• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.85-95
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• 1998

ECDIS, highlihgted as a new technology for the navigation safety, could replace the paper charts in the bridge and make the more safe navigation possible. For the marines to use the ECDIS, the infrastructrue of the ENC production and distribution, the development of IMO compliant ECDIS, the training program for the ECDIS usage and related matters are thought as the key points to be solved. Also it is necessary for the ECDIS usage and related maters are thought as the key point to be solved. Also it is necessary for the related groups, such as ECDIS manufactures, users, ENC producers, the to be involved in developing the national infrastructure altogether to promote the ECDIS usage. Upon these background, the Korean ENC pilot project was introduced and the comparison study of the SHARED project coordinated by MPA(Maritime Port Authority, Singapore) and the Canadan Pilot project has been done. With such a analysis, the Korean ENC sea trial test plan is presented.

• Korean Journal of Ichthyology
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• v.20 no.3
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• pp.173-178
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• 2008

The substrate preferences of juvenile black sea bass Centropristis striata (Linnaeus) was tested in a circular tank (1.5 m diameter${\times}$0.4 m deep) divided into two equal areas of oyster-related (oyster reef and whole oyster shell) and sand substrates. All trials were video taped for 20 min. Tapes were viewed on a monitor and locations of all fish recorded and timed with respect to substrate. $Mean{\pm}SE$ times on oyster shell were $18.1{\pm}2.0min$ (1-fish trial-1) and $17.5{\pm}1.7min$ (5-fish trial-1). $Mean{\pm}SE$ times on sand were $2.0{\pm}1.0min$ (1-fish trial-1) and $2.5{\pm}1.7min$ (5-fish trial-1). Black sea bass juveniles showed a significant preference for oyster reef and shell over sand substrate in single-fish trials (paired t-test, P<0.05) and also in five-fish trials (paired t-test, P<0.05). $Mean{\pm}SE$ times under oyster reefs were $16.6{\pm}2.0min$ in single-fish trials and $10.7{\pm}2.3min$ in five-fish trials. Mean numbers of movements among oyster reefs were $1.1{\pm}1.0$ in single-fish trials and $11.5{\pm}3.1$ in fivefish trials. Fish spent significantly less time under oyster reefs in five-fish trials, compared to single-fish trials (paired t-test, P<0.05) and they moved more frequently in five-fish trials than in single-fish trials (paired t-test, P<0.05). Significantly higher competition for a refuge in five-fish trials may induce less time under oyster reefs as well as frequent movement of black sea bass juveniles on shell substrate.

• Bulletin of the Society of Naval Architects of Korea
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• v.21 no.4
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• pp.10-20
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• 1984

When the hydrodynamic coefficients of the ship maneuvering equation are estimated by captive model test, it is difficult to take account of the scale effect between model and full scale ship. This scale effect problem can be overcome by processing the sea trial data with system identification. Extended Kalman filter is used as a system identification technique for the modification of the simulation equation as well as the estimation of hydrodynamic coefficients The phenomena of simultaneous drifting of linear coefficients occur. It is confirmed that two coefficients in each pair-$(Y_v',\;Y_r'-m'u'),\;(N_v',\;N_r')$-are simultaneously drifting and all 4 coefficients are drifting together. Particularly simultaneous drifting and 2 coefficients in each pair is more significant. It is also shown that the simultaneous drifting of 4 coefficients can be reduced by choosing the input data which have the random v'/r' curve and 4 coefficients are estimated within $2{\sim}4%$ error, which may be noise level. So, it is recommended to operate the rudder randomly in sea trial or model test for the application of system identification technique.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.84-89
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• 2008

It is hard to find experimental data for a model test of small high-speed planning boats. It is difficult to verify the performance seen in a model test for a high-speed boat because the ship-model scale-ratio is very small and the flow velocity of the circulating water channel and the X-carriage speed of the towing tank are restricted. Therefore most hull-form designs for high-speed small boats depend on the sea-trial test result for similar boats or evaluation through numerical calculations. This study investigated the anti-rolling effect of the stern sub-body in a 50-knot doss planning boat. To carry out this work, new model test procedures were set up in the actual sea. Using this method, the anti-rolling effect of the stern sub-body was investigated. A stern sub-body attached to a planning boat was proved to be effective in reducing the roll and pitch angle.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.2
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• pp.50-61
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• 2002

