• 한국재난정보학회 논문집
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• 제7권1호
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• pp.75-85
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• 2011

본 논문에서는 파일형 선박충돌방호공에 선박이 충돌하였을 때 거동을 해석하였다. 충돌방호공은 슬래브, RCP말뚝 및 이를 지지하는 지반을 비선형스프링으로 모델링하였다. 선박의 선수는 탄소성거동을 하는 쉘요소로 모델링하였으며, 선체부는 충격 시 변형이 크게 발생하지 않으므로 선형재료로 고체요소를 이용하여 모델링을 하였다. 선박의 중량의 변화에 따른 거동특성을 파악하기 위해 선박의 질량을 DWT 10000 부터 DWT 25000까지 5000씩 증가시켜 해석을 수행하였다. 또한 선박과 방호공의 충돌은 정면충돌로 고려하였으며, 충돌 속도는 5knot로 가정하였다. 선박과 방호공과의 충돌 해석은 비선형 해석 프로그램인 ABAQUS/Explicit을 이용하여 수행하였으며, 이를 통하여 선박 충돌 시 방호공의 에너지 거동을 분석하였다. 해석결과 선박의 중량이 증가할수록 선수와 슬래브의 변형에 의한 소성 소산 에너지량이 증가하는 것을 확인할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 춘계학술대회 논문집
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• pp.370-374
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• 1993

This paper describes a study on the expert system based process planning of the block division process in shipbuilding. The prototype system developed deterines the block division line of the midship of crude-oil tanker. Case-based reasoning (CBR) approach relying on previous similar cases to solve the problem is applied instead of rule-based reasoning (RBR). Similar cases are retrieved from case base according to the similarity metrics between input problem and cases. The retrieved case with the highest priority is then adapted to fit to the input problem buy adaptation rules. The adapted solution is proposed as the division line for the input problem.

• 산업경영시스템학회지
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• 제17권30호
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• pp.161-165
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• 1994

The shipbuilding industry is one of the domains which need an effective computer application. Particularly the productivity of process planning of a shipbuilding for crude -oil tanker can be greatly enhanced by introducing CAPP(Computer Aied Process Planning). In this paper we describe a prototype expert system which enables block division process planning in shipbuilding. The system determines block division lines of the midship sections of oiltanker. Case-based reasoning(CBR) approach is applied for this purpose instead of rule-based one.

• Ocean Systems Engineering
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• 제6권3호
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• pp.265-287
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• 2016

The change of the global performance of a turret-moored FPSO (Floating Production Storage Offloading) with DP (Dynamic Positioning) control is simulated, analyzed, and compared for two different internal turret location cases; bow and midship. Both collinear and non-collinear 100-yr GOM (Gulf of Mexico) storm environments and three cases (mooring-only, with DP position control, with DP position+heading control) are considered. The horizontal trajectory, 6DOF (degree of freedom) motions, fairlead mooring and riser tension, and fuel consumptions are compared. The PID (Proportional-Integral-Derivative) controller based on LQR (linear quadratic regulator) theory and the thrust-allocation algorithm which is based on the penalty optimization theory are implemented in the fully-coupled time-domain hull-mooring-riser-DP simulation program. Both in collinear and non-collinear 100-yr WWC (wind-wave-current) environments, the advantage of mid-ship turret is demonstrated by the significant reduction in heave at the turret location due to the minimal coupling with pitch mode, which is beneficial to mooring and riser design. However, in the non-collinear WWC environment, the mid-turret case exhibits unfavorable weathervaning characteristics, which can be reduced by employing DP position and heading controls as demonstrated in the present case studies. The present study also reveals the plausible cause of the failure of mid-turret Gryphon Alpha FPSO in milder environment than its survival condition.

• 대한조선학회논문집
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• 제39권1호
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• pp.100-112
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• 2002

함정은 선급의 규정을 받지 않고 독자적인 기준을 가지고 설계된다. 본 연구는 함정 설계에 적용되는 가장 권위 있는 기준이라고 할 수 있는 미해군의 규정을 중심으로 그 특성과 개념을 소개하고, 개별적인 기준이 구조 설계 시에 반영되었을 때의 설계 결과에 대해 분석함으로써 설계자가 규정식 적용의 영향을 파악하는데 도움을 주고자 하였다. 또한 함정의 최적 구조 설계를 위하여 미해군 규정에 기초하고 구조 해석 이론을 접목한 최적 설계 방법을 제시하고, 실제 함정에 대해 적용하여 봄으로써 제시된 방법의 유용성을 보였다. 본 방법의 적용 결과 종보강재와 횡늑골의 간격과 같은 주요 설계 변수가 함정 중앙 단면의 설계 결과에 미치는 영향이 분석 가능하며, 최적의 중앙 단면 설계가 얻어 질 수 있었다.

