• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.57-62
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• 2005

STX shipbuilding Co,. Ltd. has been developed a hull form and propeller of medium class container vessel. The present paper deals with numerical calculations and experimental tests for the investigation of wave resistance, viscous resistance and propeller. The characteristics of wave resistance and self propulsion factors are varied in order to find an optimized hull form. The measured results have been compared with computed results by 'WAVIS' The prediction of the caviation occurrence was predicted by 'Opti-pro' and measurement is performed in KRISO.

• Ocean Systems Engineering
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• 제5권2호
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• pp.91-107
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• 2015

Ship hull optimization is categorized as a bound, multi variable, multi objective problem with nonlinear constraints. In such analysis, where the objective function representing the performance of the ship generally requires computationally involved hydrodynamic interaction evaluation methods, the objective functions are not smooth. Hence, the evolutionary techniques to attain the optimum hull forms is considered as the most practical strategy. In this study, a parametric ship hull form represented by B-Spline curves is optimized for multiple performance criteria using Genetic Algorithm. The methodology applied to automate the hull form generation, selection of optimization solvers and hydrodynamic parameter calculation for objective function and constraint definition are discussed here.

• 한국해양공학회지
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• 제24권4호
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• pp.59-65
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• 2010

This study presents the design procedure for optimizing the semi-planing hull form, including appendages, using numerical and experimental methods. Four different referenced semi-planing hull forms were compared to determine their hydrodynamic performances, and one of the hull forms was modified for optimum operation at high-speed conditions (0.4 < $F_{NL}$ < 0.9). The optimized, semi-planing hull form was tested in the towing tank to investigate its resistance characteristics. Also, the results of the model tests with differing design parameters were used to choose the stern wedge and the spray strip to improve the hydrodynamic performance at high speeds.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권5호
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• pp.577-587
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• 2017

The recent IMO MEPC regulation on EEDI, EEOI and increased fuel cost has worsened the financial condition of the small and medium sized passenger ferry companies, and it is situated to acquire the economic ships with a pretty high resistance performance. The purpose of this research is to develop a design method on the efficient gooseneck bulb for the middle-sized passenger ferry operated in the Far East Asian seas. The hull forms are designed by varying the gooseneck bulb parameters to find the changes on the resistance performance according to the shape of bulb. The numerical series tests are made to derive the regression equation for estimating the resistance through analyzing the data statistically. This equation is set as an objective function, and then using the optimization algorithm searches for the optimal combination of the design variables. After a hull form is designed corresponding to optimized parameters.

• 한국해양공학회지
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• 제34권4호
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• pp.272-276
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• 2020

This paper presents an optimization process for a catamaran hull form. The entire optimization process was managed using the CAD-CFD integration platform CAESES. The resistance of the demi-hull was simulated in calm water using the CFD solver STAR-CCM+, and an inviscid fluid model was used to reduce the computing time. The Free-Form Deformation (FFD) method was used to make local changes in the bulbous bow. For the optimization of the bulbous bow, the Non-dominated Sorting Genetic Algorithm (NSGA)-II was applied, and the optimization variables were the length, breadth, and angle between the bulbous bow and the base line. The Lackenby method was used for global variation of the bow of the hull. Nine hull forms were generated by moving the center of buoyancy while keeping the displacement constant. The optimum bow part was selected by comparing the resistance of the forms. After obtaining the optimum demi-hull, the distance between two demi-hulls was optimized. The results show that the proposed optimization sequence can be used to reduce the resistance of a catamaran in calm water.

