Sol Ha

Multibody system dynamics simulator for process simulation of ships and offshore plants in shipyards

A simulator was developed for dynamic analysis of operations in shipyards.We based the simulator on six kernels including multibody dynamics kernel.The simulator contains some functions for motion analysis of floating platforms.The graphical user interfaces were also included for the convenience.The simulator was verified by applying to the operations in shipyards. Since various existing simulation tools based on multibody system dynamics focus on conventional mechanical systems, such as machinery, cars, and spacecraft, there are some problems with the application of such simulation tools to shipbuilding domains due to the absence of specific items in the field of naval architecture and ocean engineering, such as hydrostatics, hydrodynamics, and mooring forces. Thus, in this study, we developed a multibody system dynamics simulator for the process simulation of ships and offshore structures. We based the simulator on six kernels: the multibody system dynamics kernel, the force calculation kernel, the numerical analysis kernel, the hybrid simulation kernel, the scenario management kernel, and the collision detection kernel. Based on these kernels, we implemented a simulator that had the following Graphic User Interfaces (GUIs): the modeling, visualization, and report GUIs. In addition, the geometric properties of blocks and facilities in shipyards are needed to configure the simulation for the production of ships and offshore plants, so these are managed in a database and connected to a specific commercial CAD system in shipyards. We used the simulator we developed in various cases of the process simulation of ships and offshore plants. The results show that the simulator is useful for various simulations of operations in shipyards and offshore industries.

Design of controller for mobile robot in welding process of shipbuilding engineering

Abstract The present study describes the development of control hardware and software for a mobile welding robot. This robot is able to move and perform welding tasks in a double hull structure. The control hardware consists of a main controller and a welding machine controller. Control software consists of four layers. Each layer consists of modules. Suitable combinations of modules enable the control software to perform the required tasks. Control software is developed using C programming under QNX operating system. For the modularizing architecture of control software, we designed control software with four layers: Task Manager, Task Planner, Actions for Task, and Task Executer. The embedded controller and control software was applied to the mobile welding robot for successful execution of the required tasks. For evaluate this imbedded controller and control software, the field tests are conducted, it is confirmed that the developed imbedded controller of mobile welding robot for shipyard is well designed and implemented.

VELOCITY-BASED EGRESS MODEL FOR THE ANALYSIS OF EVACUATION PROCESS ON PASSENGER SHIPS

This study presents a velocity-based egress model, which takes into account different aspects of human behavior in an emergency situation, for the evacuation analysis on passenger ships. It was supposed that the egress model consists of three behaviors: individual, crowd, and emergency behavior. The individual behavior was represented by the body shape, walking speed, walking direction, and rotation of each passenger. The basic walking direction of each passenger was obtained as a solution to the shortest distance route to a destination using a visibility graph. The crowd behavior of the passengers was composed of two components: one is a flock behavior, a form of collective behavior of a large number of interacting passengers with a common group objective, and the other is a leader- following behavior, which causes one or more passengers to follow another moving passenger who is designated as the leader. The emergency behavior of the passengers was represented by a counterflow-avoiding behavior to avoid collision with other passengers walking in the opposite direction. Eleven basic tests and 2 examples specified in International Maritime Organization Maritime Safety Committee/Circulation 1238 were conducted, and it was confirmed that all the requirements of such tests had been met.

Simplified Model for the Weight Estimation of Floating Offshore Structure Using the Genetic Programming Method

In the initial design stage, the technology for estimating and managing the weight of a floating offshore structure, such as a FPSO (Floating, Production, Storage, and Off-loading unit) and an offshore wind turbine, has a close relationship with the basic performance and the price of the structure. In this study, using the genetic programming (GP), being used a lot in the approximate estimating model and etc., the weight estimation model of the floating offshore structure was studied. For this purpose, various data for estimating the weight of the floating offshore structure were collected through the literature survey, and then the genetic programming method for developing the weight estimation model was studied and implemented. Finally, to examine the applicability of the developed model, it was applied to examples of the weight estimation of a FPSO topsides and an offshore wind turbine. As a result, it was shown that the developed model can be applied the weight estimation process of the floating offshore structure at the early design stage.

Battle Space Model Based on Lattice Gas Automata for Underwater Warfare Simulation

To simulate complex undersea engagement, many platforms, such as submarines and battleships, participate in underwater warfare simulation. To perform an underwater simulation with reasonable communication among the platforms and environmental factors, a middleware that can treat communication and environmental factors is needed. This paper presents the battle space model, which is capable of propagating various types of emissions from platforms in underwater warfare simulation, predicting interesting encounters between pairs of platforms, and managing environmental information. The battle space model has four components: the logger, spatial encounter predictor (SEP), propagator, and geographic information system (GIS) models. The logger model stores brief data on all the platforms in the simulation, and the GIS model stores and updates environmental factors such as temperature and current speed. The SEP model infers an encounter among the platforms in the simulation, and progresses the simulation to the time when this encounter will happen. The propagator model receives various emissions from platforms and propagates these to other “within-range” platforms by considering the propagation losses and delays. The battle space model is based on the discrete event system specification (DEVS) and the discrete time system specification (DTSS) formalisms. Especially, the propagator and GIS models are based on lattice gas automata for considering an underwater acoustic field and environmental space. To verify the battle space model, simple underwater warfare between a battleship and a submarine was simulated. The simulation results with the model were the same as the simulation results without the model.

