• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.4
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• pp.61-70
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• 1982

The hydrodynamic effects on resistance and propulsive performance were studied by using the data from model test and full scale speed trials. A series of model tests on 3 geosims for a 60,000 DWT Bulk Carrier was conducted at KIMM's Ship Experimental Towing Tank and the results analyzed by 1978 ITTC Performance Prediction Method show the correlation between 3 geosim models. Also powering data of full scale speed trials were analyzed by the newly developed computer program and the correlation analysis between ship and model was studied.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.29-33
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• 2002

There are a lot of errors and little accuracy when calculating the grounding resistance with the transposition methods in the equivalent surface of hemisphere electrode. Therefore we should calculate the grounding resistance by using the mesh factor, In this paper, we would estimate the grounding value of mesh electrode with water tank model & estimation method using the reduced scale ratio of mesh electrode based on the theory of model electrode & proportional factor according to the reduced scale ratio. And also we have confirmed the accuracy of the empirical formula of model electrode by using the regression analysis.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.4
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• pp.265-273
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• 2002

In this paper, wave absorbing characteristics of a horizontal submerged punching plate are investigated throughout the calculation and the experiment. The punching plate with the array of circular holes can force the flow to separate and to form eddies of high vorticity and cause significant energy loss. As an analytic tool, the linear water wave theory and the eigenfunction expansion method is applied. Darcy's law that the normal velocity of the fluid passing through the punching plate is linearly proportional to the pressure difference between two sides of the punching plate is assumed. The proportional constant called the porous coefficient is deeply dependent to the porosity. To obtain the relationship between the porosity and the porous coefficient the systematic model test for the punching plates with 6 different porosities is conducted at 2-dimensional wave tank. It is found that the porous coefficient is linearly proportional to the porosity(b=57.63P-0.9717). It is also noted that the optimal porosity value is near P=0.1 and the optimal range of submergence depth is $d/h\\leq0.2$ within entire frequency range.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.3
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• pp.190-196
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• 2002

In order to analyze the hydrodynamic forces on fish cage systems, made of frames and nettings, under waves and current, hydraulic model experiments for square type and circular type of fish cage system were carried out in a towing tank. Both cage systems consist of net cages supported by floating frames made of two concentric pipes and four weights hanging from the bottom corners of the nets. There was little difference in the hydrodynamic force on the square type of fish cage system by wave heading under regular waves and the peak frequency of the force on each cage system was in a good agreement with that of induced irregular wave. In addition, it was also observed that the circular type of cage system was more stable to the action of waves and current than the square type.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.114-118
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• 1987

The authors carried out a model experiment to examine the hydrodynamic charactristics of the simple camber and the super-V otter board. The model otter boards are made of 1 mm thick iron plate. The simple camber otter board is made to have $12\%$ camber ratio and $432\;cm^2$ plane projected area, and the super-V otter board to have the same camber ratio as the former in every latitudinal section and almost the same plane projected area. The experiment had been done in a circular flow tank in the speed range of $0.1\~1.2m/sec$. As a result, it is examined that in the simple camber otter board the most effective angle of attack is about $25^{\circ}$, the shearing coefficient 1.47 and the drag coefficient 0.42, while in the super-V otter board they are about $20^{\circ}$, 1.40 and 0.40 respectively, so that the simple camber otter board performs a little better efficiency than the super-V otter board.

• Geotechnical Engineering
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• v.14 no.6
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• pp.139-151
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• 1998

SI anchor means the soil improvement anchor. The ground for supporting anchor is improved by JSP, and as a result, SI anchor body has about 80cm in diameter. SI anchor shows high pullout resistance by the frictional force between anchor body and ground, and the bearing capacity of anchor body. Especially the frictional force increases very much with increasing diameter of anchor body improved by JBP. In this study, model and field tests are made to analyse the mechanism of pullout resistance of SI anchor. Through model tests for the SI anchor in air dried sandy ground, strain fields of ground around SI anchor surface are analysed by a photo analysis method using the latex membrane on the wall of soil tank. The results of field tests are analysed by the strains measured by 10 strain gages attached on the inner wall of specially designed PVC pipe embedded in anchor body, and the strains of anchor body are also measured in the model tests.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.1
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• pp.52-61
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• 2001

It is necessary to obtain the well-documented local flow measurement data for the validation of CFD prediction of hydrodynamic performance. In the present paper the local flow fields around the stern region of a VLCC model with drift angles of $0^{\circ},\;5^{\circ},\;and\;10^{\circ}$ are measured. Mean velocity components are documented at St. 2 and A.P. of both port and starboard side of KVLCC in KRlSO towing tank. Flow information associated with the formation of four discrete vortices in the stern region is explored. The present experimental data can provide a good test case to validate the accuracy of numerical modeling for stern flow and maneuverability prediction of modern tanker hull forms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.6
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• pp.484-488
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• 1987

The model experiments were performed in tile circular water tank on the simple cambered and the super-V otter boards attached with the slotted fowler flap at the trailing edge in order to develop more efficient shearing characteristics. The dimension of the model otter boards was varied slightly in the flap chord ratio $0.20\~0.22$ and in the area $432\~426cm^2$ in accordance with the flap angle $30\~50^{\circ}$. The maximum shearing coefficient $C_L=1.78$ and hydrodynamic efficiency $C_L/C_D=4.0$ in the superV type were higher than their efficiencies $C_L=1.75$ and $C_L/C_D=3.7$ in the simple cambered type. As the shearing forces of the otter boards with flap were increased $20\~30\%$ mere than these without flap in spite of increasing the drag and the instability. The effect of flap should be fully investigated for the application.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.1-13
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• 1994

Procedures for the development of a preswirl stator-propulsion system for a VLCC 300K are described in this paper. The preswirl stator-propulsion system is one of the compound propulsor systems, which is used for the purpose of recovering propeller slipstream rotational energy by locating a stator in front of the propeller. The preswirl stator-propulsion system can be considered as a most reliable energy saving device because of its simple mechanism. Five stators are designed for the existing hull form and propeller, and their effects are verified by model tests. Open-water test result of the preswirl stator-propulsion system at the cavitation tunnel show $4{\sim}6%$ increase of open-water efficiency compared to that of a propeller without stators. Maximum 6.5% decrease of delivered power at the design speed(15.5knots) is expected with the designed stator based on the analysis results of resistance and self-propulsion test at the towing tank.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.601-608
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• 2019

In this study, the effect of hull appendages on the high-speed catamarans with reverse bow shapes is compared and analyzed by numerical analysis and circulating water tank model test. The reverse bow shape showed an improved wave shape by shifting the generation position of forward divergent wave to the stern direction and was effective in resistance and stable running posture (Kim et al., 2019). In the model test results of the running performance as the wave patterns and the change of the running posture due to the fin fitted with the inner side of the inverted bow and the interceptor, 1) Trim characteristics of the inverted bow 2) Improvement of superposition of inner wave by Fin 3) The trim control by the fin and the interceptor is considered to be effective in reducing the impact of the two hull connection decks (wetdeck).