• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.465-471
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• 2005

A method of calculation fur propagating and focusing of focused beams generated in antenna arrays, using BPM(Beam Propagation Method), is presented in this paper. Based on the diffraction theory, the beam focusing and Propagation is studied specially for the case of the antenna way fed by the Rotman lens that is able to focus microwave power on its focal arc or generate multiple beams. There are difficulties in performing a full-wave simulation using a commercial EM simulation tool for propagating and focusing of beams because of the structural complexity and the feeding assignment of the antenna array. Therefore, as an alternative solution, the BPM is presented to calculate the beam propagation from the aperture-type antennas. From the point of view of optics, the propagations of the lens have been simplified from the Fresnel diffraction integral to the Fourier transform. Using Fourier Transform, a beam propagation method is developed to show improvement of the resolution by controlling the wavefront of wave Propagating from an aperture-type antenna array. The beam width(or spot size) and the intensity are calculated for a focused beam propagating from an array having $10\lambda$ of its size. For the beams with $20\lambda,\;30\lambda$, and $50\lambda$ of geometrical focal length, the half-power beam widths(or spot size) are about 1.1\lambda,\;1.3\lambda,\;and\;1.9\lambda$ respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.753-760
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• 2009

In this paper, a novel planar spiral antenna of multi-tabs is proposed for wireless power transmission system based on low frequency magnetic inductive coupling. The proposed antenna has higher transmission efficiency than conventional antennas such a rectangular spiral antenna and a spiral antenna. Also, it has a useful property of uniform power transmission in the region of the antenna aperture. For verification, a transmitting antenna and a receiving one for a wireless power transmission system using magnetic inductive coupling of 132 kHz low frequency are designed and tested. The transmitting antenna has three-tabs spiral of unequal-space for higher uniform magnetic coupling in the antenna aperture. For reducing the receiving antenna size, two receiving antennas of unequal space two-tabs on one-side and series double sides as well are designed, respectively. From measurement, transmission efficiency of the proposed antennas is improved up to $3{\sim}10$ dB compared to conventional antennas.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.7-17
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• 2007

An analysis and design theory of an aperture-coupled cavity-fed back-to-back microstrip directional coupler is presented for the efficient and optimized design. For this purpose, an equivalent network is developed, and simple but accurate calculations of circuit element values are described. Design equations of the coupler are derived based on the equivalent circuit. In order to determine various structural design parameters, the evolutionary hybrid optimization method based on the genetic algorithm and Nelder-Mead method is invoked. As a validation check of the proposed theory and optimized design method, a 10 dB directional coupler was designed and fabricated. The measured coupling was 10.3 dB at 3 GHz, and the return loss and isolation were 31.8 dB and 30.5 dB, respectively. The directional coupler also showed very good quadrature phase characteristics. Good agreements between the measured and the design specifications fully validate the proposed network analysis and design procedure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1040-1049
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• 2006

A design method for minimizing transmission loss of a broadband right-angle transition from a coaxial cable to a microstrip line is presented. The right-angle transition has been widely used where printed circuit applications need to be fed from behind the ground plane using coaxial line. To obtain the minimized transmission loss over the whole operating frequency range of the transition, design parameters such as ground aperture and probe diameters, ground aperture offset, and stub length are optimized using a commercial electromagnetic simulation software. Results are presented for the optimum right-angle transition from an SMA connector to a microstrip line on common reinforced 0.787 mm thick PTFE substrates. Measurements of a fabricated transition show that reflection coefficient is less than -22 dB and insertion loss is less than 0.45 dB over $0.05{\sim}20GHz$.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1015-1022
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• 2023

