• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.46-46
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• 2017

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.2
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• pp.183-192
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• 2020

This study conducted the experiment for the development of the low pressure type SCR system. The experimental equipment of SCR system was installed, which was widely used as the nitrogen oxides abatement system, and the demonstration experiment was conducted to see that it met the Tier III regulation according to the IMO NOx Technical Code. The SCR system demonstration experiment was divided into three stages: SCR system component operation test, engine parameter test by engine load, and NOx abatement performance and ammonia slip verification test. The final performance of the SCR system was verified through analysis of NOx abatement performance and ammonia slip test results for each load variation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.1
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• pp.71-79
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• 2024

In compliance with environmental regulations at sea and the introduction of unmanned autonomous ships, electric propulsion ships are garnering significant attention. Induction machines used as propulsion electric motor (PEM) have maintenance advantages, but speed control is very complicated and difficult. One of the most commonly used techniques for speed control is DTC (direct torque control). DTC is simple in the reference frame transformation and the stator flux calculation. Meanwhile, two-level and three-level voltage source inverters (VSI) are predominantly used. The three-level VSI has more flexibility in voltage space vector selection compared to the two-level VSI. In this paper, speed is controlled using the DTC method based on the specifications of the PEM. The speed controller employs a PI controller with anti-windup functionality. In addition, the characteristics of the two-level VSI and three-level VSI are compared under identical conditions. It was confirmed through simulation that proper control of speed and torque has been achieved. In particular, the torque ripple was small and control was possible with a low DC voltage at low speed in the three-level VSI. The study confirmed that the application of DTC, using a three-level VSI, contributes to enhancing the system's response performance.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.269-269
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• 2019

The ships are turning for the purpose of collision avoidence and change of course. It is possible that ships have capsizing accident when improper loading of cargo and excessive use rudder angle in turning. It is difficult for navigation officers to recognize the danger of heeling during a turn, because the dynamic state of the ship changes in real time. Thus, in this study, ship's heeling angle was predicted during turning using the maneuverability indices estimated from the ship's autopilot. The maneuverability indices estimated through the Kalman filter of Autopilot is real-time predictable. The turning radius was obtained from the estimated Index of turining ability and calculations of the heeling angle were possible in turning. It is intended to be used as a basic data on the prevention of danger heeling angle during turning.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1124-1128
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• 2021

As regulations of emissions from ships become more stringent, electric propulsion systems have been increasingly used to solve this problem in vessels ranging from large merchant ships to small and medium-sized ships. Methods for improving the efficiency of the electric propulsion system include the improvement of power sources; the use of a system linked to environmentally friendly power sources, such as batteries, fuel cells, and solar power; and the development of hardware and control methodology for rectifiers, power conversion devices, and propulsion motors. The method using a phase-shifting transformer with diodes has been widely used for rectification. Power semiconductor devices with grid connection to an environmentally friendly power source using DC distribution, a variable speed power source, and the application of small and medium-sized electric propulsion systems have been developed. Accordingly, the demand for active front-end (AFE) rectifiers is increasing. In this study, a method using a neural network rather than a conventional proportional-integral controller was proposed to control the AFE rectifier. Tested controller data were used to design a neural network controller trained through MATLAB/Simulink. The neural network controller was applied to a rectification system designed using PSIM software. The results indicated the effectiveness of improving the waveform and power factor DC output stage according to the load variation. The proposed system can be applied as a rectification system for small and medium-sized environmentally friendly ships.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.398-407
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• 2018

Standard guidelines for marine accident investigation have been prepared through the enforcement of the Casualty Investigation code as of January 2010. In addition, as the International Maritime Organization (IMO) recommended contracting the state to manage a marine incident system established under this code, Korea also has newly established provisions for a marine incident system in the 'Act on the Investigation of and Inquiry into Marine Accidents' also as of 2010. The Korean Maritime Safety Tribunal (KMST) has made a multilateral effort to prevent marine accidents through the efficient operation of a marine incident system, but this system has not been properly activated. This study examines the operational status and problems of a marine incident system and analyzes the marine incident systems of foreign countries and similar transportation agencies such as railroads and aviation. Options include switching to voluntary reporting of marine incidents, transferring responsibility to a non judicial private organization, expanding incentive systems for a marine incidents, revising regulation and preparing detailed implementation guidelines.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.408-414
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• 2018

Various studies have been conducted to reduce marine accidents. However, research on marine incidents is only marginal. There are many reports of marine incidents, but the main content of existing studies has been qualitative, which makes quantitative analysis difficult. However, quantitative analysis of marine accidents is necessary to reduce marine incidents. The purpose of this paper is to analyze marine incident data quantitatively by applying big data techniques to predict marine incident trends and reduce marine accident. To accomplish this, about 10,000 marine incident reports were prepared in a unified format through pre-processing. Using this preprocessed data, we first derived major keywords for the Marine incidents at sea using text mining techniques. Secondly, time series and cluster analysis were applied to major keywords. Trends for possible marine incidents were predicted. The results confirmed that it is possible to use quantified data and statistical analysis to address this topic. Also, we have confirmed that it is possible to provide information on preventive measures by grasping objective tendencies for marine incidents that may occur in the future through big data techniques.