• ETRI Journal
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• 제45권1호
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• pp.138-149
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• 2023

In this study, the problem of blind signal separation for coprime planar arrays is investigated. For coprime planar arrays comprising two uniform rectangular subarrays, we link the signal separation to the tensor-based model called coupled canonical polyadic decomposition (CPD) and propose an improved coupled trilinear decomposition approach. The output data of coprime planar arrays are modeled as a coupled tensor set that can be further interpreted as a coupled CPD model, allowing a signal separation to be achieved using coupled trilinear alternating least squares (TALS). Furthermore, in the procedure of the coupled TALS, a Vandermonde structure enforcing approach is explicitly applied, which is shown to ensure fast convergence. The results of Monto Carlo simulations show that our proposed algorithm has the same separation accuracy as the basic coupled TALS but with a faster convergence speed.

• ETRI Journal
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• 제33권6호
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• pp.849-856
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• 2011

This research introduces three new fractal array configurations that have superior performance over the well-known Sierpinski fractal array. These arrays are based on the fractal shapes Dragon, Twig, and a new shape which will be called Flap fractal. Their superiority comes from the low side lobe level and/or the wide angle between the main lobe and the side lobes, which improves the signal-to-intersymbol interference and signal-to-noise ratio. Their performance is compared to the known array configurations: uniform, random, and Sierpinski fractal arrays.

• 전자공학회논문지
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• 제50권5호
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• pp.208-217
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• 2013

평면센서배열을 사용하는 소나시스템에서 송수신빔을 수평, 수직방향으로 분리하여 형성할 수 있다면, 빔형성에 필요한 연산량과 공간을 줄일 수 있는 장점들이 있다. 하지만 일반적으로 소나시스템에서 사용되는 평면센서배열은 공간상 수평, 수직방향으로 분리되지 않는다. 따라서 기존의 수평, 수직방향 분리 가중치를 이용하여 송수신빔을 분리하여 형성하면 목표로 하는 수평, 수직 빔 특성과 차이가 발생된다. 본 논문에서는 공간상 분리가 되지 않는 평면센서배열에 대해 효과적으로 분리된 수평, 수직 가중치를 적용하여 목표로 하는 수평, 수직 빔 특성을 얻기 위한 새로운 기법을 제안하였다. 제안한 기법은 평면센서 배열의 수평, 수직방향으로 영향을 미치는 유효센서수를 구해 분리된 수평, 수직 가중치에 적용시킨다. 이를 통해 목표로 하는 수평, 수직 가중치의 오차 합이 최소화되도록 반영시킴으로써 각 방향으로 목표로 하는 빔 특성을 가지도록 한다.

• 한국정밀공학회지
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• 제20권7호
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• pp.120-127
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• 2003

A novel three degrees of freedom sensing method utilizing binary grid pattern image and vision camera is presented. The binary grid pattern image is designed by Pseudo-Random Binary Arrays and referenced to encode in-plane position of a moving stage of the contact-free planar actuator. First, the yaw motion of the stage is detected using fast image processing and then the other planar positions, x and y, are decoded with a sequence of images. This method can be applied to the system that needs feedback of in-plane position, with advantages of a good accuracy and high resolution comparable with the encoder, a relatively compact structure, no friction, and a low cost. In this paper, all the procedures of the above sensing mechanism are described in detail, including simulation and experiment results.

• Advances in robotics research
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• 제2권2호
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• pp.141-149
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• 2018

In image processing and robotic applications, two-dimensional (2D) black and white patterned planar markers are widely used. However, these markers are not detectable in low visibility environment and they are not changeable. This research proposes an active and adaptive marker node, which displays 2D marker patterns using light emitting diode (LED) arrays for easier recognition in the foggy or turbid underwater environments. Because each node is made to blink at a different frequency, active LED marker nodes were distinguishable from each other from a long distance without increasing the size of the marker. We expect that the proposed system can be used in various harsh conditions where the conventional marker systems are not applicable because of low visibility issues. The proposed system is still compatible with the conventional marker as the displayed patterns are identical.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.59-60
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• 2008

GaN-based light-emitting diodes (LEDs) with ZnO nanorod arrays on a planar indium tin oxide (ITO) transparent electrode were demonstrated. ZnO nanorods were grown into aqueous solution at low temperature of $90^{\circ}C$. Under 20 mA current injection, the light output efficiency of the LED with ZnO nanorod arrays on ITO was remarkably increased by about 40 % of magnitude compared to the conventional LED with only planar ITO. The enhancement of light output by the ZnO nanorod arrays is due to the formation of side walls and a rough surface resulting in multiple photon scattering at the LED surface.

• Journal of electromagnetic engineering and science
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• 제6권2호
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• pp.123-129
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• 2006

This paper presents a method of reducing penetration of penetrated electromagnetic fields through a narrow slot with parallel wire arrays in a planar conducting screen of infinite extent. An integral equation for the aperture electric field on the narrow slot is derived and solved by applying Galerkin's method of moments. When a plane wave is excited to the narrow slot, the aperture electric field is easily controlled by the parallel wire arrays connected on the slot and therefore the magnitude of the penetrated electric field is effectively reduced by loading the parallel wire arrays. The numerical results show that the magnitude of the penetrated electromagnetic field can be effectively reduced by installing the parallel wire arrays on the slot. The results of the calculated penetration electric fields are in good agreement with that of the measured results.

• 한국광학회:학술대회논문집
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• 한국광학회 1995년도 광학 및 양자전자학 워크샵 논문집
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• pp.43-52
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• 1995

For massicely parallel optical interconnections, we propose three types of planar optical configurations for crossover photonic switching netweek, backboard optical signal distribution, and high speed packet address detection. The planar overalsy allow 2-D pixel arrays located on a wafer scale intergated circuit to be interconnected in a compact and vibrationally robust configuration. By the laser writing technique surface relief of microopical Fresnel lenses and multiplex gratigs used in the planar optics are successfully fabricated.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.438-443
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• 2010

In this paper, behaviors of photonic crystal (PC) radiative structures and antenna arrays have been compared for two types of uniform and binomial excitations. Appropriate duality has been shown between them. These results can be generalized to other types of excitation and arrangement of photonic crystal radiative arrays such as linear, planar and circular arrays of three dimensional (3D) photonic crystal termination resonators. Using these results in designing photonic circuits has some advantages for shaping a particular radiative beam at the photonic crystal exit, for instance reducing the divergence angle of the main lobe in order to enhance the directivity, for better coupling, or for splitting the emitted beam, for dividing the output beam to the next devices in photonic integrated circuits (PIC). For analysis and simulation of the photonic crystal structures, the finite difference time domain (FDTD) method has been employed.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.289-292
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• 2005

Two planar inverted-F antenna (PIFA) arrays are proposed as an alternative model to generate input and radiation characteristics of two orthogonal oriented circular loops, which has polarization diversity, but inherent mechanical instability of two orthogonal loops, in particular, in installation and operation conditions. Two $1\times2$ PIFA sub-arrays are orthogonally placed on a ground plane and two different feeding networks are applied to control horizontal and vertical radiation current flows for each sub-array, respectively. Equivalence of scattering parameters and radiation patterns between two antennas are validated by the available commercial simulator.