• Korean Journal of Remote Sensing
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• v.39 no.1
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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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• v.14 no.8
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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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.530-536
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• 2017

The accident of the small vessel is increasing due to the growth of the sea and service industry. According to data from National Statistical Office, for 100 ton less than small ship accident, the most of the shipping incident generated in the small ship by 84% of the total shipping incident in 2015. The radar obligatory mounting is enforced to the small vessel in order to conclude this problem. However, the problems including the maintenance cost and transmission power etc. happens high if the existing pulse radar is mounted in the small vessel. In this development, the development is for small ship fixed type radar the object. And in this paper, by using the phase array antenna revolving electronically around the beam, the antenna which it is applicable to the marine fixed type radar which can solve above problem was made and it tested.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.1
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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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• v.40 no.5
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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.

• Journal of Advanced Navigation Technology
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• v.20 no.2
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• pp.116-126
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• 2016

In this study, has designed the ship application system for efficient data integration management of onboard ship and shore application/service utilizing data collected onboard ship, and has implemented the module. In order to supports onboard ship and shore service utilizing onboard ship collected data and provide a easy to access among individual devices, the ship application system applied the XML structure of ISO 16425 and the data sharing system model discussed in IALA, and the common module for system operation, a windows service for data collection/integral management, and web service module for management has been implemented.

• Journal of Navigation and Port Research
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• v.30 no.2
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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.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.591-596
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• 2018

In Designing a Small Ship, the Design of the Trim for Sailing has a great influence on the Stability of the Ship as well as Resistance. The Center of Gravity of a Ship is mostly determined during Initial Design. This Study confirms the Effect of Trim on changes in Vertical Center of Gravity by Numerical Analysis for a Small Catamaran. The Results were examined in a Model test. However, No Model tests were conducted while varying the changes in Vertical Center of Gravity. Nonetheless, Investigation was completed for the Purpose of presenting Vertical Center of Gravity results according to plans for the Trim during Initial Design of a Small Ship. In order to verify the Results of Numerical Analysis, a Comparison with Experimental results was carried out. Alternation of Trim angle and Resistance performance according to changes in the Center of Gravity were studied.

• Journal of Ocean Engineering and Technology
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• v.17 no.2
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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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.