• Title/Summary/Keyword: Acoustic monitoring

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A Study on Monitoring of the MAP for Non-magnetic Material by AE Signal Analysis (AE신호 분석을 통한 비자성체의 자기연마 모니터링에 관한 연구)

  • Lee, Sung-Ho;Kim, Sang-Oh;Kwak, Jae-Seob
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.3
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    • pp.304-309
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    • 2011
  • A monitoring system for magnetic abrasive polishing process is necessary to ensure the polishing products the high quality and integrity. Acoustic emission (AE) signal is known to reflect the material removal phenomena in other machining processes. In a case of the magnetic abrasive polishing of non-magnetic materials, application of AE method is very difficult because of lower machining force on the surface of workpiece and the level of AE signal is extremely lower. In this study, AE sensor-based monitoring system is applied to the magnetic abrasive polishing. The relation between the level of the AE RMS and the surface roughness during the magnetic abrasive polishing of magnesium alloy steel is investigated.

Early Shell Crack Detection Technique Using Acoustic Emission Energy Parameter Blast Furnaces (음향방출 에너지 파라미터를 이용한 고로 철피균열의 조기 결함탐지 기술)

  • Kim, Dong-Hyun;Lee, Sang-Bum;Bae, Dong-Myung;Yang, Bo-Suk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.1
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    • pp.45-52
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    • 2016
  • Blast furnaces are crucial equipment for steel production. A typical furnace risks unexpected accidents caused by contraction and expansion of the walls under an environment of high temperature and pressure. In this study, an acoustic emission (AE) monitoring system was tested for evaluating the large-scale structural health of a blast furnace. Based on the growth of shell cracks with the emission of high energy levels, severe damage can be detected by monitoring increases in the AE energy parameter. Using this monitoring system, steel mill operators can establish a maintenance period, in which actual shell cracks can be verified by cross-checking the UT. From this study, we expect that AE systems permit early fault detection for structural health monitoring by establishing evaluation criteria based on the severity of shell cracking.

Acoustic Wave Propagation Characteristics Corresponding to the Cut-off Frequency in Gas Pipeline (가스 배관의 차단 주파수에 따른 음파전달특성 연구)

  • Kim, Min-Soo;Lee, Sang-Kwon;Jang, Sang-Yup;Koh, Jae-Pil
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.7
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    • pp.693-700
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    • 2008
  • High-Pressure gas Pipeline which is buried in underground has the Possibility that will be exposed to unexpected dangerous impact of construction equipment. To protect from this kind of danger, the real-time health monitoring system of the high-pressure gas pipeline is necessary. First of all, to make the real-time health monitoring system clearly, the acoustic wave propagation characteristics which are made from various construction equipment impacts must be identified. In link of technical development that prevents the damage of high-pressure gas pipeline, this paper gives FEM(finite element method) and BEM(boundary element method) solutions to identify the acoustic wave propagation characteristic of the various impact input signals which consist of Direc delta function and convolution signal of 45 Hz square signal and random signal.

Application of Acoustic Emission Technique for Detection of Crack in Notched Concrete Beams (노치가 있는 콘크리트 보에서 균열검출을 위한 음향방출기법의 적용)

  • Jin, Chi-Sub;Lee, Nae-Chul;Shin, Dong-lk;Kwon, Sung-Jin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.3 no.4
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    • pp.215-220
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    • 1999
  • Concrete micro-cracks that are grown while the structures are under construction or in service, propagate gradually or rapidly by external forces and environmental effects. As described above, almost concrete structures generally have cracks, so for the safety and durability of structures, studies to detect cracks using nondestructive tests have been treated in great deal. The purpose of this study is to evaluate characteristics of AE signals detected from notched concrete beams bending test with different loading using one of nondestructive test, Acoustic Emission (AE) method. Furthermore this study predicts the location of initial crack and measures direction of crack propagation for on-line monitoring before the crack really grows in structures by using two-dimensional AE source location based on rectangular method with three-point bending test. This will allow efficient maintenance of concrete structures through monitoring of internal cracking based on acoustic emission method.

