• 제목/요약/키워드: Marine noise

검색결과 488건 처리시간 0.019초

DWT와 GPS/INS융합 알고리즘을 이용한 수면이동체의 위치 인식 (Localization of the surface vehicles using DWT and GPS/INS fusion algorithm)

  • 유한동;이인욱;최원석;이장명
    • 로봇학회논문지
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    • 제10권1호
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    • pp.1-8
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    • 2015
  • This paper proposes a study for accurate surface localization system using DWT(Discrete Wavelet Transform) and GPS/INS fusion algorithm. Because the propagation in the underwater is not passed by characteristics of the medium unlike the ground, the sonar system like DVL is used instead of GPS. But since these systems are installed on the seafloor and operated, a long time is required for installation and navigation systems are limited outside of the range area. And it is difficult to estimate position in a three-dimensional considering the depth in actual marine environment. In this paper, before the development of underwater localization system, precisely estimated position system is proposed in a two-dimensional by developing surface localization system using removing noise and disturbance with DWT and relatively inexpensive GPS and INS sensor.

Semiautomated Analysis of Data from an Imaging Sonar for Fish Counting, Sizing, and Tracking in a Post-Processing Application

  • Kang, Myoung-Hee
    • Fisheries and Aquatic Sciences
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    • 제14권3호
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    • pp.218-225
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    • 2011
  • Dual frequency identification sonar (DIDSON) is an imaging sonar that has been used for numerous fisheries investigations in a diverse range of freshwater and marine environments. The main purpose of DIDSON is fish counting, fish sizing, and fish behavioral studies. DIDSON records video-quality data, so processing power for handling the vast amount of data with high speed is a priority. Therefore, a semiautomated analysis of DIDSON data for fish counting, sizing, and fish behavior in Echoview (fisheries acoustic data analysis software) was accomplished using testing data collected on the Rakaia River, New Zealand. Using this data, the methods and algorithms for background noise subtraction, image smoothing, target (fish) detection, and conversion to single targets were precisely illustrated. Verification by visualization identified the resulting targets. As a result, not only fish counts but also fish sizing information such as length, thickness, perimeter, compactness, and orientation were obtained. The alpha-beta fish tracking algorithm was employed to extract the speed, change in depth, and the distributed depth relating to fish behavior. Tail-beat pattern was depicted using the maximum intensity of all beams. This methodology can be used as a template and applied to data from BlueView two-dimensional imaging sonar.

프로펠러의 비정상하중에 의해 발생하는 소음의 이론적 추정 (Theoretical Prediction of Noise Generated by Unsteady Loading of Marine Propellers)

  • 이창섭;조충호
    • 대한조선학회논문집
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    • 제36권3호
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    • pp.29-40
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    • 1999
  • 캐비테이션이 발생하지 않는 프로펠러의 정상 및 비정상 하중에 의해 음장에 유기되는 소음을 지배하는 음파 방정식에 대한 주파수 영역에서의 수치 해석법을 정립하였다. 본 연구를 통하여 음압 스펙트럼에서 날개 통과 진동수 배수의 소음만이 발생한다는 것을 보였으며, 이때 적용되는 파수는 반류의 불균일성에 기인하는 조화성분과 프로펠러의 회전에 의해 발생되는 Doppler 효과가 고려되도록 표현되어야 함을 보였다. 특정 전진속도에서 하중이 없도록 설계된 날개수가 2인 모형 프로펠러에 대한 이론적 추정과 실험결과를 비교함으로써, 정상상태인 경우 날개 두께 효과가 매우 중요하나, 비정상상태에서는 날개하중의 변화에 의한 소음의 영향이 커서 정상상태에 비하여 두께효과가 비교적 적게 기여함을 알 수 있었다.

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워터제트 추진기 유입관의 내부유동 전산해석 (Numerical Internal Flow Analysis of Intake Duct of Waterjet Propulsion)

  • 윤현석;박원규;전호환;김문찬
    • 대한조선학회논문집
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    • 제42권1호
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    • pp.1-9
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    • 2005
  • Waterjet propulsion is widely used to thrust high speed marine vessels in excess of 30-35 knots by virtue of the high propulsive efficiency, good maneuverability, and less cavitation. From the aspect of power loss, approximately $7-9\%$ of the total power is lost in intake duct due to the flow separation, nonuniformity, etc. Thus, detail understanding of flow phenomena occurring within intake duct is essential to reduce the power loss, as well as noise and vibration. The present work solved 30 incompressible RANS equations to provide complicated viscous flow features of intake duct. The numerical results were compared with experiments and good agreements were obtained for three jet velocity ratios.

Development of eco-friendly and lightweight insulation panels for offshore plant

  • Jung, Jae-Deok;Hong, Suk-Yoon;Song, Jee-Hun;Kwon, Hyun-Wung;Joo, Won-Ho;Kim, Sung-Hoon
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제8권6호
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    • pp.554-562
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    • 2016
  • Recently, regulations pertaining to the noise and vibration environment of offshore plants have been strengthened. For example, the NORSOK standards have been applied, which are very strict regulations that are comparable to those applied to passenger ships. Furthermore, the use of porous materials, such as those used in most of the current insulating panels, has been forbidden. Therefore, honeycomb-backed Micro-Perforated Plates (MPPs) are now regarded as next-generation absorber materials. This paper reports the results of parametric studies that were performed using numerical methods to determine the effect of the thickness on the performance of a honeycomb panel and the effect of the perforation ratio on the MPP performance. The numerical results were verified through experiments. Finally, we propose a combined honeycomb/MPP panel where the MPP is placed between upper and lower honeycomb panels and one end surface is also replaced with an MPP.

