• 대한원격탐사학회지
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• 제39권1호
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• pp.77-86
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• 2023

Ship detection is widely used in areas such as maritime security, maritime traffic, fisheries management, illegal fishing, and border control, and ship detection is important for rapid response and damage minimization as ship accident rates increase due to recent increases in international maritime traffic. Currently, according to a number of global and national regulations, ships must be equipped with automatic identification system (AIS), which provide information such as the location and speed of the ship periodically at regular intervals. However, most small vessels (less than 300 tons) are not obligated to install the transponder and may not be transmitted intentionally or accidentally. There is even a case of misuse of the ship'slocation information. Therefore, in this study, ship detection was performed using high-resolution optical satellite images that can periodically remotely detect a wide range and detectsmallships. However, optical images can cause false-alarm due to noise on the surface of the sea, such as waves, or factors indicating ship-like brightness, such as clouds and wakes. So, it is important to remove these factors to improve the accuracy of ship detection. In this study, false alarm wasreduced, and the accuracy ofship detection wasimproved by removing wake.As a ship detection method, ship detection was performed using machine learning-based random forest (RF), and convolutional neural network (CNN) techniquesthat have been widely used in object detection fieldsrecently, and ship detection results by the model were compared and analyzed. In addition, in this study, the results of RF and CNN were combined to improve the phenomenon of ship disconnection and the phenomenon of small detection. The ship detection results of thisstudy are significant in that they improved the limitations of each model while maintaining accuracy. In addition, if satellite images with improved spatial resolution are utilized in the future, it is expected that ship and wake simultaneous detection with higher accuracy will be performed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권8호
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• pp.3350-3365
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• 2020

A considerable literature has recently grown up on the theme of ship wireless communications. However, much of the research up to now has been descriptive in the offshore area. There has been little quantitative analysis of wireless communication in inland waterways, which has received considerable attention lately. Until now, only the effects on inland river environment are examined. What is less clear is the nature of channel change caused by the antenna movement. Here we explore the moving ship-to-fixed-ship fading characteristics at 5.9 GHz for an inland waterway in the city center of China. The ship motion trajectory is designed in order to determine the effect of changes in the antenna position. We evaluate the channel fading characteristics of inland waterway, which are highly correlated with the distance between transmitter and receiver. We demonstrate that the line-of-sight component, as well as the components from multipath with obstruction reflections, contributes largely to the mean power gap. Our findings reveal critical ship-to-ship characteristics in inland waterway, which definitely contribute to the field of ship wireless communications.

• 한국정보통신학회논문지
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• 제21권3호
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• pp.530-536
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• 2017

해양 산업과 서비스업의 성장으로 인하여 소형 선박의 사고가 증가하고 있다. 이러한 문제를 해결하기 위하여 소형 선박에 레이더 의무 장착을 시행하고 있다. 하지만 기존의 펄스 레이더를 소형 선박에 설치하면 유지보수 비용 및 높은 송신 전력등의 문제들이 발생한다. 본 연구에서는 전자적으로 빔을 회전하는 위상배열안테나를 이용하여 상기문제를 해결가능한 선박용 고정형 레이더에 적용 가능한 안테나를 제작하여 시험하였다. 그 결과 정면에 대한 빔 폭은 $5^{\circ}$내외로 레이더에 적용에 대한 가능성을 볼 수 있었다.

• 대한조선학회논문집
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• 제40권1호
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• pp.47-54
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• 2003

The majority of small/medium sized shipbuilders in Korea is poor in capital and then, should be restructured as an efficient production system with low investment. Due to considering this situation, the cooperative work system is proposed, in this study, as more effective production system for small/medium sized shipbuilder The cooperative work system Is the production system that many small/medium sized shipbuilders in a group jointly share the common facilities except minimum equipments and have managerial cooperation such as joint purchase of raw materials. The efficiency of cooperative work system is proved from economic and technical point of view with the case study of FRP shipbuilders of Sapjin industrial complex located at Mokpo area.

• Journal of Advanced Marine Engineering and Technology
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• 제40권5호
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• pp.447-452
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• 2016

The use of gas as fuel, particularly liquefied natural gas (LNG), has increased in recent years owing to its lower sulfur and particulate emissions compared to fuel oil or marine diesel oil. LNG is a low temperature, volatile fuel with very low flash point. The major challenges of using LNG are related to fuel bunkering, storing, and handling during ship operation. The main components of an LNG fuel system are the bunkering equipment, fuel tanks, vaporizers/heaters, pressure build-up units (PBUs), and gas controlling units. Low-pressure dual-fuel (DF) engines are predominant in small LNG-powered vessels and have been operating in many small- and medium-sized ferries or LNG-fueled generators.(Tamura, K., 2010; Esoy, V., 2011[1][2]) Small ships sailing at coast or offshore rarely have continuous operation at constant engine load in contrast to large ships sailing in the ocean. This is because ship operators need to change the engine load frequently due to various obstacles and narrow channels. Therefore, controlling the overall system performance of a gas supply system during transient operations and decision of bunkering time under a very poor infrastructure condition is crucial. In this study, we analyzed the fuel consumption, the system stability, and the dynamic characteristics in supplying fuel gas for operating conditions with frequent engine load changes using a commercial analysis program. For the model ship, we selected the 'Econuri', Asia's first LNG-powered vessel, which is now in operation at Incheon Port of South Korea.

