• Title/Summary/Keyword: 능동 신호 처리

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Development of the Planar Active Phased Array Radar System with Real-time Adaptive Beamforming and Signal Processing (실시간으로 적응빔형성 및 신호처리를 수행하는 평면능동위상배열 레이더 시스템 개발)

  • Kim, Kwan Sung;Lee, Min Joon;Jung, Chang Sik;Yeom, Dong Jin
    • Journal of the Korea Institute of Military Science and Technology
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    • v.15 no.6
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    • pp.812-819
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    • 2012
  • Interference and jamming are becoming increasing concern to a radar system nowdays. AESA(Active Electronically Steered Array) antennas and adaptive beamforming(ABF), in which antenna beam patterns can be modified to reject the interference, offer a potential solution to overcome the problems encountered. In this paper, we've developed a planar active phased array radar system, in which ABF, target detection and tracking algorithm operate in real-time. For the high output power and the low noise figure of the antenna, we've designed the S-band TRMs based on GaN HEMT. For real-time processing, we've used wavelenth division multiplexing technique on fiber optic communication which enables rapid data communication between the antenna and the signal processor. Also, we've implemented the HW and SW architecture of Real-time Signal Processor(RSP) for adaptive beamforming that uses SMI(Sample Matrix Inversion) technique based on MVDR(Minimum Variance Distortionless Response). The performance of this radar system has been verified by near-field and far-field tests.

Comprehensive analysis of deep learning-based target classifiers in small and imbalanced active sonar datasets (소량 및 불균형 능동소나 데이터세트에 대한 딥러닝 기반 표적식별기의 종합적인 분석)

  • Geunhwan Kim;Youngsang Hwang;Sungjin Shin;Juho Kim;Soobok Hwang;Youngmin Choo
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.4
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    • pp.329-344
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    • 2023
  • In this study, we comprehensively analyze the generalization performance of various deep learning-based active sonar target classifiers when applied to small and imbalanced active sonar datasets. To generate the active sonar datasets, we use data from two different oceanic experiments conducted at different times and ocean. Each sample in the active sonar datasets is a time-frequency domain image, which is extracted from audio signal of contact after the detection process. For the comprehensive analysis, we utilize 22 Convolutional Neural Networks (CNN) models. Two datasets are used as train/validation datasets and test datasets, alternatively. To calculate the variance in the output of the target classifiers, the train/validation/test datasets are repeated 10 times. Hyperparameters for training are optimized using Bayesian optimization. The results demonstrate that shallow CNN models show superior robustness and generalization performance compared to most of deep CNN models. The results from this paper can serve as a valuable reference for future research directions in deep learning-based active sonar target classification.

Noise Attenuation Effect According to the Direction of Canceling Speaker in Duct-acoustic System (덕트-음향 시스템에서 소거용스피커 방향에 따른 소음감소효과)

  • Lee, Hyung-Seok;Lee, Eung-Suk
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.7
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    • pp.51-57
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    • 2009
  • In this paper, we studied on an attenuation effect of automobile exhaust noise according to the direction of canceling speaker in duct-acoustic ANC system. Automobile exhaust noise was recorded at 800rpm, 3500rpm and 5000rpm of a diesel engine. Directions of canceling speaker can be set to $30^{\circ}$, $90^{\circ}$ and $150^{\circ}$ against the primary noise flow by acrylic ducts to be made for the experimentation. DSP board used to control the ANC system. The algorithm of this ANC system applied the Filtered-x-LMS algorithm that is modified to compensate for a property of DSP input signal and the secondary-path effect. As an experiment result, the direction of canceling speaker was proved to influence the reduction effect of noise. The $150^{\circ}$ duct in the attenuation effect of noise showed a better result than the $90^{\circ}$ or $30^{\circ}$ duct.

