• 대한조선학회논문집
• /
• 제40권4호
• /
• pp.8-15
• /
• 2003

This paper presents the method for developing an optimum hull form with minimum wave resistance using SQP(sequential quadratic programming) as an optimization technique. The wave resistance is evaluated by a Rankine source panel method with non-linear free surface conditions and the ITTC 1957 friction line is used to predict the frictional resistance coefficient. The geometry of the hull surface is represented and modified using B-spline surface patches. The optimization method is applied to Series 60 hull and KCS(KRISO 3600 TEU Container Ship). The obtained results prove that the method is appropriate for preliminary hull form design.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제7권5호
• /
• pp.785-794
• /
• 2015

To obtain low resistance and high efficiency energy-saving ship, minimum total resistance hull form design method is studied based on potential flow theory of wave-making resistance and considering the effects of tail viscous separation. With the sum of wave resistance and viscous resistance as objective functions and the parameters of B-Spline function as design variables, mathematical models are built using Nonlinear Programming Method (NLP) ensuring the basic limit of displacement and considering rear viscous separation. We develop ship lines optimization procedures with intellectual property rights. Series60 is used as parent ship in optimization design to obtain improved ship (Series60-1) theoretically. Then drag tests for the improved ship (Series60-1) is made to get the actual minimum total resistance hull form.

• 대한조선학회논문집
• /
• 제37권4호
• /
• pp.11-18
• /
• 2000

본 논문은 조파저항 성능 평가법을 비선형 계획법에 적용해서 선수 형상의 최적화에 응용한 연구결과이다. 조파저항은 비점성 포텐셜 유동의 가정으로 랜킨 소오스법(Rankine source method)을 이용하여 계산하였고 최적화 기법으로는 SQP(Sequential Quadratic Programming)법을 이용하였다. 선수형상의 표현과 변경은 스플라인(spline)함수를 이용하였으며 본 방법에 의하여 조파저항이 최소가 되는 선수형상의 결정이 가능하였다. 또한 마찰저항공식과 경험식으로 주어지는 형상영향계수(from factor)를 고려한 점성저항을 첨가하여 총 저항이 최소가 되는 선수 형상도 도출하여 서로 비교하였다.

• 대한조선학회지
• /
• 제19권4호
• /
• pp.31-37
• /
• 1982

Developing a minimum wave resistance hull form which is satisfying the given requirements such as displacement and speed is one of the important problems in ship hydrodynamics. The theoretical approach conducted by Pien was successful in developing an optimized hull form, however, which can not be applied directly to practical hull form without manual lines fairing process. To avoid this difficulty, source distribution which arrived after the optimization was put into a fictitious restricted channel and as a result practicably modified hull form was derived by stream line tracing. The wave resistance of the hull thus obtained was calculated by solving the simplified integral equation suggested by Kan. The resistance at design point is almost same with that of the original hull which was represented by source distribution on the vertical rectangular center plane. It is therefore recommended to use the derived hull form for the hull which obtained after manual lines fairing process at Pienoid method. Further researches both in theory and experiment are necessary before this concept is put into practical application.

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

• International Journal of Ocean System Engineering
• /
• 제3권1호
• /
• pp.1-9
• /
• 2013

A design procedure for a ship with minimum resistance had been developed using a numerical optimization method called SQP (Sequential Quadratic Programming) combined with computational fluid dynamics (CFD) technique. The frictional resistance coefficient was estimated by the ITTC 1957 model-ship correlation line formula and the wave-making resistance coefficient was evaluated by the potential-flow panel method with the nonlinear free surface boundary conditions. The geometry of the hull surface was represented and modified by B-spline surface modeling technique during the optimization process. The Series 60 ($C_B$=0.60) hull was selected as a parent hull to obtain an optimized hull that produces minimum resistance. The models of the parent and optimized hull forms were tested at calm water condition in order to demonstrate the validity of the proposed methodolgy.

• 대한조선학회지
• /
• 제7권2호
• /
• pp.41-60
• /
• 1970

Despite it's limitations, the existing Stream Line Tracing Method(Inverse Method) can be applied effectively to the design of better hull forms with practical proportions. Most of the calculating mechanism by the method for hull form design has been achieved. In this paper, authors have tried to improve the quality of wave making resistance on the 10,000GT liner among FY'67 Korean Standard Ship Form. Some numerical results obtained in this work and designed new lines are shown.

• 대한조선학회지
• /
• 제17권1호
• /
• pp.19-24
• /
• 1980

From the singularity distribution which obtained by minimum wave resistance condition, optimum hull form is obtained by stream line trancing method as Inui and Pien did. Thus obtained hull form has a extruded bottom along a keel line. Therefore the hull form must be modified to have flat bottom. This modification process is conducted by putting a fictitious bottom. It is found out that the wave resistance does not significantly alter at design speed even though the hull form has remarkably changed at the bottom. Therefore flattening the bottom by the effect of depth may be more rational for practical hull form design than ordinary manual hull-form modification.

• 한국해양공학회지
• /
• 제18권3호
• /
• pp.32-39
• /
• 2004

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 different optimal hull forms. The frictional resistance has been estimated using the ITTC 1957 model-ship correlation line formula, and the wave resistance has been evaluated using a potential-flow panel method that is based on Rankine sources with nonlinear free surface boundary conditions. The geometry of a hull surface has been modified using B-spline surface patches, during the whole optimization process. The numerical analyses have been carried out for the modified Wilgey hull at three different speeds (Fn=0.25, 0.316, 0.408), and the calculation results were compared.

• 한국산업안전학회:학술대회논문집
• /
• 한국안전학회 1997년도 춘계 학술논문발표회
• /
• pp.67-75
• /
• 1997

To establish testing method for ignition energy of explosive powders caused by electrostatic discharge, one testing method using a very small quantity of tested powders ( Frima ) was proposed, and the influence of discharge - limiting resistance connected in series into a capacitive discharge circuit on ignition energies of explosive powders was investigated using, as tested powders. As a result the minimum ignition energy was 9 mJ when discharge-limiting resistance was 300 k$\Omega$. The reason for the dependence of ignition energy on discharge-limiting resistance was thought to the difference in the type of electrostatic discharge, such as arc or glow discharge, from the observation of discharging wave forms.