• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.3
• /
• pp.421-429
• /
• 2008

Various kinds of ship are operated to transport cargo or passengers at sea in the world. Most of the important auxiliary machineries installed in those ships are fluid machineries such as pumps, compressors, and fans. A large percentage of fluid machinery is pumps which are classified turbo and positive displacement pumps. This paper analyzes only positive displacement pumps. This thesis has two aims: (a) to analyze the present status of pumps installed in merchant and training ships and (b) to find the correlation among sea going pump kW, port pump kW, total pump kW, GE kW, ME MCR, number of pumps, ME kgf, pump kgf. Based on ship's type, this paper seeks to find special characteristics as a result of analyzing head, flow rate, and kW. Moreover this paper analyzes and compares number of pumps, pump kW/ME MCR, pump kW/GE kW under the conditions of seagoing and berthing according to ship's type.

• Journal of Mechanical Science and Technology
• /
• v.14 no.11
• /
• pp.1257-1266
• /
• 2000

The flow field if a ship's propulsion mechanism of Weis-Fogh type is studied by the discrete vertex method. The wing in a channel is approximated by a finite number of bound vortices, and free vortices representing the separated flow are introduced from the trailing edge if the wing. The time histories of the thrust, the drag, and the moment acting on the wing are calculated, including the unsteady force due to the change of strength of the bound vortices. These calculated values agree well with the experimental values. The flow field of this propulsion mechanism is numerically clarified.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.2
• /
• pp.426-437
• /
• 1993

The flowfield of Weis-Fogh type ship's Propulsion is visualized by numerical simulations using the discrete vortex method and by the hydrogen bubble technique. The simulations are performed by assuming that the separations occur at the trailing edge of the wing. The streak lines and time lines are calculated by introducing the tracers at adequate intervals. They agree well with experimental results. The flowfield is unsteady and complex, but the properties of the flow are clarified by numerical and experimental visualization.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.11
• /
• pp.1518-1526
• /
• 1997

The dynamic properties of a ship's propulsion mechanism of Weis-Fogh type are studied by the discrete vortex method. The wing in the channel is approximated by a finite number of bound vortices and free vortices representing the separated flow are introduced from the trailing edge of the wing. The time histories of the thrust, the drag, and the moment acting on the wing are calculated, including the unsteady force due to the change of strength of the bound vortices. These calculated results show a similar tendency to the experimental ones qualitatively and the dynamic properties of this propulsion mechanism are numerically clarified.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.14 no.2
• /
• pp.1-9
• /
• 1977

Streamlines around a ship's hull can be calculated by using streamline tracing method replacing the ship section with distribution of singularity. The influence of frame lines on the stream surrounding a hull surface, however, can not be found. Jinnaka studied on streamlines for Lewis form by applying the slender body theory. The influence of frame lines on stream surrounding a hull surface is well found in Jinnaka's method. In this paper streamline calculation method for chine type has been developed by using conformal transformation and applying slender body theory as Jinnaka did. Three kinds of model-one of series 62 for chine type, V.L.C.C. and high speed craft built in Korea for Lewis form-were used for streamline calculation;

• Journal of the Society of Naval Architects of Korea
• /
• v.31 no.3
• /
• pp.112-118
• /
• 1994

In this paper, statistical approach to prediction of A-weighted noise level in ship cabins. based on multiple linear regression analysis, is conducted. The best regression formula is composed of seven parameters of the deadweight, the type of ship, the location of engines and cabins, the type of deckhouse and the propeller skew angle. Verification work was carried out with other 210 cabins' data in 6 ships. As a result, the formula ensures the accuracy of 3 dB(A) in 77 % of cases.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.05a
• /
• pp.70-75
• /
• 2001

