• Title/Summary/Keyword: underwater target

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A Study on Underwater-Pipe Video Image Mosaicking using Digital Photogrammetry (수치사진측량을 이용한 수중 파이프 비디오 모자익 영상 제작에 관한 연구)

  • Kang, Jin-A;Kwon, Kwang-Seok;Kim, Byung-Guk;Oh, Yoon-Seuk
    • Journal of the Korean Association of Geographic Information Studies
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    • v.11 no.4
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    • pp.150-160
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    • 2008
  • The present domestic underwater and ocean facilities management depends on analysis with the naked eye. This study performs quantitative analysis to improve conventional methods, analyze spatial situation of underwater facilities. This research is divided into two steps; underwater image distortion correction and image mosaic step. First, underwater image distortion correction step is for the production of underwater target, calculates the correction parameters, and then developed the method that convert the original image point to whose distortion is corrected. Second step is for the obtaining pipe images installed in the underwater, corrects the distortion, and then transforms a coordinates of the correction pipe image. After coordinate transformation, we make the mosaic image using the singularities. As a result, when we measure the distance between pipe and underwater ground and compare with calculation value on mosaic image, it is showed that RMSE is 0.3cm.

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The auditory thresholds and fish behaviors to the underwater sounds for luring of target secies at the set-net in the coast of Cheju(II) -Critical ratios of the yellow tail(Seriola quinqueradiata)- (연안정치망 주요대상어종의 청각역치와 유집방음에 대한 행동반응(II) -방어(Seriola quinqueradiata)의 임계비)

  • 안장영
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.35 no.1
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    • pp.19-24
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    • 1999
  • This paper is second part on the auditory thresholds and fish behaviors to the underwater sounds for luring of target species at the set-net in the coast of Cheju. In order to obtain the critical ratio of yellow tails(Seriola quinqueradiata) and the emission level of underwater sound for luring of them, we make experiments to measure the auditory threshold of them using conditioning with electric shock. In state that the white noise with 10dB higher sound pressure level than ambient noise is emitted, the auditory thresholds of yellow tails are measured with 100~116.5dB and they are higher than those in state of no emission of white noise by the masking effects of it. Although sound pressure level of background noise go down, the auditory thresholds go up with frequency above than 300Hz.The critical ratio of yellow-tails in frequency of 80Hz, 100Hz, 200Hz, 500Hz, 800Hz are 46dB, 40dB, 50dB, 52dB, 60dB, 70dB respectively. The sound pressure level of which the signal sound is recognized by yellow tails under the ambient noise is above 100dB and the critical ratio of them is above 40dB.

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The Functional Extension of the Underwater Vehicle Modeling and Simulation Tactics Manager using the Script Embedding Method (스크립트 임베딩을 활용한 수중운동체 M&S 전술처리기의 기능 확장)

  • Son, Myeong-Jo;Kim, Tae-Wan;Nah, Young-In
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.5
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    • pp.590-600
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    • 2009
  • In the simulation of underwater vehicles such as a submarine or a torpedo, various type of simulations like an engineering level simulation for predicting the performance precisely and an engagement level simulation for examining the effectiveness of a certain tactic is required. For this reason, a tactics manager which can change the behavior of a simulation model according to external tactics is needed. In this study the tactics manager supporting a script language and engine which can represent various tactics and can help users define external input tactics for the tactic manager easily is suggested. Python and Lua which are representative among script languages have been compared and analyzed from the viewpoint of a tactic manage, and the tactic manger using the script engines of those script languages was implemented. To demonstrate the effectiveness of the tactic manager, a target motion analysis simulation of the warfare between a submarine and a surface ship.

Preprocessing performance of convolutional neural networks according to characteristic of underwater targets (수중 표적 분류를 위한 합성곱 신경망의 전처리 성능 비교)

  • Kyung-Min, Park;Dooyoung, Kim
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.6
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    • pp.629-636
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    • 2022
  • We present a preprocessing method for an underwater target detection model based on a convolutional neural network. The acoustic characteristics of the ship show ambiguous expression due to the strong signal power of the low frequency. To solve this problem, we combine feature preprocessing methods with various feature scaling methods and spectrogram methods. Define a simple convolutional neural network model and train it to measure preprocessing performance. Through experiment, we found that the combination of log Mel-spectrogram and standardization and robust scaling methods gave the best classification performance.

Active Sonar Target/Nontarget Classification Using Real Sea-trial Data (실제 해상 실험 데이터를 이용한 능동소나 표적/비표적 식별)

  • Seok, J.W.
    • Journal of Korea Multimedia Society
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    • v.20 no.10
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    • pp.1637-1645
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    • 2017
  • Target/Nontarget classification can be divided into the study of shape estimation of the target analysing reflected echo signal and of type classification of the target using acoustical features. In active sonar system, the feature vectors are extracted from the signal reflected from the target, and an classification algorithm is applied to determine whether the received signal is a target or not. However, received sonar signals can be distorted in the underwater environments, and the spatio-temporal characteristics of active sonar signals change according to the aspect of the target. In addition, it is very difficult to collect real sea-trial data for research. In this paper, target/non-target classification were performed using real sea-trial data. Feature vectors are extracted using MFCC(Mel-Frequency Cepstral Coefficients), filterbank energy in the Fourier spectrum and wavelet domain. For the performance verification, classification experiments were performed using backpropagation neural network classifiers.

