• Journal of Advanced Marine Engineering and Technology
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• 제33권2호
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• pp.344-354
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• 2009

Side scan sonar using acoustic wave plays a very important role in the underwater, sea floor, and shallow marine geologic survey. In this study, we have acquired side scan sonar data for the underwater man-made structures, artificial reefs and fishing grounds, installed and distributed in the survey area. We applied digital image processing techniques to side scan sonar data in order to improve and enhance an image quality. We carried out digital image processing with various kinds of filtering in spatial domain and frequency domain. We tested filtering parameters such as kernel size, differential operator, and statistical value. We could easily estimate the conditions, distribution and environment of artificial structures through the interpretation of side scan sonar.

• 한국군사과학기술학회지
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• 제15권3호
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• pp.272-287
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• 2012

The optimal use of sonar systems for detection is a practical problem in a given ocean environment. In order to quantify the mission achievability in general, measure of effectiveness(MOE) is defined for specific missions. In this paper, using the specific MOE for detection, which is represented as cumulative detection probability(CDP), an integrated software package named as Optimal Acoustic Search Path Planning(OASPP) is developed. For a given ocean environment and sonar systems, the discrete observations for detection probability(PD) are used to calculate CDP incorporating sonar and environmental parameters. Also, counter-detection probability is considered for vulnerability analysis for a given scenario. Through modeling and simulation for a simple case for which an intuitive solution is known, the developed code is verified.

• 로봇학회논문지
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• 제15권1호
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• pp.1-7
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• 2020

In this paper, we introduce the methodology that utilizes deep learning-based front-end to enhance underwater feature matching. Both optical camera and sonar are widely applicable sensors in underwater research, however, each sensor has its own weaknesses, such as light condition and turbidity for the optic camera, and noise for sonar. To overcome the problems, we proposed the opti-acoustic transformation method. Since feature detection in sonar image is challenging, we converted the sonar image to an optic style image. Maintaining the main contents in the sonar image, CNN-based style transfer method changed the style of the image that facilitates feature detection. Finally, we verified our result using cosine similarity comparison and feature matching against the original optic image.

• 소음진동
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• 제9권5호
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• pp.1036-1041
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• 1999

This paper aims for the development of the high power sonar system for measuring the velocity of a moving object. The high power sonar system transmits two gated 190 kHz sinusoidal signals with 1.6 [ms] time interval to the moving object. Then the sonar system detects and calculates the changed time delay of the reflected ultrasonic signals in order to derive the velocity of the moving object. The transmission part uses a high power amplifier so that 250 W gated sinusoidal signals can be transmitted to the transmitter. 1M RAM is utilized for transmitting and storing of the ultrasonic signals. The time delay is calculted by the cross-correlation technique between the transmitted signals and the received signals. The measured value from the high power sonar system is compared with directly measured values by photo diodes. The result confirms the adjacency to 0.3% error.

• 한국군사과학기술학회지
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• 제15권5호
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• pp.630-634
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• 2012

It is very important to place receiver in multistatic sonar. Inefficient placement of the receiver reduce detection probability and to increase the probability of detection should be used more receivers. Therefore, detection of targets in searching area, detection performance of limited receiver depends on how to place. Through the optimized receiver placement, detection area between each sonar as much as possible avoid duplication, as optimization, the minimum receiver can be maintained detection performance. In this paper we prove mathematical verification of maximum signal excess value based on sonar placement and we calculate a signal excess value by using computer simulations and suggest optimal sonar placement.

• 전자공학회논문지
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• 제51권8호
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• pp.11-19
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• 2014

최근 능동 소나 시스템은 다중 목표물 탐지가 가능하도록 높은 거리 분해능을 얻기 위해 협대역 시스템에서 광대역 시스템으로 발전하고 있다. 하지만, 목표물 탐지 및 파라미터 추정 등의 성능 향상을 위해서는 광대역 신호처리가 요구되며, 이로 인해 연산량의 증가가 불가피하다. 본 논문에서는 hyperbolic frequency modulation (HFM) 펄스를 사용하는 광대역 능동소나 시스템에서 연산량의 증가를 최소화 하면서도 고속으로 목표물의 탐지 및 속도정보 추정을 할 수 있도록, 확장 레플리카를 이용한 광대역 HFM 탐지기 설계 방법을 제안한다. 모의실험을 통해 제안된 방법이 기존의 필터뱅크를 이용한 광대역 소나 탐지기법에 비해 탐지 및 도플러 추정에서 약간의 성능 열화가 있지만, 연산량 측면에서 매우 우수함을 보인다.

