• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.324-330
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• 2023

Aids to navigation, which provide information about a ship's position, direction, and the location of obstacles, are crucial for uninterrupted maritime services. This study aimed to analyze accidents involving aids to navigation that resulted in service disruptions and identify the key factors associated with these accidents. Aids to navigation accident data from 2000 to 2022 were utilized to achieve this. We categorized accidents by accident type, cause, region, season, and type of navigation aid and established a network through correlation analysis. Bayesian networks based on aids to navigation accidents were assigned prior probabilities, and the factors that increased the probability of accidents for different types of aids to navigation were identified. The findings can be used to infer the causes of unreported aids to navigation accidents and serve as foundational data for the prevention of such accidents.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.388-389
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• 2012

Current offshore wind power towers are made of steel. As the capacity of wind power increases, the tower structures become higher. Steel structures have buckling problem and their increased slenderness ratios make them weak against buckling and vibration. In this study, double skinned composite tubular (DSCT) offshore wind power tower was proposed and its optimum design method was suggested. Fiber reinforced polymer (FRP) and steel were considered as material of the tubes. And both materials satisfied the required capacity.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.27-31
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• 2003

Underwater acoustic navigation systems are classified into three systems: ultra-short baseline (USBL), short baseline (SBL), and long baseline (LBL). Because the USBL system estimates the angle of a submersible, the estimation error becomes large if the submersible is far from the USBL transducer array mounted under a support vessel. SBL and LBL systems estimate submersible's location more accurately because they have wider distribution of measuring sensors. Especially LBL systems are widely used as a navigation system for deep ocean applications. Although it is most accurate system it still has estimation errors because of noise, measurement error, refraction and multi-path of acoustic signal, or wrong information of the distributed transponders. In this paper the estimation error of the LBL system are analyzed from a point of sensitivity. It is assumed that the error exists only in the distance between a submersible and the transponders. For this purpose sensitivity of the estimated position with respect to relative distances between them is analyzed. The result says that estimation error is small if the submersible is close to transponders but not near the ocean bottom.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.51-56
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• 2006

부유식 해상공항과 같은 초대형 부체 구조물(VLFS)의 연안역 설치 후 발생할 수 있는 배후의 해빈변형을 예측하기 위한 토대를 마련하기 위한 기초 연구를 수행하였다. 이를 위해 일정 사면을 가진 천해역에서의 실험 결과를 통하여 비교적 수심이 깊은 곳에 설치된 매립식 구조물 배후에서의 파랑 및 해빈류를 개관하였으며, 매립식 및 부유식 해상 구조물 설치 시 주변 해역의 파랑 및 해빈류장을 계산하였다. 파랑장에 있어서 라프라스 방정식 토대로 유한요소법을 도입한 3차원 파랑 변형 계산을 수행함으로써 매립식 및 부유식 구조물 모두에 대해 적용 가능하였으며, 해상 구조물의 설치 형식이 매립식 및 부유식 경우에 대해 파랑, 해빈류 분포의 변화를 관찰할 수 있었다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.175-180
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• 2006

This study is carried out the investigation of nonlinear characteristics of the ocean based on the field wave observation data acquired the western sea area in Jeju island during one year. It is aimed to offer the fundamental data for Freak wave forecasting in real sea. For this, the nonlinearity parameters of ocean waves, which are Skewness, Atiltness, Kurtosis and Spectrum band width parameter, are introduced, and the parameters are compared and discussed with some characteristic wave components, ie, significant wave height, maximum wave height, and so on.

