• Communications of the Korean Mathematical Society
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• v.36 no.4
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• pp.829-833
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• 2021

We investigate the Möbius transformation action of PSL(2, ℝ) on the set of mutually distinct ordered triple points of ℝ ∪ {∞}.

• Bulletin of the Korean Mathematical Society
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• v.23 no.2
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• pp.161-166
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• 1986

Through the paper, we consider functions f analytic in the unit disk D={z:vertical bar z vertical bar <1} normalized by f(0)=0 and f'(0)=1. Following Rogosinski [5], we let T denote the class of all typically-real functions f which preserve half-plane in the following sense.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1321-1324
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• 2007

In this paper, the in-plane end vibration of a cylindrical shell has been analyzed. The theoretical result has showed that the strong in-plane vibration at the ends of the cylindrical shell can be generated by the evanescent wave field, which is excited along about half the length of the shell. This has been also observed from experimental result. The evanescent waves are generated due to mode conversion of elastic waves at the ends of the cylindrical shells. The results show that the strong in-plane end vibration can be generated in cylindrical shells.

• Journal of electromagnetic engineering and science
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• v.18 no.1
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• pp.46-51
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• 2018

In this paper, a planar printed hybrid short/open-ended slot antenna with capacitive coupling feed strips is proposed for hepta-band mobile applications. The proposed antenna is comprised of a slotted ground plane on the top plane and two capacitive coupling feed strips with a chip inductor on the bottom plane. At the low frequency band, the short-ended long slot fed by strip 1 generates its half-wavelength resonance mode, whereas the T-shaped open ended slot fed by strip 2 generates its quarter-wavelength resonance mode for the high frequency band. The antenna provides a wide bandwidth covering GSM850/GSM900/DCS/PCS/UMTS/LTE2300/LTE2500 operation bands. Moreover, the antenna occupies a small volume of $15mm{\times}50mm{\times}1mm$. The operating principle of the proposed antenna and the simulation/measurement results are presented and discussed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.4
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• pp.395-401
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• 1996

In this paper, the propagation characteristics due to the horizontal water temperature variations in the sea such as thermal fronts is analyzed by the ray theory. Two models for the temperature anomaly layer are chosen. One is a plane type and the other is a cylindrical type. In the plane type, the temperature increases linearly from a isothermal region to 5km with the gradient of about $2^{\circ}C.$/km, and decreases with the same gradient in next 5km. In the cylindrical type, water temperature increases only with the same gradient from a half cylindrical thermal boundary surface. The result showed that the gradient of acoustic rays decreases in the temperature increasing region and vice versa in temperature decreasing region. And, the transmission loss due to the temperature variation was less than O.2dB in the plane type model as well as in the cylindrical one.

• Steel and Composite Structures
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• v.5 no.4
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• pp.305-326
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• 2005

The inelastic buckling behaviour of continuously restrained two and three-span continuous beams subjected to concentrated loads and uniformly distributed loads are studied in this paper. The restraint type considered in this paper is fully restrained against translation and elastic twist applied at the top flange. These types of restraints are most likely experienced in industrial structures, for example steel-concrete composite beams and half through girders. The buckling analysis of continuous beam consists of two parts, firstly the moment and shear distribution along the member are determined by employing force method and the information is then used for an out-of-plane buckling analysis. The finite element method is incorporated with so-called simplified and the polynomial pattern of residual stress. Owing to the inelastic response of the steel, both the in-plane and out-of-plane analysis, which is treated as being uncoupled, extend into the nonlinear range. This paper presents the results of inelastic lateral-torsional and lateral-distortional buckling load and finally conclusions are drawn regarding the web distortion.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1109-1114
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• 2003

In this paper, the electric characteristic of the SGPS with slot in the ground plane is similar to the parallel resonant circuit. When the slot length in SGPS is equal to the half wavelength of specific frequency, the characteristic of SGPS represent the large attenuation at the specific frequency. We found out the relation between attenuation and resistor on the slot in SGPS and we designed the variable attenuator for MMIC using the variable resistor. This attenuator can be applied to AGC circuit in transceiver if the PIN diode is used replace for resistor.

• Earthquakes and Structures
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• v.9 no.4
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• pp.753-766
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• 2015

An investigation has been carried out for the propagation of torsional surface waves in an inhomogeneous prestressed layer over an inhomogeneous half space when the upper boundary plane is assumed to be rigid. The inhomogeneity in density, initial stress (tensile and compressional) and rigidity are taken as an arbitrary function of depth, where as for the elastic half space, the inhomogeneity in density and rigidity is hyperbolic function of depth. In the absence of heterogeneities of medium, the results obtained are in agreement with the same results obtained by other relevant researchers. Numerically, it is observed that the velocity of torsional wave changes remarkably with the presence of inhomogeneity parameter of the layer. Curves are compared with the corresponding curve of standard classical elastic case. The results may be useful to understand the nature of seismic wave propagation in geophysical applications.

• Steel and Composite Structures
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• v.20 no.5
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• pp.1103-1117
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• 2016

The present investigation is to study the plane problem in initially stressed thermoelastic half-space with voids due to thermal source. Lord-Shulman (Lord and Shulman 1967) theory of thermoelasticity with one relaxation time has been used to investigate the problem. A particular type of thermal source has been taken as an application of the approach. Finite element technique has been used to solve the problem. The components of displacement, stress, temperature change and volume fraction field are computed numerically. The resulting quantities are depicted graphically for different values of initial stress parameter. The relaxation time and the initial stress parameter have a significant effect on all distributions.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.367-375
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• 2014

In this paper, a novel triple-band circular-ring monopole antenna with a half-circular ring and ground slot for wireless local area network/Worldwide Interoperability of Microwave Access (WLAN/WiMAX) applications is proposed. The proposed antenna consists of one circular ring, a half-circular ring and a rectangular slot in the ground plane. Based on the concept, a prototype of the proposed triple-band antenna was designed, fabricated and tested. The numerical and experiment results demonstrated that the proposed antenna satisfied the -10 dB impedance bandwidth requirement while simultaneously covering the WLAN and WiMAX bands. Furthermore, this paper presents and discusses the 2D radiation patterns and 2D gains according to the results of the experiment.