• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.187-195
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• 2012

In this paper, we propose the optimization of subarray configurations for linear array to minimize the side lobe level (SLL) in sum beam pattern based on the genetic algorithm. The operations of genetic algorithm are modified to be applied to subarray configurations. Using the proposed method, we construct subarray structure with 16 irregular subarray elements from 40 linear array elements to minimize the SLL in sum beam pattern in case of applying the adaptive beamforming(ABF) to suppress the jamming power, whose the SLL is 10 dB lower than that of regular subarray configuration.

• Progress in Medical Physics
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• v.27 no.1
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• pp.37-45
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• 2016

In proton therapy, in vivo proton beam range verification is very important to deliver conformal dose to the target volume and minimize unnecessary dose to normal tissue. For this purpose, a multi-slit prompt-gamma camera module made of 24 scintillation detectors and 24-channel signal processing system is under development. In the present study, we have developed and tested a dual-mode signal processing system, which can operate in the energy calibration mode and the fast data acquisition mode, to process the signals from the 24 scintillation detectors. As a result of performance test, using the energy calibration mode, we were able to perform energy calibration for the 24 scintillation detectors at the same time and determine the discrimination levels for the detector channels. Further, using the fast data acquisition mode, we were able to measure a prompt-gamma distribution induced by a 45 MeV proton beam. The measured prompt gamma distribution was found similar to the proton dose distribution at the distal fall-off region, and the estimated beam range was $17.13{\pm}0.76mm$, which is close to the proton beam range of 16.15 mm measured by an EBT film.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2151-2156
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• 2006

Beamforming for underwater acoustic communication (UAC) is affected by the broadband feature of UAC signal, which has relatively low currier frequency as compared to the signal bandwidth. The narrow-band assumption does not hold good in UAC. In this paper, we discuss a broadband FIR beamformer for UAC using the baseband equivalent way signal model. We consider the broadband FIR beamformer for QPSK UAC with carrier frequency 25kHz and symbol rate 5kHz. Array geometry is a uniform linear way with 8 omni-directional elements and sensor spacing is the half of the carrier wavelength. The simulation results show that the broadband n beamformer achieves nearly optimum signal to interference and noise ratio (SINR) and outperforms the conventional narrowband beamformer by SINR 0.5dB when two-tap FIR filter is employed at each sensor and the inter-tap delay is a quarter of the symbol interval. The broadband FIR beamformer performance is more degraded as the FIR filter length is increased above a certain value. If the inter-tap delay is not greater than half of the symbol period, SINR performance does not depend on the inter-tap delay. More training period is required when the inter-tap delay is same as the symbol period.

• The Journal of the Acoustical Society of Korea
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• v.25 no.6
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• pp.305-311
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• 2006

In this paper the performance of a array invariant method is evaluated for source-range estimation in horizontally stratified shallow water ocean waveguide. The method has advantage of little computationally effort over existing source-localization methods. such as matched field processing or the waveguide invariant and array gain is fully exploited. And. no knowledge of the environment is required except that the received field should not be dominated by purely interference This simple and instantaneous method is applied to simulated acoustic propagation filed for testing range estimation performance. The result of range estimation according to the SNR for the underwater impulsive source with broadband spectrum is demonstrated. The spatial smoothing method is applied to suppress the effect of mutipath propagation by high frequency signal. The result of performance test for range estimation shows that the error rate is within 20% at the SNR above 10dB.

• The Journal of the Acoustical Society of Korea
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• v.23 no.3
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• pp.214-220
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• 2004

A computationally efficient algorithm is presented for 3-D near-field source localization using a uniform circular away (UCA). Algebraic relations are demonstrated between the incident angles (elevation angle and azimuth angle) under the far-field assumption and the actual near-field location (range. elevation angle, and azimuth angle). Using these relations as paths to follow to the peak of the 3-D MUSIC spectrum, the proposed algorithm replaces the 3-D search required in the conventional 3-D MUSIC with a 1-D path following after a 2-D initialization. thereby reducing the computational burden.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.448-458
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• 2013

In this paper, we present the performance and the experimental results of the adaptive beamformer in the radar system with the planar active array. The study of the adaptive beamformer has already been performed in several literatures, but it is difficult to find the results or examples those are implemented in the actual radar system. Here we employ the adaptive beamformer to the practical radar system with subarray architecture. The performance of beamformer will be demonstrated by modeling and simulation and finally the far-field experimental results.

• Smart Media Journal
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• v.5 no.3
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• pp.25-29
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• 2016

This paper presents research for non-contact gesture recognition system using EPS(Electronic Potential Sensor) for measuring the human body of electromagnetic fields. It implemented a signal acquisition and signal processing system for designing a system suitable for motion recognition using the data coming from the sensors. we transform AC-type data into DC-type data by applying a 10Hz LPF considering H/W sampling rate. in addition, we extract 2-dimensional movement information by taking difference value between two cross-diagonal deployed sensor.

• Journal of Advanced Navigation Technology
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• v.20 no.3
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• pp.218-225
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• 2016

Null steering and beam steering are known well as anti-jamming methods in GPS anti-jamming system. Null steering gets a noise attenuation effect for the direction of jamming and beam steering earns additional gain synthesis for the direction of satellite signals. According to the research in the article for signal processing, it expresses that the N array antenna is effective for N-1 number of jamming signal by math public interest, however, the two algorithms analysis is not unknown for the operating condition of the realistic vehicle. In this paper, we modeled anti-jamming system using 4 and 7 array antenna and showed the two algorithms performance (PM, LCMV) when considering the number of antenna array, jammers and vehicle position (horizontal, vertical). In result, we showed that the case of vertical position of the vehicle which has large tilt angle for the relative position of satellites and jammers, has about 10 dB gain more in comparison with one of vertical position in spite of same JSR condition.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.7
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• pp.166-175
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• 1989

In this paper, we present a method which is based on the concept of the rotation of subspaces. This method is highly related to the angle (or distance) between subspaces arising in many applications. An effective procedures is first derived for finding the optimal transformation matrix which rotates one subspace into another as closely as possible in the least squares sense , and then this algorithm is applied to the solution to general direction-of-arrival estimation problem of multiple broadband plane waves which may be a mixture of incoherent, partially coherent or coherent. In this typical application, the rotation of signal subspaces (ROSS) algorithm is effectively developed to achieve the high performance in the active systems for the case in which the noise field remains invariant with the measurement of the array spectral density matrix (or data matrix). It is not uncommon to observe this situation in sonar systems. The advantage of this techniques is not to require the preliminary processing and spatial prefiltering which is used in Wang-Kaveh's CSS focusing method. Furthermore, the array's geometry is not restricted. Simulation results are presented to illustrate the high performance achieved with this new approach relative to that obtained with Wang-Kaveh's CSS focusing method for incoherent sources and forward-backward spatial smoothed MUSIC for coherent sources including the signal eigenvector method (SEM).

• Annual Conference of KIPS
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• 2017.04a
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• pp.688-689
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• 2017

본 논문에서는 Beacon 신호를 이용하여 현재위치정보 도출하고 그를 활용하는 어플리케이션을 개발하였다. Beacon을 바둑판 배열로 설치하고 이를 스마트폰과 서버의 통신을 이용하여 삼각측량법으로 자신의 위치를 도출한다. 이를 이용하여 GPS신호가 닿지 않는 지하나 건물에서 네비게이션 역할을 수행하고, 나아가서 다른 스마트폰의 위치까지 확인가능하다.