• 한국지리정보학회지
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• 제11권4호
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• pp.150-160
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• 2008

현재 국내의 수중 및 해양 시설물 관리는 아날로그 필름에 의한 육안분석에 의존하고 있다. 본 연구에서는 이러한 방법을 개선하기 위하여 보다 정량적인 수중시설물의 공간적인 상태를 분석하고자 하였다. 본 연구는 수중영상 왜곡보정과 모자익 제작의 두 단계로 나누어 진행하였다. 수중영상 왜곡보정 단계에서는 수중 타겟을 제작하고 타겟 격자점으로부터 왜곡계수를 산출한 후, 수중영상으로 포착한 영상점을 왜곡이 보정된 영상점으로 위치 보정하는 기술을 개발하였다. 그리고 모자익 제작 단계에서는 먼저, 수중에 송유관 형태의 파이프를 설치한 후 영상을 획득하였으며, 왜곡보정을 실시한 후 보정된 파이프 영상을 좌표 변환 후, 산출된 특이점을 바탕으로 모자익 영상을 제작하고 필터링을 통해 외곽선 추출하고 파이프와 수중바닥과의 거리를 계산하였다. 그 결과, 실제 파이프와 수중지반과의 거리가 6cm일 때 평균 RMSE 0.3cm로 나타났다.

• 수산해양기술연구
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• 제35권1호
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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.

• 한국군사과학기술학회지
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• 제12권5호
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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.

• 한국음향학회지
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• 제41권6호
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• pp.629-636
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• 2022

본 논문은 합성곱 신경망 기반 수중 표적 분류기의 성능 향상을 위한 최적의 전처리 기법을 제시한다. 실제 선박 수중신호를 수집한 데이터 세트의 주파수 분석을 통해 강한 저주파 신호로 인한 특성 표현의 문제점을 확인하였다. 이를 해결하기 위해 다양한 스펙트로그램 기법과 특성 스케일링 기법을 조합한 전처리 기법들을 구현하였다. 최적의 전처리 기법을 확인하기 위해 실제 데이터를 기반으로 합성곱 신경망을 훈련하는 실험을 수행하였다. 실험 결과, 로그 멜 스펙트로그램과 표준화 및 로버스트정규화 스케일링 기법의 조합이 높은 인식 성능과 빠른 학습 속도를 보임을 확인하였다.

• 한국멀티미디어학회논문지
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• 제20권10호
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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.

• 한국군사과학기술학회지
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• 제4권1호
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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.

• 지구물리
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• 제5권1호
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• pp.51-62
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• 2002

지표레이다(GPR)를 이용하여 하상 퇴적물 조사를 수행하였다. 조사지역은 수심이 약 2.5 m 정도로 얕고, 물이 흐르지 않는 호수이며, 조사대상인 뻘(mud)층의 두께가 얇아 GPR이 매우 효율적인 탐사방법이다. 조사결과 수심하부 층서구조, 즉 mud층, 모래층, 자갈 및 기반암의 구조를 확실하게 파악할 수 있었다. 특히 mud층의 분포 및 총 퇴적량은 향후 이 지역에서의 준설을 위한 기초자료로 매우 중요하게 사용될 수 있을 것이다.

• 한국해양공학회지
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• 제34권3호
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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.

• 한국농공학회논문집
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• 제49권3호
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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.

• 수산해양기술연구
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• 제47권2호
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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.