• 한국해양공학회지
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• 제19권2호
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• pp.74-81
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• 2005

A 3-D localization method of an autonomous underwater vehicle (AUV) has been developed, which can solve the limitations oj the conventional localization, such as LBL or SBL that reduces the flexibility and availability of the AUV. The system is composed of a mother ship (small unmanned marine prober) on the surface of the water and an unmanned underwater vehicle in the water. The mother ship is equipped with a digital compass and a GPS for position information, and an extended Kalman filter is used for position estimation. For the localization of the AUV, we used only non-inertial sensors, such as a digital compass, a pressure sensor, a clinometer, and ultrasonic sensors. From the orientation and velocity information, a priori position of the AUV is estimated by applying the dead reckoning method. Based on the extended Kalman filter algorithm, a posteriori position of the AUV is, then, updated by using the distance between the AUV and a mother ship on the surface of the water, together with the depth information from the pressure sensor.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제14권4호
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• pp.288-294
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• 2014

Understanding a ship's present position has been one of the most important tasks during a ship's voyage, in both ancient and modern times. Particularly, a ship's dead reckoning (DR) has been used for predicting traffic situations and collision avoidance actions. However, the current system that uses the traditional method of calculating DR employs the received position and speed data only. Therefore, it is not applicable for predicting navigation within the harbor limits, owing to the frequent changes in the ship's course and speed in this region. In this study, planned routes were applied for improving the reliability of the proposed system and predicting the traffic patterns in advance. The proposed method of determining the dead reckoning position (DRP) uses not only the ships' received data but also the navigational patterns and tracking data in harbor limits. The Mercator sailing formulas were used for calculating the ships' DRPs and planned routes. The data on the traffic patterns were collected from the automatic identification system and analyzed using MATLAB. Two randomly chosen ships were analyzed for simulating their tracks and comparing the DR method during the timeframes of the ships' movement. The proposed method of calculating DR, combined with the information on planned routes and DRPs, is expected to contribute towards improving the decision-making abilities of operators.

• 한국항해항만학회지
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• 제33권2호
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• pp.99-104
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• 2009

The Kinematic GPS is well known to provide a quite good accuracy of positioning within an level. Although kinematic GPS assures high precision measurement on the basis of an appreciable distance between a reference station and an observational point, it has measurable distance restriction within 20 km from a reference station on land. Therefore, it is necessary to make out a simple and low-cost method to obtain accurate positioning information without distance restriction In this paper, the velocity integration method to get the precise velocity information of a ship is explained. The experimental results of Zig-zag maneuver and Williamson turn as the ship's maneuvering test, and other experimental results of ship's movement during leaving and entering the port with low speed were shown. From the experimental results, ship's course, speed and position are compared with those obtained by kinematic-GPS, velocity integration method and dead reckoning position using Gyro-compass and Doppler-log.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 Asia Navigation Conference
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• pp.49-55
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• 2006

Kinematic GPS provides quite good accuracy of position in cm level. Though K-GPS assures high precision measurement in cm level on the basis of an appreciable distance between a station and an observational point, but it has measurable distance restriction within 20 km from a reference station on land. So it is necessary to make out a simple and low-cost method to obtain accurate positioning information without distance restriction. In this paper, the velocity integration method to get the precise velocity information of ship is explained. Next two experimental results (Zig-zag maneuvering test and Williamson turn) as the ship's maneuvering test and also the experimental results of leaving and entering port as slow speed ship's movement were shown. In these experimental results, ship's course, speed and position are compared with those obtained by kinematic-GPS, velocity integration method and dead reckoning position using Gyro-compass and Doppler-log.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2022년도 춘계학술대회
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• pp.313-314
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• 2022

지능형 해상교통정보서비스(바다내비)는 선박에 설치한 LTE-Maritime 송수신기 및 AIS 등의 선박 장비로부터 육상 센터에 주기적으로 수집한 선박들의 위치 정보 기반으로 선박의 충돌·좌초 등을 예방할 수 있도록 실시간 예방 정보를 선박에 제공한다. 그러나 위 서비스는 선박의 위치를 측정하는 GPS 위치 정보가 LTE-Maritime 또는 AIS 망을 통해 전송되는 과정 중에 끊기거나 위치 튐 및 지연 등의 현상이 발생할 수 있어 선박 위치 정보의 신뢰성을 떨어드릴 수 있다. 본 연구는 확률에 기반한 최적 추정 필터인 칼만필터를 이용하여 기존 수신 위치정보를 기반으로 선박 위치 예측을 통해 비정상 구간에서도 어느 정도 신뢰성 있는 위치 정보를 추정하는 것을 목표로 한다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.856-867
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• 2020

