• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.2
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• pp.41-51
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• 2004

In this paper, the beam steering dipole phased array antenna systems for IMT-2000 base station have been designed. The designed beam steering dipole phased array antenna systems are constituted by the antenna part and the beam steering control system part. The antenna part is designed by the proposed flat dipole for the broadband characteristics, and the 8${\times}$8 dipole array antenna is constructed by the proposed flat dipole for the directional radiation pattern. Besides the vertical power divider is designed for the vertical power distribution. The beam steering control system part is designed the horizontal power divider for the horizontal power distribution, the 4-bit phase shifters and the driving circuit of phase shifters for the horizontal beam tilting. In order to evaluate a performance of the designed antenna systems, they were fabricated and the radiation characteristics were measured. From the measured results, we found that the horizontal beams were tilted by the each control signals, and the measured radiation characteristics showed good agreement with the design goals.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.208-217
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• 2013

When a beamforming can be processed separately in horizontal and vertical directions with the planar arrays used in sonar systems, there are several merits such as that practically reduce the required computations and volumes. However, the common planar arrays used in sonar systems are generally non-separable, so the beamforming with separable weighting results in the differences between the desired beam characteristics and the resultant beam characteristics. In this paper, we propose a new separable weighting method which can achieve the wanted beam characteristics by using the separable weights in horizontal and vertical directions for the non-separable planar arrays. In order to achieve the wanted beam characteristics, the proposed method minimizes the differences between the desired weights and the resultant weights based on the number of effective sensors in horizontal and vertical directions of the planar arrays.

• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.142-148
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• 2007

A mechanically induced long-period fiber grating array was fabricated and its transmission characteristics were measured. The grating away consisted of a rubber cover and a 45 cm metal bar with 10 grating groups. Each grating group was composed of 60 gratings. The period of the grating of the grating groups was increased by $10{\mu}m$ increments from $690{\mu}m$ to $780{\mu}m$. The long period fiber grating was induced when the pressure was applied on the long period grating array and the resonant wavelength depended on the position of applied pressure. The experimental results shows that this long period fiber grating away can be used as a various band rejection filter or a fiber optic sensor.

• The Journal of the Acoustical Society of Korea
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• v.22 no.4
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• pp.329-336
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• 2003

Intra-Vascular Ultra-Sound (IVUS) transducers were developed for the application to diagnose coronary diseases. The transducer consists of 32 piezoelectric elements with a front insulation layer and a polymeric acoustic backing layer on a hollow alumina tube. The optimal geometrical structure of the transducer was designed through theoretical analysis of radiation patterns of the transducer. Samples of the IVUS transducers of the diameter of 3㎜ were fabricated to illustrate the design scheme. For the piezoelectric elements, 2-2 mode piezocomposite materials were employed. Experimental performance of the transducers showed good agreement with the design results, which verified feasibility of the transducer for IVUS applications.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.10
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• pp.63-71
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• 2009

The patch antennas with an array of pins with excellent radiation characteristics are investigated for several substrate thicknesses. The patch length of a pin array patch antenna for the maximum suppression of radiation in the horizontal plane decreases as the substrate thickness increases. The radiation in the horizontal plane of a pin array patch antenna is very small compared to that of a conventional patch antenna. The increase of forward radiation and the decrease of backward radiation of a pin array patch are obtained compared to those of a conventional patch antenna. The half-power beamwidth of E-plane radiation pattern of a pin array patch antenna is narrow compared to that of a conventional patch antenna so that the directivity is improved.

• Composites Research
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• v.20 no.3
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• pp.25-30
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• 2007

This paper describes the basic design and fabrication of smart skin antenna for phased array applications. The smart skin phased array antenna, of which radiation pattern can be electrically steerable without mechanical rotation, has to meet the both mechanical and electrical performance. The smart skin antenna is a honeycomb sandwich structure to enhance the mechanical performance such as strength, weight and so on. The example of smart skin antenna integrated with radome is designed with the resonant frequency of 5 GHz, circular polarization, 2 by 2 subarray, and a coaxial probe-fed excitation. In addition, the performance of raw microstrip patch antenna uncovered radome is investigate. The fabricated smart skin antenna shows a reasonable performance with gain of 12.2 dBi and frequency bandwidth of 6.4 %.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2066-2070
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• 2008