22000TEU급 컨테이너선박의 메인 엔진 시동용 공기압축기의 구조 강도 해석에 관한 연구 (Analytical Study on the Structural Strength of an Air Compressor for Main Engine Starting of 22000TEU Class Container Ships)

  • 김순경;이진우
    • 한국기계가공학회지
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    • 제14권5호
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    • pp.60-67
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    • 2015
  • The compressor is used for many fields not only in the industrial sector, but also as a general household product. The energy consumption required for the compressor operation is very large. The reciprocation compressor is widely used as an air compressor. Regarding the reciprocating air compressor, the discharge of the gas compacted by the method of compressing the gas by using the oscillation of the piston is generated by the piston reciprocation 1 church 1 number. When compressing after compressing the air by the oscillation of the piston, the marine reciprocating air compressor is the vibration generated in the compressor and surrounding structure due to the energy of the generated inertia. If the effect of these harmful elements can be reduced, it supports the service of the vessel. In addition, accidents generated by the noise of the vibration can be prevented. Therefore, in this research, firstly, the structural analysis of the piston part was performed, the safety factor in all results was drawn based upon this, and the reliability of the interpretation was examined in order to create the optimal design for the air compressor.

Underwater Acoustic Research Trends with Machine Learning: Active SONAR Applications

  • Yang, Haesang;Byun, Sung-Hoon;Lee, Keunhwa;Choo, Youngmin;Kim, Kookhyun
    • 한국해양공학회지
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    • 제34권4호
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    • pp.277-284
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    • 2020
  • Underwater acoustics, which is the study of phenomena related to sound waves in water, has been applied mainly in research on the use of sound navigation and range (SONAR) systems for communication, target detection, investigation of marine resources and environments, and noise measurement and analysis. The main objective of underwater acoustic remote sensing is to obtain information on a target object indirectly by using acoustic data. Presently, various types of machine learning techniques are being widely used to extract information from acoustic data. The machine learning techniques typically used in underwater acoustics and their applications in passive SONAR systems were reviewed in the first two parts of this work (Yang et al., 2020a; Yang et al., 2020b). As a follow-up, this paper reviews machine learning applications in SONAR signal processing with a focus on active target detection and classification.

프로펠러 날개의 피로강도에 관한 연구 (A Study on the Fatigue Strength of Propeller Blades)

  • 노인식;이창섭
    • 대한조선학회논문집
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    • 제48권6호
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    • pp.539-543
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    • 2011
  • Recently, to reduce the noise and vibration levels of ships, high skewed marine propellers with thinner thickness are adopted widely, however, such propeller design trend causes to reduce the strength of blades. Propeller blades are rotating continuously in irregular wake field of ships. So, it is necessary to examine the strength of them precisely including from a viewpoint of fatigue strength. In present paper, the fatigue strength of propeller blades was investigated. Firstly, fatigue tests for Al Bronze, the representative propeller material, were carried out. The S-N curve was obtained for the assessment of the fatigue crack initiation life. And the material properties C, m for the fatigue crack propagation analysis based on the Paris' equation were derived. For the 2nd stage, the structural responses of propeller blades in irregular ship wake field was carried out using the finite element analysis code. And the fatigue strength of propeller blades were considered based on the calculated stress levels and material characteristics for fatigue strength.

칼만필터를 이용한 선박 거동 예측에 관한 연구 (A Study on the ship movement estimation by using Kalman filter)

  • Le, Dang-Khanh;Kim, Jin-Man;Nam, Taek-Kun
    • 한국항해항만학회:학술대회논문집
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    • 한국항해항만학회 2012년도 추계학술대회
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    • pp.261-262
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    • 2012
  • 본 연구에서는 레저선박 및 소형선박을 위한 지능형 충돌방지 시스템에 대한 언급하고 있다. 이 시스템의 기능은 선박으로부터 이동 물체까지의 거리와 속도를 추정하고 해당 물체와의 충돌을 회피하기 위한 제어신호를 발생하는 것이다. 본 논문에서는 칼만필터를 이용하여 대상물체의 위치와 속도를 추정하는 방법에 대해 소개한다. 실제 실험단계에서는 레이저센서를 이용하여 대상물체의 거리를 계측하고 계측된 신호에 필터링을 적용하여 대상물의 위치와 속도를 검출하게 된다. 제안한 기법의 유용성을 검증하기 위해 물체의 위치 및 속도추정에 대한 시뮬레이션을 수행하였다.

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연속된 레이더 영상을 이용한 해수면 복원 연구 (Study on Sea Surface Reconstruction Using Sequent Radar Images)

  • 박준수
    • 한국해양공학회지
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    • 제27권6호
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    • pp.100-105
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    • 2013
  • This paper presents a sea surface reconstruction method that uses measured radar images by applying filtering techniques and identifying wave characteristics of the surrounding the Ieodo ocean research station using WaveFinder (X-band wave measurement radar), which is installed in the station. In addition, the results obtained from real radar images are used to verify the reconstructed sea surface. WaveFinder is a marine system that was developed to measure wave information in real time. The WaveFinder installed in the station could acquire sequent images for the sea surface at constant time intervals to obtain real time information (Wave height, mean wave period, wave directionality, etc.) for the wave by getting a three-dimensional spectrum by applying an FFT algorithm to the acquired sequent images and wave dispersion relation. In particular, we found the wave height using the SNR (Signal to noise ratio) of the acquired images. The wave information measured by WaveFinder could be verified by comparing and analyzing the results measured using the wave measurement instrument (Sea level monitor) in the station. Additionally, the wave field around the station could be reconstructed through the three-dimensional spectrum and the inverse FFT filtering from the analyzed results for the measured radar images. We verified the applicability of the sea surface reconstruction method by comparing the measured and simulated sea surfaces.