• 한국항해항만학회지
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• 제47권2호
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• pp.66-74
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• 2023

With the increase of interest in developing Maritime Autonomous Surface Ships (MASS), an optimal ship route planning is gradually gaining popularity as one of the important subsystems for autonomy of modern marine vessels. In the present paper, an optimal ship route planning model for MASS is proposed using a nonlinear MPC approach together with a nonlinear MMG model. Results drawn from this study demonstrated that the optimization problem for the ship route was successfully solved with satisfaction of the nonlinear dynamics of the ship and all constraints for the state and manipulated variables using the nonlinear MPC approach. Given that a route generation system capable of accounting for nonlinear dynamics of the ship and equality/inequality constraints is essential for achieving fully autonomous navigation at sea, it is expected that this paper will contribute to the field of autonomous vehicles by demonstrating the performance of the proposed optimal ship route planning model.

• 한국항행학회논문지
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• 제22권6호
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• pp.507-513
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• 2018

자율운항선박은 인간의 개입을 최소화하고, 선박에게 주어진 임무를 안전하게 수행하기 위해 운항에 필요한 다양한 정보를 자동으로 수집 관리하며, 선박이 스스로 판단하여 정해진 목적지까지 부분 또는 전체 항로를 자율적으로 운항하거나, 필요시 부분적으로 원격관제에 의해 운항을 가능하게 하는 선박운항기술을 말한다. 이러한 선박의 안전운항을 위해 선박에 탑재된 다양한 항해 통신장비 및 엔진, 기관 등의 각종 센서로 부터 신호를 수집 및 관리하기 위해서는 공통플랫폼 기술이 필요하다. 이 논문에서 제안하는 공통플랫폼은 스마트 선박 구현의 핵심으로 육상과 선박 간의 위성통신 또는 지상파 통신으로 연결된 통신 환경에서 실시간으로 원활한 정보 교환을 통해 육상의 관제국에서 모니터링과 원격관제를 지원하여 해상의 안전한 선박 운항을 가능하게 한다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권4호
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• pp.177-184
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• 2010

In this study, geometric modeling techniques and their application to ship modeling and design are presented. Traditionally the hull shape is defined by using curves called the lines and various necessary computations are performed based on the discrete points obtained from the lines. However, some applications find difficulty in using the lines such as seakeeping analysis, which requires the computation of wetted part that is changing dynamically over time. To overcome such a problem and increase accuracy and efficiency in computation, two essential geometric modeling techniques, surface modeling and surface-to-surface intersection, are introduced and their application to ship modeling and analysis including hydrostatic computation, slamming and seakeeping analyses is presented.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2009년도 추계학술대회
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• pp.243-244
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• 2009

선박의 표면은 소형선박에서부터 대형까지 매끄럽지 않고 어느 정도의 표면조도(surface roughness)를 가지고 있다. 표면조도는 표면저항과 열전달을 증가시키기 때문에 선박의 설계시 고려해야 될 중요한 설계인자 중 하나이다. 때문에 표면조도에 따른 주위유동에 관한 연구와 조도변화에 따른 유동 및 난류에 대한 연구가 지속적으로 이루어지고 있다. 선박의 표면조도는 선박에서 뿐만 아니라 기계나 항공까지 광범위하게 적용이 가능하며 가용 분야 또한 매우 넓다. 본 연구에서는 레저선박의 표면조도 간격변화에 따른 표면유동에 어떠한 영향을 끼치며 표면조도 영역에 따른 경계층에 대한 실험적 연구를 수행하였다.

• 한국소음진동공학회논문집
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• 제23권6호
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• pp.563-573
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• 2013

The ship radiated noise level fluctuates by the interference between direct and reflected paths. The effect of sea surface reflection path on interference depends strongly on sea surface roughness. This paper describes error characteristics of ship acoustic signature estimation by sea surface scattering effect. The coherent reflection coefficient which explains a magnitude of sea surface scattering and its resultant interference acoustic field is analyzed quantitatively as a function of a grazing angle, effective surface height, frequency, source-receiver range and depths of source and receiver. Theoretical interference acoustic field is compared with experimental result for two different sea surfaces and five different frequencies by changing source-receiver range. It is found that both matches well each other and a magnitude of interference acoustic field is decreasing by increasing a grazing angle, effective surface height, frequency, and depths of source and receiver and decreasing source-receiver range. For given experimental conditions, the transmission anomaly which is a bias error of ship acoustic signature estimation, is about a range of 1~3 dB. The bias error of an existing ship radiated noise measurement system is also analyzed considering wind speed, source depth and frequency.

