• 대한임베디드공학회논문지
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• 제12권5호
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• pp.277-286
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• 2017

This paper introduces mathematical modelling and control algorithm of expendable mine disposal vehicle. This vehicle has two longitudinal thrusters, one vertical thruster and internal mass moving system which can control pitch rate. Also, the vehicle has an optical camera and forward looking sonar for underwater mine detection and classification. The vehicle is controlled via an optical cable connected with operating console on the mother ship. We describe the vehicle's 6DOF dynamic model and controller which can track the desired trajectory for the way-point tracking. These simulation results shows guidance and maneuvering performance which has other sensor data or not.

• 소음진동
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• 제11권2호
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• pp.226-233
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• 2001

It is essential to analyze structural vibrations due to turbulent wall pressure fluctuations over a body surface which moves through a fluid, because the vibrations can be a severe source of noise affecting to passengers in airplanes and SONAR performance. Generally, this kind of problems have been solved for very simplified models, e.g. plates, which can be applied to the wavenumber domain analysis. In this paper, a finite element modeling of the walt pressure fluctuations is investigated, which can be applied to those over arbitrary smooth surfaces. It is found that the modeled wall pressure fluctuation at nodes becomes uncorrelated at higher frequencies and at lower flow speeds, and the response is over-estimated due to the aliased power. Then the frequency range available for uncorrelated loading model and two power correction schemes are presented.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.817-824
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• 2000

It is essential to analyze structural vibrations due to turbulent wall pressure fluctuations over a body surface which moves through a fluid, because the vibrations can be a severe source of noise affecting to passengers in airplanes and SONAR performance. Generally, this kind of problems have been solved for very simplified models, e.g. plates, which can be applied to the wavenumber domain analysis. In this paper, a finite element modeling of the wall pressure fluctuations over arbitrary smooth surfaces is investigated. It is found that the modeled wall pressure fluctuation at nodes becomes uncorrelated at higher frequencies and at lower flow speeds, and the response is over-estimated due to the aliased power. Finally, the frequency range available for uncorrelated loading model and two power correction schemes are presented.

• 한국음향학회지
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• 제27권5호
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• pp.221-228
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• 2008

소나 시스템에서 참조 신호를 이용하여 어레이 형상을 추정하는 경우, 참조 신호는 어레이와 충분히 떨어져 있지 않기 때문에 근거리 신호 모델링이 필요하다. 근거리 신호 모델링을 기반으로 하는 어레이 형상 추정 기법은 일반적으로 수신된 참조 신호의 공간 공분산 행렬을 이용한다. 이러한 기법 중 1개의 참조 신호만을 이용하여 공간 공분산 행렬의 고유치 분해 후 최대 고유치에 해당하는 고유 벡터를 참조 신호의 조향 벡터로 구성하여 어레이 형상을 추정하는 근거리 고유벡터 기법이 있다. 본 논문에서는 1개 이상의 참조 신호를 이용하여 공간 공분산 행렬로부터 구한 잡음 부공간과 신호 부공간이 서로 직교한다는 특성을 이용하여 Newton-type 반복 기법으로 센서 위치를 추정해 나가는 간략화된 부공간 근사 기법을 제안한다. 또한 근거리 고유 벡터 기법과 간략화된 부공간 근사 기법의 성능을 다양한 환경에서 분석해 본다. 모의 실험 결과 한 개의 참조 신호를 이용하는 경우에 근거리 고유 벡터 기법과 간략화된 부공간 근사 기법이 거의 동일한 성능을 보임을 확인할 수 있었다. 또한 근거리 고유 벡터 기법이 참조 신호를 2개 이상 사용할 수 없는데 반해 간략화된 부공간 근사 기법은 두 개의 참조 신호를 이용함으로써 참조 신호의 입사 방향에 관계없이 안정적인 형상 추정 결과를 얻을 수 있음을 확인하였다.

• 한국해양공학회지
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• 제33권3호
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• pp.289-299
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• 2019

Various sizes of ROVs are being utilized in offshore industrial, scientific, and military applications all around the world. Because of innovative developments in science and technology, image acquisition devices such as sonar devices and cameras have been reduced in size and their performance has been improved. Thus, we can expect better accuracy and higher resolution even in the case of exploration using a small ROV. The purpose of this paper is to prepare a standard procedure for the identification of unidentified hazardous materials found during the National Oceanographic Survey. In this paper, we propose an IDEF (Integrated DEFinition) method modeling technique to identify unidentified targets using a small ROV. In accordance with the proposed procedure, an ROV survey was carried out on target No.16 with a four-ton-class fishing boat as a support vessel on September 18th of 2018 in the sea near Daebu Island. Unidentified targets, which were not known by the multi-beam data obtained from the ship, could be identified as concrete pipes by analyzing the HD camera and high-resolution sonar images acquired by the ROV. The whole proposed procedure could be verified, and the survey with the small ROV required about 10 days to identify the target in one place.