• 대한조선학회지
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• 제24권2호
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• pp.11-19
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• 1987

A Series 60, $C_b=0.60$ model was tested in the towing tank of Seoul National University. Total resistance, hull attitude, wake distributions and wave measured at FR condition(free trim and sinkage) and FX condition(fixed trim and sinkage). From the measured data, residual, viscous and wave pattern resistance components were evaluated and compared. It is found that the changes in wetted surface area should be considered in predictions of frictional resistances, and can be easily found from hydrostatic data and measured mean sinkages without additional tests. Applications of the concept to the geosim tests of Series 60, Wigley, Lucy Ashton models show that the conventional extrapolation method can be improved considerably.

• 수산해양기술연구
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• 제28권2호
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• pp.228-239
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• 1992

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. Some numerical results for series 60, C sub(b) =0.6, hull are presented in this paper. The wave pattern and wave resistance are computed at two Froude numbers, 0.267 and 0.304. These results are better than those of Michell's thin ship theory in comparison with measured results. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

• Journal of Ship and Ocean Technology
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• 제9권3호
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• pp.1-13
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• 2005

A design procedure for a ship with minimum total resistance has been developed using a numerical optimization method called SQP (Sequential Quadratic Programming) to search for optimized hull form and CFD(Computational Fluid Dynamics) technique. The friction resistance is estimated using the ITTC 1957 model-ship correlation line formula and the wave making resistance is evaluated using a potential-flow panel method based on Rankine sources with nonlinear free surface boundary conditions. The geometry of hull surface is represented and modified using B-spline surface patches during the optimization process. Using the Series 60 hull ($C_B$ =0.60) as a base hull, the optimization procedure is applied to obtain an optimal hull that produces the minimum total resistance for the given constraints. To verify the validity of the result, the original model and the optimized model obtained by the optimization process have been built and tested in a towing tank. It is shown that the optimal hull obtained around $13\%$ reduction in the total resistance and around $40\%$ reduction in the residual resistance at a speed tested compared with that of the original one, demonstrating that the present optimization tool can be effectively used for efficient hull form designs.

• 대한조선학회논문집
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• 제31권4호
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• pp.58-65
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• 1994

계산격자크기의 변화에 따른 해의 특성을 이해하는 것은 중요하며, 특히 벽함수를 사용하지 않는 난류모형을 사용할 때 더욱 그러하다. 본 논문에서는 배주위의 3차원 난류유동장에 대한 수치해의 격자의존성에 대한 수치계산적인 조사를 수행한다. 본 연구에서는 수정된 sub-grid-scale 난류모형과 함께 유한체적법을 사용하며 복잡한 배의 기하학적 형상에 적합한 비직교의 곡선좌표계를 수치적으로 만들어 사용한다. 그리고 수학선형인 Wigley 선형과 Series 60($C_B=0.8$) 선형에 대하여 수치계산적인 연구를 수행하고, 수치해의 격자의존성을 보이기 위하여 여러가지 격자크기에 대한 계산결과들을 서로 비교하였으며 실험결과와도 비교해 보인다.

• 대한조선학회지
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• 제25권4호
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• pp.7-12
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• 1988

국제선형시험수조회의의 저항시험에 관한 표준선형인 Series 60, $C_B=0.60$에 대하여 서로 크기가 다른 5척의 모형선을 국내의 선형시험수조 보유기관(한국기계연구소 선박분소, 현대선박해양연구소, 서울대학교, 인하대학교)에서 제작, 교환하여 상사모형시험을 수행하였다. 이 결과를 Hughes 및 Telfer의 방법에 따라 해석하여 형상계수와 모형선의 크기 및 예인속도와의 관계를 파악하고자 했다. 이 선형에 대해서 형상계수는 Reynolds 수 뿐만 아니라 Froude 수에 따라서도 변화하는 것을 확인하였다. 또한 현행의 형상계수를 이용한 실선저항추정법이 공학적 유용성을 가지고 있음을 재확인하였다. 선형특성이 다른 여러 선형에 대해서 상사모형시험을 실시하므로서 보편적인 원리를 파악하는 것이 필요하다고 판단된다.

