• Journal of the Korean Magnetics Society
• /
• v.18 no.6
• /
• pp.221-224
• /
• 2008

This paper describes the equivalent dipole modeling method utilizing a singular value decomposition technique from analysis data by the FNREMUS Detailled Modeller software based on BEM which can predict the underwater electric field signal due to a galvanic corrosion phenomenon on a naval vessel. The proposed dipole modeling method was successfully verified in good agreement with predicted BEM data at 30 m depths through the comparison of average differences. The proposed dipole modelling method can be effectively used in the prediction and analysis of static electric field signature distributions generated from a naval vessel at any different depths.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.50 no.1
• /
• pp.75-82
• /
• 2014

In vibration analysis of ships, the principle aim is to determine the natural frequencies and excitation frequencies, and use this information to avoid resonances and vibration damage. The simplest method is to prevent resonance conditions, which is effective as long as the natural frequencies and excitation frequencies can be regarded as independent from environmental conditions. For ships that use electric propulsion systems, the sources of vibration are reduced compared with those caused by a diesel engine or other combustion-based propulsion systems. However, the frequency spectrum of these vibrations may be different; therefore, to understand the characteristics of the electric propulsion, we also should investigate how the ship responds to these vibrations. We focused on a 1,000-ton deadweight (DWT) ocean-research vessel using an electric propulsion system and analyzed the response to vibration.

• Journal of Ocean Engineering and Technology
• /
• v.27 no.5
• /
• pp.1-9
• /
• 2013

Because the environmental regulations for ships are getting tighter, green ships employing eco-friendly technology have recently received a large amount of attention. Among them, various studies for electric propulsion ships have been carried out, particularly in the United States, European Union, and Japan. On the other hand, research related to electric propulsion ships in Korea is in a very nascent stage. In this paper, an estimation process based on the rough requirements of ship-owners for the operating performance of electric propulsion ships is proposed. In addition, the estimation process is applied to a small fishing boat for verification of the process. These results are expected to be used as design guidelines in the early stage of the design process for electric propulsion ships.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.10 no.1
• /
• pp.37-47
• /
• 2018

Dynamic simulation is critical for electrical ship studies as it obtains the necessary information to capture and characterize system performance over the range of system operations and dynamic events such as disturbances or contingencies. However, modeling and simulation of the interactive electrical and mechanical dynamics involves setting up and solving system equations in time-domain that is typically time consuming and computationally expensive. Accurate assessment of system dynamic behaviors of interest without excessive computational overhead has become a serious concern and challenge for practical application of electrical ship design, analysis, optimization and control. This paper aims to develop a systematic approach to classify the sophisticated dynamic phenomenon encountered in electrical ship modeling and simulation practices based on the design intention and the time scale of interest. Then a novel, comprehensive, coherent, and end-to-end mathematical modeling and simulation approach has been developed for the latest Medium Voltage Direct Current (MVDC) Shipboard Power System (SPS) with the objective to effectively and efficiently capture the system behavior for ship-wide system-level studies. The accuracy and computation efficiency of the proposed approach has been evaluated and validated within the time frame of interest in the cast studies. The significance and the potential application of the proposed modeling and simulation approach are also discussed.

• Journal of Power Electronics
• /
• v.14 no.2
• /
• pp.402-412
• /
• 2014

This paper proposes a novel electric propulsion system for naval ships, which consists of Active Front End (AFE) converters directly connected to battery Energy Storage Modules (ESMs). Employing the proposed AFE converters with ESMs in the power systems of naval ships can enhance the reliability and quality of the electric power. Furthermore, the fuel-efficiency of the generator can be improved by a higher loading factor of the generator and its prime movers. The proposed AFE configuration does not require an additional dedicated DC/AC converter for the ESMs. Instead of that, the AFE converter itself can control the DC link voltage and the discharging and/or charging of the ESMs. A control scheme to achieve these control objectives is also presented in this paper. The overall power system, including the generators and electrical loads of a naval ship, is implemented by a small scaled Power Hardware-In-the-Loop (PHIL) simulator. Through this experimental setup, the proposed system configuration and the power control strategies are verified. It is shown that the fuel-efficiency and transient dynamics can be improved in the normal and contingency operation modes.

• Journal of the Society of Naval Architects of Korea
• /
• v.30 no.1
• /
• pp.10-19
• /
• 1993

Design optimisation generally necessitates a tool of assessing the economics of designs. This paper proposes a method of assessing the economics of marine electric generating systems. The pay back period(PBP) and the net present valuve(NPV) of the investment for a designed project are properly converted into a economic index. The mechanical factors dominating the easiness in operating the system are also assessed and quantified to form a index which eventually is added to the economic index producing a comprehensive economic index. The method has been tested on a design example and it's validity has been shown.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.876-878
• /
• 2008

The galvanic corrosion of a vessel, or systems fitted to minimize the ship's corrosion such as ICCP(Impressed Current Cathodic Protection) system and sacrificial anodes, can lead to significant electrical current flow in the sea. The presence of vessel's current sources associated with corrosion will give rise to detectable electric field surrounding the vessel and can put it at risk from mine threats. For this reason, it is necessary to design corrosion protection systems so that they don't only prevent a hull corrosion but also minimize the electric field signature. In this paper, we describe theoretical backgrounds of underwater electric field signature due to corrosion and corrosion protection system on naval vessels and analysis results of the electric field according to ICCP anode arrangement.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.1
• /
• pp.134-145
• /
• 2021

It is common to optimize the propulsion control system through a so-called tuning process that modifies the parameter values of the propulsion control software during a ship commissioning. However, during this process, if the error of the initial setting value is large, the tuning time may take too long, or the propulsion equipment can be seriously damaged. Therefore, we conducted research on the design of a propulsion controller that applied a Processor lever controller even for inexperienced people with relatively little experience in tuning propulsion control software to be able to reduce the tuning time while protecting the propulsion system. Through simulation, by comparing the execution result of propulsion control lever commands through the PI controller without applying the Processor lever controller. We analyzed the improvement of the Overshoot and propulsion performance. The simulation results showed that the safety of the propulsion system increased because Overshoot of approximately 9.74%, which occurred when the Processor lever function was not applied.

• Journal of the Society of Naval Architects of Korea
• /
• v.42 no.2 s.140
• /
• pp.151-158
• /
• 2005

The concept of recent cruise ship design is changing rapidly according to the expansion of cruise fleet sizes, emphasis on passenger safety and tightened requirements for ecotourism. In this view point, this study focuses on investigative analysis for the recent trends in cruise ship design and construction. Based on the shipyard production logs and the cruise industry's annual news, the data for principal dimensions of newly built cruise ships, their hull forms and propulsion devices and the characteristics of cabin and public spaces are collected and analysed. As expected, it is found that the size of cruise ships is growing and the design concept is becoming more leisure-oriented for all ages rather than lust sightseeing. For producing a greater ton/pax ratio, the adoption of podded electric propulsion system, outside cabins and balcony spaces is a common trend in recent cruise ship design.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.11 no.1
• /
• pp.35-41
• /
• 2008

Overtopping wave energy convertor is an offshore wave energy convertor for collecting the overtopping waves converting the water pressure head into electric power through the hydro turbines. This paper presents a numerical wave tank based on the commercial CFD code Fluent. The Reynolds Averaged Naiver-Stokes and VOF model is utilized to generate the 2D numerical linear propagating waves, which has been validated by the analytical solutions. Several incident wave conditions and shape parameters are calculated in the optimal designing investigation of the overtopping characteristics and discharge for the overtopping wave energy convertor.