Low Pass Filter Design using CMOS Floating Resister (CMOS Floating 저항을 이용한 저역통과 필터의 설계)

  • 이영훈
    • Journal of the Korea Society of Computer and Information
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    • v.3 no.2
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    • pp.77-84
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    • 1998
  • The continuous time signal system by development of CMOS technology have been receiving consideration attention. In this paper, Low pass filter using CMOS floating resistor have been designed with cut off frequency for speech signal processing. Especially a new floating resistor consisting entirely of CMOS devices in saturation has been developed. Linearity within $\pm$0.04% is achieved through nonlineartiy via current mirrors over an applied range of $\pm$1V. The frequency response exceeds 10MHz, and the resistors are expected to be useful in implementing integrated circuit active RC filters. The low pass filter designed using this method has simpler structure than switched capacitor filter. So reduce the chip area. The characteristics of the designed low pass filter using this method are simulated by pspice program.

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Noise Attenuation Effect According to the Direction of Secondary Sound Source in Duct ANC System (Duct ANC System에서 부가음원 방향별 소음감소효과)

  • Lee, Eung-Suk;Lee, Hyung-Seok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.3
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    • pp.251-260
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    • 2009
  • In this paper, we studied on an attenuation effect of automobile exhaust noise according to the direction of canceling speaker in ANC system. Automobile exhaust noise was recorded at 800 rpm, 3500 rpm and 5000 rpm of a diesel engine. Directions of canceling speaker can be set to $30^{\circ}$, $90^{\circ}$ and $150^{\circ}$ against the primary noise flow by acrylic ducts to be made for the experimentation. DSP board with TMS320C6416 chip of Texas Instrument Co. used to control the ANC system. The algorithm of this ANC system applied the Filtered-x-LMS algorithm that is modified to compensate for a property of DSP input signal and the secondary-path effect. As an experiment result, the direction of canceling speaker was proved to influence the reduction effect of noise. The $150^{\circ}$ duct in the attenuation effect of noise showed a better result than the $90^{\circ}$ or $30^{\circ}$ duct.

Autofocus Phase Compensation of Velocity Disturbed UUV by DPC Processing with Multiple-Receiver (다중 수신기 DPC 처리에 의한 속도 교란 수중 무인체의 자동초점 위상 보상)

  • Kim, Boo-il
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.10
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    • pp.1973-1980
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    • 2017
  • In the case of a small UUV operating an active synthetic aperture sonar, various velocity disturbances may occur on the path due to the influence of external underwater environment, and this causes phase errors in coherent synthetic aperture processing, which has a large influence on the detected image. In this paper, when a periodic sinusoidal velocity disturbance is generated in the traveling direction, the phase generated by the round trip slope range at each position is estimated the cross correlation coefficient for multiple received signals and compensated the position variation in the overlapped DPC by the average value within the maximum allowable width. Through simulations, it has been confirmed that the images degraded by the velocity disturbance amplitude and fluctuating frequency of the UUV are removed from the false targets and the performance of azimuth resolution is improved by the proposed phase compensation method.

A Desigin of real sound service based-on object in Smart mobile devices (스마트 모바일 기기에서의 객체 기반 실감 음원 서비스 구현)

  • Jung, Jong-Jin;Lim, Tae-Beom;Lee, Seok-Pil
    • Annual Conference of KIPS
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    • 2011.04a
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    • pp.685-688
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    • 2011
  • 앞으로의 멀티미디어 기기시장은 기존의 단순 복합 디지털 기기들이 아닌 사용자 감성 및 취향 제어가 가능한 인간 친화적 지능형 멀티미디어 기기가 주류를 이룰 것이다. 이미 IT 기능이 기존의 '정보의 소통'에서 '감성의 소통'으로 진화 중에 있으며, 미래시대에는 느낌까지 디지털 신호로 전달 가능한 기술이 발달 될 것이다. 이에 맞추어 사람의 감성, 주변 분위기, 섬세한 공간 정보를 전달하는 사실적인 오디오 개발 및 인프라가 구축되어 모든 멀티미디어 제품에 적용된다면, 사용자는 보다 현장감 있게 멀티미디어를 즐길 수 있을 것이다. 최근 스마트폰의 확산과 더불어 각종 다양한 음악서비스를 제고하는 웹/앱 형태의 어플리케이션이 증대되고 있는 바, 본 논문에서는 안드로이드 기반 스마트 모바일 기기에서 다양한 오디오 정보를 청취자에게 제공하고 이를 활용하여 청취자가 다양하게 오디오 재생 / 제어하여, 일방적으로 청취자가 오디오를 듣는 수준이 아니라 청취자 취향에 따라 다양하게 오디오를 감상 할 수 있는 서비스를 구현하였다.

