• Journal of Advanced Marine Engineering and Technology
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• v.21 no.5
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• pp.474-481
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• 1997

Waterjet propulsion generally refers to propulsion of ships by internally mounted pumps with proper ducting. This arrangement of the actuator component of the system leads to the fundamental differences with respects to screw propeller system. In this paper, the basic hydrodynamic characteristics of waterjet propulsion was outlined to clarify the application consideration and proposal for carrying out model self-propulsion tests with waterjet propelled models was presented. The results of model self-propulsion tests carried out in the Hyundai Maritime Research Institute towing tank with catamaran ship were presented.

• 한국기계연구소 소보
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• s.10
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• pp.63-77
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• 1983

This paper presents the hydrodynamic performance characteristics of a planing boat which was tested with a new dynamometer system specifically designed to measure towing force along the thrust plane, the change in trim angle and the vertical displacement of the model center of gravity from still water condition. The test conditions include systematic variations in the three positions of LCG and the three load coefficients of a high speed planing boat.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.1
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• pp.58-68
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• 2002

The model experiments for the Eastern sea bottom trawl were conducted for the 3 types of ground ropes and 2 types of seabeds to examine drag characteristics according to towing speed. The model net was based on the net of trawler with 750ps and made by 1/78 of a full scale net. This experiments focused on the drags for 3 types of ground rope, the serving wire, the original and the chain types and 2 types of seabeds, mud and sand of bottom. The results obtained are summarized as follows 1. In the case of the sand bottom, the drags by 3 types of ground rope were orderly increased in turn of the chain, the serving wire and the original type. But, in the case of the mud bottom, the drag of the original type is higher than that of the serving wire type and less than the chain type. 2. In the case of the serving wire type of ground rope, the drags by the diameters of ground rope, ø 1.3, ø 1.9, ø 2.6 and ø 3.25 were increased respectively by 23g, 25g, 32g and 42g at the towing speed of 0.4m/s. 3. The drags of ground ropes were increased exponentially in proportion to the towing speed, in the same way in all of three types of ground rope. 4. The ratios of drag of ground rope against that of the trawl net by the type of ground rope at the towing speed of 0.4m/s on the mud bottom were 0.69 in the chain type, 0.64 in the serving wire type and 0.67 in the original type respectively. 5. The Coefficient of drag($C_d$) by type of ground rope according to the towing speed were 10.0~56.7, 3.0~l6.0 and 1.5~8.5 respectively in turn of the chain type, the serving wire type and the original type on the mud bottom, and that on the sand bottom were 10.0~60.0, 3.0~14.0 and 1.2~6.0 respectively In turn of the chain type, the serving wire type and the original type.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.597-603
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• 2012

It is necessary to accurately evaluate the resistance performance and estimate the towing power of a tugboat for safety towing operation at actual seas. In this study, we have carried out the model tests firstly to investigate the resistance performance and flow characteristics around the tugboat in still water. The experiments are performed in infinite depth in circulation tank using 1/33.75 scaled model from 5kts to 10kts(designed speed 7kts) considering the effect of adverse and favorable current. Then the numerical calculations are executed to analyze the response amplitude operator and added resistance on tugboat due to the waves. The results obtained by the present computation are compared with the those acquired from the experiments in still water. As a result, it is noted that the added resistance become larger at head sea and higher speed conditions. We can also observe that the EHP increase 70 percent in comparison with those in still water.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.91-95
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• 2007

It tries to develop a collect system for floating garbage flowed into the sea Based on the study on the characteristics of floating garbage in rainy season, it confirmed the structure and specification of each device and tested its performance on the sea It showed tint the collection device of this system could sweep more than 15 meters of sea area at a time when a ship moves with the efficiency of the spreading device. It means tint it is more efficient in collecting garbage than now in use garbage collecting ships. The water height of the net to which the garbage is finally input maintained more 50cm within the towing speed of 5kt. It indicates tint the garbage input performance is good The collect system of this research showed good performance collecting 200kg of garbage into the net for each test of collecting floating garbage.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.3
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• pp.102-116
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• 1992

This report is to provide a comparison of the hydrodynamic characteristics of a single strut SWATH(Small Waterplane Area Twin Hull) model and a tandem(twin) strut SWATH model. The hydrodynamic characteristics included are the resistance in calm water, 6 degree freedom of motion responses in stationary and with forward speeds, and wave loadings etc. All these quantities are measured in the towing tank and compared with the computational results. Based on the present study, the pros and cons for single and tandem strut SWATH designs are clarified and some design suggestions are made.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.2
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• pp.1-10
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• 2003

It is important to understand the flow characteristics such as wave and wake development around a ship for the design of the hull forms with better resistance and propulsive performance. The experimental results explicating the local flow characteristics are also invaluable for validation of the physical and numerical modeling of CFD codes, which are recently gaining acknowledgements as efficient tools for hull form evaluation This paper describes velocity and wave profiles measured in the towing tank for the KRISO 138K LNG Carrier (KLNG) model with propeller and rudder. The results contained in this paper can provide the valuable information on the effect of propeller and rudder on stern flow characteristics of the modern commercial hull form, furthermore, the present experimental data will provide important database for CFO validation.

• Journal of Ship and Ocean Technology
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• v.1 no.1
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• pp.15-25
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• 1997

A series of towing tank tests were carried out for 18 full ship models of high block coefficients. The resistance coefficients and wake distribution at the propeller plane were measured and carefully examined. Regression analysis was employed to find out the relationships with the hull form parameters. Equations for wave resistance coefficient, form factor, and nominal wake are given. A harmonic analysis of measured wake was performed to look into the influence of the local stern shape on the magnitude of fluctuating wake components at three different radii. The amplitude of wake harmonics was also expressed by regression quations. It was found that the regression formulas were very useful in estimating resistance and circumferential wake characteristics of full ship models. It was also considered that the formulas presented in this paper could be utilized in the hull form improvement in a preliminary design.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.4 s.148
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• pp.440-450
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• 2006

In this paper, we suggest a design concept of defining the propeller geometry by stacking up the blade sections aligned with propeller surface streamlines. Numerical and experimental propeller open water(P.O.W.) characteristics of a newly designed propeller are presented. The surface streamlines for a propeller are obtained by using the panel method. Redefinition of the blade sections aligned with the streamlines is provided together with 8-spline modeling, by which we manufacture model propellers. We carried out the P.O.W, tests in a towing tank in order to show the effect of the present method on P.O.W. characteristics.

• Journal of Ship and Ocean Technology
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• v.4 no.1
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• pp.28-36
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• 2000

Numerical simulation based on the superposition of ring waves generated by the linear periodic source distributions for the plunger type wave maker was accomplished. The characteristics of directional spreading function were investigated. Mirror images are also introduced to consider reflections of side-wall together with the reflection coefficient to account for the imperfect reflection from the real side wall in the long experimental towing tank. Unexpected spurious waves, resulting from the combined effect of finite breadth of segmented wave maker, wavelength and main wave maker, wavelength and main wave propagating direction, were observed in the line source method and also in the analysis of the directivity. The influence of spurious waves to the directional spreading function was also investigated.