• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.226-229
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• 1989

This paper presents a navigation control method for a vision guided robot. The robot is equipped with one camera, an IBM/AT compatible PC, and a sonar system. The robot can either follow track specified on a monitor screen or navigate to a destination avoiding any obstacles on its way. The robot finds its current position as well as its moving direction by taking an image of a circular pattern placed on the ceiling.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.241-241
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• 2011

실제 해상운용시험을 통해 취득한 단일빔/다중빔 측면주사음탐기 초음파영상을 비교하여 다중빔 측면 주사음탐기의 경우 운용 시 제약조건을 얼마나 향상시켰는지 이 논문에서 소개한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1243-1249
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• 2014

The naval mine is the explosives that are installed in the water in order to attack surface ships or submarines. So mine warfare is a very important component of naval operations. In this paper, first, understanding of the general concept about mine warfare. Second, introduce the mine hunting progress and mine sweeping progress. And then, suggest the system design method of mine counter measure warfare using several functions. The functions are mine area detection algorithm for side scan sonar image using Adaboost algorithm, and calculation to mine hunting progress rate and mine sweeping progress rate. And techniques that lead the mine disposal vehicle(MDV) to mine.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.679-687
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• 2019

This paper presents the autonomous swimming technology developed for an Autonomous Underwater Vehicle (AUV) operating in the underwater jacket structure environment. To prevent the position divergence of the inertial navigation system constructed for the primary navigation solution for the vehicle, we've developed kinds of marker-recognition based underwater localization methods using both of optical and acoustic cameras. However, these two methods all require the artificial markers to be located near to the cameras mounted on the vehicle. Therefore, in the case of the vehicle far away from the structure where the markers are usually mounted on, we may need alternative position-aiding solution to guarantee the navigation accuracy. For this purpose, we develop a sonar image processing based underwater localization method using a Forward Looking Sonar (FLS) mounted in front of the vehicle. The primary purpose of this FLS is to detect the obstacles in front of the vehicle. According to the detected obstacle(s), we apply an Occupancy Grid Map (OGM) based path planning algorithm to derive an obstacle collision-free reference path. Experimental studies are carried out in the water tank and also in the Pohang Yeongilman port sea environment to demonstrate the effectiveness of the proposed autonomous swimming technology.

• The Journal of the Acoustical Society of Korea
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• v.28 no.8
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• pp.761-767
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• 2009

The detection of target echoes in a sonar image is usually difficult since reverberation is originated by the returns reflected around the boundary and volumes. Under the scenario of the target presence around the reverberation, the detection performance of existing algorithms is degraded. Since they have a similar statistical features. But proposed detector gives improvement existing algorithms Under this scenario. In this paper, 4 segmentation contrast box algorithm using maximum contrast value is proposed based on statistical segmentation, which gives better detection performance in the sense of reducing false alarms. The simulations validate the effectiveness of the proposed algorithm.

• 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.

• Electrical & Electronic Materials
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• v.9 no.8
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• pp.825-830
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• 1996

In this study, Characteristics of Ultrasonic Transducer fabricated with porous piezoelectric resonator, 3-D underwater object restoration using the self made ultrasonic transducer and modified SCL(Simple Competitive Learning) neural network are investigated. The self-made transducer was satisfied the required condition of ultrasonic transducer in water, and the modified SCL neural network using the acquired object data 16*16 low resolution image was used for object restoration of $32{\times}32$ high resolution image. The experimental results have shown that the ultrasonic transducer fabricated with porous piezoelectric resonator could be applied for SONAR system.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1495-1497
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• 1996

In this study, Object restoration of ultrasonic transducer fabricated with porous piezoelectric ceramics using Modified SCL(Simple Competitive Learning) neural networks are presented. Using the acquired object data $16{\times}16$ pixels, Modified SCL neural networks using the $16{\times}16$ low resolution image was used for object restoration of $32{\times}32$ high resolution image. The experimental results show that the ultrasonic transducer fabricated with porous piezoelectric ceramics could be applied for sonar system.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.2
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• pp.225-234
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• 2018

A Multibeam Echo Sounder (MBES) is commonly used for rapid seafloor mapping. We herein present a time-domain integrated system simulation technique for MBES development. The Modeling and Simulation (M&S) modules consist of four parts: sensor array signal transmission, propagation and backscattering modeling in the ocean environment, beamforming of the received signals, and image processing. Also, the simulation employs a ray-theory-based algorithm to correct the reconstructed bathymetry, which has errors due to the refraction caused by the vertical sound velocity profile. The developed M&S technique enables design parameter verification and system parameter optimization for MBES. The framework of this technique can also be potentially used to characterize the seabed properties. Finally, typical seafloor images are presented and discussed.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.193-200
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• 2013

In this paper, underwater acoustic image classification of a cylindrical object using the Hough transformation is proposed. Hough transformation is often used to classify a cylindrical object in the optical systems. However, it is difficult to apply to the underwater acoustic image system because of lower resolution and noisier underwater environments. Thus, the cylindrical object was modeled and its geometric depth(GD) pixels were restored in order to make them suitable for the Hough transformation by using moving average filter and a polynomial interpolation method. As a result, restored GD pixels are similar to original ones and test results show high performance in classification.