• 한국CDE학회논문집
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• 제2권2호
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• pp.77-84
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• 1997

This paper is concerning the development of multiple neural networks system of problem domains where the complete input space can be decomposed into several different regions, and these are known prior to training neural networks. We will adopt oblique decision tree to represent the divided input space and sel ect an appropriate subnetworks, each of which is trained over a different region of input space. The overall architecture of multiple neural networks system, called the federated architecture, consists of a facilitator, normal subnetworks, and tile networks. The role of a facilitator is to choose the subnetwork that is suitable for the given input data using information obtained from decision tree. However, if input data is close enough to the boundaries of regions, there is a large possibility of selecting the invalid subnetwork due to the incorrect prediction of decision tree. When such a situation is encountered, the facilitator selects a tile network that is trained closely to the boundaries of partitioned input space, instead of a normal subnetwork. In this way, it is possible to reduce the large error of neural networks at zones close to borders of regions. The validation of our approach is examined and verified by applying the federated neural networks system to the configuration design of a midship structure.

• 대한조선학회논문집
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• 제40권6호
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• pp.58-68
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• 2003

Despite the availability of 3D CAD systems, the designers in shipyards still use 2D CAD systems because of the need to produce drawings rapidly and a shortage of labor. The design information of ship structure contained in 2D drawings is represented by symbols that are well known among designers in shipyard. The shapes of symbols are recognized by analysis of experienced and knowledgeable designers. We propose a method for automatic recognition of 2D symbols and extraction of design information from the midship drawings. The shape and rationale of 20 symbols used in ship design have been analyzed, and symbols have been classified according to the analysis. Based on the classified symbols, the developed system recognizes the symbols expressed in 2D drawings. The meaningless geometric shape is translated into the design information including designer's intents. The extracted design data can be applied to the downstream design process in shipyards, and the 3D ship model can be automatically created.

• 대한조선학회논문집
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• 제33권1호
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• pp.135-144
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• 1996

본 논문에서는 범용 전문가 시스템 쉘을 이용하여 구조설계, 특히 선박의 중앙 횡단면 구조설계를 지원할 수 있는 전문가 시스템(ESMID)을 개발하였다. 기존의 전문가 시스템과는 달리 여기서는 효율적인 설계 전문가시스템을 구현하기 위하여 지식베이스와 공학 데이타베이스, 사용자 인터페이스, 그리고 공학 계산 프로그램들이 통합된 시스템을 구현하였다. 본 시스템의 유효성을 검증하기 위하여 64K 살물선에 적용하여 구조설계를 수행하였다. 기존의 전문가시스템에 데이타베이스, 그래픽 사용자 인터페이스 등의 환경들이 접목됨으로써 초보자도 쉽게 구조설계를 수행할 수 있게 된다.

• 대한조선학회지
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• 제24권2호
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• pp.20-28
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• 1987

In general, preliminary hull form design is performed by changing a parent hull form using a computer to satisfy given requirements, e.g., principal dimensions, displacement, $L_{CB}$, and etc. Principal dimensions, $C_b,\;L_{CB}$ and midship sections are the only parameters to be modified in the traditional hull form variation methods available for preliminary design. In this paper, a method is presented in which local cross sections as well as principal dimensions and midship sections are modified according to design requirements. The method gives hydrostatic curves of modified hull form simultaneously. An optimization technique to satisfy the constraints of hydrostatic characteristics such as maximizing KM as a design requirement is also considered.

• 수산해양교육연구
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• 제19권1호
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• pp.129-136
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• 2007

The component parts of the shell plate of a ship are steel. but the screw propeller or the bow thruster is a compound of bronze, nickel and aluminum. On account of the these different components between metals of the shell plate, the screw propeller and the bow thruster, which are underwater, the shell plate of a ship is corroded by the action of ionization. Authors investigated the corrosion loss of the zinc anodes which were attached to the bottom shell of the training ship Kaya for about two years. The obtained results were as follows:1. In case of the shell plate the difference of the corrosion loss according to port and starboard was almost nothing. But the corrosion loss of the forward part was more than that of the aftward part.2. There was little difference in the corrosion loss between the forward and the aftward part on the bilge keel.3. The corrosion loss of the fore, midship and aft part on the false keel were 24.7%, 22.4% and 23.9% respectively.4. The corrosion loss of the fore and the aft part on the false keel was more than that of the midship part.5. The corrosion loss of the bow thruster was greater than any other parts.6. The nearer the zinc anode to the screw propeller the more the corrosion loss on the stern frame, and the situation was also same as on the rudder.

