• Journal of the Korea Society of Computer and Information
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• v.15 no.7
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• pp.67-74
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• 2010

TIn this paper, it is designed the polarization selective antenna for UHF RFID system. The proposed antenna is consist of microstrip patch antenna with dual feeding and two SPDT switches and a SP4T switch and 3dB hybrid coupler. Through control of voltage of switches, the proposed reader antenna can select horizontally linear polarization, vertically linear polarization, left-hand circular polarization (LHCP) and right hand circular polarization (RHCP). The proposed reader antenna satisfied 2:1 VSWR at 902MHz~928MHz. and it has under 3dB AR(axial ratio). Peak gain of antenna is 7.71dBi, 7.55dBi with linear polarization and 7.31dBic, 7.81dBic with circular polarization at x-y plane. Also Axial ratio of antenna is 2.01~2.83dB and 2.02~2.60dB respectively. It is satisfied 3dB axial ratio.

• Journal of IKEEE
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• v.16 no.3
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• pp.173-176
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• 2012

This paper introduces a novel horn antenna for circular polarization using a planar-type radiator. This antenna can be divided to two parts, microstrip antenna and square horn. The microstrip antenna has the role of feeder and polarizer of the horn antenna, and it is designed to stacked type having metal spacer for high gain, high isolation and wideband characteristic. Using the proposed antenna structure, the horn antenna needs not additional structure such as feeder and polarizer, and the size of it can be considerably reduced. The horn antenna has typical gain of 8dBi and 3-dB axial-ratio bandwidth around 4.9%.This antenna can widely used for various antenna system for mobile and satellite communication using circular polarization expecially in high frequency band.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.293-296
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• 2005

This paper presents the design of linear and circular polarization baseball- shaped circular microstrip antenna (BCMA) with 3-dimensional structure using perturbation effect to reduce its size, which runs at 1.575GHz frequency bandwidth. As a result, the size of linear polarized antenna could be reduced up to 23.7% in patch diameter and 41.8% in its area. Linear polarized antenna has -26.04dB of return loss, 69MHz(4.38%) of -l0dB bandwidth, 4.51dBd of gain, and its -3dB beamwidth are 99$^{\circ}$ in E-plane, 83$^{\circ}$ in H-plane. Circular polarized antenna has -17.43dB of return loss, 113.7MHz(7.2%) of -l0dB bandwidth, 2dBd of gain, 2dB of axial ratio and its -3dB beamwidth are 87$^{\circ}$, 86$^{\circ}$ x-axis polarized, 80$^{\circ}$, 84$^{\circ}$ y-axis polarized. It has 82mm of diameter, which is 28.5% of linear polarized CMPA. Therefore, in this paper we verified that baseball-shaped 3-dimensional structure of circular microstrip patch antenna applied with perturbation effect is appropriate for miniaturization.

• Steel and Composite Structures
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• v.7 no.1
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• pp.19-34
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• 2007

This paper presents results of a non-linear finite element analysis of axially loaded slender hollow structural section (HSS) columns, strengthened using high modulus carbon-fiber reinforced polymer (CFRP) longitudinal sheets. The model was developed and verified against both experimental and other analytical models. Both geometric and material nonlinearities, which are attributed to the column's initial imperfection and plasticity of steel, respectively, are accounted for. Residual stresses have also been modeled. The axial strength in the experimental study was found to be highly dependent on the column's imperfection. Consequently, no specific correlation was established experimentally between strength gain and amount of CFRP. The model predicted the ultimate loads and failure modes quite reasonably and was used to isolate the effects of CFRP strengthening from the columns' imperfections. It was then used in a parametric study to examine columns of different slenderness ratios, imperfections, number of CFRP layers, and level of residual stresses. The study demonstrated the effectiveness of high modulus CFRP in increasing stiffness and strength of slender columns. While the columns' imperfections affect their actual strengths before and after strengthening,the percentage gain in strength is highly dependent on slenderness ratio and CFRP reinforcement ratio, rather than the value of imperfection.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1287-1292
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• 2012

In this paper, a dual polarization patch antenna operates at the wide bandwidth of 1.525GHz~1.665GHz was designed and fabricated. To obtain the wide bandwidth and high gain, increased height of air floor from GND was applied, and to get wide band axial ratio and high gain, parasitic patch was applied. The simulation and measurement showed good agreements, the VSWR was less than 1.9 at the frequency bandwidth, the return loss was less than -10dB, and the LHCP(Left Hand Circular Polarization) and RHCP(Right Hand Circular Polarization) isolation was less than -13dB at the frequency bandwidth.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2004-2010
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• 2018