• 해양환경안전학회지
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• 제24권4호
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• pp.467-474
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• 2018

본 연구의 목적은 2가지 선속에서 운항하는 선박의 선형 설계 자동화에 관한 것이다. 가장 기본적인 선박의 형상을 가지는 60계열($C_B=0.6$) 선박을 대상선박으로 선택하여 연구를 수행하였다. 선박 형상의 향상 방향은 저항성능 향상의 관점이며, 특히 선박의 형상과 밀접한 관계를 가지는 조파저항성능을 향상하기 위한 선박 형상 설계 자동화를 수행하였다. 본 연구의 목적을 실현하기 위하여 최적화 기법과 저항 성능을 예측하는 기법 그리고 선형의 형상을 변경하는 기법을 접목하여 선박 형상 설계 자동화 소프트웨어를 개발하였으며, 개발된 소프트웨어를 대상선박에 적용하였다. 최적화 기법으로는 순차이차계획법(sequential quadratic programming method)를 사용하였으며, 조파저항성능을 예측하기 위하여 포텐셜기저 패널법(potential-based panel method)을 사용하였다. 선박 형상의 변경은 가우시안형 수정함수법(Gaussian-type modification function method)를 개발하여 적용하였다. 개발된 소프트웨어를 사용하여 대상선박의 서로 다른 두 가지 선속에 대하여 설계를 수행하고 그 결과를 서로 비교하였다. 그리고 개발된 프로그램의 타당성을 검증하기 위하여 모형시험을 수행하여 구한 실험값과 수치해석을 수행하여 구한 계산값을 서로 비교하였다.

• 대한조선학회논문집
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• 제36권4호
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• pp.105-115
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• 1999

선형설계는 보증속도와 재화중량을 만족하는 선체형상을 설계하는 작업이다. 선형은 선박설계 전과정을 통해 주요한 key drawing으로 작용하므로 일단 결정된 선형을 수정하는 것은 각 설계 부분에 재 작업을 요구하게 되므로, 선형결정 전에 보증속도 등의 기본 조건을 완전히 만족시키지 않으면 안 된다. 그럼에도 불구하고, 초기에 선형을 개발하는데 주어지는 기간은 매우 제한되어 있어, 성능보장을 위한 안정적인 설계 procedure를 확보하지 않으면 안 된다. 이 같은 제약과 생산성을 위한 고려사항이 같이 작용되어 일반적으로 조선소 선형개발실에서는 기존 실적선 중 유사선을 모선형으로 하여 설계대상선으로 변환하는 방법을 사용하고 있다. 또한 최근에는 초기선형 개발 단계에서 성능의 검토를 CFD에 의존하는 경우가 일반화되고 있으며, 이를 위해서는 순정도 높은 다수의 예비선형을 준비해야 한다. 제한된 개발기간 속에서 완성도 높은 다종의 예비선형을 생성하는 선형 설계 전산 시스템의 개발을 위해 본 연구에서는 모선변환을 위한 개량된 변형함수법을 개발하고, 형상요소들을 객체화하여 객체간의 연관성 설정에 의한 자동갱신 기능을 구현하였다. 이런 시스템에 의해 설계자는 원하는 형상으로 수정하는 데만 주력하면, 형상요소간의 matching 문제(consistency)는 시스템이 해결함으로서, 고정도의 선형을 신속하게 완성하는 것이 가능토록 하였다.

• 해양환경안전학회지
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• 제21권5호
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• pp.558-570
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• 2015

18,000 TEU 급 대형 컨테이너 운반선의 그린쉽 설계에 관한 연구로 기본설계와 에너지 효율 향상 관점에서 선형 최적화 과정을 4단계로 나누어 체계적으로 연구를 수행하였다. 첫째, 환경적 측면 및 법규 등을 고려하여 대형 컨테이너 운반선의 경제성 평가를 수행하였다. 둘째, 기본설계 및 성능 관점에서 단축선형과 쌍축선형의 특징을 조사하였다. 셋째, 설계 흘수 및 속도에서 저항과 추진 성능을 향상시키기 위한 단축 및 쌍축선의 선형 최적화를 CFD와 모형시험을 통해 수행하였으며 최적 선형의 성능 향상을 확인하였다. 마지막으로 실제 운항조건을 고려한 추정된 운항 흘수와 속도에서 CFD를 통해 최적화된 최종 선형을 제시하였다. 본 연구를 통해서 대형 컨테이너 운반선의 그린쉽 설계를 위해 고려해야 할 사항을 살펴보았고 그에 따른 선형 최적화를 수행하였으며 설계 흘수와 실제 운항조건 및 연료 소모량을 고려한 총 에너지 효율식을 이용하여 최적화된 단축 및 상축 선형의 에너지 효율 개선을 확인하였다.