본 연구는 인공신경망(Artificial Neural Networks: ANNs)기법의 일종인 자기조직화(Self Organizing Map: SOM) 이론을 이용한다. 자기조직화 특성을 이용하여 스스로 학습이 가능하고, 구조상 수행이 빨라 학습 단계에 소요되는 시간을 줄 일 수 있는 장점을 가진 자기조직화 이론을 도입하고, 수질자료 중 전체 유기물의 양을 나타내며 난분해성 물질에 대한 해석이 가능하고 재현성이 탁월한 TOC 와 강우-유출량 자료의 분포적 양상과 특징을 분석하여 예측을 위한 모형화 과정에 기여하고자 한다. 최적의 Map Size와 Map Array 결정을 위해 수집된 강우와 유출량자료 및 TOC 자료에 대해 Garcia의 경험식을 이용하여 Map을 구성하는 단위구조의 총 수(M)를 산정하여 M값에 따른 종방향 및 횡방향 크기를 결정하는 다수의 Map 크기를 검토하고, 또한 Map 배열은 2차원 배열의 사각형배열(Rectangular array)과 육각형배열(Hexagonal array)에 대해서도 복합적으로 검토하여 최적의 특성조건을 결정하여 강우-유출 및 TOC 관계의 분할특성을 분석한다.

• Journal of IKEEE
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• v.24 no.3
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• pp.917-920
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• 2020

In this paper, we studied the derivation method of isoflux radiation for a planar array antenna. The presented array antenna was designed for considering of 1U-sized CubeSAT with Ku-band communications. For the presented array antenna, 8×8 radiating elements were arranged, and the distance between radiating elements was set of half-wavelength. The excited current weighting for each radiating elements was calculated by the signal processing technique used in the design of the low-pass filter. As a result of analysis of the method proposed in this paper, it was confirmed that a seamless isoflux pattern can be derived.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.12C
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• pp.1299-1305
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• 2002

Tx/Rx dual microstrip array antennas for satellite communications are designed, fabricated, and measured in this paper. They have a Right Handed Circular Polarization (RHCP) for Tx and Left Handed Circular Polarization (LHCP) for Rx. Two stacked patches are used for wideband characteristics and corner-truncated square patches are adopted for a circular polarization. To enhance bandwidth characteristics of a circular polarization, 2${\times}$1 sequential rotation mays are applied. From the measured results, 8${\times}$1 microstrip may antennas have a good agreement with those of the simulation. Therefore the array antennas are applicable to satellite communication antennas, active phased may antennas, and radiators in other antennas.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.333-336
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• 2000

본 논문에서는 Monte-Carlo simulation과 deterministic simulation을 합성한 방법으로 특성허용 패턴을 만족하는 개별소자의 오차범위를 가중치에 따라 차별적으로 규정을 하였다. 일반적으로 사용되는 통계적인 방법은 불규칙한 특성을 갖는 랜덤오차를 정규분포를 갖는 랜덤변수로 모델링을 하여 허용 패턴으로부터 오차의 범위를 규정하는데, 이렇게 구해진 범위는 개별소자의 가중치의 영향을 고려하지 않고 일률적인 특성을 나타낸다는 단점이 있다. 이에 반해 deterministic simulation을 통해서 얻어진 오차의 범위는 가중치에 따라서 상대적인 범위를 결정할 수 있지만 해석 하고자하는 배열소자의 개수에 따라서 계산량이 지수승으로 증가하는 단점이 있어 10개 이상의 소자를 갖는 배열에는 적합하지 않다. 이러한 단점을 보완하기 위해서는 본 논문에서는 Monte-Carlo simulation과 deterministic simulation의 합성적 방법을 사용해서 배열소자의 증가에 따른 계산량의 증가를 줄이면서 각 가충치에 따라 상대적인 개별오차의 허용범위를 결정하였다. 그리고 이렇게 규정된 오차의 범위를 간단한 모의 실험을 통해서 검증하였다.