• 한국전산유체공학회지
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• 제20권4호
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• pp.21-27
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• 2015

Flow field around the KRISO 3600TEU container ship is computed using a surface generated based on interpolations of station lines, which are given in a body plan of the ship, without using any CAD program. An interpolation method is suggested based on inscribed circles to generate curves between two neighboring station lines. The interpolated surface is saved in a STL format to use the snappyHexMesh utility of the openfoam. Computed resistance of the ship is compared with experimental and other computational results and the effects of the interpolation of neighboring station lines on the computed resistance are investigated. The suggested method is applied to calculate the flow field around a submarine with appendages. The surface triangulations for the hull and the appendages are generated without consideration of each other, then those surface triangulations are simply combined to provide a grid generator with the body boundary. The junctures of the hull and the appendages are identified automatically during the grid generation procedure. Tip vortex is captured, which travels downstream from the tip of the appendages.

• 대한조선학회논문집
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• 제51권5호
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• pp.419-428
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• 2014

This paper presents a numerical simulation method for the flow around advancing ships in regular waves by using a rectilinear grid system. Because the grid lines do not consist with body surface in the rectilinear grid system, the body geometries are defined by the interaction points of those grid lines and the body surface. For the satisfaction of body boundary conditions, no-slip and divergence free conditions are imposed on the body surface and body boundary cells, respectively. Meanwhile, free surface is defined with the modified marker density method. The pressure on the free surface is determined to make the pressure gradient terms of the governing equations continuous, and the velocity around the free surface is calculated with the pressure on the free surface. To validate the present numerical method, a vortex induced vibration (VIV) phenomenon and flows around an advancing Wigley III ship model in various regular waves are simulated, and the results are compared with existing and corresponding research data. Also, to check the applicability to practical ship model, flows around KRISO Container Ship (KCS) model advancing in calm water are numerically simulated. On the simulations, the trim and the sinkage are set free to compare the running attitude with some other experimental data. Moreover, flows around the KCS model in regular waves are also simulated.

• 한국CDE학회논문집
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• 제4권4호
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• pp.381-390
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• 1999

In this study, a pseudo ship structure data model for the :.hip cargo hold structure based on STEP is proposed. The proposed data model is based on Application Reference Model of AP218 Ship Structure which is the model that specifies conceptual structures and constraints used to describe the information requirements of an application. And the proposeddata model refers the Ship Common Model framework for the model architecture which is the basis for ongoing ship AP development within the ISO ship-building group and the ship product definition information model of CSDP research project for analyzing the relationship between ship structure model entities. The proposed data model includes Space, Compartment. Ship Structural System, Structural Part and Structural Feature of cargo hold. To generate this data model schema in EXPRESS format, ‘GX-Converter’was used which enables user to edit a model in EXPRESS format and convert schema file in EXPRESS format. Using this model schema, STEP physical file containing design data for ship cargo hold data structure was generated through SDAI programming. The another STEP physical file was also generated containing geometry data of ship cargo hold which was extracted and calculated by SDAI and external surface/surface intersection program. The geometry information of ship cargo hold can be then transferred to commercial CAD system, for example, Pro/Engineer. Examples of the modification of the design information are also Presented.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.195-199
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• 2005

Wave breaking phenomenon near the fore body of a ship is numerically simulated. The ship advance with uniform velocity in calm water. For the simulation, incompressible Navier-Stokes equations and continuity equation are adopted as governing equations. The simulation is carried out in staggered variable mesh system with finite difference method. Marker and Cell(MAC) method and Marker-Density method are employed to track the free surface. Body boundary conditions are satisfied with the adoption of porosity method and no-slip condition on the hull surface. The ship model has a wedge type fore-body, and the computational domain is an appropriate region around the fore-body. The computation results are compared with some experimental results. Also the difference of the free surface tracking methods are discussed.

• 대한조선학회논문집
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• 제29권3호
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• pp.15-20
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• 1992

이 논문에서는 화가의(Painter's) 알고리듬을 사용하여 3차원 자유형상곡면(Three dimensional free form surface)을 가시화하는 방법을 개발하였고, 특히 선체형상은 Open 균일 B-Spline 곡면으로 정의하였다. 컴퓨터그래픽스를 응용하여 와이어프레임, 숨은면제거, 묘영등의 가시화를 위한 프로그램을 완성하였다. 또한 선체곡면의 순정을 검토하기 위해 Gaussian 곡률값을 15등급으로 구분하여 등급별 색(color)처리 하였다.