• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.204-209
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• 2004

It is well known fact that acoustic positioning systems are absolutely needed for various underwater operations. According to the distances between their sensors they are classified into three parts: long baseline(LBL), short baseline(SBL), and ultra-short baseline(USBL). Among them the USBL system is widely used because of its simplicity, although it is the most inaccurate. Recently, in order to increase the positioning accuracy, various USBL systems using broadband signal such as MFSK(Multiple Frequency Shift Keying) are produced. However, their positioning accuracy is still limited by background noise and reflected waves. Therefore, there is difficulty in applying the USBL system using MFSK signal in a shallow water with noisy conditions. In order to examine the effect of the noise and wave reflections this paper analyze position errors for various conditions using numerical simulations. The simulation results say that tile SNR must be greater than 20dB and errors in the vertical direction are slightly increased by wave reflections by upper and lower boundaries.

• 한국수산과학회지
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• 제23권6호
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• pp.451-456
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• 1990

Underwater acoustic navigation and position fixing systems have been extensively used not only in surface position fixing but also in underwater position fixing. Tn recently, application of these systems has been in the field of underwater inspection of offshore platforms, where it is vital to track the position of an unmanned submersible or diver carrying underwater cameras and nondestructive testing equipment. But these systems are included the fixing errors as results of a signal with additive noise, the attenuation of sound and the interference effects due to multipath reflection and forward scattering. In this paper to improve the position fixing by the supershort baseline acoustic position system, a method to apply the Kalman filter to the fix of the system is proposed and the digital simulation under noise condition is conducted. The optimal positions by the Kalman filter are compared with original positions, and it is confirmed that the results of the pro-posed method are evidently more accurate.

• 한국인터넷방송통신학회논문지
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• 제14권1호
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• pp.31-36
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• 2014

실내에서의 위치기반 서비스를 위한 실내 위치 인식 기술에 대한 연구가 활발하다. 음향 신호와 TDOA 기술을 기반으로 하는 3차원 위치 인식 시스템에 있어서, 마이크 센서의 개수와 배열 위치에 따라 추정된 위치의 오차 특성이 달라지므로, 본 논문에서는 마이크 센서의 배열과 측정된 거리 차이값의 오차 크기에 따른 추정 위치의 오차를 DOP로 분석하고, 그 추정 위치 오차 패턴과 추정 위치 오차값을 고려하여 최적의 마이크 배열을 결정하는 방법에 대해서 연구하였다.

• 한국수산과학회지
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• 제37권5호
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• pp.433-439
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• 2004

The movement range and diurnal behavior of red seabream (Chrysophrys major) tagged by the ultrasonic pinger externally were measured by acoustic telemetry techniques in the marine ranch of Tongyeong on 20 March to 30 October, 2003. The movement of fishes was monitored with the radio-acoustic linked positioning (RAP) buoy system and VR2 receivers. The test fishes showed behavior. pattern going to deep waters and returning to shallow waters. They moved gradually to deep waters as time goes by. They had a tendency to move wider range in night-time than day-time. It was found that the test fishes rarely showed a significant response to the artificial reefs.

• 수산해양기술연구
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• 제43권2호
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• pp.116-125
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• 2007

An experiment to acoustically analyze the shape of gill-net in the current was conducted in Jaran Bay, Gosung, Korea on the 9th to 10th September(spring tide) and 28th to 29th September(neap tide) 2006. It was measured by a 3D underwater positioning system with a radio-acoustic linked positioning buoys. Six of 7 acoustic transmitters used in the experiment were attached on the float line of the gill-net and the other was fixed on the sea bed. During spring tide, the maximum movement of the gill-net was 27.0m(22:00) in the west(4.4cm/s, $311.9^{\circ}$) and 20.6m(04:00) in the east(3.9cm/s, $66.5^{\circ}$). The maximum extension of the gill-net(the distance between P1 and P6) was 119.8m(21:00, 11.6cm/s, $321.9^{\circ}$) and the minimum was 109.9m(23:00, 16.1cm/s, $88.5^{\circ}$). During neap tide, the maximum movement was 38.0m(20:00) in the east(9.6cm/s, $278.2^{\circ}$) and 11.0m(12:00) in the west(1.9cm/s, $232.1^{\circ}$). The maximum extension was 99.6m(14:00, 12.5cm/s, $94.7^{\circ}$) and the minimum was 85.0m(06:00, 9.0cm/s, $265.8^{\circ}$). During spring tide, the maximum height of the gill-net from the sea bed was 3.7m(02:00, 7.4cm/s, $151.6^{\circ}$) and the minimum was produced the three times as 1.5m. At that time, the current speed and direction was 17.9cm/s and $85.3^{\circ}$(23:30), 16.1cm/s and $249.4^{\circ}$(05:00), and 13.7cm/s and $291.4^{\circ}$(06:30), respectively. During neap tide, the maximum height was 3.6m(12:30, 2.1cm/s, $242.3^{\circ}$) and the minimum was 1.5m(14:00, 12.5cm/s, $94.7^{\circ}$).