• 한국음향학회지
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• 제39권6호
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• pp.541-548
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• 2020

수상함용 선체부착형소나의 한계를 극복하기 위해서 해상작전헬기용 디핑소나를 많은 나라에서 운용중이다. 디핑소나는 탐지거리가 짧지만 수상함의 생존성을 보장하고, 해양환경에 따라 심도를 조절하여 탐지성능을 향상시킬 수 있는 장점이 있다. 본 논문에서는 최적화 알고리즘을 적용하여 해상작전헬기용 디핑소나의 최적심도를 산출하는 방법을 제안하였다. 또한, 소나의 성능을 평가하기 위해 해양환경, 표적의 심도, 디핑소나의 심도를 고려하도록 소나성 능함수를 정의하였다. 계산시간 단축을 위해 최적화 알고리즘중 하나인 Simulated Annealing(SA)를 적용하여 최적 심도를 산출하였다. 알고리즘의 정확도 검증을 위하여 최적화 기법을 적용하여 산출한 최적심도를 목적함수 계산 결과와 비교하였다. 또한, 우리나라 동해해역에서 해양환경에 따른 최적심도를 산출하였다.

• 융합신호처리학회논문지
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• 제12권4호
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• pp.315-321
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• 2011

선박이나 함정에서 일반적으로 사용되는 SONAR 신호용 CRT 모니터 디스플레이 시스템은 벡터 주사 방식을 사용한다. 그래서 시스템의 처리회로가 복잡하고, 부품 생산이 폐쇄되어 부품 수급이 어렵고 가격이 고가이다. FPGA 기반 임베디드 프로세서 시스템은 회로를 단순화함과 더불어 코어설계를 쉽게 재구성함으로써 각종 응용 적용에 유연하고, 저가격대로 고속 성능을 제공한다. 본 논문은 기존 CRT시스템의 문제점을 극복하기 위해서 FPGA 임베디드 프로세서 시스템을 사용하여 SONAR 신호 LCD 디스플레이 시스템을 구현하였다. 제안한 접근법은 기존 시스템에 비해 X-Y 편향과 CRT 제어 블록을 FPGA 임베디드 프로세서 시스템으로 대체함으로써 시스템 구성의 단순성과 유연성을 확보할 수 있고, 또한 저가격화를 가능하게 한다. 구현된 시스템은 SONAR 신호를 실시간으로 획득하고 LCD에 디스플레이하는 것이 가능하다.

• 한국정밀공학회지
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• 제30권3호
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• pp.308-316
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• 2013

This paper proposes an observation model for a particle filter-based localization using a sonar grid map. The proposed model estimates a predicted observation by considering the properties of a sonar sensor which has a large angular uncertainty. The proposed model searches a grid which has the highest probability to reflect a sonar beam using the following procedures; (1) the reliable area of a single sonar data is determined using the footprint association model; (2) the detection probability of each grid cell in a sonar beam coverage in estimated. The proposed model was applied to the particle filter based localization, and was verified by experiments in indoor environments.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
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• pp.218-223
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• 1999

A piezoelectric flextentional deep-water sonar transducer has been simulated using a coupled FE-BEM. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with extern리 electrical excitation conditions as well as external acoustic pressure loading conditions. Different results are available such as steady-state frequency response for RX and TX, displacement modes, directivity patterns, back-scattering patterns, resonant frequencies, bandwidths, quality factors, transmitting voltage (TV) responses, input receiving sensitivity (RS) responses. White the present barrel-stave typed sonar transducer of the piezoelectric material is being simulated, the external surface of the transducer is modified in order to allow the same water pressure to be applied to the inner and the outer surfaces of the transducer. With this modification for deep-water application, the resonance frequency of the modified flextentional sonar transducer becomes much lower than that of the unmodified flextentional sonar transducer. The results of the present sonar transducer modelling are also compared with those of a commercial package such as ATILA.