In this paper, we propose DLP(Dual Linear Polarization) antenna with aperture coupled feeding structure for private network. The proposed antenna has general aperture coupled structure and design two port between top and bottom layer to obtain the enhanced isolation. Also, The size of each substrate(top and bottom layer) is 34.0 mm(W)×34.0 mm(L), which is designed on the FR-4 substrate which thickness (h) is 1.0 mm, and the dielectric constant is 4.4. Also, the size of patch antenna is 12.70 mm(W2)×14.60 mm(L3), and it is located on the top layer. The size of feeding line is 24.0 mm(W2)×1.6 mm(L3), and is located at the bottom layer Also, rectangular slot is located on the ground plane between top layer and bottom layer. From the fabrication and measurement results, bandwidths of 300 MHz (4.52 to 4.82 GHz) for feeding port 1, and 170 MHz (4.65 to 4.82 GHz) for feeding port 2 are obtained on the basis of -10 dB return loss and transmission coefficient S21 is got under the -30 dB. Also, cross polarization isolation between each feeding port obtained

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.131-138
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• 1998

기상폭발은 가연성물질이나 산화제의 성질 및 공간의 상태에 크게 의존하며, 밀폐공간에서 일어날 경우에는 그 공간을 구성하고 있는 벽면의 강도 둥에 의해 폭발현상이 달라진다. 밀폐공간의 가로, 세로, 높이 중 임의의 두 방향 치수비가 1보다 극단적으로 다르지 않은 거주공간의 경우 공간내의 가연성 혼합기의 농도분포, 공간을 구성하고 있는 벽면 가운데 약한 부분의 강도 및 넓이, 개방되고 있는 창등의 개구부의 넓이등의 상태가 폭발 특성에 대한 변수가 된다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.188-190
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• 1999

현재 지하주차공간의 자연환기방식에 대한 우리나라 건축법규의 기준은 150m$^2$ 이내마다 1개소이상의 외기와 면하는 2m$^2$이상의 개구부를 천창 혹은 Dry Area를 설치하도록 규정하고 있다. 이 지하공간에서의 자연환기는 풍력, 온도차, 차량출입구에 의한 환기를 들 수 있으나 주로 풍력에 의한 환기가 대부분을 차지한다.(중략)

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1089-1095
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• 2003

In this paper, the 26 GHz band omnidirectional antenna that produces an isotropic radiation pattern in the azimuth plane and a directive radiation pattern in the elevation plane was designed by using reflector antennas. To investigate the reliability of the designed antenna, that was analyzed by using the aperture field method and the calculated value was compared with the measured value. An good agreement was achieved between the calculated characteristics and the experimental performance. We found that the designed antenna in this paper can be used as the omnidirectional antenna with reflectors and the analysis method in this paper can be used for the analysis of this type antenna.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.147-158
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• 1998

The purpose of thesis is to analyze the radiation characteristics of the parabola reflector antenna. The equivalent sources are used to compute the radiation fields in the far-zone utilizing the aperture integration. Using these results, we obtain the efficiency parameters associated with reflector : aperture efficiency, spillover efficiency, as the function of F/D, diameter beam squint angle and misarrangement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.830-838
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• 2003

In this paper, TX/RX dual operation microstrip single antenna for satellite communication is designed, analyzed, fabricated and measured. TX/RX frequency ranges are 14.0∼l4.5 GHz, 11.7∼12.75 GHz in respectively and vertical and horizontal polarizations are used for TX and RX. This antenna uses microstrip direct feeding for RX and aperture coupled strip-line feeding for TX and accommodates stacked elements for a high directivity and wide impedance bandwidth. In an analysis of single element, FDTD and MOM was compared and FDTD analysis was more accurate because of the consideration of finite structure and imperfect two ground planes. The proposed structure facilitates generally to an extension of two dimensional array and lower an unwanted radiation by strip-line feed in TX. TX/RX 8${\times}$4 array has a return loss below -10 dB, -14 dB in TX, RX respectively and a gain ranging from 19.1∼20.7 dB in TX, 21.2∼21.8 dB in RX which has a radiation efficiency of 43∼5l %, 52∼57 %.