• Title/Summary/Keyword: Acoustic camera

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Shock Compression of Metal using High Energy Laser and Innovative Applications (고 에너지를 이용한 충격파 발생과 응용)

  • Lee, Hyun-Hee;Yoh, Jai-Ick
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.04a
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    • pp.353-357
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    • 2007
  • We have been setting up experiments on propagation of shock waves generated by the pulsed laser ablation. One side of a thin metal foil is subjected to laser ablation as a shock wave propagates through the foil. The shock wave, which penetrates through the foil is reflected by an acoustic impedance which causes the metal foil to high-strain rate deform. This short time physics is captured on an ICCD camera. The focus of our research is applying shock wave and deformation of the thin foil from the ablation to accelerating micro-particles to a very high speed.

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Development of monitoring system to prevent inflow of marine life into the nuclear power plant (해양생물의 원전 취수구 유입 방지를 위한 모니터링 시스템 개발)

  • Tae-Jong KANG;Eun-Bi MIN;Joong-Ro SHIN;Doo-Jin HWANG
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.60 no.3
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    • pp.277-289
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    • 2024
  • Climate change has led to a significant increase in jellyfish populations globally, causing various problems. For power plants that use nearby seawater for cooling, the intrusion of jellyfish into intake systems can block the flow, leading to reduced output or even shutdowns. This issue is compounded by other small marine organisms like shrimp and salps, making it urgent to develop solutions to prevent their intrusion. This study addressed the problem using the BioSonics DT-X 120 kHz scientific fish finder to conduct preliminary tank experiments. We also deployed underwater acoustic and camera buoys around the intake of nuclear power plant, utilizing a bidirectional communication system between sea and land to collect data. Data collection took place from July 31, 2023 to August 1, 2023. While harmful organisms such as jellyfish and salps were not detected, we successfully gathered acoustic data on small fish measuring backscattering strength (SV). Analysis showed that fish schools were more prominent in the evening than during the day. The highest fish distribution was observed at 3:30 AM on July 31 with an SV of -44.8 dB while the lowest was at 12:30 PM on the same day with an SV of -63.4 dB. Additionally, a solar-powered system was used to enable real-time data acquisition from sea buoys with smooth communication between the land server and the offshore buoy located 1.8 km away. This research developed an acoustic-based monitoring system for detecting harmful organisms around the intake and provided foundational data for preventing marine organism intrusion and planning effective measures.

Measurement of 3-D Flow inside a Micro Curved-tube using Digital Micro Holographic Particle Tracking Velocimetry (디지털 Micro Holographic PTV기법을 이용한 미세 곡관 내부 3차원 유동 측정)

  • Kim, Seok;Lee, Sang-Joon
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2579-2584
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    • 2007
  • A digital micro holographic particle tracking velocimetry (HPTV) system consisting of a high-speed camera and a single laser with acoustic optical modulator (AOM) chopper was established. The digital micro HPTV system was applied to water flow in a micro curved-tube for measuring instantaneous 3-D velocity field data consecutively. The micro curved-tube is using to reproduce the dorsal aorta or utilize in various lap-on-a-chip. The temporal evolution of a three-dimensional water flow in the micro curved-tube (the curvature, ${\kappa}$=1/${\phi}$, 2/${\phi}$, 4/${\phi}$, 8/${\phi}$) of 100 ${\mu}m$ and 300 ${\mu}m$ inner diameters was obtained and mean velocity field distribution was obtained by statistical-averaging the instantaneous velocity fields.

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Identification and Reduction Method for Refrigerator Contraction and Expansion Noise (냉장고 수축팽창 소음원의 규명과 저감 방법)

  • Kim, Wonjin;Park, Seong Kyu
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.4
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    • pp.723-729
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    • 2013
  • The contraction and expansion noise of a refrigerator are investigated, and some effective methods are proposed to reduce the level and occurrence frequency of noise. First, the noise of a refrigerator is measured to estimate the frequency spectrum and occurrence frequency of noise. Second, a sound visualization was conducted using an acoustic camera to determine the location of the noise source. From the results, it was observed that the internal part mainly producing noise was the third shelf in the freezer room. A method to estimate the acceleration on the location of the noise source is introduced to analyze the contraction and expansion noise precisely and accommodate experimental convenience. Noise reduction methods such as the replacement of the existing shelf with glass shelves, adoption of rail slides, and increase of roughness on the contact surface of the shelf are proposed and tested.

An Experimental Study on Wakes behind a Circular and a Square Cylinder in a Horizontal Circular Tube (수평원통관 내에서 원형 및 정사각 실린더의 후류에 관한 실험적 연구)

  • Chang, Tae-Hyun;Lee, Myung Jae
    • Journal of the Korean Society of Industry Convergence
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    • v.6 no.3
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    • pp.253-259
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    • 2003
  • An experimental study was performed for turbulent flow behind a circular and a square cylinder by using 2-D PIV(Particle Image Velocimetry) technique in a cylindrical tube. The Reynolds number investigated were 10,000, 30,000 and 50,000. The measuring system consists of CCD camera. Ar-ion laser, image grabber and a host computer. The mean velocity vector, time mean axial velocity, turbulent intensity and Reynolds shear stress were measured along the test tube. The results are compared each other for the circular and the square cylinder.