This paper aims to provide the most useful method of determining an optimum LCB position and design direction of fore- and aft-body hull shape for a SLBV. It is known that the SLBV has a lower length-to-beam ratio, larger Cb and simpler stern shape designed for the installation of azimuth thrusters comparing to those of conventional LNG carriers. Due to these specific particulars of SLBV, the optimum LCB position was very different to that of conventional LNG carrier. And various approaches were applied to determine the optimum fore- and aft-body hull shape. The design direction for the optimum hull-form was evaluated as the minimization of the total resistance which includes the wave-making resistance and form-drag with numerical simulation.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.768-783
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• 2020

Typically, a Dynamic Positioning System (DPS) uses a PID feed-back system, and it often adopts a wind feed-forward system because of its easier implementation than a feed-forward system based on current or wave. But, because a ship's drifting motion is caused by wind, current, and wave drift loads, all three environmental loads should be considered. In this study, a motion predictive control for the PID feedback system of the DPS is proposed, which considers the three environmental loads by utilizing predicted drifted ship positions in the future since it contains information about the three environmental loads from the moment to the future. The prediction accuracy for the future drifted ship position is ensured by adopting deep learning algorithms and a replay buffer. Finally, it is shown that the proposed motion predictive system results in better station-keeping performance than the wind feed-forward system.

• 전기학회논문지
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• 제68권3호
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• pp.480-488
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• 2019

In this paper, we propose an obstacle avoidance system for an unmanned ship to navigate safely in dynamic environments. Also, in this paper, one-dimensional low-cost lidar sensor is used, and a servo motor is used to implement the lidar sensor in a two-dimensional space. The distance and direction of an obstacle are measured through the two-dimensional lidar sensor. The unmanned ship is controlled by the application at a Tablet PC. The user inputs the coordinates of the destination in Google maps. Then the position of the unmanned ship is compared with the position of the destination through GPS and a geomagnetic sensor. If the unmanned ship finds obstacles while moving to its destination, it avoids obstacles through a fuzzy control-based algorithm. The paper shows that the experimental results can effectively construct an obstacle avoidance system for an unmanned ship with a low-cost LiDAR sensor using fuzzy control.

• 한국항해항만학회지
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• 제46권5호
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• pp.435-440
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• 2022

The development and introduction of a Maritime Autonomous Surface Ship (MASS) are some of the most important changes leading to the fourth industrial era in the maritime area. The term 'MASS' refers to a ship operating independently, without human intervention, to reduce maritime accidents caused by human errors. Recent UK findings MASS also noted that particularly the dynamic positioning system will be considered to apply as newly function to a MASS. The DP system, a ship system developed decades ago and used for specific purposes like offshore operations, provides various functions to facilitate the accurate movements of the vessel, and operators can make decisions within the DP system, in addition to the ordinary ship system. In this paper, it would like to present the connection and application method with the main technical elements of the DP system in connection with the main technology of the DP system to achieve the safe operation of a MASS. In particular, among various position reference systems, the capability plot function of DP system, and the "follow target" mode in the operation mode are attractive functions that can contribute to the safe operation of autonomous ships.

• 전자공학회논문지SC
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• 제48권4호
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• pp.86-93
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• 2011

파도 및 바람 그리고 그 외의 다른 요인들에 의해 복합적으로 움직이는 모선 선박의 운동을 정확하게 알아야 배의 형상 및 자세를 제어할 수 있다. 예를 들어 레이더 추적 장비는 기후의 영향은 받지 않으나 물체에 반사된 신호로 위치 추적을 해야 하기 때문에 잡음도 (Noise Level)가 높아 정확도가 떨어진다. 이를 해결하기 위해 본 논문의 목적은 GPS의 절대 위치를 이용하여 배의 이전 상태 및 현재 상태를 정확히 알아서 다음 진행 상황을 예측하는데 있다. 그러나 GPS의 원천 오차와 배가 고정적이지 않는 오차로 인하여 단순하게 GPS의 값을 읽어 배의 형상을 나타낼 수 없기 때문에 본 논문에서는 이러한 GPS좌표의 오차를 줄이고 정확한 지점을 추정하기 위한 알고리즘을 제시하여 선박의 형상과 위치를 알려준다.