• 한국인터넷방송통신학회논문지
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• 제15권6호
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• pp.155-161
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• 2015

스마트폰의 이용이 크게 활성화됨에 따라 실내에서의 스마트폰의 위치 추정에 관한 연구 개발이 매우 활발하다. 스마트폰에서 발생된 음향 신호를 여러 개의 마이크로 수신하여 스마트폰의 상대 위치를 추정하는 연구가 진행되어 왔으며, 음향 신호의 전파 다중 경로 문제를 완화시키기 위한 트리거 신호가 제안되어 효과가 검증되었다. 그러나 단순한 트리거 방식의 경우 스마트폰과 측정 장치 사이의 거리 차이나, 주변 소음이 있는 경우에 오차가 발생하는 문제가 있다. 본 논문에서는 이 문제를 해결하기 위한 동적 트리거 임계값 기술이 제안되었고 실험으로 검증되었다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.249-256
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• 2004

KRISO/KORDI is currently developing a deep-sea unmanned underwater vehicle (UUV) system which is composed of a launcher, an ROV, and an AUV. Two USBL acoustic positioning systems will be used for UUV's navigation. One is for the deep sea positioning of all three vehicles and the other is for AUV's guidance to the docking device on the launcher. In order to increase the position accuracy MFSK(Multiple Frequency Shift Keying) broadband signal will be used. As the first step to the implementation of a USBL system, this paper studies USBL positioning algorithm using MFSK signals. Firstly, the characteristics of MFSK signal is described with various MFSK parameters: number of frequencies, frequency step, center frequency, and pulse length. Time and phase delays between two received signals are estimated by using cross-correlation and cross-spectrum methods. Finally an USBL positioning algorithm is derived by converting the delays to difference of distances and applying trigonometry. The simulation results show that the position accuracy is improved highly when both cross-correlation and cross-spectrum of MFSK signals are used simultaneously.

• 한국재난정보학회:학술대회논문집
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• 한국재난정보학회 2023년 정기학술대회 논문집
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• pp.325-326
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• 2023

해상 사고 시 일반 전파를 이용한 통신 시스템으로 찾기 어려운 수중 위치 추적에 사용하기 위해 몸에 부착할 수 있는 크기의 소형화된 수중 음향 모듈을 제작하고 이를 서해 상에서 거리에 따른 음향 신호를 측정했다.

• 한국산학기술학회논문지
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• 제11권3호
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• pp.808-814
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• 2010

본 논문에서는 수중에서 이동하는 무인잠수정의 위치를 측정하는 방법 중의 하나인 단기선 방식(SBL)에 의한 무인잠수정(ROV)의 위치측정 실험을 하이드로폰(Hydrophone)과 DAQ(Data Aquisition) 시스템을 이용하여 수조에서 수행하였다. 실험을 위해서 4개의 하이드로폰 센서를 $3{\times}3{\times}1.7m$의 크기의 수조 벽면에 고정하여 수신 장치로 사용하고, 1개의 하이드로폰 센서는 무인잠수정에 장착하여 송신장치(Pinger)로 사용하였다. 무인잠수정 및 수조 벽에 고정된 센서들이 신호를 송수신함으로써 상호간의 위치추적이 가능하게 하는 실험을 수행하였다. 측정된 신호는 DAQ 시스템을 이용하여 데이터를 취득하였고, LabView 프로그램을 이용하여 실시간으로 무인잠수정의 위치를 계산하여 출력하였다. 위치추정에 사용된 알고리즘은 삼각측량법을 사용하였으며, X, Y방향에 대해서는 비교적 오차가 적은 추정 결과를 나타내었으나 Z방향에 대하여서는 상대적으로 큰 오차를 보여 위치제어용 데이터로 사용할 수 가 없었다. 이에 대한 해결방법으로 무인잠수정에 장착된 수심측정 센서를 이용하여 보완할 수 있을 것으로 본다. 설계된 위치측정 시스템은 추후 실해역 실험을 거쳐 성능시험을 수행하고자 한다.

• International Journal of Ocean System Engineering
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• 제1권2호
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• pp.89-94
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• 2011

Underwater localization is a crucial capability for reliable operation of various types of underwater vehicles including submarines and underwater robots. However, sea water is almost impermeable to high-frequency electromagnetic waves, and thus absolute position fixes from Global Positioning System (GPS) are not available in the water. The use of acoustic telemetry systems such as Long Baseline (LBL) is a practical option for underwater localization. However, this telemetry network system needs to be pre-deployed and its availability cannot always be assumed. This study focuses on demonstrating the validity of terrain-based localization techniques in a GPS-denied underwater environment. Since terrain-based localization leads to a nonlinear estimation problem, nonlinear filtering methods are required to be employed. The extended Kalman filter (EKF) which is a widely used nonlinear filtering algorithm often shows limited performance under large initial uncertainty. The feasibility of using a particle filter is investigated, which can improve the performance and reliability of the terrain-based localization.