• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.29-30
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• 2006

GIS 예방진단을 위해 개발한 "UHF 온라인 부분방전 상시감시시스템"을 실 변전소에 설치하여 실증시험을 수행하였다. 345 kV급 변전소의 GIS 2개 bay를 감시하기 위해, GIS에 설치된 총 14개의 UHF 센서로부터 측정된 방전신호를 변전소 switchyard에 설치된 local unit에서 수집하였다. Local unit에서 UHF 대역의 방전신호를 디지털 신호로 변환한 후, 광섬유를 통해 변전소 급전분소에 설치된 중앙서버에 전송토록 하였다. 중앙처리장치에서는 단위 방전신호의 분석 및 트랜드 분석이 가능하며, 사용자에게 자동으로 방전원인을 알려준다. 설치된 상시감시시스템은 우수한 외부 잡음제거능력을 보였으며, 측정된 방전신호를 요약하여 사용자에게 reporting하는 등 다양한 편의성을 제공하고 있다.

• The Journal of the Acoustical Society of Korea
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• v.42 no.4
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• pp.357-363
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• 2023

In underwater signal processing, separating individual signals from mixed signals has long been a challenge due to low signal quality. The common method using Short-time Fourier transform for spectrogram analysis has faced criticism for its complex parameter optimization and loss of phase data. We propose a Triple-path Recurrent Neural Network, based on the Dual-path Recurrent Neural Network's success in long time series signal processing, to handle three-dimensional tensors from multi-channel sensor input signals. By dividing input signals into short chunks and creating a 3D tensor, the method accounts for relationships within and between chunks and channels, enabling local and global feature learning. The proposed technique demonstrates improved Root Mean Square Error and Scale Invariant Signal to Noise Ratio compared to the existing method.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.225-233
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• 2024

Active sonar transmits sound waves to detect covertly maneuvering underwater objects and detects the signals reflected back from the target. However, in addition to the target's echo, the active sonar's received signal is mixed with seafloor, sea surface reverberation, biological noise, and other noise, making target recognition difficult. Conventional techniques for detecting signals above a threshold not only cause false detections or miss targets depending on the set threshold, but also have the problem of having to set an appropriate threshold for various underwater environments. To overcome this, research has been conducted on automatic calculation of threshold values through techniques such as Constant False Alarm Rate (CFAR) and application of advanced tracking filters and association techniques, but there are limitations in environments where a significant number of detections occur. As deep learning technology has recently developed, efforts have been made to apply it in the field of underwater target detection, but it is very difficult to acquire active sonar data for discriminator learning, so not only is the data rare, but there are only a very small number of targets and a relatively large number of non-targets. There are difficulties due to the imbalance of data. In this paper, the image of the energy distribution of the detection signal is used, and a classifier is learned in a way that takes into account the imbalance of the data to distinguish between targets and non-targets and added to the existing technique. Through the proposed technique, target misclassification was minimized and non-targets were eliminated, making target recognition easier for active sonar operators. And the effectiveness of the proposed technique was verified through sea experiment data obtained in the East Sea.

• Proceedings of the Acoustical Society of Korea Conference
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• 1991.06a
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• pp.117-121
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• 1991

본 논문은 견인선(tow-ship)에서 발생하는 자체 잡음을 제거하여 수중 신호처리 시스템에서 표적 탐지(target detection)와 표적 식별(target identification) 등의 성능 향상을 위하여 표적 방향으로 형성된 빔의 출력을 원시 입력신호(primary input)로 사용하고 견인선 방향으로 형성된 빔의 출력을 참고 입력신호(reference input)로 사용한 적응 잡음 제거기(adaptive noise canceller)에 대해 연구하였다. 잡음 제거를 위해 사용되는 계수들은 LMS(Least Mean Square) 알고리듬을 이용하여 조정하였다. 컴퓨터 시뮬레이션을 통하여 TDL(Tapped-Delay Line) 구조와 LAT(LATtice) 구조를 갖는 적응 잡음 제거기 성능을 여러 가지 환경에서 비교, 관찰하였다. 두 알고리듬을 사용할 경우, 자체 잡음이 어떠한 형태로 나타나더라도 제거시킬 수 있음을 보여 주었으나 고유값 분포율(eigenvalue spread ratio)이 큰 경우에는 LMS-LAT가 LMS-TDL보다 수렴 속도뿐만 아니라 성능면에서도 우수함을 보였다.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.145-151
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• 2024

Recently, ship hull-mounted passive sonar system solution is needed in the perspective of improving target detection and elimination of vibration-induced noise. Our research team suggests acousticvibration matching method using front and rear signal of a sensor as the improvement of the problem above. Thus in this paper, theoretical background about matching method and its application on finite element method based multi-physics simulation are described. Furthermore, it is shown that target detection and hull vibration performance are improved by using matching method under the condition of our sensor system. Finally, practicality and future research are discussed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.305-309
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• 2004

