• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.43-48
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• 2000

In this paper, an actively controlled anti-rolling system is considered to reduce the rolling motion of the ship. In this control system, a small auxiliary mass is installed on the upper area of the ship, and actuator us connected between the auxiliary mass and a ship. The actuator reacts against the auxiliary mass, applying inertial control forces to the ship to reduce the rolling motion in the desired manner. In this paper, we apply the PID controller to design the anti-rolling control system for the controlled ship. And the experimental result shows that the desirable control performance is achieved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.150-155
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• 2012

Water jet propulsion system has low efficiency than screw propeller at low speed, but has been applied in high speed ship due to its better cavitation performance and high rotation capacity. In this study, a numerical analysis was conduct to understand the flow in the propulsion system of 200HP grade water jet for small ship. As the result, it could be confirmed that total pressure and force of the flow was increased through the impeller and the straight-ability of discharging flow to outlet was improved by guide vane. Also, the reliability of numerical analysis was secured by comparing peripheral velocity calculated by design values with that calculated by numerical analysis.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.198-202
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• 2003

A small circulating water channel (CWC) for experiments ocean engineering is designed and made through the co-work of a company, MESTEC, and a college, Inha Technical Research Institute. General function of the elements of CWC are explained. The velocities in the test section are measured and analysed to estimate the performance of the CWC. The result of the velocity distribution is acceptable for experiments of ocean engineering.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.262-269
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• 2022

According to the statistics of marine accidents occurring in Korea since the past 10 years, the proportion of small fishing boats having a gross tonnage of less than 10 tons was confirmed to be as high as 47.51% of the total marine accidents. Additionally, the trend of marine accidents involving small fishing boats has been increasing steeply compared with that of other ship types/sizes (gross tonnage); hence, countermeasures must be prepared urgently. The Korea maritime transportation authority proposed the introduction of a self inspection system to improve the ship inspection system of small fishing vessels. Futhermore the Ministry of Oceans and Fisheries recently prepared and implemented the 'Remote Method of Vessel Inspection Guidelines' to introduce non-face-to-face inspection methods. In this study, a self inspection approval system was presented as a method for reducing marine accidents of small fishing vessels. Moreover, a mobile application was developed to prepare a standardized remote method, and its effectiveness was analyzed. Resultantly, the necessity of introducing a mobile application-based ship inspection system was confirmed with the introduction of a self inspection approval system that could induce voluntary safety management in fishing vessel owners. Additionally, we confirmed that the self inspection approval system could effectively reduce marine accidents by raising the safety awareness of ship owners.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.3
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• pp.373-380
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• 2018

The small coastal vessel registered in Korea, small coastal vessels with a gross tonnage of 10 tons or less account for 94.6 % and among them, aged vessels over 16 years age indicate 40.6 %. In order to reduce GHG emissions from small coast vessels, discussions are underway to replace aging ships' propulsion units with eco - friendly propulsion facilities, and the electric propulsion ship is emerging as one of the measures. The electric propulsion system using the DFE rectifier, which was applied in the conventional large commercial vessel, was effective in reducing the harmonics and improving the DC output voltage of the DC link stage, but it occupied a large volume and caused an increase in the overall system price. Therefore, in this paper, we propose an electric propulsion system using AFE rectifier with a small volume of system that can be applied to a small coastal vessel. In order to analyze the effectiveness of the overall system, the load profile was applied to obtain accurate and rapid speed tracking performance of the propulsion motor affected by the speed load. In addition, the power factor and total harmonic distortion factor of the voltage and current on the improved power output side are derived through simulation.

• Journal of Korea Ship Safrty Technology Authority
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• v.13
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• pp.49-57
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• 2004

선망어업은 우리나라 근해어업을 대표하는 어업으로서 출어 1일당 어획량, 어서 1톤당 어획량 등에서 타 업종을 압도하고 있을 뿐만 아니라 고등어 등 대중성 어종을 어획하고 있어 국민 식생활에도 크게 기여하고 있다.

• Bulletin of the Society of Naval Architects of Korea
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• v.16 no.3
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• pp.9-19
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• 1979

A method of improving rudder effectiveness by applying a rotating cylinder to a rudder(so called "rotating-cylinder rudder") has been experimentally studied. Also, the improvements in ship's maneuvering characteristics with its application has been analytically evaluated. It has been shown that this improvement is significant.

• Selected Papers of The Society of Naval Architects of Korea
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• v.2 no.1
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• pp.79-105
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• 1994

A ship in waves is suffered from the various wave loads that comes from its motion throughout its life. Because these loads are dynamic, the analysis of a ship structure must be considered as the dynamic problem precisely. In the rationally-based design, the dynamic structural analysis is carried out using dynamic wave loads provided from the results of the ship motion calculation as a rigid body. This method is based on the linear theory assumed low wave height and small amplitude of motion. But at the rough sea condition, high wave height, compared with ship's depth, induce the large ship motion, so the ship section configuration under waterline is rapidly changed at each time. This results in a non-linear problem. Considering above situation in this paper, a strength analysis method is introduced for the hull girder among waves considering non-linear hydrodynamic forces. This paper evaluates the overall or primary level of the ship structural dynamic loading and dynamic response provided from the non-linear wave forces, and bottom flare impact forces by momentum slamming theory. For numerical calculation a ship is idealized as a hollow thin-walled box beam using thin walled beam theory and the finite element method is used. This method applied to a 40,000 ton double hull tanker and attention is paid to the influence of the response of the ship's speed, wave length and wave height compared with the linear strip theory.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.784-789
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• 2015

It was carried out a review of operating limit analysis for small high-speed boat by author. In general, a review of ship's seakeeping performance is performed in the step of ship design, but this study was carried out in the state of completion of boat. Motion performance of Pitch, Vertical and Lateral acceleration and Slamming were satisfied in some encounter angle but deck wetness was not satisfied in all it does the analysis. As a result, sea state rather than the speed and encounter angle of vessel have a greater effect on the seakeeping performance of target vessel. It seems to be due to the size of the target ship.

• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.305-314
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• 2023

In this study, a mathematical model of a 9.77 G/T small fishing vessel was established based on captive model tests. The powering and manoeuvring performances of the vessel in the harbor and coastal sea were focused on, so captive model tests were conducted up to the full-scale speed of 8 knots. Propeller open water, resistance, and self-propulsion tests of a 1/3.5-scaled model ship were performed in a towing tank, and the full-scale powering performance was predicted. Hydrodynamic coefficients in the mathematical model were obtained by rudder open water, horizontal planar motion mechanism tests of the same model ship. In particular, in static drift and pure yaw tests which were conducted at a speed of 2 to 8 knots, the linear hydrodynamic coefficients varied with the ship speed. The effect of the ship speed on the linear coefficients was considered in the mathematical model, and manoeuvring motions, such as turning circles and zig-zags, were simulated with various approach speeds and analyzed.