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Partial Discharge Monitoring Technology based on Distributed Acoustic Sensing (분포형 광음향센싱 기반 부분방전 모니터링 기술 연구)

  • Huioon, Kim;Joo-young, Lee;Hyoyoung, Jung;Young Ho, Kim;Myoung Jin, Kim
    • Journal of Sensor Science and Technology
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    • v.31 no.6
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    • pp.441-447
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    • 2022
  • This study describes a novel method for detecting and measuring partial discharge (PD) on an electrical facility such as an insulated power cable or switchgear using fiber optic sensing technology, and a distributed acoustic sensing (DAS) system. This method has distinct advantages over traditional PD sensing techniques based on an electrical method, including immunity to electromagnetic interference (EMI), long range detection, simultaneous detection for multiple points, and exact location. In this study, we present a DAS system for PD detection with performance evaluation and experimental results in a simulated environment. The results show that the system can be applied to PD detection.

Design and Performance Evaluation of Hierarchical Protocol for Underwater Acoustic Sensor Networks (수중음파 센서네트워크를 위한 계층별 프로토콜의 설계 및 성능 평가)

  • Kim, Ji-Eon;Yun, Nam-Yeol;Kim, Yung-Pyo;Shin, Soo-Young;Park, Soo-Hyun;Jeon, Jun-Ho;Park, Sung-Joon;Kim, Sang-Kyung;Kim, Chang-Hwa
    • Journal of the Korea Society for Simulation
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    • v.20 no.4
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    • pp.157-166
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    • 2011
  • As underwater environment monitoring system's interest has increased, the research is proceeding about underwater acoustic sensor network. Underwater sensor network can be applicable to many fields, such as underwater environment monitoring, underwater resource exploration, oceanic data collection, military purposes, etc. It is essential to define the PHY-MAC protocol for revitalization of the underwater acoustic sensor network which is available utilization in a variety of fields. However, underwater acoustic sensor network has to implement by consideration of underwater environmental characteristics, such as limited bandwidth, multi-path, fading, long propagation delay caused by low acoustic speed. In this paper, we define frequency of adjusted PHY protocol, network topology, MAC protocol, PHY-MAC interface, data frame format by consideration of underwater environmental characteristics. We also present system configuration of our implementation and evaluate performance based on our implementation with test in real underwater field.

Energy-efficient intrusion detection system for secure acoustic communication in under water sensor networks

  • N. Nithiyanandam;C. Mahesh;S.P. Raja;S. Jeyapriyanga;T. Selva Banu Priya
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.17 no.6
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    • pp.1706-1727
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    • 2023
  • Under Water Sensor Networks (UWSN) has gained attraction among various communities for its potential applications like acoustic monitoring, 3D mapping, tsunami detection, oil spill monitoring, and target tracking. Unlike terrestrial sensor networks, it performs an acoustic mode of communication to carry out collaborative tasks. Typically, surface sink nodes are deployed for aggregating acoustic phenomena collected from the underwater sensors through the multi-hop path. In this context, UWSN is constrained by factors such as lower bandwidth, high propagation delay, and limited battery power. Also, the vulnerabilities to compromise the aquatic environment are in growing numbers. The paper proposes an Energy-Efficient standalone Intrusion Detection System (EEIDS) to entail the acoustic environment against malicious attacks and improve the network lifetime. In EEIDS, attributes such as node ID, residual energy, and depth value are verified for forwarding the data packets in a secured path and stabilizing the nodes' energy levels. Initially, for each node, three agents are modeled to perform the assigned responsibilities. For instance, ID agent verifies the node's authentication of the node, EN agent checks for the residual energy of the node, and D agent substantiates the depth value of each node. Next, the classification of normal and malevolent nodes is performed by determining the score for each node. Furthermore, the proposed system utilizes the sheep-flock heredity algorithm to validate the input attributes using the optimized probability values stored in the training dataset. This assists in finding out the best-fit motes in the UWSN. Significantly, the proposed system detects and isolates the malicious nodes with tampered credentials and nodes with lower residual energy in minimal time. The parameters such as the time taken for malicious node detection, network lifetime, energy consumption, and delivery ratio are investigated using simulation tools. Comparison results show that the proposed EEIDS outperforms the existing acoustic security systems.

