• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1585-1591
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• 2009

This paper describes a new method for extracting characteristic impedance of transmission line using Substrate Integrated Artificial Dielectric (SIAD). The new procedure to calculate the characteristic impedance of SIAD transmission line is described with the proper equations and basic transmission line theory. The characteristic impedance is determined as an almost fixed value in the proposed method, while it fluctuates according to frequency in the previous method. As the result, the effective dielectric constant of SIAD transmission line is calculated as a fixed value rather than fluctuating one. In order to show the validity of the proposed method, SIAD microstrip lines are simulated and measured, and characteristic impedances and effective dielectric constant are calculated and compared to the previous method.

• Communications of the Korean Mathematical Society
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• v.32 no.1
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• pp.107-118
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• 2017

In this paper we study CR-submanifolds of maximal CR-dimension by investigating extrinsic behaviors of integral curves of characteristic vector field on them. Also we consider the notion of ruled CR-submanifold of maximal CR-dimension which is a generalization of that of ruled real hypersurface and find some characterizations of ruled CR-submanifold of maximal CR-dimension concerning extrinsic shapes of integral curves of the characteristic vector field and those of CR-Frenet curves.

• Journal of the Chungcheong Mathematical Society
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• v.27 no.2
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• pp.287-295
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• 2014

In this paper, we prove that the image of the representation of the automorphism group of a supersingular K3 surface of Artin-invariant 1 over odd characteristic p on the global two forms is a finite cyclic group of order p + 1. Using this result, we deduce, for such a K3 surface, there exists an automorphism which cannot be lifted over a field of characteristic 0.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.9
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• pp.685-690
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• 1987

Adaptive design of IIR digiral filters using equation error method has been studied. In this paper, a design technique of IIR digital filters using output error method with adaptive compensator is presented. In computer simulation results, it is shown that flat response characteristic in pass-band, below-40[dB] attenuation characteristic in stop-band, sharf cut-off characteristic in transition-band, and phase characteristic is linearin pass-band.

• Bulletin of the Korean Mathematical Society
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• v.54 no.3
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• pp.911-916
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• 2017

A Damek-Ricci space is a typical locally harmonic manifold, which is a generalization of the rank one symmetric space of the non-compact type. In this paper, we determine explicitly the characteristic function of a Damek-Ricci space by calculating the determinant of a Jacobi tensor.

• Korean Journal of Computational Design and Engineering
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• v.8 no.4
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• pp.262-269
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• 2003

An approach to compute characteristic curves such as section curves, reflection characteristic lines, and asymptotic curves on a surface is introduced. Each problem is formulated as a surface-plane inter-section problem. A single-valued function that represents the characteristics of a problem constructs a property surface on parametric space. Using a contouring algorithm, the property surface is intersected with a horizontal plane. The solution of the intersection yields a series of points which are mapped into object space to become characteristic curves. The approach proposed in this paper eliminates the use of traditional searching methods or non-linear differential equation solvers. Since the contouring algorithm has been known to be very robust and rapid, most of the problems are solved efficiently in realtime for the purpose of visualization. This approach can be extended to any geometric problem, if used with an appropriate formulation.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.558-563
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• 2005

In this paper, the effect of volute area distribution on the performance characteristic curve of a centrifugal pump were numerically studied using a commercial CFD code. To reduce the shutoff head, maintaining head and efficiency at a design flow rate, the flat head-capacity characteristic curves in which the head varies only slightly with capacity from shutoff to design capacity are frequency required. In order to control the shutoff head of a pump, several volute area distributions were proposed as a main parameter with the same impeller geometry. The calculation results show that the characteristic curve of a centrifugal pump can be controlled by modifying the area distribution with the same volute outlet area.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.57-60
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• 2001

This paper reports on speaker-Recognition of context independence-speaker recognition in the field of the speech recognition. It is important to select the parameter reflecting the characteristic of each single person because speaker-recognition is to identify who speaks in the database. We used Mel Frequency Cesptrum Coefficient and Vector Quantization to identify in this paper. Specially, it considered to find characteristic-vector of the speaker in different from known method; this paper used the characteristic-vector which is selected in MFCC Parameter Space. Also, this paper compared the recognition rate according to size of codebook from this database and the time needed for operation with the existing one. The results is more improved $3\sim4\%$ for recognition rate than established Vector Quantization Algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.197-197
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• 2000

In this paper, we present a novel method for design of fuzzy Logic controllers by defining a set of characteristic parameters (CFLCS). These parameters are extracted and defined by examining the structure and characteristics of the individual components of FLCs and parameterizing those. Based upon this formulation, a series of simulations is conducted for plants having simple dynamics in order to see the performance of this proposed method. The simplicity and effectiveness of this method are discussed in detail.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.3
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• pp.224-229
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• 2004

In order to control the railway noise, the radiation characteristic of the noise when the train passes by should be analyzed. Generally, the major noise sources of the Korea Train Express are the rolling noise and power unit noise up to 300km/h. In this paper, a train model that is considered to be a row of point sourcesis introduced to analyze the radiation characteristic. The analysis results are compared with the measurement ones. It is shown that the propagation characteristic of the rolling noise is a dipole type and the noise generated by the power unit is radiated as a cosine type. With increasing of the train speed, the noise level at a receiving point is increased in the direction of motion and reduced in the direction opposite to the motion. The analysis results including the moving effect of the noise source at 300km/h show good agreement with the measurement results.