• Journal of the Korean Institute of Navigation
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• v.7 no.2
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• pp.65-113
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• 1983

A lot of studies of ship's economy are on the traditional fields such asreducing propulsion resistance, raising cargo handling rates and lessening building consts, but there are few researches on the merchant ship's economy concerning their deadweights and speeds according to shipping companies managerial cercumstances. Contrary to the contemporary trend that "the bigger, the better, if the cargo handling rate could increased sufficiently to hold down port time to that rate of smmaler vessels", this paper demonstrates the existence of certain limits in ship's size and speed according to the coditions of the freight rates, voyage distances, cargo handing rates, prices of fuel oil, interst rates etc. Fom the curves of criteria contour for various ship's deadweights and speeds which are depicted from the gird search method, one can get the costs and the yearly profit rates under the conditiions of large volume with long term contracts for the transportation of bulk cargoes. In estimating ship's transportation economy, the auther takes the position that the profit rate method is properer than the cost method, and introduces the calculation table of the voyage profit rate index. The use of the criteria contours will be of help to ship owners in determining the size and speed of the ship which will be built or purchased and serve in a certain trade route.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.364-379
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• 2019

Wave-induced ship motion and load responses are usually investigated on the assumption that the incident waves are long-crested. The realistic sea waves are however short-crested irregular waves. Real practice reveals that the ship motion and load responses induced by short-crested waves are different from those induced by long-crested waves. This paper aims to conduct a comprehensive study on ship motions and loads in different wave fields. For this purpose, comparative studies by small-scale model towing tank test and large-scale model sea trial are conducted to experimentally identify the difference between ship motions and loads in long-crested and short-crested irregular waves. Moreover, the influences of directional spreading function of short-crested waves on ship motions and loads are analyzed by numerical seakeeping calculation. The results and conclusions obtained from this study are of great significance for the further extrapolation and estimation of ship motions and loads in short-crested waves based on long-crested wave response results.

• Journal of Korean Port Research
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• v.6 no.2
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• pp.33-42
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• 1992

In this paper we investigate the motion response of a moored ship in the fluid region sheltered by inclined breakwaters. The matched asymptotic expansion technique is employed to analyze the wave fields scattered by the inclined breakwaters. Fluid domain is subdivided into the ocean, entrance and sheltered regions. Unknown coefficients contained in each region can be determined by matching at the intermediate zone between two neighboring regions. The wave field generated by the ship motion can be analyzed in terms of Green's function method. To obtain the velocity jump across the ship associated with the symmetric motion modes, the sheltered region is further divided into near field of the ship and the rest field. The image method is introduced to consider the effect of the pier near the ship. The integral equation for the velocity jump is derived by the flux matching between the inner region and the outer region of a moored ship. Throughout the numerical calculation it is found that the inclined angle width of entrance of breakwaters as well as the location of moored vessel play an important role in the motion response of a moored ship.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.3
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• pp.258-273
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• 1987

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.3
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• pp.27-38
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• 1986

In the recent years, the finite element method has been a leading method in calculating the strength of ship hull structural members. But such a calculation has many difficulties in constructing data, reducing CPU-time and connecting it with optimal design. This paper describes more efficient method for three dimensional strength calculation of the hull structure of oil tanker by using the slope-deflection method, and the computer program based on this method is developed. The results of the calculation by using this method are compared with those by using the SAP4 program based on the finite element method. Some advantages are obtained from the application of the slop-deflection method described in this paper in the calculation of the hull structure oil tanker.

• 한국기계연구소 소보
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• s.9
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• pp.153-167
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• 1982

From first-order thin-ship theory, we can obtain the" wave resistance, wave amplitude functions, wave elevation along the hull, sinkage and trim of a ship moving with constant speed into calm water. Generally, these calculations of ship is called with Michell’s Theory, and there is all the difference between calculated wave resistance and residual resistance from conventional wave resis¬tance test. But, these calculated results are important reference materials for initial hull form design procedure. Various calculated results for Shearer’ s Model, Wigley’s Model and Series 60 4210W Model have been calculated using this theory. The results are compared with the corresponding experimental values, and the agreement between theoretical and experimental values is considered satisfactory.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.17-22
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• 1993

The intersection problem of three-dimensional free form surfaces can be solved by geometrical and numerical methods. Up to now, the subdivision technique, which is classified under the former, has been largely employed to find the cross section of ship hull form. In this paper, an algorithm is presented for intersecting ship hull form in high speed. The high speed calculation algorithm is based on simple numerical methods, such as the secant method, false position method and bisection method. The algorithm is directly applicable to depicting arbitrary ship cross sections, drawing ship lines and constructing the offset table.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.6
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• pp.30-36
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• 2003

To improve survivability of damaged ship, assessment of stability and structural safety, and behavior analysis in wave is required. Prediction of sinking time, damage stability and structural strength considering progressive flooding and dynamic force in wave is very important. To do it, a geometric model which can be express damaged ship is prepared. This paper described the geometric modeler for survivability assessment of damaged ship. The modeler is developed based on 3-D geometric modeling kernel, ACIS. The hull form and compartment definition is available fundamentally. And requirement for modeler contains data generation and interface for hydrostatic calculation, behavior analysis, and longitudinal strength analysis and so on. To easy access modeling system by conventional user such as crew, user interface is developing.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.2
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• pp.14-20
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• 1986

Through the momentum considerations, added resistance of a ship in regular waves are studied within the framework of the linear potential theory for a ship moving with a constant mean forward speed. In this paper, added resistance in head waves with comparably small wave length is focused by modifying the Marou's method. The strength of the singularities for the Kochin function is modified by considering the diffraction potentials. Slender body theory is used to determine the diffraction potentials as Adachi did. The response of a ship motion is found by using new strip method. For the purpose of comparison with the present method, calculation was also conducted by Marou's and Gerritsma-Beukelman's method. Numerical calculations are performed for five different models, that is, series 60(Cb=0.6, 0.7, 0.8), S7-175 container ship and blunt bow model. Numerical results obtained by the present method show relatively good corelations comparing with experimental results in the region under considerations.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.202-207
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• 2001

The added resistance of a ship advancing in waves can be split into the resistance due to the radiation wave and the resistance due to the diffraction wave. In this study, the former has been calculated by a method based on Maruo's formula. The latter must be calculated by other methods. Ship motion is calculated by the usual strip method. The amplitude of two dimensional far-field waves is calculated using the improved Green integral equation. The present numerical method can be used for the estimation of the added resistance due to the radiation wave since the present numerical result is much smaller than other existing numerical results considered to be overestimated.