This paper - following 'Functional requirement of marine waste cleaning ships and organization of the fleets'[1] - describes on the preliminary conceptual design procedure for the multi-purpose marine waste cleaning system for shallow waters. The working area of this system is Yellow Sea and part of South Sea of South Korea. As the first step, we determined the functional requirements including the daily target of waste collecting. Then, the preliminary conceptual design and general arrangements were carried out. In order to evaluate the safety and efficiency of this designed system, the stability check and the computer graphic simulation were carried out. Finally, the sea trial performance test of integrated systems in Yeosoo ports was performed and the designed system was shown its validity and effectiveness.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.4
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• pp.29-45
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• 1991

Lip type stern tube sealing systems have used in almost all the middle or large ships which are being constructed in these days. It seems that the pressure fluctuation of the seal ring interspace, the cross-section profile and the materials quality of the seal rings have great effects on the sealing fuction of this sealing system. In this paper, the mechanical movement of lip seal ring which plays the most important role in stern tube sealing system and the possibility of leakage caused by pressure fluctuation are studied by theory and experiment. Using the finite element method for the axi-symetric object which receives the torsional load, the displacement and stress analysis of the seal rings, and also the possibility of crack occurance is checked by theoretical analysis. If the force which seal ring lip periphery receives is too small, there will be the possibility of leakage caused by the pressure fluctuation of the seal ring interspace, and if this force is too large, the frictional force between the seal ring and the liner will become problematical. The possibility of leakage caused by hardening of seal ring materials and creep phenomena of tested seal rings are also examined. The trial seal rings were designed and manufactured using the program of displacement and stress analysis developed in this study and the experimental apparatus to test the trial seal rings was also designed and manufactured. This trial seal rings were fitted in the experimental apparatus which was made in the same form as an actual stern tube. The one side of this apparatus was filled with sea water and the other side of it was filled with the lubricating oil. The leakage of oil and sea water was checked and the temperature was measured, rotating the propeller shaft at the constant velocity by D.C. motor. It was proved that the trial seal rings made in Viton rubber functioned excellenty but the trial seal rings made in N.B.R. rubber had problem in its durability.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.6
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• pp.366-374
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• 2021

This paper presents the analysis of the speed-power performance in the real sea using a large container vessel data provided as a test bed from a shipping company. To perform a speed trial of the vessel during a commercial voyage, the on-board measuring device and various operation data acquisition systems were mounted on the vessel for long-term performance monitoring and the voyage operated under the container loading condition close to the design draft was adopted. The content of this paper consists of Part I and Part II. Part I, such as this paper, contains the speed trial method and analysis results of the operating vessel. Part II contains the analysis of the speed-power characteristics change over time and before and after hull cleaning using operation data measured from the voyage operated under a condition similar to the speed trial.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.606-613
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• 2007

The 6m class high speed boat is developed with a durable hull and inflatable tube, which is called RIB(Rigid Inflatable Boat), for the purpose of marine leisure. In the stage of the conceptual design, its requirements to be optimized are determined based on the presented information of similar marine leisure RIBs. The 3-D graphical technique using Marine Rhino is utilized to optimize the compartment layout of RIB. The stability analysis is performed for the light and full load conditions with and without the inflatable tube. In addition, the sea keeping and hydrodynamic performance was tested using the proto-type ship in the sea condition. From the results of the computation and the sea trial test, it shows that the performance of the marine leisure RIB satisfies the speed, the convenience, and the stability requirements. This study provides the typical information of the design factors and the procedure to manufacture the marine leisure RIB.

• Journal of Ocean Engineering and Technology
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• v.30 no.6
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• pp.458-467
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• 2016

In this paper, a strongly coupled method for investigating the interaction between a cable and tow-fish is presented. The nodal position finite element method was utilized to analyze the nonlinear cable dynamics, and 6DOF equations of motion were employed to describe the 3D rigid body motion of the tow-fish. Combining cable and tow-fish systems into a single formulation allowed the two nonlinear systems to be strongly coupled into a unified nonlinear system. This strongly coupled system was numerically integrated in the time domain using a predictor/multi-corrector Newmark algorithm. To demonstrate the validity, efficacy, and applicability of the current approach, two different scenarios (virtual and sea trial) were simulated, and the simulation results were validated using the physical plausibility and the sea trial test.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.314-319
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• 2021

The measurement of the Underwater Radiated Noise (URN) for the underwater vehicle should consider both the acoustic interference due to the surface reflection and the calculation of the Closet Point of Approach (CPA). In this paper, I tried to analyze the underwater vehicle's URN using the Lloyd's mirror effect. First, the theoretical Lloyd's mirror pattern was compared with the sea trial result, and the sea trial results corresponded well with the theoretical predicted pattern. And then the CPA distance could be estimated by the Lloyd's mirror pattern. As a results, acoustic source level shows the spectral fluctuation due to the acoustic interference of the Lloyd's mirror effect.