• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.3-4
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• 2006

In this paper, a development of shaft power measuring system for a rotating machinery is discussed. It is important that the exact power measurement of marine engine since the engine power is related to ship's usage and its shaft design. The engine equipped on the ship is assumed to rotating machine which can generate mechanical power by electrical energy. Two gearwheel and magnetic sensors are applied to measure torsional angle on the shaft. High resolution encoder is also applied to compensate the output signal from gearwheel. The calculation of shaft power is executed using measured signal and angular velocity of rotating machine.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.73-76
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• 2005

Recently, the demand for the Floating, Production, Storage, and Offloading facility (FPSO) which has some economic and technical advantages, has increased in offshore oil production areas. FPSO vessel dose not have self-propulsion system, but has additional facilities for oil production and positioning system. Main noise sources such as gas turbines, compressors, and pumps, are located on top of the hull (Topside area). In general, the noise regulation for the offshore structure is severer than that of the cargo ship and acceptable noise limit of cabin is specified as 45 dB(A). This paper describes the noise characteristics and the countermeasures for FPSO Topside area through investigation of noise analysis and site measurement results. Proper countermeasures, considering the characteristics of sources and receiver spaces, were applied from the noise prediction and various measurement results. Finally, this ship was successfully delivered with excellent noise properties.

• Journal of the Korean Institute of Navigation
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• v.21 no.3
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• pp.49-54
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• 1997

It is very important to measure and monitor hull stress which is caused by a buoyant force and a weight of cargo for safety of ship. However, an exact measurement of hul stress, using the traditional strain gage which is made of metal or semiconductor, is very difficult, because a ship would be exposed by the severe temperature environment of $-20 ^{\circ}C$ to $80 ^{\circ}C$. This paper propose a new concept strain gage which can improve accuracy and compensage effectively affects due to temperature. The strain gage is consists of two parts. One is the Hull Deformation Amplifier which introuce several lever and link system, and another is a transducer converting distance into voltage signal. The HDA measure the amount of deformation and amplify it. And a lever and link system of the HDA is introduced for compensating temperature deformation by installing in perpendicular direction without stress. This paper also reports on the results of the experiments to verify linearity of the strain gage.

• Journal of the Korean Institute of Navigation
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• v.23 no.2
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• pp.29-42
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• 1999

An accurate method of estimating ship maneuverability needs to be developed to evaluate precisely and improve the maneuverability of ships according to the water depth. In order to estimate maneuverability by a mathematical model. The hydrodynamic forces acting on a ship hull and the flow field around the ship in maneuvering motion need to be estimated. The ship speed new the berth is very low and the fluid flow around a ship hull is unsteady. So, the transient fluid motion should be considered to estimate the drag force acting on the ship hull. In the low speed and short time lateral motion, the vorticity is created by the body and grow up in the acceleration stage and the velocity induced by the vorticity affect to the body in deceleration stage. For this kind of problem, CFD is considered as a goof tool to understand the phenomena. In this paper, the 2D CFD code is used for basic consideration of the phenomena to solve the flow in the cross section of the ship considering the ship is slender and the water depth is large enough. The flow fields Added and hydrodynamic forces for the some prescribed motions are computed and compared with the preliminary experiment results. The comparison of the force with measurement is shown a fairly good agreement in tendency. The 3D Potential Calculation based on the Hess & Smith Theory is employed to predict the surge, sway added mass and yaw added moment of inertia of hydrodynamic coefficients for M/V ESSO OSAKA according to the water depth. The results are also compared with experimental data. Finally, the sway added mass of hydrodynamic coefficients for T/S HANNARA is suggested in each water depth.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.5
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• pp.371-379
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• 2016

In the ship design process, ship motion and propulsion performance in sea waves became very important issues. Especially, prediction of ship propulsion performance during real operation is an important challenge to ship owners for economic operation in terms of fuel consumption and route-time evaluation. Therefore, it should be considered in the early design stages of the ship. It is thought that the averaged value and fluctuation of effective inflow velocity to the propeller have a great effect on the propulsion performance in waves. However, even for the nominal velocity distribution, very few results have been presented due to some technical difficulties in experiments. In this study, flow measurements near the propeller plane using a stereo PIV system were performed. Phase-averaged flow fields on the propeller plane of a KVLCC2 model ship in waves were measured in the towing tank by using the stereo PIV system and a phase synchronizer with heave motion. The experiment was carried out at fully loaded condition with making surge, heave and pitch motions free at a forward speed corresponding to Fr=0.142 (Re=2.55×106) in various head waves and calm water condition. The phase averaged nominal velocity fields obtained from the measurements are discussed with respect to effects of wave orbital velocity and ship motion. The low velocity region is affected by pressure gradient and ship motion.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.674-680
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• 2014