• 한국해양공학회지
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• 제33권4호
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• pp.322-329
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• 2019

The magnitude of the roll motion of a floating structure depends on the roll damping acting on the body. In other words, the roll damping of a floating structure must be accurately obtained in order to precisely evaluate the roll motion. Various methods are used to evaluate the roll damping of a floating structure, such as the linear potential theory, computational fluid dynamics (CFD), and model tests. However, it is difficult to evaluate the roll motion of a floating structure with appendages such as a bilge keel and riser slot due to the limitation of ignoring the viscous effects in the linear potential theory. Among these methods, a model test based on a free decay test and harmonic excited roll motion (HERM) is known to be the most reliable method to estimate the roll damping of the floating structures. In this study, model tests using free decay and HERM techniques were performed in the Ocean Engineering Basin (OEB) of KRISO with various types of midship sections. The roll damping results were estimated based on post-processing methods using both techniques, and the roll damping results were compared.

• 한국해양공학회지
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• 제12권3호통권29호
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• pp.86-95
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• 1998

CAD/CAM program developers have made substantial progress in enabling engineers to design, analyze, visualize, visualize, and simulate the performance of structures and systems. Many researchers, however, agree that there is still a way to go before the existing commercial computer software can be used in ship structural analysis to their full potential as solvers which can identify opportunities to reduce man-hours and cut costs. CAD systems used for these works in ship yards are general-purposed and not custom-tailored for ship structures, which force end-users to do tiresome and routine works. The new preprocessor "MeshGen" announced in this study can load several ship types and user-friendly generate their FE meshes employing the object-oriented approach based on the parametric and top-down design. Also "MeshGen" reduces dramatically the time required to prepare CAD models under window-based environments on desktop personal computers and makes it much easier and faster for end-users to change topology and material properties.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.188-192
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• 2004

A Numerical analysis method is developed in order to compute the flaw and wave field for 2-dimensional floating body in the free roll motion with 3 degrees of freedom. Navier-Stokes and continuity equations are gaverning equations in tire present study. Finite Difference method is introduced to discretize the governing equation. The free surface is traced by the interface tracking method and the grid system is fitted to boundaries including free surface and body surface, which is moving in the flow field. The numerical scheme is based on Maker and Cell method. For the sake of validation of the numerical method, the computed roll decay factors according to tire midship section shapes are compared with measured results. The numerical results are discussed in order to understand the effect of midship section shape on roll motion.

• 한국해양공학회지
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• 제14권4호
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• pp.9-16
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• 2000

This paper deals with the numerical and experimental study on the characteristics of the flow around a sunken vessel. Numerical simulation of the two dimensional steady flow on the midship section are carried out by the CFD code which is developed by using finite volume method and which includes the standard $textsc{k}$-$\varepsilon$ model with standard wall function. A experimental study is also carried out for the 1/100 scale model in circulating water channel. A velocity fields around the ship are measuremed by using particle image velocimetry technique. And the fluid forces acting on the ship hull by uniform current are measured by two axis load cell. The computed and measured velocity fields on the midship section are compared with each other in the view point of velocity dstribution and reattachement length, which shows good agreement in quality. The drag force on the vessel also showed the same tendency in both computational and experimental results. However, the quantitative disagreements are shown due to the three dimensional effect of the experiment. The result are used to determine the functional efficiency and stability of the vessel as a artificial reef.

• 대한조선학회논문집
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• 제28권2호
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• pp.12-20
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• 1991

지금까지 선체구조 설계 관련 정보는 주로 도면을 통해서 전해져 왔으나 최신의 컴퓨터 관련 기술인 CAD 시스템이나 DBMS등을 이용하면 설계과정에서의 중복작업을 없앰으로서 설계생산성을 크게 높일 수 있다. 본연구에서는 선체구조 설계 관련 정보를 데이터 베이스관리시스템을 통하여 일관화하기 위해서 선체 중앙부 구조부재들의 배치형상과 속성정보들에 대한 데이터 모델링을 시도하였으며, 그 적용예로서 산적화물선의 중앙부 구조형상을 컴퓨터 그래픽을 이용하여 가시화 하였다. 데이터모델의 구조는 관계형으로 하였으며 선체구조의 접속관계정보를 이용하여 구조부재의 배치형상처리를 용이하게 하였다. 결과로서 나온 데이타 관계형 데이터베이스 관리시스템 'ORACLE'을 통해 저장되고 질의어를 통해 다른 시스템에서 직접 사용될 수 있음을 보였다.