We propose a small active antenna to receive Global Navigation Satellite System (GNSS) signals, i.e., Global Positioning System (GPS) L1 (1,575MHz) and Russian Global Navigation Satellite System (GLONASS) L1 (1,600 MHz) signals. A two-stage low-noise amplifier (LNA) with more than 27 dB gain is implemented in the bottom layer of a three-layer antenna package. In addition, a hybrid coupler is used to combine signals from pair of proximately coupled orthogonal feeds with $90^{\circ}$ phase difference to achieve the circular polarization (CP) characteristic. Three layers of high permittivity (${\varepsilon}_r=10$) substrates are stacked and effectively integrated to have a small dimension of $64mm{\times}64mm{\times}7.42mm$ (including both circuit and antenna). The reflection coefficient of the fabricated antenna at the target frequency is below -10 dB, the measured antenna gain is above 26 dBic and the measured noise figure is less than 1.4 dB.

• Journal of the Semiconductor & Display Technology
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• v.17 no.2
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• pp.20-25
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• 2018

In this paper, we have designed circularly polarized array antenna for 5.8GHz microwave wireless power transmission. To obtain high antenna gain, we studied a single patch antenna, a $2{\times}1$ array antenna, a $2{\times}2$ array antenna, a $2{\times}4$ array antenna, and a $4{\times}4$ array antenna. Commonly, characteristics of each antenna have a frequency of 5.8 GHz and Right Hand Circular Polarization(RHCP) of circular polarization. Also, the results were obtained with the design to each antenna that the return loss was less than -10dB and the axial ratio was less than 3dB. The gain of the antennas was 6.08dBi for a single patch antenna, 9.69dBi for a $2{\times}1$ array antenna, 12.99dBi for a $2{\times}2$ array antenna, 15.72dBi for a $2{\times}4$ array antenna and 18.39dBi for a $4{\times}4$ array antenna. When the elements of the array antenna were increased, it was confirmed that it increased by about 3dBi.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.331-340
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• 2011

The application of newly developed fiber-sheet and steel-plate composite plate (FSP) as a means of improving strength and ductility capacity of concrete cylinders under axial compression load through confinement is investigated experimentally in this study. An experimental investigation involves axial load tests of two types of FSP strengthening material, two anchoring methods, and three concrete strengths. The FSP-confined cylinder tests showed that FSP provided a substantial gain in compressive strength and deformability. The performance of FRP-confined cylinders was influenced by type of the FSP strengthening material, the anchoring method, and concrete compressive strength. The FSP failure strains obtained from FSP-confined cylinder tests were higher than those from FRP-confined cylinder tests. The magnitude of FSP failure strain was related to the FSP composite effectiveness. The effects of FSP confinement on the concrete microstructure were examined by evaluating the internal concrete damage using axial, radial, and volumetric strains. From the observations obtained in this investigation, it is believed that FSP is one of the best solutions for the confinement of concrete compressive members.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.707-712
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• 2008

In this paper, the sequentially rotated array(SRA) antenna with 256 elements applicable for satellite broadcasting reception was designed by arraying this triple(4+8+4 element) SRA antenna as a sub-array antenna. The structure of a triple SRA antenna is a combination of three coaxial shells composed with 4 elements of inner shell and 8 elements of middle shell and 4 elements of outer shell. In accordance with the optimum design rules for realizing a high gain antenna, the sequential array factors(M, P) of inner shell and outer shell have been chosen M=4 and P=1 and that of middle shell has been chosen M=8 and P=1. The results of the simulation and the measurement for the proposed triple(4+8+4 element) SRA antenna and the SRA antenna with 256 elements show good characteristics on the integration, bandwidth of the axial ratio and the cross-polarization, the gain respectively.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.505-508
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• 2012

A permanent magnet flux switching (PMFS) machine has a simple rotor, whilst both magnets and coils are set in the stator, resulting in easy removal of heat due to both copper loss and eddy current loss in magnets. However, the volume of magnets used in PMFS machines is usually larger than in conventional PM machines, and leakage flux does exist at the non-airgap side. To make full use of the magnets and gain higher power density, a novel 3-dimensional (3D) field PMFS machine is developed. It combines merits of the tubular linear machine, external-rotor rotary machine and axial-flux rotary machine, hence, offers high power density and peak torque capability, as well as efficient utility of magnets owing to the unique configuration of triple airgap fields.