Monitoring systems of informations for ship performance have become important gradually for economical management of existing ship. Monitoring of NOx emission from marine diesel engines is one of them. The measurement of NOx emission, however has been many difficulties due to technical and costly problems. A monitoring by prediction method of NOx on-board ship according to sailing condition of ship could be an useful method. In this paper, it is discussed about modified method of one-zone model which has been utilized usually for analyzing the combustion process. The modified method is able to calculate the temperature of burned region from the result by one-zone model. Influences which excess air ratio during combustion process affected for the gas temperature and NOx emission were investigated. From the results variation of excess air ratio during combustion process could be estimated inversely through the comparison with measurement of NOx emission.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.58-63
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• 2005

The estimation of springing responses for recent ships is carried out, and application to a ship design is described. To this aim, springing effects on hull girder were re-evaluated, including non-linear wave excitations and torsional vibrations of the hull. The Timoshenko beam model was used to calculate stress distribution on the hull girder, using the superposition method. The quadratic strip method was employed to calculate the hydrodynamic forces and moments on the hull. In order to remove the irregular frequencies, we adopted 'rigid lid' on the hull free surface level, and addedasymptotic interpolation along the high frequency range. Several applications were carried out on the following existing ships: The Bishop and Price's container ship, S-175 container ship, large container, VLCC, and ore carrier. One of them is compared with the ship measurement result, while another with that of the model test. The comparison between the analytical solution and the numerical solution for a homogeneous beam-type artificial ship shows good agreement. It is found that Most springing energy comesfrom high frequency waves for the ships having low natural frequency and North Atlantic route etc. Therefore, the high frequency tail of the wave spectrum should be increased by $\omega$$\^{-3}$ instead of $\omega$$\^{-4}$ or $\omega$$\^{-5}$ for the springing calculation.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.8
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• pp.939-946
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• 2007

The purpose of this study is to measure and analyze the ship's indoor thermal conditions and also to integrate experimental database of those, supplied and controlled by ship's HVAC. On this study, temperature, humidity and air volume of 6 different needs' cabin are measured on a newly-launched training ship during 2nd through 5th of April, 2007. Followings are the results of this study. (1)Because only partial loads are needed in spring season, the air volume from diffusers are measured as below 20%. (2)The temperatures are ranged between $20{\sim}25^{\circ}C$ and those are within comfort temperature range proposed by AHREA. (3)But humidities in cabins are very low and it could be the reason of a cold and/or a skin disease. (4)From the student cabins' measurements which have different supply diffuser(s), it is clear that the design is suitable for this case. (5)Because of low humidity, only 16.1% among the measured data are satisfied with the comfort standard range proposed by ASHREA. To improve the predictability and the comfort, HVAC should maintain the humidity as $40{\sim}60%$.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.173-178
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• 2004

The estimation of springing responses for recent ships are carried out and application to a ship design are described. To this aim, springing effects on hull girder were re-evaluated including non-linear wave excitations and torsional vibrations of the hull. The Timoshenko beam model was used to calculate stress distribution on the hull girder by the superposition method. The strip method was employed to calculate the hydrodynamic forces and moments on the hull. In order to remove the irregular frequencies, we adopted 'rigid lid' on the hull free surface level and added asymptotic interpolation along the high frequency range. Several applications to the existing ships were carried out. They are Bishop and Price's container ship, S-175 container ship, large container, VLCC and ore carrier. One of them is compared with ship measurement result while another with that of model test. Comparison between analytical solution and numerical one for homogeneous beam type artificial ship shows good agreement. It is found that most springing energy came from high frequency waves for the ships having low natural frequency and North Atlantic route etc. Therefore, the high frequency tail of the wave spectrum should be increased by $\omega^{-3}\;instead\;of\;\omega^{-4}\;or\;\omega^{-5}$ for springing calculation.

• Journal of Navigation and Port Research
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• v.27 no.1
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• pp.15-30
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• 2003

The shipboard working environment of coastal patrol ship is very inferior to the ground working environment and it cause the avoidance of shipboard working and the aging of crew. Especially the noise in ship cause on occupational shipboard working hardness of hearing. Hence to reduce the shipboard working fatigue is necessary by the security of the comfortable shipboard working environment and residence environment. in this paper, firstly we evaluate the shipboard working by suing the measurement results of the evaluation results of the shipboard working environment.