A Study of the Development of PC-Based Source Location System using Acoustic Emission Technique (음향방출기법을 이용한 PC기반 위치표정시스템 개발에 관한 연구)

  • Lee, M.R.;Lee, J.H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.3
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    • pp.205-211
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    • 2003
  • Acoustic emission (AE) technique has been applied to not only mechanical property testing but also on-line monitoring of the el)tire structure or a limit zone only. Although several AE devices have already been developed for the on-line monitoring, the price of these systems is very high and it is difficult for the field to apply yet. In this study, wc developed a specially designed PC-based source location system using the A/D board. The source location technique is very important to identify the source, such as crack, leak detection. However, since the AE waveforms obtained from transducers are very difficult to distinguish the defect signals, therefore, it is necessary to consider the signal analyses of the transient waveform. Wavelet Transform (WT) is a powerful tool for processing transient signals with temporally varying spectra that helps to resolve high and low frequency transients components effectively In this study, the analyses of the AE signals are presented by employing the WT analyses. AE results are compared the PC-based source location system using A/D board with the commercial AE system.

Preliminary study of passive acoustic monitoring of finless porpoises Neophocaena asiaeorientalis around the Southwest offshore wind farm in Korea (서남해 해상풍력 실증단지 주변에서의 수동 음향 관측을 이용한 상괭이 모니터링 가능성 연구)

  • Yoon, Young Geul;Yang, Wonjun;Choi, Jee Woong
    • The Journal of the Acoustical Society of Korea
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    • v.40 no.6
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    • pp.537-545
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    • 2021
  • Due to the accelerated development and transformation of coastal waters by humans, damage to marine mammals is a concern. To understand how coastal development may affect marine mammals, it is essential to determine their distribution characteristics. In this study, the appearance of finless porpoises was confirmed by passive acoustic monitoring around the Southwest offshore wind farm in July, 2020. Although there were no visual observation results of finless porpoises in the research area, the clicks measured in the offshore wind farm were verified by comparing with acoustic characteristics of the clicks measured in the area with a high detection rate. During the experimental period, clicks of finless porpoises were recorded for ten consecutive days, and Clicks per Porpoise Positive Minute (CPPM) was 40.7 clicks min-1, Porpoise Positive Minutes (PPM) was 9.7 %, Encounter duration and waiting time were 18.2 min and 94.9 min respectively. This study provides information on the appearance of them in the Southwest offshore wind farm and this result may help to monitor the impact of marine mammals from wind farm operation.

In-situ measurement of Ce concentration in high-temperature molten salts using acoustic-assisted laser-induced breakdown spectroscopy with gas protective layer

  • Yunu Lee;Seokjoo Yoon;Nayoung Kim;Dokyu Kang;Hyeongbin Kim;Wonseok Yang;Milos Burger;Igor Jovanovic;Sungyeol Choi
    • Nuclear Engineering and Technology
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    • v.54 no.12
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    • pp.4431-4440
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    • 2022
  • An advanced nuclear reactor based on molten salts including a molten salt reactor and pyroprocessing needs a sensitive monitoring system suitable for operation in harsh environments with limited access. Multi-element detection is challenging with the conventional technologies that are compatible with the in-situ operation; hence laser-induced breakdown spectroscopy (LIBS) has been investigated as a potential alternative. However, limited precision is a chronic problem with LIBS. We increased the precision of LIBS under high temperature by protecting optics using a gas protective layer and correcting for shotto-shot variance and lens-to-sample distance using a laser-induced acoustic signal. This study investigates cerium as a surrogate for uranium and corrosion products for simulating corrosive environments in LiCl-KCl. While the un-corrected limit of detection (LOD) range is 425-513 ppm, the acoustic-corrected LOD range is 360-397 ppm. The typical cerium concentrations in pyroprocessing are about two orders of magnitude higher than the LOD found in this study. A LIBS monitoring system that adopts these methods could have a significant impact on the ability to monitor and provide early detection of the transient behavior of salt composition in advanced molten salt-based nuclear reactors.