The problem for parameters estimation of the received signals impinging on array sensors has long been of great research interest in a great variety of applications, such as radar, sonar, and land mobile communications systems. Conventional subspace-based algorithms, such as MUSIC and ESPRIT, require an extensive computation of inverse matrix and eigen-decomposition. In this paper, we propose a new parameters estimation algorithm via nonlinear minimization, which is simplified computationally and estimates signal parameters simultaneously.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.2
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• pp.28-34
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• 2011

In this paper, we present integer and fractional motion estimation IP for H.264/AVC encoder by hardware-oriented algorithm. In integer motion engine, the reference block is used to share for consecutive current macro blocks in parallel processing which exploits data reusability and reduces off-chip bandwidth. In fractional motion engine, instead of two-step sequential refinement, half and quarter pel are processed in parallel manner in order to discard unnecessary candidate positions and double throughput. The H.264/AVC motion estimation chip is fabricated on a MPW(Multi-Project Wafer) chip using the chartered $0.18{\mu}m$ standard CMOS 1P5M technology and achieves high throughput supporting HDTV 720p 30 fps.

• 전자공학회논문지 IE
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• v.47 no.4
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• pp.18-27
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• 2010

This paper is designed the efficient Data Acquisition System for an vibration of rotatory machines. The Data Acquisition System is consist of the analog logic having signal filer and amplifier, and digital logic with ADC, DSP, FPGA and FIFO memory. The vibration signal of rotatory machines acquired from sensors is controlled by the FPGA device through the analog logic and is saved to FIFO memory being converted analog to digital signal. The digital signal process is performed by the DSP using the vibration data in FIFO memory. The vibration factor of the rotatory machinery analysis and diagnosis is defined the RMS, Peak to Peak, average, GAP, FFT of vibration data and digital filtering by DSP, and is need to follow as being happened the event of vibration and make an application to an warning system. It takes time to process the several analysis step of all vibration data and the event follow, also special event. It should be continuously performed the data acquisition and the process, however during processing the input signal the DSP can not be performed to the acquisited data after then, also it will be lose the data at several channel. Therefore it is that the system uses efficiently the DSP and FPGA devices for reducing the data lose, it design to process a part of the signal data to FPGA from DSP in order to minimize the process time, and a process to parallel process system, as a result of design system it propose to method of faster process and more efficient data acquisition system by using DSP and FPGA than signal DSP system.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.237-245
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• 2020

In decades, active sonar, which transmits signals and detects incident signals reflected by underwater targets, has been significantly studied since passive sonar in Anti-Submarine Warfare (ASW) detection performance becomes lowered, as underwater threats become their radiated noise reduced. In general, active sonar using Hull-Mounted Sonar (HMS) adjusts vertical tilt (depression) and sequentially transmits multiple Linear Frequency Modulation (LFM) subpulses which have non-overlapped bands, i. e. 1 kHz ~ 2 kHz, 2 kHz ~ 3 kHz, in order to reduce shadow zones. Recently, however, Generalized SFM (GSFM), which is generalized form of SFM, is proposed, and it is confirmed that subpulses of GSFM have orthogonality among each other depending on setting of GSFM parameters. Hence, in this paper, we applied GSFM to active target detection using HMS to improve the performance by the signal processing gain obtained from enlarged bandwidths of GSFM subpulses compared to those of LFM subpulses. Through simulation, we verified that when the number of subpulses is three, the matched filter gain of GSFM is approximately 5 dB higher than that of LFM.

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.83-91
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• 2001

This paper proposes the Focused beamforming to estimate the location of target residing near to the observation platform in the underwater environment. The Focused beamforming technique provides the location of target by the coherent summation of a series of incident spherical waveforms considering distinct propagation delay times at the sensor array. But due to the movement of the observation platform and the variation of the underwater environment, the shape of the sensor array is no longer to be linear but it becomes distorted as the platform moves. Thus the Focused beamforming should be peformed regarding to the geometric shape variation at each time. To estimate the target location, the artificial image plane comprised of cells is constructed, and the delays are calculated from each cell where the target could be proximity to sensors for the coherent summation. After the coherent combining, the beam pattern can be obtained through the Focused beamforming on the image plane. Futhermore to compensate the variation of the shape of the sensor array, the paper utilizes the Nth-order polynomial approximation to estimate the shape of the sensor array obeying the water pulley modeling. Simulation results show the performance of the Focused beamforming for different frequency bands of the radiated signal.