• 한국해양공학회지
• /
• 제28권2호
• /
• pp.93-101
• /
• 2014

In general, particle simulation methods such as the MPS(Moving Particle Simulation) or SPH(Smoothed Particle Hydrodynamics) methods have some serious drawbacks for pressure solutions. The pressure field shows spurious high fluctuations both temporally and spatially. It is well known that pressure fluctuation primarily occurs because of the numerical approximation of the partial differential operators. The MPS and SPH methods employ a pre-defined kernel function in the approximation of the gradient and Laplacian operators. Because this kernel function is constructed artificially, an accurate solution cannot be guaranteed, especially when the distribution of particles is irregular. In this paper, we propose a particle simulation method based on the moving least-square technique for solving the partial differential operators using a Taylor-series expansion. The developed method was applied to the hydro-static pressure and dam-broken problems to validate it.

• 대한조선학회논문집
• /
• 제53권1호
• /
• pp.18-28
• /
• 2016

In shipbuilding, the scheduling system is susceptible to sudden changes and thus it turns to be difficult to predict the differences between schedule and production records in advance. A computer-based simulation is commonly utilized to overcome the discrepancies occurred in estimating workloads and resulting processing times. The main drawback of this simulation-based solution is its limited applicability because, in most cases, each shipyard requires specific and customized simulation environment. By standardizing the planning data of the midterm scheduling system, as proposed in this paper, the efficiency of the current simulation model can be enhanced. To present an alternative approach, this paper begins with the analysis of the complex planning data structure of several shipyards and then proceeds to construct a standard data structure based on the neutral format. An interface application is developed for the data transaction and simulation in on-line environment. As a result, a simulation-based production management of shipyards can be achieved by the efficient prediction of planning and scheduling.

• 한국CDE학회논문집
• /
• 제17권5호
• /
• pp.324-332
• /
• 2012

In this paper, a method for calculating the contact force and the frictional force caused by contacts between the wire rope and the rigid body is introduced based on multibody dynamics. And the method is applied to a simulation of contacts between the wire rope and the shell plate of a block that can occur during shipbuilding. The wire rope is composed of a number of lumped masses and the wire rope segments that connect the masses. After calculating the position of interference, we inserted a contact node into the wire rope. We then derived the equations of motion of the wire rope and the rigid body using augmented formulation based on multibody dynamics taking into account the constraints between the contact node and the rigid body. Using the equations, we were able to obtain the constraint force between the contact node and the rigid body, and calculate the contact force and the frictional force, based on which the position of the contact node was corrected. Finally, we applied our results to perform simulation of contacts between the wire rope and the shell plate of a block in order to verify the efficacy of the method proposed in this paper.

• 대한조선학회논문집
• /
• 제46권1호
• /
• pp.78-86
• /
• 2009

A capacity calculation and process analysis is a very important part for the entire ship production planning. Ship's production plan is set up with a concept that the product is produced based on the capacity achievable by the processes while general manufacturing sets up the production plan based on product lead-time. Therefore, in case the calculation of capacity for each process of shipbuilding yard is different from actual conditions, a series of production plan - ship table composition, dual schedule plan and execution schedule plan, etc - may accumulate errors, lose reliability of planning information and cause heavy cost deficit in this course. In particular, in case of new shipbuilding yard, stocks between processes are built up and half blocks are not supplied in timely manner, and that is sometimes due to the clumsiness of the operator but it is more often because of the capacity to execute each process is not logically calculated. Therefore, this paper presents the process to calculate the assembly leadtime and assembly process capacity for shipbuilding yard assembly factory. This paper calculated the block type for calculation of assembly lead time based on block DAP(detailed assembly procedure), and introduced cases that calculate production capacities by assembly surface plate by considering the surface plate occupied area of the blocks that change depending on assembly field area and assembly processes through assembly simulation.

• 한국정보통신학회논문지
• /
• 제17권8호
• /
• pp.1761-1768
• /
• 2013

디지털 선박 생산기술은 조선소에서 필연적으로 발생하는 재계획 및 재작업에 따른 비용과 시간을 절감할 수 있는 기술이다 이 기술을 효율적으로 적용하기 위해서는 적용 가능한 . 분야에 대한 전략수립이 반드시 이루어져야 한다. 본 논문에서는 조선소 생산계획 업무 프로세스를 분석하여 디지털 선박생산 기술을 적용하기 위한 전략을 수립하는 것을 목표로 한다. BPR방법론을 기반으로 현행 생산계획 업무프로세스를 분석하고, 워크플로우를 모델링하여 병목프로세스를 도출한다. 도출된 병목프로세스를 심도있게 분석하여 핵심개선기회 다이어그램을 작성하고, 프로세스시뮬레이션을 수행하여 적용시나리오 생성뿐만 아니라 기대효과도 산출한다. 디지털 선박생산기술의 적용전략은 조선소에서 양질의 제품에 필요한 건조 비용 및 시간을 줄일 수 있는 밑그림을 제공할 것으로 사료된다.

• 대한조선학회논문집
• /
• 제53권2호
• /
• pp.127-134
• /
• 2016

This paper presents practical issues for test and evaluation(T&E) methods to develop defense systems. Our argument is motivated by several domestic defense cases and the cases lead us to discuss two main factors for reliable defense systems development: 1) statistical approaches and 2) technical schemes. Specifically, statistical approaches enable to provide credible interpretations about T&E results in the decision-making process. With practical T&E results of the “Red Shark” torpedo, we performed statistical hypothesis tests and suggest a minimum sample size to accept the hypothesis. Next, technical schemes have more direct effects on improving reliability of developed defense systems and we shortly introduce tools development for systems verification that is required to integrate several sub-systems, e.g., combat, sensor, weapon, and communication systems, within a defense system. We additionally summary some domain cases using modeling and simulation techniques for successful T&E. In closing, we expect that the paper shows empirical investigation and lessons learned with these two practical issues, which provides a guide those who desire to make decisions about reliable defense systems development.

• 대한조선학회논문집
• /
• 제55권2호
• /
• pp.116-123
• /
• 2018

These days, geographic information system has released in everyday life and industries. However, the shipyard only uses it to manage the layout of the yard. In this study, we apply the Geographic Information System to shipbuilding block logistics simulation to analyse the behavior of bogies and forklifts carrying blocks and materials in the shipyard. The shipyard manages daily block logistics plans at the execution planning stage. However, since it is a daily plan, it is difficult to respond to an unexpected situation immediately, and application to judge a certain value or higher value is insufficient. Therefore, a simulation model was created using the shape and attribute information inherent in the geographic information system to verify and improve the block logistics of the mid-and long-term yards. Through this simulation model, we will analyse loads on the workplace, stockyard, and road, and contribute to overall logistics improvement from the point of view of resource planning. In addition, the results of the simulation are reflected in the planning, to help support various decisions.

• 전산구조공학
• /
• 제26권1호
• /
• pp.66-74
• /
• 2013

• Journal of Welding and Joining
• /
• 제20권1호
• /
• pp.18-22
• /
• 2002

• 한국해양공학회지
• /
• 제21권4호
• /
• pp.8-14
• /
• 2007

A particle method recognized as one of gridless methods has been developed to investigate incompressible viscous flaw. The method is more feasible and effective than conventional grid methods for solving the flaw field with complicated boundary shapes or multiple bodies. The method is consists of particle interaction models representing pressure gradient, diffusion, incompressibility and the boundary conditions. In the present study, the models in case of various simulation condition were checked with the analytic solution, and applied to the two-dimensional Poiseuille flow in order to validate the developed method.