• 대한조선학회지
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• 제22권2호
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• pp.35-48
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• 1985

The present work develops a method of evaluating thrust deduction and wake for different loads of the propeller using the concerted application of the theoretical tools and experimental techniques. It also shows the applicability of the new method to the design of optimum hull form. Firstly, the problem of hull-propeller interaction was analyzed in terms of inviscid as well as viscous components of the thrust deduction and wake. The wavemaking resistance of a hull and propeller were mathematically represented by sources on the hull surface and sink on the propeller plane, respectively. The strength of sink was determined by utilizing the radial distributions of propeller load and nominal wake. The resistance increment due to a propeller and the axial perturbation flow induced by the hull in the propeller plane were calculated. Especially, the inviscid component of the thrust deduction was calculated by subtraction the wavemaking resistance of a bare hull, the wavemaking resistance of a free-running propeller and the augmentation of propeller resistance due to hull action from the wavemaking resistance of the hull with a propeller. The viscous components of the thrust deduction and wake were estimated as functions of propeller load which were established by the propeller load varying test after deduction the calculated inviscid components. Secondly, an analysis method of powering performance was developed based on the potential theory and the propeller load varying test. The hybrid method estimates the thrust deduction, wake and propeller open-water efficiency for different propeller load. This method can be utilized in the analysis of powering performance for the propeller load variation such as the added resistance due to hull surface roughness, the added resistance due to wind, etc. Finally, the hybrid method was applied to the optimum design of hull form. A series of afterbody shapes was obtained by systematically varying the waterplane and section shapes of a parent afterbody without changing the principal dimensions, block coefficient and prismatic coefficient. From the comparison of the predicted results such as wavemaking resistance, thrust deduction, wake and delivered power, an optimum hull form was obtained. The delivered power of the optimized hull form was reduced by 5.7% which was confirmed by model tests. Also the predicted delivered power by the hybrid method shows fairly good agreement with the test result. It is therefore considered that the new analysis method of powering performance can be utilized as a practical tool for the design of optimum hull form as for the analysis of powering performance for the propeller load variation in the preliminary design stage.

• 수산해양기술연구
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• 제53권4호
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• pp.446-455
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• 2017

The improvement of resistance performance for the 4.99 ton class fishing boats was shown. The 4.99 ton fishing boats are the most commonly used one in the Korean coastal region. The evaluation of resistance performance was estimated by the Computational Fluid Dynamics (CFD) analysis. The CFD simulation was performed by the validation for various types of bow shapes on the hull. The optimized hull form from the simulation was selected and showed the best resistance performance. This hull type was tested on the towing tank in the National Institute of Fisheries Science (NIFS). The effective horsepower (EHP) was estimated by the resistance test on the towing tank with the bare hull condition. The drag force on the three service speed conditions was obtained for the resistance analysis to power prediction. The measured drag forces are compared with the results from the CFD simulation with one another. As results of the model tests, it was confirmed that the shape of the bow is an important factor in the resistance performance. The effective horsepower decreased about 30% in comparison with the conventional hull form. Also, the resistance performance improved the reduction of required horsepower, which especially contributed to the energy-saving for the fisheries industry. In the CFD analysis, the resistance performance improved slightly. In this case, the ratio of the residual resistance ($C_R$) in the total resistance ($C_T$) was high. Therefore, the CFD analysis was not enough to satisfy with reflection for the free surface and wave form in the CFD procedure. Both model test and CFD calculation in this study can be applied to the initial design process for the coastal fishing vessel.