• 한국항행학회논문지
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• 제20권2호
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• pp.116-126
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• 2016

본 논문에서는 선내에서 수집되는 데이터를 이용하는 선박과 육상의 어플리케이션 서비스의 효율적인 데이터 통합관리를 위한 선박용 어플리케이션 시스템을 설계하고 모듈을 구현하였다. 선박용 어플리케이션 시스템은 선내 수집 데이터를 활용하는 선박과 육상의 서비스를 지원하고 개별 장비간 원활한 연동 서비스를 제공하기 위하여 IALA에서 논의되고 있는 데이터 공유 시스템 모델과 ISO 16425의 XML 구조를 적용하였으며, 시스템 운영을 위한 공통 모듈과 데이터 수집 및 통합관리를 위한 윈도우 서비스, 관리를 위한 웹서비스 모듈을 구현하였다.

• 한국항해항만학회지
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• 제30권2호
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• pp.125-130
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• 2006

Waves, which are the main source of ship motions in a seaway, considerably affect the performance of a ship. The study of waves and their impact on ship motions within harbors is an important aspect of the design and operation of harbors. The prediction of incoming groups of waves is particularly important for evaluating ship motion within a harbor. Such a prediction makes it possible to evaluate ship safety more accurately. The wave transformation model reported here is applied to actual ports based on Boussinesq wave equations both non-linear and dispersive wave processes be considered in order to capture physical effects such as wave shoaling, refractions, reflection and diffraction in variable depth environments. The prediction of incoming groups of waves is particularly important for evaluating ship motion within a harbor, Such a prediction makes it possible to evaluate ship safety more accurately and provide safe wave informations for navigation. Furthermore, a wave information support system is proposed for entering ships as one technique for improving the safety of ship operations. This system predicts the run of waves and reduces the danger by identifying the most dangerous point near the harbor entrance at the small wave groups.

• 해양환경안전학회지
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• 제24권5호
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• pp.591-596
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• 2018

소형선박 설계에 있어 항주에 따른 설계 종경사 결정은 선체저항 뿐만 아니라 항주 안정성에 많은 영향을 주고 있다. 이는 초기 설계 시 선박의 무게중심 결정을 시작으로 대부분 결정된다. 본 연구는 소형 쌍동선박에 대해 수치해석을 통한 수직방향 무게중심 변화에 따른 종경사 영향을 확인하고, 이를 모형시험에서 결과를 검토하였다. 다양한 수직방향 무게중심 변화에 따른 모형시험 검토는 이뤄지지 못했지만, 향후 신조 소형선박 초기설계시 보다 나은 종경사 자세를 고려한 수직방향 무게중심 위치 제시를 목적으로 연구를 수행하였다. 수치해석 결과의 검증을 위하여 모형시험과 자세 비교를 수행하였다. 무게중심의 변화에 따른 종경사 각도 및 저항성능의 변화가 연구되었다.

• 한국해양공학회지
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• 제17권2호
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• pp.60-66
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• 2003

In this paper, an actively controlled anti-rolling system is considered, in order to reduce the rolling motion of a ship. In this control system, a small auxiliary mass is installed on the upper area of the ship, and an actuator is connected between the auxiliary mass and the ship. The actuator reacts the auxiliary mass, applying inertial control forces to the ship to reduce the rolling motion in the desired manner. In this paper, we introduce LMI based H$_{\infty}$ control approach to design the anti-rolling control system for the controlled ship. And the experimental results show that the desirable control performance can be achieved.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.312-315
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• 2003

The paper presents a small. unmanned remote controlled probing ship that can reduce the cost for acquiring data of marine and coastal environments. The control system is composed of three microprocessors. one is for overall mission control. another for control of propulsion motors. and the other for sensor operation. For communication system, we adopt direct and indirect methods based on the wireless modem of commercial cellular telephone. The former is a direct communication between the modems of the ship and the server. and the latter is an indirect communication via internet between the ship and the server. The system is equipped with a digital compass and a GPS system for position estimation, and extended Kalman filter is used for the data association. The performance of the ship is demonstrated with the results produced by sets of experiments.