• 대한조선학회논문집
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• 제38권1호
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• pp.43-51
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• 2001

본 연구는 랜킨소오스법과 저차 패널법을 이용하여 파랑 중 선박의 비정상 문제를 해석하였다. 기본유동을 균일 입사 유동(소위 Kelvin 유동)과 이중모형 유동의 두 가지로 가정하여 지배방정식과 경계조건을 만족하는 해를 구하고 비교하였다. 수정 Wigley 선형과 Series 60($C_B=0.7$) 선형에 대해 동유체력을 계산하여 실험 값 및 기존의 계산 값과 비교하였다. 이중모형에 의한 계산 값이 균일 입사 유동에 의한 계산 값보다 실험 치에 보다 더 가까운 결과를 보였다.

• 대한조선학회논문집
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• 제51권6호
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• pp.459-479
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• 2014

This paper considers experimental and numerical studies on added resistance in waves. As the numerical methods, three different methods, strip method, Rankine panel method and Cartesian-grid method, are applied. The computational results of vertical motion response and added resistance are compared with the experimental data of Series 60($C_B=0.8$) hull, S175 containership and KVLCC2 hull. To investigate the influence of above-still water hull form, a Rankine panel method is extended to two nonlinear methods: weakly-nonlinear and weak-scatterer approaches. As nonlinear computational models, three ships are considered: original KVLCC2 hull, 'Ax-bow' and 'Leadge-bow' hulls. Two of the three models are modified hull forms of original KVLCC2 hull, aiming the reduction of added resistance. The nonlinear computational results are compared with linear results, and the improvement of computational result is discussed. As experimental approach, a series of towing-tank experiment for ship motions and added resistance on the three models (original KVLCC2 hull, 'Ax-bow' and 'Leadge-bow') are carried out. For the original KVLCC2 hull, uncertainty analysis in the measurement of vertical motion response and added resistance is performed in three waves conditions: ${\lambda}/L=0.5$, 1.1, 2.0. From the experimental results, the effects of hull form on added resistance are discussed.

• 대한조선학회논문집
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• 제47권5호
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• pp.671-679
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• 2010

This paper introduces a new hull form design method for the bow of a full ship, by actively applying the relation between the fore-body hull form and its wave resistance characteristics. For the hull form design, the Series 60($C_B=0.8$) hull is chosen as the parent ship, and Kracht's charts are used to determine the parameters of the bulbous bow in the early stages of hull form design. Several hull forms have been tested in order to obtain enough hull form variations with various bow shapes and design parameters in the search of the best design. In order to investigate the resistance characteristics of the designed hull forms, numerical simulations with corresponding model tests have been rigorously performed. For the numerical simulations, the Marker-density method is employed to track the nonlinear phenomena of the free surface(program IUBW). Model tests have also been performed to achieve an improved research performance using the designed hulls. Both numerical and experimental results show that the wave resistance of the hull forms can be effectively diminished if the bows are designed using the method introduced in this research. It is also expected that this research can facilitate better productivity in hull form design, especially at the preliminary design stage of a full ship type vessel.

• 대한조선학회지
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• 제25권3호
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• pp.19-25
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• 1988

The three-dimensional boundary value problem for the unsteady motion of a ship which is translating and oscillating on the free surface of a deep water formulated. Under the assumption that the forward speed is small and order of $\varepsilon$, all formulations are made up to the first order of $\varepsilon$. For the numerical calculation, the three-dimensional source distribution method is applied, and the triangular elements are used to represent the hull surface. The results for the added mass and the damping coefficient for Series 60, $C_B=0.7$ at Fn=0 and Fn=0.2 shows good agreements with those of Inglis, Chang, and Inglis and Price.

• 대한조선학회지
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• 제24권1호
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• pp.9-16
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• 1987

The second-order steady horizontal force and vertical moment are derived for a freely-floating body in water of finite depth. Momentum relations are used in terms of the Kochin function in the fluid region far from the body. The general results look very similar to those for deep water. The water depth is formally reflected in terms of the ratio between the phase and group velocities of incident waves. Computations are made for a Series 60 hull($C_B=0.6$) and are compared with the corresponding results of deep water. It is shown that the vertical drift moment for slender ships becomes completely free from water depth when the wave-ship length ratio is taken as parameter.