A Study on the Aperiod Bearing Only TMA (비주기 Bearing 표본입력에 대한 BOTMA 연구)

  • 이동훈
    • Journal of the Korea Institute of Military Science and Technology
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    • v.4 no.1
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    • pp.30-40
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    • 2001
  • This paper presents a study on the design and simulation of bearing only target motion analysis to enhance the TMA capability using SONAR in underwater environment. A bearing only target motion analysis algorithm using aperiod bearing input signals has been developed and simulated in the MATLAB.

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지표레이다(GPR) 탐사에 의한 하상퇴적물 조사

  • Jang, Hyeon-Sam;Jeong, Seong-Tae
    • Journal of the Korean Geophysical Society
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    • v.5 no.1
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    • pp.51-62
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    • 2002
  • Investigation of underwater sedimentary layers has been carried out with GPR(Ground Penetration Radar) survey. FPR survey has been proved to be very satisfactory since the target area has shallow water depth of about 2.5 m, is a lake with no water flow, and the thickness of mud layer, which is a main survey target, is relatively thin. The results clearly showed the underwater sedimentary layers, which includes mud, sand, gravel and basement layer. Specially, the distribution and total amount of mud layers from the survey results can be used as a basic data for the dredging of mud layer in the area.

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Trajectory Tracking Performance Analysis of Underwater Manipulator for Autonomous Manipulation

  • Chae, Junbo;Yeu, Taekyeong;Lee, Yeongjun;Lee, Yoongeon;Yoon, Suk-Min
    • Journal of Ocean Engineering and Technology
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    • v.34 no.3
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    • pp.180-193
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    • 2020
  • In this study, the end-effector tracking performance of a manipulator installed on a remotely operated vehicle (ROV) for autonomous underwater intervention is verified. The underwater manipulator is an ARM 7E MINI model produced by the ECA group, which consists of six joints and one gripper. Of the six joints of the manipulator, two are revolute joints and the other four are prismatic joints. Velocity control is used to control the manipulator with forward and inverse kinematics. When the manipulator approaches a target object, it is difficult for the ROV to maintain its position and posture, owing to various disturbances, such as the variation in both the center of mass and the reaction force resulting from the manipulator motion. Therefore, it is necessary to compensate for the influences and ensure the relative distance to the object. Simulations and experiments are performed to track the trajectory of a virtual object, and the tracking performance is verified from the results.

Optimum Mix Proportions of Latex Modified Repair Mortar for Agricultural Underwater Concrete Structure (수중에 노출된 농업용 콘크리트 구조물 보수용 라텍스개질 모르타르의 적정 배합비 도출)

  • Won, Jong-Pil;Lee, Jae-Young;Park, Chan-Gi;Lee, Sang-Woo;Kim, Wan-Young
    • Journal of The Korean Society of Agricultural Engineers
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    • v.49 no.3
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    • pp.43-50
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    • 2007
  • The purpose of this study was to determine the optimum mix proportion of latex modified mortar for agricultural underwater concrete structures repair. The experimental variables included a latex and antiwashout admixture amount, binder-sand ratio, water-binder ratio. This study were evaluated a repair performance and environment effect of latex modified repair mortar for agricultural underwater concrete structures. The pH test was conducted to evaluated the environmental effect and the flow test was peformed to evaluated the workability. Also, compressive, flexural and bond tests were conducted. Test results show that the optimum mix proportion of latex modified repair mortar for agricultural underwater concrete structures, was achieved by 1:1.5 binder-sand ratio, 5% latex ratio (weight of binder), 1.3% antiwashout admixture ratio (weight of binder), 0.33 water-binder ratio and 10% silica lune replacement ratio (weight of cement). The environmental effect and repair performance of optimum mix proportion satisfied all target performance.

Performance characteristics of a multi-directional underwater CCTV camera system to use in the artificial reef survey (인공어초 조사용 다방향 수중 CCTV 카메라 시스템의 성능 특성)

  • Lee, Dae-Jae
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.47 no.2
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    • pp.146-152
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    • 2011
  • Underwater CCTV camera systems are increasingly replaced the traditional net approach of assessing the species, numbers and aggregation patterns of marine animals distributing around the artificial reefs installed in the inshore fishing grounds, in particular, in relation to the biological investigation of behavior and distribution patterns of target fishes. In relation to these needs, we developed a multi-directional underwater CCTV camera system to use in detecting and tracking marine animals in the artificial reef ground. The marine targets to be investigated were independently tracked by using a camera module toward the bottom and four camera modules installed in the interval of $90^{\circ}$ in horizontal plane and inclination of $45^{\circ}$ in vertical plane of the CCTV system without the overlap of video frames by each camera module. From the results of several field tests at sea, we believe that the developed multi-directional underwater CCTV camera system will contribute to a better understanding in evaluating the effect of artificial reefs installed in the inshore fishing grounds.