• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2777-2784
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• 2011

In this paper, DOA(direction of arrival) of multiple incident signals received from linear array antenna and circular array antenna, which is based on nonparametric estimation algorithm, and adaptive beam-forming algorithm are studied and analyzed. In nonparametric estimation algorithm, we minimize a regularized objective function for finding a estimate of the signal energy as a function of angle, using nonquadratic norm which leads to supper resolution and noise suppression. And then, DOA is estimated by the signal and noise spatial steering vector, and adaptive beam-forming pattern is improved by weight vectors obtained from the spatial vector. Especially, the discrimination ability of DOA and the adaptive beam-forming ability according to antenna array methods and the number of array elements are compared and considered.

• Journal of electromagnetic engineering and science
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• v.18 no.4
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• pp.267-269
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• 2018

In this letter, the null steering of a circular array is presented using a modified array factor (AF) for a global positioning system (GPS) anti-jam. The seven radiating elements were designed using a mu-zero resonance (MZR) circularly polarized (CP) antenna arranged toward the center. Since the radiating elements, which are arranged toward the center, have a CP characteristic, the AF of the seven radiating elements has to be modified considering the rotation angle of the nth radiating element. The phases of input ports can be calculated to implement a nulling of radiation patterns where the modified AF is zero. To verify the modified AF for null steering in the desired direction, two cases of power dividers operating in $L_2$ band (1.2276 GHz) were fabricated to achieve pattern nulling at a certain angle. The modified AF can be confirmed by a comparing the simulated and measured radiation patterns.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.936-943
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• 1986

The lasing wavelengths and gain characteristics of the array modes of channel-substrate planar(CSP) lasers are presented. The gain values of array modes are determined from the complex coupling coefficients calculated using the fields of neighborig elements of the array. The computations show that for index guided lasers which have fields that are almost real valued, or have only slight phase curvature, the highest order array mode will have preferred oscillation. The inphase or fundamental mode, which produces only one major lobe in the far-field radiation pattern, will have the lowest modal gain of all array modes. Some of the devices discussed have modal gain differences of less than 10 cm**-1 between the highest and fundamental modes. For optical field confinement factors of about 20%, this gain difference corresponds to avtive layer gains of approximately 50**-1.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.501-505
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• 2003

There are many antenna array errors. They will distort the array beam pattern and result in an increased sidelobe level. A calibration technique is proposed for correcting the antenna array errors such as mutual coupling and unequal feeder characteristics. These are modeled as a matrix representing the interaction between the radiating elements. The matrix is estimated from the measured array response vectors. The antenna array errors are corrected by modifying the beamforming weight vector. It is verified by the electromagnetic simulation and experiment that the proposed technique reduces the sidelobe level and increases the antenna gain.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.199-205
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• 2004

There are many antenna array errors. They will distort the array beam pattern and result in an increased sidelobe level. A calibration technique is proposed for correcting the antenna array errors such as mutual coupling and unequal feeder characteristics. These are modeled as a matrix representing the interaction between the radiating elements. The matrix is estimated from the measured array response vectors. The antenna array errors are corrected by modifying the beamforming weight vector. It is verified by the electromagnetic simulation and experiment that the proposed technique reduces the sidelobe level and increases the antenna gain.

• Journal of the Korean institute of surface engineering
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• v.52 no.5
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• pp.239-245
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• 2019

To increase the throughput of tip-based nanolithography (TBN), one approach is to use a large array of such tips working in parallel. It is important to maintain co-planarity between the tip array and the writing surface. A slight misalignment can cause large discrepancies of contact force and feature sizes. We report a capacitive proximity sensor built-in with the TBN array for leveling an arrayed polymer pen array. The device allows alignment between an array of writing tips and the writing substrate without contact and contamination. The angular sensitivity of the sensor is $0.05^{\circ}$ for an array with maximum tip-to-tip separation of 100 mm.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.165-168
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• 1999

This paper concerns a least square approach to optimizing a thinned antenna array with respect to antenna spacing to improve the sidelobe performance. A least square method based on a modified version of the modified perturbation method is proposed to efficiently synthesize an optimum pattern in a thinned array. It is demonstrated that the array performance improves with the proposed method, compared with the conventional method.

• The Journal of the Acoustical Society of Korea
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• v.18 no.4E
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• pp.37-42
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• 1999

This paper concerns a modified perturbation method and a least square approach to synthesize an optimum beam pattern of a thinned sensor array with respect to element spacing. In the modified perturbation, the antenna spacing is perturbed iteratively such that the sidelobes are equalized via a linear programming approach. The least square approach is proposed to improve the array performance for the thinned array using the fact that the number of sidelobes is more than the number of element spacings. It is demonstrated that the least square approach performs better than the modified perturbation method.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.9
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• pp.8-14
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• 1992

The radiation pattern of a rectangular-grid array antenna consisted of rectangular waveguides is represented by multiplication of its element and array factors. Calculated radiation patterns for excitation of TES110T mode inside the waveguides suffer from the blindness at a particular direction on E-plane. Numerical simulations show that the blindness can be removed by inserting dielectric plug inside the waveguides or covering dielectric sheath in front of the waveguides.

• Smart Structures and Systems
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• v.12 no.1
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• pp.73-95
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• 2013

Nine deoxyribonucleic acid (DNA) sequences were used to functionalize single-walled carbon nanotube (SWNT) sensors to detect the trace amount of methanol, acetone, and HCl in vapor. DNA 24 Ma (24 randomly arranged nitrogenous bases with one amine at each end of it) decorated SWNT sensor and DNA 24 A (only adenine (A) base with a length of 24) decorated SWNT sensor have demonstrated the largest sensing responses towards acetone and HCl, respectively. On the other hand, for the DNA GT decorated SWNT sensors with different sequence lengths, the optimum DNA sequence length for acetone and HCl sensing is 32 and 8, separately. The detection of methanol, acetone, and HCl have identified that DNA functionalized SWNT sensors exhibit great selectivity, sensitivity, and repeatability with an accuracy of more than 90%. Further, a sensor array composed of SWNT functionalized with various DNA sequences was utilized to identify acetone and HCl through pattern recognition. The sensor array is a combination of four different DNA functionalized SWNT sensors and two bare SWNT sensors (work as reference). This wireless sensing system has enabled real-time gas monitoring and air quality assurance for safety and security.