A Study of Evaluating VR Learning Styles on User Attention and Memory (가상현실 교육설계방식에 따른 학습자 주의와 학습 기억에 관한 연구)

  • Park, Kyoung-Shin;Goo, Ja-Young
    • The KIPS Transactions:PartB
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    • v.14B no.2
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    • pp.119-126
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    • 2007
  • This paper presents a study investigating the effects of VR learning style on user attention and memory. The study involved users performed the guided or unguided style learning in the virtual environment while user attention was measured through physiological sensors (EEG, ECG, and GSR) and an eye tracking system. The users experienced the five specific events in a virtual environment associated with different stimuli, while they were given more specific goals during the guided task whereas they were given more goal asking them to actively search for the interesting items during the unguided task. The subject's attentions workload, feelings, memories about VR experience were measured by using a variety of physiological sensors during the task, video analysis, and post test survey. The results showed that the unguided task followed by the guided task made a considerable learning effect by giving a preview effect to the user. Moreover, the guided task drew more user attention and mental workload than the unguided task did.

A Study on the New Active Tilt Control Systems for Improving Passenger′s Feeling of Ground Vehicles in Urban Area (도시형 지상 차량의 승차감 향상을 위한 새로운 능동형 기울임 제어 시스템에 관한 연구)

  • 소상균;변기식
    • Journal of the Institute of Convergence Signal Processing
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    • v.2 no.2
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    • pp.103-110
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    • 2001
  • To reduce the traffic congestion and parking problems in urban areas tall and narrow vehicles have interested as a means to increase the utilization of existing freeways and parking facilities. The stability problem for those narrow vehicles which might be caused can be reduced by tilting the body toward the inside of the turn. The Direct Tilt Control(DTC) system and the Steering Tilt Control(STC) system have been proposed for those narrow vehicles. In this paper, as one of the performance improvement for that kind of vehicle a new control system to use the merits of both the DTC system and the STC system is proposed. Because two different control systems fight each other, the switching control scheme is applied as a means to prevent fighting. Also, the method in order to achieve the smoothly changed control system when the system is switched from the DTC to the STC or from the STC to the DTC, the appropriate type of control gain is designed.

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Real-time passive millimeter wave image segmentation for concealed object detection (은닉 물체 검출을 위한 실시간 수동형 밀리미터파 영상 분할)

  • Lee, Dong-Su;Yeom, Seok-Won;Lee, Mun-Kyo;Jung, Sang-Won;Chang, Yu-Shin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.2C
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    • pp.181-187
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    • 2012
  • Millimeter wave (MMW) readily penetrates fabrics, thus it can be used to detect objects concealed under clothing. A passive MMW imaging system can operate as a stand-off type sensor that scans people in both indoors and outdoors. However, because of the diffraction limit and low signal level, the imaging system often suffers from low image quality. Therefore, suitable statistical analysis and computational processing would be required for automatic analysis of the images. In this paper, a real-time concealed object detection is addressed by means of the multi-level segmentation. The histogram of the image is modeled with a Gaussian mixture distribution, and hidden object areas are segmented by a multi-level scheme involving $k$-means, the expectation-maximization algorithm, and a decision rule. The complete algorithm has been implemented in C++ environments on a standard computer for a real-time process. Experimental and simulation results confirm that the implemented system can achieve the real-time detection of concealed objects.