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The Mechanical Properties Evaluation on Lay-up Orientation Effect of CFRP Laminate Composite with the Hole Notch (원공노치를 가진 CFRP의 적층방향에 따른 기계적 특성 평가)

  • Tae, Young-Il;Yun, Yu-Seong;Kwon, Oh-Heon
    • Journal of the Korean Society of Safety
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    • v.17 no.1
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    • pp.25-32
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    • 2002
  • The tensile tests for [0/90]s, [90/0]s, and $[0/{\pm}45/90]s$ laminate composite were accomplished with acoustic sensor and failure processes were recorded by a video camera in real time. Also SEM examinations for fracture and side surface were carried out. The purpose of study is estimation of the failure mechanism and the mechanical properties effected by lay-up orientation for CFRP laminate composite with the hole notch. From the results, mechanical properties were obtained and they are similar between two kinds of cross-ply orientation in CFRP laminate composites, but not on $[0/{\pm}45/90]s$. And accordings to increasing the load, accumulate AE count was increased, regardless of lay-up orientation. Futhermore, failure mechanism was described by a video monitoring and SEM.

Microphone Array Design for Noise Source Imaging (소음원 영상화를 위한 마이크로폰 배열 설계)

  • ;Glegg, Stewart A.L.
    • Journal of KSNVE
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    • v.7 no.2
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    • pp.255-260
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    • 1997
  • This paper describes 3-dimensional volume array of 4 microphones including a reference microphone which is capable of imaging wideband noise source position in 2-dimensional image plane. The cross correlation function and corresponding imaging function between a reference microphone and other microphone, are derived as a function of noise source position. The magnitude of the imaging function gives noise source mapping in image plane. Since the image plane is selective from a rectangular and a cylindrical plane, noise source position information such as range and bearing relative to the array is identified very much easily. Simulation results for typical source configurations confirms the applicability of the proposed array in noise control field.

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A Study on Characteristics of Impact Fracture in CFRP Laminate Plates (탄소섬유강화 복합재 적층판의 충격파괴 특성에 관한 연구)

  • Yang, I.Y.;Jung, J.A.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.5
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    • pp.38-46
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    • 1995
  • In this paper, an experimental study on the effects of the impact damage and the perforation characteristic of CFRP laminates with different fiber stacking orientation and ply number was done through an observation of interrelations between the impact energy vs. transmitted energy and the impact energy vs. absorbed energy per unit volume. The velocities of the ball before or after impact are measured by the high-speed camera. And when CFRP laminates are subjected to tranverse impact by a steel ball(${\phi}10$), the delamination shapes generated by impact damage are observed by using SAM (Scanning acoustic Microscope).

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Characteristics on Temperature Evolution in the Metallic Specimen by Ultrasound-Excited Thermography

  • Choi, M.Y.;Park, J.H.;Kang, K.S.;Kim, W.T.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.3
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    • pp.200-206
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    • 2010
  • In ultrasound-excited thermography, the injected ultrasound to an object is transformed to heat and the appearance of defects can be visualized by thermography camera. The advantage of this technology is selectively sensitive to thermally active defects. Despite the apparent simplicity of the scheme, there are a number of experimental considerations that can complicate the implementation of ultrasound excitation thermography inspection. Factors including acoustic horn location, horn-crack proximity, horn-sample coupling, and effective detection range all significantly affect the detect ability of this technology. As conclusions, the influence of coupling pressures between ultrasound exciter and specimen was analyzed, which was dominant factor in frictional heating model.

Characterizing Geomorphological Properties of Western Pacific Seamounts for Cobalt-rich Ferromanganese Crust Resource Assessment (서태평양 해저산의 망간각 자원평가를 위한 해저지형 특성 분석)

  • Joo, Jongmin;Kim, Jonguk;Ko, Youngtak;Kim, Seung-Sep;Son, Juwon;Pak, Sang Joon;Ham, Dong-Jin;Son, Seung Kyu
    • Economic and Environmental Geology
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    • v.49 no.2
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    • pp.121-134
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    • 2016
  • We characterize the spatial distribution of Cobalt-rich ferromanganese crusts covering the summit and slopes of a seamount in the western Pacific, using acoustic backscatter from multibeam echo sounders (MBES) and seafloor video observation. Based on multibeam bathymetric data, we identify that ~70% of the summit area of this flattopped seamount has slope gradients less than $5^{\circ}$. The histogram of the backscatter intensity data shows a bi-modal distribution, indicating significant variations in seabed hardness. On the one hand, visual inspection of the seafloor using deep-sea camera data exhibits that the steep slope areas with high backscatter are mainly covered by manganese crusts. On the other hand, the visual analyses for the summit reveal that the summit areas with relatively low backscatter are covered by sediments. The other summit areas, however, exhibit high acoustic reflectivity due to coexistence of manganese crusts and sediments. Comparison between seafloor video images and acoustic backscatter intensity suggests that the central summit has relatively flat topography and low backscatter intensity resulting from unconsolidated sediments. In addition, the rim of the summit and the slopes are of high acoustic reflectivity because of manganese crusts and/or bedrock outcrops with little sediments. Therefore, we find a strong correlation between the acoustic backscatter data acquired from sea-surface multibeam survey and the spatial distribution of sediments and manganese crusts. We propose that analyzing acoustic backscatter can be one of practical methods to select optimal minable areas of the ferromanganese crusts from seamounts for future mining.