Intensive experimental investigations were carried out to provide information of the effects of inflow on the rolling characteristics and stability of ships, which becomes great concern in relation to ship's capsizing. A series of systematic experiments have been performed considering the effects cf combined motion of roll-heave-sway and relevant parameters, such as roll angle and period, tank water height etc. To accommodate this type of experiments with 3-degree of freedom of motion, a bench tester has been developed and verified using existing data. Also, theoretical application of anti-roll tank has been incorporated to support the process of investigation. A model of Ro-Ro ships is used in the present study as this type of vessels, as well as fishing vessels, with large open decks, can loose stability rapidly when there is inflow on the decks.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1997.10a
• /
• pp.185-202
• /
• 1997

Hull forms of ancient ships in Korea and China have been changed according to their voyages and routes. Therefore it is necessary for shipbuilding engineers to reestablish the ancient shipbuilding history, and to presume, restore and revive the lost cultural inheritances. We, however, do not have many historical documents or credible materials that can our ancestors' great shipbuilding techniques : at the same time we do not have paid much attention to the research on such documents and materials. This paper aims not only to study and compare shifting process of ancient ship's hull forms in Korea and China by making use of verifiable materials obtained in the process of excavating and restoring Shinan ancient ship. The results of comparing structural characteristics and hull forms of ancient ships in Korea and China and as follwing : (1) Korean ancient ships have transverse beam instead of frame . Judged from the bottomform, Korean ancient ships are grooved clinker type ships of flat bottom type, in which bottom planking is fixed by wooden bar. (2) Chinese ancient ships have transverse bulkhead structure instead of frame, Judged from the bottom form , Chinese ancient ships are rabetted clinker type ships of V-bottom type with a bar keel. The form , the position, and the size of a sail are closely related with the wind force. It is not only quite difficult to presume forms and sizes of ancient ships' sails precisely, but also impossible to come to an accurate conclusion wihtout much experience. Current 10-year-statistics of the wind force are used to obtain presumed routes of ancient ships in Korea and China. Conclusions obtained from the hull form , sail form and size , and mast height of Shinan ancient ship will provide credible data for sea trade routes and transformation capability, and wil be used for effective materials on the study of the shifting process of ancient ships in Korea and China.

• Journal of the Society of Naval Architects of Korea
• /
• v.55 no.5
• /
• pp.401-414
• /
• 2018

Planing hull type ships are often equipped with interceptor or trim tab to improve the excessive trim angle which leads to poor resistance and sea keeping performances. The purpose of this study is to design a controller to control the attitude of the ship by controllable stern interceptor and validate the effectiveness of the attitude control by the towing tank test. Embedded controller, servo motor and controllable stern interceptor system were equipped with planing hull type model ship. Prior to designing the control algorithm, a model test was performed to identify the system dynamic model of the planing hull type ship including the stern interceptor. The matrix components of model were optimized by Genetic Algorithm. Using the identified model, PID controller which is a classical controller and sliding mode controller which is a nonlinear robust controller were designed. Gain tuning of the controllers and running simulation was conducted before the towing tank test. Inserting the designed control algorithm into the embedded controller of the model ship, the effectiveness of the active control of the stern interceptor was validated by towing tank test. In still water test with small disturbance, the sliding mode controller showed better performance of canceling the disturbance and the steady-state control performance than the PID controller.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.4
• /
• pp.467-474
• /
• 2018

The purpose of this study is related to automatic hull-form design for ships operating at two speeds. Research was conducted using a series 60 ($C_B=0.6$) ship as a target, which has the most basic ship hull-form. Hull-form development was pursued from the viewpoint of improving resistance performance. In particular, automatic hull-form design for a ship was performed to improve wave resistance, which is closely related to hull-forms. For this purpose, we developed automatic hull-form design software for ships by combining an optimization technique, resistance prediction technique and hull-form modification technique, appling the software developed to a target ship. A sequential quadratic programming method was used for optimization, and a potential-based panel method was used to predict resistance performance. A Gaussian-type modification function was developed and applied to change the ship hull-form. The software developed was used to design a target ship operating at two different speeds, and the performance of the resulting optimized hull was compared with the results of the original hull. In order to verify the validity of the program developed, experimental results obtained in model tests were compared with calculated values by numerical analysis.