• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.518-523
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• 2009

Main source of URN(Underwater Radiated Noise) which is related to the ship's survivability is divided into two groups. Cavitation is main source of URN when the speed of ship is upper than CIS(Cavitation Inception Speed). But when the speed of ship is lower than CIS, main source of URN is structure-borne noise on the hull which is originated from propulsion system, pump system or transmitted vibration of pipe system. In this paper, to reduce the vibration of discharge pipe and valve system, back flow prevent globe valve and new rubber mount are applied to the ship. As the result of applying new valve and mount, the vibration is reduced drastically.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.6
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• pp.599-606
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• 2009

Main source of URN(underwater radiated noise) which is related to the ship's survivability is divided into two groups. Cavitation is the main source of URN when the speed of ship is upper than CIS(cavitation inception speed). But when the speed of ship is lower than CIS, the main source of URN is the structure-borne noise on the hull which is originated from propulsion system, pump system and trnasmitted vibration of the pipe system. In this paper, to reduce the vibration of discharge pipe and valve system, back flow prevent globe valve and new rubber mount are applied to the ship. As the result of applying new valve and mount, the vibration is reduced drastically.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.2
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• pp.191-198
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• 2014

As an NMEA 2000 is a standard for communicate to other electronic equipment, it implemented a Universal gateway based on this ship's network. To implement a NMEA 2000 based Universal gateway, it is porting a NMEA 2000 stack source and CAN device driver source to board, and then it connected a board that equip with various communication protocol(CAN, RS232, USB, Ethernet port). To verify converted ship's data to a developed gateway, it connected pc based simulater program and monitoring program to a developed board. so we can see a ship's data through NEMA 2000 network. We verified a gateway performance and analyzed a generated ship's data from simulator program through a monitoring program that was connected a gateway and NMEA 2000 network. so it was designed, implemented to allow monitoring through utilizing a communication method that user wants.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.48-55
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• 2010

When a large ship is advancing in waves, ship undergoes the hydroelastic response, which has influences on structural stability and the fatigue destruction etc. of the ship. Therefore, to predict accurate hydroelastic response, it is necessary to analyze hydroelastic response including fluid-structure interaction. In this research, a ship is divided into many hull elements to calculate the fluid forces and wave exciting forces on each elements using three-dimensional source distribution method. The calculated fluid forces and wave exciting forces are assigned to nodes of hull elements. The neighbor nodes are connected with elastic beam elements. We analyzed hydroelastic responses, and those are formulated by using finite element method. Particularly, to estimate the influence of forward speed on the hydroelastic responses, we use two different methods : Full Hull Rotation Method(FHRM) and Sectional Hull Rotation Method(SHRM).

• Journal of Magnetics
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• v.21 no.4
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• pp.503-508
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• 2016

The roll- and pitch-induced eddy currents create a magnetic field that contributes to the total magnetic signature of naval vessels. The magnetic signature is of concern, as it exposes the ship to the threat of modern influence mines. It is estimated that the eddy current is the second most important source contributing to a ship's underwater magnetic field following the ferromagnetic effect. In the present paper, the finite element (FE) method is used to predict the eddy current signature of a real ship. The FE model is validated using the measurements of the Canadian research vessel CFAV QUEST at the Earth's Field Simulator (EFS) in Schirnau, Germany. Modeling and validation of the eddy current magnetic signature for a real ship represents a novelty in the field. It is shown that the characteristics of this signature depend on frequency. Based on these results, a ship's degaussing system could be improved to cancel both the ferromagnetic and the eddy current contribution to the magnetic signature simultaneously, reducing the susceptibility to sea mines.

• Journal of Power System Engineering
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• v.14 no.1
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• pp.53-58
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• 2010

A three-dimensional source distribution method is presented for the prediction of motions and vertical bending moments of ships travelling with forward speed in regular waves. Comparisons between theoretical and experimental results are shown for the motion responses and vertical bending moment of the S175 container ship model by Watanabe et al. The model ship was made of synthetic resins so as to simulate bending rigidity of a full scale ship. Numerical results are compared with experimental and numerical ones obtained in the literature. The results of comparison confirmed the validity of the proposed approach.

• Journal of Hydrospace Technology
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• v.2 no.1
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• pp.18-26
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• 1996

It is normal practice to consider bending wave modes only, when one applies SEA (Statistical Energy Analysis) to ship structures because of complexities in SEA modeling and evaluation of coupling loss factors for inplane modes. According to the result of Tratch[1], the inplane wave modes becomes important for the analysis of a foundation structure as the distance from the source and receiver increases. In this paper, the effect of inplane wave modes on structure-borne noise propagation in ship structures is presented. It is shown that the inplane wave could increase the noise level more than 10 dB compared with the results without inplane wave modes at high frequency bands for compartments far from the source location.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.2
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• pp.228-239
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• 1992

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. Some numerical results for series 60, C sub(b) =0.6, hull are presented in this paper. The wave pattern and wave resistance are computed at two Froude numbers, 0.267 and 0.304. These results are better than those of Michell's thin ship theory in comparison with measured results. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.196-205
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• 2018

This paper presents an algorithm for passive localization of a ship by applying the ray back-propagation technique to the ship radiation noise data. The previous method [S. H. Abadi, D. Rouseff and D. R. Dowling, J. Acoust. Soc. Am. 131, 2599-2610 (2012)] estimates the position of a sound source in the near-field environment with no array tilt by using the RBD (Ray-based Blind Deconvolution) and ray back-propagation techniques. However, when there exists an array tilt, the above method leads to a large position estimation error. In order to overcome the problem, this study proposes an algorithm that estimates the position of a sound source by correcting the array tilt using the RBD and ray back-propagation techniques. The proposed algorithm was verified by using the ship noise of SAVEX15 (Shallow-water Acoustic Variability EXperiment in 2015) experimental data.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.5
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• pp.587-598
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• 1999

In recent years emissions of pollutants from ship sources, especially NOx and SOx, is controlled by IMO(International Maritime Organization). The emissions of pollutants from ship sources in Pusan is considerably large, because the number of ship's coming and going in Pusan port is larger than that of other ports in Korea. Since Pusan is under the strong influence of land-sea breezes, pollutants emitted from ship sources will be transported into the inland. Control of emissions from ship sources is required to devise effectively the policy of air quality management in Pusan. Therefore this paper considered the present condition of total pollutant sources and emission characteristics including in coastal urban area.