• Journal of Navigation and Port Research
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• v.35 no.10
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• pp.793-798
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• 2011

ENCs are encoded using a numerical charts developed for publishing paper charts and serviced in forms of grid styles. For this reason, the density of ENCs' sounding information is not consistent and that requires improved methods. In this study, K-Means, ISODATA clustering algorithm as classification methods for satellite image was reviewed and adopted to this case study. The designed algorithm includes loading module for ENC data, improvement algorithm of sounding information, writing module of ENC data. According to the results of algorithm, we could confirm the improved result.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.167-168
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• 2022

선박을 운항함에 있어 최적항로를 결정하는 것은 항해시간과 연료 소모를 줄이는 중요한 요인 중의 하나이다. 기존에는 항로를 결정하기 위해 항해사의 전문적인 지식이 요구되지만 이러한 방법은 최적의 항로라고 판단하기 어렵다. 따라서 연료비 절감과 선박의 안전을 고려한 최적의 항로를 생성할 필요가 있다. 연료 소모량 혹은 항해시간을 최소화하기 위해서 에이스타 알고리즘, Dijkstra 알고리즘을 적용한 연구가 있다. 하지만 이러한 연구들은 최단거리만 구할 뿐 선박의 안전, 해상상태 등을 고려하지 못한다. 이를 보완하기 위해 본 연구에서는 강화학습 알고리즘을 적용하고자한다. 강화학습 알고리즘은 앞으로 누적 될 보상을 최대화 하는 행동으로 정책을 찾는 방법으로, 본 연구에서는 강화학습 알고리즘의 하나인 Q-learning을 사용하여 선박의 안전을 고려한 최적의 항로를 생성하는 기법을 제안 하고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.69-70
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• 2013

IPCC (International Panel on Climate Change) reported that the arctic sea-ice extent has been decreased by 2.7% per decades since satellite observations in 1978. The decreased sea-ice extent has gained an international attention due to its economical benefits from the NSR (Northen Sea Route). The NRS - not a clearly defined single route, but a number of alternative routes across the top of Russiahas a 37 % reduction in sailing distance, comparing to the SSR (Southen Sea Route) passing thourgh the Suez Canal. Sailing days are consequently reduced from 30 days to 20 days. Also, it is estimated that the Northen Sea has 20 to 25% of world's oil resources and occupies 40% of the world's fishery production. As Republic of Korea was admitted as an observer to the Arctic Council on May 15, 2013, there has been increasing needs to explore new route in the Northen Sea. In this situation, Korea Institute of Ocean Science & Technology (KIOST) is preparing a plan for the development of Arctic-circle Ocean Environmental Information System to support the ice navigation and resource exploration in the Arctic. We will introduce a conceptual design of a satellite-based ice navigation supporting system for the northern sea route.

• Proceedings of KOSOMES biannual meeting
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• 2003.05a
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• pp.141-151
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• 2003

In this study the writer would like to study the art of navigation in the Era of Silla. For the purpose of this study, the writer studied ship's log book of Ennin's Diary, the ancient ship's structures of Korean, Chinese, Japanese, winds and ocean currents around Korean Peninsular which effect the navigation of sailing ship, and ancient reference books and materials. The result of this study. in the ship's structure in the Era of Silla. bottom structure is considered flat and V-Shaped type, and sailing ship had anchor, sail, considerable deckhouse, transverse bulkhead. And the ship's main materials of sailing ship was wood. partially used irons in the panting structures. In the art of navigation, navigators used winds, ocean current, anchor, sail, depth and color of sea water, lights, ballast. Especially navigators used astrologers and geomancers for astronomical observation, weather forecast, natural phenomena.

• International Journal of Ocean System Engineering
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• v.1 no.2
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• pp.102-109
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• 2011

This paper describes the implementation of a precise underwater navigation solution using a multiple sensor fusion technique based on USBL, GPS, DVL and AHRS measurements for the operation of a remotely operated mine disposal vehicle (MDV). The estimation of accurate 6DOF positions and attitudes is the key factor in executing dangerous and complicated missions. To implement the precise underwater navigation, two strategies are chosen in this paper. Firstly, the sensor frame alignment to the body frame is conducted to enhance the performance of a standalone dead-reckoning algorithm. Secondly, absolute position data measured by USBL is fused to prevent cumulative integration error. The heading alignment error is identified by comparing the measured absolute positions with the DR algorithm results. The performance of the developed approach is evaluated with the experimental data acquired by MDV in the South-sea trial.