form, we make the analysis that section information of lake was indispenably required(e.g. stratification analysis) possible in GSIS environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7A
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• pp.1257-1263
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• 2001

In the paper, the p-ranks and characteristics polynomials of cyclic difference sets are derived by expanding the trace expression of their characteristic sequences. By using this method, it is shown that the 3-ranks and characteristic polynomials of Helleseth-Kumar-Martinsen (HKM) difference set and Lin difference set can be easily obtained.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.11
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• pp.387-393
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• 1983

This paper descrives the computational algorithm for determination of system characteristic constants using diakoptic method. When the system charateristic contants of large scale power system are calculated by using sensitivity matrix method which requires the inversion of Jacobian matrix, the necessary computing time and memory requirements increase very largely. Diakoptic mothods is benefit to get around these problems, and it is applied to a model system compared with the integrated method to discuss the efficiency of the algorithm.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.137-140
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• 2003

Shorted-turns can have significant effects on a generator and its performance. Shorted-turn sensor for synchronous generator's field winding have been developed. One of effective method detecting inter-turn short circuits on round rotor winding is a method using sensor detecting. But the method needs duplicate design of sensor for characteristic change according to types and forms of generator Thus sensing skill without sensor depend on change of electric property in generator. For the reason, this paper presents shorted-turns phenomenon and the characteristic analysis of shorted-turns In synchronous generator by using 2-D finite element method(FEM).

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.42-45
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• 2002

A novel characteristic value extraction method based on morphological spatial frequency is proposed. Morphological spatial frequency defined by morphological pattern distribution function is introduced. Superiority of the method was proved for various images by experiment. Furthermore the fact that the proposed method does not need threshold to obtain binary image provides its applicability to content-based image retrieval.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.7
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• pp.379-386
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• 2002

This paper deals with dynamic analysis method of a slotless type permanent magnet linear synchronous motor(PMLSM) using 3-dimensional space harmonic method. The results are good agreement with FEA results because that slotless type PMLSM has simple structure and no saturation of core. And then, Under open-loop control, starting characteristic is analyzed by voltage equation combining with dynamic equation. In order to obtain more accuracy results, this paper use instantaneous back-EMF and thrust instead of back-EMF constant and thrust constant.