Simplified nonlinear model for the weight estimation of FPSO plant topside using the statistical method

The weight information of an FPSO plant, especially of the FPSO (floating, production, storage, and off-loading), is one of the important data needed to estimate the amount of production material (e.g. plates) and to determine the suitable production method for its construction. In addition, the weight information is a key factor that affects the building cost and the production period of the FPSO plant. Although the importance of the weight has long been recognised, the weight, especially of the topside, has been roughly estimated using the existing design and production data as well as the designers experience. To improve this task, a nonlinear simplified model for the weight estimation of the FPSO plant topside using the statistical method was developed in this study. To do this, various past records on the estimation of the weight of the FPSO plant were collected through literature survey, and then correlation analysis and multiple regression analysis were performed to develop a nonlinear simplified model for weight estimation. Finally, to evaluate the applicability of the developed model, it was applied to an example of the weight estimation of the FPSO plant topside. The results showed that the developed model can be applied to the weight estimation process of the FPSO plant at the early design stage.

GPU-accelerated Reliability Analysis Method using Dynamic Reliability Block Diagram based on DEVS Formalism

This paper adopts the system configuration to assess the reliability instead of making a fault tree (FT), which is a traditional method to analyze reliability of a certain system; this is the reliability block diagram (RBD) method. The RBD method is a graphical presentation of a system diagram connecting the subsystems of components according to their functions or reliability relationships. The equipment model for the reliability simulation is modeled based on the discrete event system specification (DEVS) formalism. In order to make various alternatives of target system, this paper also adopts the system entity structure (SES), an ontological framework that hierarchically represents the elements of a system and their relationships. To enhance the calculation time of reliability analysis, GPU-based accelerations are adopted to the reliability simulation.

Development of Battle Space Model Based on Combined Discrete Event and Discrete Time Simulation Model Architecture for Underwater Warfare Simulation

ABSTRACTThis paper presents the battle space model, which is capable of propagating various types of emissions from platforms in underwater warfare simulation, predicting interesting encounters between pairs of platforms, and managing environmental information. The battle space model has four components: the logger, spatial encounter predictor (SEP), propagator, and geographic information system (GIS) models. The logger model stores brief data on all the platforms in the simulation, and the GIS model stores and updates environmental factors such as temperature and current speed. The SEP model infers an encounter among the platforms in the simulation, and progresses the simulation to the time when this encounter will happen. The propagator model receives various emissions from platforms and propagates these to other “within-range” platforms by considering the propagation losses and delays. The battle space model is based on the discrete event system specification (DEVS) and the discrete time system specification (DTSS) formalisms. To verify the battle space model, simple underwater warfare between a battleship and a submarine was simulated. The simulation results with the model were the same as the simulation results without the model.

Physics-based Salvage Simulation for Wrecked Ship Considering Environmental Loads

선박이 침몰한 이후 선 내 남아있는 원유에 의한 오염을 방지 하여 환경적인 피해를 막고, 사고의 원인을 파악하여 추가적인 사고를 예방하기 위해 침몰 선박의 인양이 필요하다. 선박의 인 양을 위해서는 여러 가지 사항이 고려되어야 한다. 우선 선박 내 부로 해수가 유입되기 때문에 부력이 거의 상실된 상태에서 침몰 선박의 중량과 내부에 있던 화물의 이동에 따른 무게 중심의 위 치를 파악해야 한다. 그리고 안전을 고려한 다양한 인양 방법이 검토되어야 한다. 인양 방법이라 함은 인양을 위해 이용할 해상 크레인과 같은 장비를 선정하고, 인양 시 침몰 선박과 장비의 연 결 방법을 선택하는 것이다. 장비 연결 시 대부분 체인 또는 와 이어 로프가 사용되며, 이때 작용하는 하중을 정확히 계산할 필 요가 있다. 그렇지 않을 경우 인양 중 체인 또는 와이어 로프가 끊어진 사고가 발생할 수 있다. 인양 방법에 대한 여러 가지 대안이 선정되면 각 대안이 실제 로 적용 가능한지에 대한 인양 시뮬레이션이 필요하다. 인양 시 뮬레이션의 범위는 해저면에서부터 침몰 선박을 이탈시킨 뒤 해 수면까지 들어올리는 전체 과정을 의미한다. 예를 들어 해상 크 레인을 이용하여 인양을 한다고 가정하였을 때, 해상 크레인의 각 와이어 로프에 작용하는 하중에 따라 인양 가능 여부의 판단 및 안전 계수 등의 계산을 시뮬레이션을 통해 수행할 수 있다. 인양 시뮬레이션에서 가장 중요한 것은 바로 인양력(lifting pISSN:1225-1143, Vol. 52, No. 5, pp. 387-394, October 2015

Layout Method of a FPSO (Floating, Production, Storage, and Off-Loading Unit) Using the Optimization Technique

In the case of a floating offshore plant such as FPSO (Floating, Production, Storage, and Off-loading unit), many equipment should be installed in the limited space, as compared with an onshore plant. At this time, special conditions, such as the movement due to external force by wind and wave, salt content, and so on, should be also considered because the floating offshore plant should be operated in the special environment of ocean. The requirement for an optimal layout method of the plant has been raised due to much considerations for layout design. Thus, a layout method of the floating offshore plant was proposed in this study. For this, an optimization problem for layout was mathematically formulated, and then an optimization algorithm was implemented based on the genetic algorithm or mixed integer linear programming in order to solve it. To evaluate the applicability of the proposed method, it was applied to an example of FPSO and LNG FPSO topsides. As a result, it was shown that the proposed method can be applied to layout design of the floating offshore plant.Copyright