• 대한조선학회지
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• 제13권1호
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• pp.1-9
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• 1976

Using the computer programs for calculation of natural vibrations of ship's hull developed by the authors et al., an investigation into influences of various parameters on the accuracy of calculation was done through example calculations of a 30,000 DWT petroleum products carrier M/S Sweet Brier built by Korea Shipbuilding and Engineering Corporation. The methodical principles employed for the computer program development are as follows; (a) the ship system is reduced to an equivalent discrete elements system conforming to Myklestad-Prohl model, (b) the problem formulation is of transfer matrix method, and (c) to obtain solutions an extended $G\ddot{u}mbel's$ initial value method is introduced. The scope of the investigation is influences of number of discrete elements, choice of significant system parameters such as rotary inertia, bending stiffness and shear stiffness, and simplification of distributions of added mass and stiffness as trapezoidal ones referred to those of midship section on the calculation accuracy. From the investigation the followings are found out; (1) To obtain good results for the modes up to the seven-noded thirty or more divisions of the hull is desirable. For fundamental mode fifteen divisions may give fairly good results. (2) The influence of rotary inertia is negligibly small at least for the modes up to the 5- or 6- noded. (3) In the case of assuming either bending modes or shear modes the calculation results in considerably higher frequencies as compared with those based on Timoshenko beam theory. However, the calculation base on the slender beam theory surprisingly gives frequencies within 10% error for fundamental modes. (4) It is proved that to simplify distributions of added mass and stiffness as trapezoidal ones referred to those of midship section is a promising approach for the prediction of natural frequencies at preliminary design stage; provided good accumulation of data from similar type ships, we may expect to obtain natural frequencies within 5% error.

• 대한조선학회지
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• 제22권3호
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• pp.1-8
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• 1985

In this paper, the motion response and wave load of a container ship are treated by a nonlinear motion theory, which is similar to that used by Yamamoto et. al.[1]. This paper deals with the vertical motion response in oblique waves and the effect of the Smith correction in buoyancy force calculation. In the present computation, for S-175 container ship model our result also shows that the ratio of the motion peak to peak value to the wave height decreases as the wave height increases, which was obtained earlier by Yamamoto et.al.[3]. On the other hand the nondimensional midship bending moment increases as the wave height increases. These nonlinear effects are dominant near the resonance frequency, and depend on the hull form and forward speed. However, it is found that these nonlinear effects are significant for tanker model.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1992년도 춘계학술발표회 한국항해학회
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• pp.21-43
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• 1992

The recently-developed automated vessels require a system which evaluates the operating condition of the ship at present position form weather information as well as sensors; forecasts the operation condition the sea state to come in foreseeable future ; and suggests the optimum course and speed for ship's sa-fety. According to a study deck wetness propeller racing slamming rolling vertical acceleration lateral acce-leartion vertical bending moment at midship etc. were chosen as the factors for evaluating seakeeping per-formance. As a mater of fact there is no developing the hardware of a system which could consider all the factors onseakeeping performance. This study introduces a theoretical method which makes it possible to evaluate the seakeeping perfor-mance byapplying a theory from reliability engineering and thereby establishing a safety space. lation of stochastic processes with the factors presently adopted for evaluating sekakeeping performance. and develops the overall eseakeeping performance evaluation system in consideration of the safety of human being cargoes and the ship This method of evaluation shall be of much use in developing the practical system of seakeeping perfor-mance of a ship in waves.

• 대한조선학회지
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• 제20권2호
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• pp.21-26
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• 1983

In this light of economical engineering, the optimal configurations of ship structure that can save weights, production costs and operation costs should be investigated. This paper presents the general method of optimization based on non-linear programming and its application to weight and/or cost minimization of ship structure. Oil tanker is chosen as a ship type because of simple layout and easy calculation of stress. With the data of 16,200 DWT oil tanker built by KSEC 1980, this paper shows the procedure mentioned above by means of SUMT combined with two selected search methods. Then the differences between original and redesigned tanker structures are discussed.

• 대한조선학회지
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• 제20권1호
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• pp.29-33
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• 1983

The loading condition, of a ship, especially a multi-purpose cargo carrier, in service, is often changed. Then, the prediction of natural frequency changes is necessary to provide measures for prevention of ship vibrations. In this paper a simplified method for the above purpose is presented. The bases of the method are analytical solutions for the lateral vibrations of uniform Timoshenko beams carrying a concentrated mass and the Dunkerley's formula. In this method a ship in the standard ballast condition is reduced to a uniform Timoshenko beam having same system parameters as those of the midship section. To investigate the validity of the proposed method, numerical calculations are carried out for a 46,000 DWT bulk carrier and compared with detailed calculations based on the finite difference method. Even in cases those the cargoes in a hold, length of which is about 13% of the ship's length, are reduced to a concentrated mass, the proposed method gives results of several percent differences from the detailed calculations up to the six-noded mode.