• Journal of Ocean Engineering and Technology
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• v.29 no.5
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• pp.392-397
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• 2015

An autonomous underwater vehicle (AUV) can perform flexible operations even in complex underwater environments because of its autonomy. Localization is one of the key components of this autonomous navigation. Because the inertial navigation system of an AUV suffers from drift, observing fixed objects in an inertial reference system can enhance the localization performance. In this paper, we propose a method of AUV localization using visual measurements of underwater structures. A camera measurement model that emulates the camera’s observations of underwater structures is designed in a particle filtering framework. Then, the particle weight is updated based on the extracted visual information of the underwater structures. The proposed method is validated based on the results of experiments performed in a structured basin environment.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.3-4
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• 2019

본 논문에서는 복잡한 해상교통 환경 하에서도 해양 안전을 도모할 수 있는 강화학습 기반 지능형 선박 항해 에이전트 개발의 사전단계로서 기존의 강화학습 환경을 분석하였다. 강화학습 기반 접근법은 선박 항해 에이전트 스스로가 복잡하고 동적인 해상교통 환경을 이해하고 주어진 목표를 달성할 수 있도록 도와주는데, 이를 위해서는 에이전트 자신을 제외한 모든 사항들이 정의되는 환경을 보다 정확하고 효과적으로 개발하는 것이 매우 중요하다. 실제 해상교통 환경은 학습 환경으로의 모델링 및 에이전트 학습의 난이도가 매우 높은 환경으로 학습환경이 가질 수 있는 여러 속성들을 적절히 설정하여 선박 항해 에이전트의 활용 목적에 맞는 가성비 높은 환경을 구축하는 것이 바람직하다.

• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.66-74
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• 2023

With the increase of interest in developing Maritime Autonomous Surface Ships (MASS), an optimal ship route planning is gradually gaining popularity as one of the important subsystems for autonomy of modern marine vessels. In the present paper, an optimal ship route planning model for MASS is proposed using a nonlinear MPC approach together with a nonlinear MMG model. Results drawn from this study demonstrated that the optimization problem for the ship route was successfully solved with satisfaction of the nonlinear dynamics of the ship and all constraints for the state and manipulated variables using the nonlinear MPC approach. Given that a route generation system capable of accounting for nonlinear dynamics of the ship and equality/inequality constraints is essential for achieving fully autonomous navigation at sea, it is expected that this paper will contribute to the field of autonomous vehicles by demonstrating the performance of the proposed optimal ship route planning model.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.01a
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• pp.493-494
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• 2023

해상에서 운항되는 선박에서 인명사고가 발생하면 육상과 달리 적시에 의료지원을 받기 구조적으로 어렵다. 특히 연안선박의 경우 원양선에 비해 상대적으로 고령의 선원들이 승무하고 있기 때문에 인명사고가 빈번하며 인명사고에 취약하다. 본 연구는 AR과 VR과 같은 실감기술을 기반으로하는 연박선박의 원격의료지원 모델 개발하기 위한 방향성을 제시하고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.197-198
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• 2018

In recent years, diversified demand for marine utilization has been increasing not only through the development projects for the utilization of the conventional coastal zone but also by the development of marine leisure sports and marine energy. It is very important to understand the characteristics of blue for safe and economical utilization of the ocean. Using the observed wave data, we derive the wave parameters to represent the irregular sea state proposed in the previous studies and examine the relationship between them to confirm the characteristics of the ocean wave.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.42-43
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• 2014

As MSI(Maritime Safety Information), navigational, meteorological warnings and forecasts, was included as one of service in the MSP(Maritime Service Portfolio), which is lists of shore based service in the e-Navigation driven by IMO for safety navigation and marine protection, and was tested in the european test bed project on e-Navigation, it's considered as one of important e-Navigation service. This paper developed a prototype of MSI service to prepare e-navigation era, which is very important in a navigation environment. Current status on MSI and NAVTEX was surveyed, and several points on limitations and improvements in the NAVTEX operations were summarized. Basic study on the MSI service prototype was developed based on S-100, which is recognized as baseline to develop CMDS(Common Maritime Data Structure) of e-Navigation.

• Journal of Navigation and Port Research
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• v.32 no.1
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• pp.37-45
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• 2008

The research on an E-Navigation(E-Nav) strategy development has recently carried out by the IMO sub-committee on safety of navigation(NAV). The design of communication system architecture is a key factor in the E-Nav strategy development and it may drive the direction of a national R&D project on future navigational and marine communication systems. This study aims at designing a standard model of E-Nav communication network architecture, which enhances navigational safety and provides additional benefits in marine transportation. To achieve this purpose, authors have suggested E-Nav services, which are divided into five categories, i.e., safety and security, maritime meteorology, distress, business, and infotainment, by analyzing the related user requirements. As results, this paper proposes the E-Nav communication network architecture that consists of the navigation and communication equipments.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.721-727
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• 2006

Ammoniac nitrogen excretion is not able to be removed in ocean fish farm. It is the reason for fish being dead in large quantities or declining feeding activity that ammoniac nitrogen is not removed efficiently in ocean fish farm. Because of declining with feeding activity, it is true that feed is wasted for the present. To solve this problem, NH3, one of environment factors in ocean fish farm, monitoring system is suggested to be formed in this paper.

• Asian review of World Histories
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• v.4 no.2
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• pp.191-205
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• 2016

The Periplus of the Erythraean Sea is a Roman period guide to trade and navigation in the Indian Ocean. Justly famous for offering a contemporary and descriptive account of early Indian Ocean trade, the work has been subject to and a point of departure for numerous studies. Its extensive influence on scholarship is, however, also problematic, as it reflects the limited information and cultural and personal bias of its unknown author. Arguably this might have led scholars to overemphasise so-called western or Roman participation in early Indian Ocean trade. Network analysis allows us to map, visualize and measure interconnectedness in the Periplus Maris Erythraei. Many of these connections are not explicitly mentioned in the text, but by connecting not only places with places, but also products with places that export and import them, we get a partly different impression of Indian Ocean trade from that conventionally gathered from the Periplus. It allows us to ask questions about the relationship between coastal cabotage and transoceanic shipping, to identify regional trading circuits, and unexpected centres of long-distance exchange.

• Journal of Ocean Engineering and Technology
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• v.17 no.6
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• pp.83-90
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• 2003

This paper presents an underwater hybrid navigation system for a semi-autonomous underwater vehicle (SAUV). The navigation system consists of an inertial measurement unit (IMU), and a Doppler velocity log (DVL), accompanied by a magnetic compass. The errors of inertial measurement units increase with time, due to the bias errors of gyros and accelerometers. A navigational system model is derived, to include the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 20. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors, and correct the state equation when the measurements are available. Simulation was performed with the 6-d.o,f equations of motion of SAUV, using a lawn-mowing survey mode. The hybrid underwater navigation system shows good tracking performance, by updating the error covariance and correcting the system's states with the measurement errors from a DVL, a magnetic compass, and a depth sensor. The error of the estimated position still slowly drifts in the horizontal plane, about 3.5m for 500 seconds, which could be eliminated with the help of additional USBL information.