• 한국항행학회논문지
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• 제24권6호
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• pp.485-490
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• 2020

최근 국내 조선 산업과 IT융합기술에 대한 연구가 활발한 가운데 선박 안전운항을 위한 위성탐지 기술 발달로 선박에서는 장거리 식별추적 장치 및 자동식별 장치의 의무화로 선박이동 상황을 모니터링 할 수 있어 안전항해에 도움을 주고 있으나, 무중항해 시 시정 상태를 레이다에 의존하는 항해사에게 위험을 경보해 줄 수 있는 안전장치 개발이 필요하다. 이에 광센서를 이용하여 감지하고 알려주는 해무 감지 경보 시스템을 개발하였다. 제작된 해무 감지 경보 시스템은 소형, 저 전력의 광센서 송수신기와 센싱 데이터 처리 모듈로 구성되었다. 시험을 통해 해무가 있는 경우와 없는 경우 각각에 대해 제작된 해무 경보 시스템은 해무 농도를 검출하는 것을 확인하였다. 또한 해무 농도에 따라 선박 엔진 RPM 조절이 가능하고, 결과적으로 선박의 안전 운항을 보조 장치로 활용 가능함을 확인하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2015년도 추계학술대회
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• pp.53-54
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• 2015

The maritime industry is expanding at an alarming rate and as such there is a perpetual need to improve situation awareness in the maritime environment using new and emerging technology. Tracking is one of the numerous ways of enhancing situation awareness by providing information that may be useful to the operator. The tracking system described herein comprises determining existing states of own ship, state prediction and state compensation caused by random noise. The purpose of this paper is to analyze the process of tracking and develop a tracking algorithm by using ${\alpha}-{\beta}-{\gamma}$ tracking filter under a random noise or irregular motion for use in a warship. The algorithm involves initializing the input parameters of position, velocity and course. The actual positions are then computed for each time interval. In addition, a weighted difference of the observed and predicted position at the nth observation is added to the predicted position to obtain the smoothed position. This estimation is subsequently employed to determine the predicted position at (n+1). The smoothed values, predicted values and the observed values are used to compute the twice distance root mean square (2drms) error as a measure of accuracy of the tracking module.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.281-284
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• 2006

After building a ship in a shipyard, there are so many repeated inspection of welding seam defects and painting status before delivering to the ship's owner. An inspection on the bottom part of a ship in commercial service should be done in every two years for the purpose of safety and for the prevention of ship speed deterioration. conventional welding seam inspection systems are rely on the visual inspection by human or the ultrasonic inspection for the selective part of a ship. This paper suggests a remote controlled inspection system for the examination of large ships or steel structures. The proposed system moves in contact with the ship under inspection and have a CCD camera to provide visual-guidance information to a remotely located human worker. Additionally this system utilizes a weld line tracking algorithm for an optimal position control. We verified the effectiveness of the inspection system by experimental data.

• The Journal of the Acoustical Society of Korea
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• 제17권3E호
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• pp.22-26
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• 1998

This paper proposes a simple method to measure system's performance in target tracking problems. Essentially employing the Cramer-Rao Lower Bound (CRLB) on tracking accuracy, an algorithm of predicting system's performance under various scenarios is developed. The input data is a collection of measurements over tim from sensors embedded in Gaussian noise. The target of interest may not maneuver over the processing time interval while the own ship observing platform may maneuver in an arbitrary fashion. The proposed approach is demonstrated and discussed through simulation results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.635-638
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• 1998

This paper proposes a simple method to measure system's performance in target tracking problems. Essentially employing the Cramer-Rao lower bound (CRLB) on trakcing accuracy, an algorithm of predicting system's performance under various scenarios is developed. The input data is a collection of measurements over time fromsensors embedded in gaussian noise. The target of interest may not maneuver over the processing time interval while the own ship observing platform may maneuver in an arbitrary fashion. Th eproposed approach is demonstrated and discussed through simulation results.

• Journal of Ship and Ocean Technology
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• 제7권4호
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• pp.32-40
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• 2003

Numerical simulation code is developed to study the formation of liquid drops from a nozzle into another quiescent liquid. The Navier-Stokes equations for two immiscible, incompressible, Newtonian fluids are solved on a fixed, staggered grid of cylindrical axisymmetric coordinates. Interfacial motion is captured using a Front-Tracking Method. The time variation of interfacial shape simulated by the code is in excellent agreement with experiments. Simulation results show that the viscosity ratio affects the size of the satellite drops.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.195-199
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• 2005

Wave breaking phenomenon near the fore body of a ship is numerically simulated. The ship advance with uniform velocity in calm water. For the simulation, incompressible Navier-Stokes equations and continuity equation are adopted as governing equations. The simulation is carried out in staggered variable mesh system with finite difference method. Marker and Cell(MAC) method and Marker-Density method are employed to track the free surface. Body boundary conditions are satisfied with the adoption of porosity method and no-slip condition on the hull surface. The ship model has a wedge type fore-body, and the computational domain is an appropriate region around the fore-body. The computation results are compared with some experimental results. Also the difference of the free surface tracking methods are discussed.

• 항공우주시스템공학회지
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• 제10권3호
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• pp.44-51
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• 2016

This paper describes the operational concept of the Aegis ship's missile defense. Recently, North Korea conducted a fourth nuclear-weapon test that involved the launch of a long-range missile and the underwater launch of an SLBM. The ground-based BMD (Ballistic Missile Defense) system is very limited for the SLBM of a miniaturized nuclear warhead; therefore, it is necessary to build a reliable sea-based missile-defense system. The ROK Navy has, however, only utilized the Aegis ship that is designed with a search-and-tracking sensor but is without a ballistic-missile interception capability. Given this information, this work focuses on the operational concept of the Aegis BMD by comparing the BMD capabilities of the ROK with those of the U.S.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.882-884
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• 2003

We present an application of digital video images for object tracking. In order to track a fixed object, which was shoot on a moving vehicle, this study develops a shape-based matching algorithm to implement the tracking task. Because the shape-based matching algorithm has scale and rotation invariant characteristics, therefore it can be used to calculate the similarity between two variant shapes. An experiment is performed to track the ship object in the open sea. The result shows that the proposed method can track the object in the video images even the shape change largely.

• 한국항해항만학회지
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• 제44권5호
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• pp.423-429
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• 2020

A ship's automatic steering system is the basis for addressing control difficulties related to course-changing and course-keeping during navigation through heading angle control, and is a link in realizing unmanned and autonomous ships. This study proposes a robust RCGA-based linear active disturbance rejection controller (LADRC) design method considering environmental disturbances, measurement noise, and model uncertainties in designing a ship heading controller for use when the ship is sailing. The LADRC consisted of a transient profile, a linear extended state observer, and a PD controller. The control gains in the LADRC with the linear extended state observer were adjusted by RCGAs to minimize the integral of the time-weighted absolute error (ITAE), which is an evaluation function of the control system. The proposed method was applied to ship heading control, and its effectiveness was validated by comparing the propulsive energy loss between the proposed method and a conventional linear PD controller. The simulation results showed that the proposed method had the advantages of lower propulsive energy loss, more robustness, and higher tracking precision than the conventional linear PD controller.