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다물체계 운동 방정식 선형화를 통한 해상 풍력 발전기 동적 거동의 주파수 영역 해석 방법에 관한 연구
구남국(Namkug Ku),노명일(Myung-Il Roh),하솔(Sol Ha),신현경(Hyun-Kyoung Shin) (사)한국CDE학회 2015 한국CDE학회 논문집 Vol.20 No.1
In this study, we describe a method to analysis dynamic behavior of an offshore wind turbine in the frequency domain and expected effects of the method. An offshore wind turbine, which is composed of platform, tower, nacelle, hubs, and blades, can be considered as multibody systems. In general, the dynamic analysis of multibody systems are carried out in the time domain, because the equations of motion derived based on the multibody dynamics are generally nonlinear differential equations. However, analyzing the dynamic behavior in time domain takes longer than in frequency domain. In this study, therefore, we describe how to analysis the system multibody systems in the frequency domain. For the frequency domain analysis, the non-linear differential equations are linearized using total derivative and Taylor series expansions, and then the linearized equations are solved in time domain. This method was applied to analysis of double pendulum system for the verification of its effectiveness, and the equations of motion for the offshore wind turbine was derived with assuming that the wind turbine is rigid multibody systems. Using this method, the dynamic behavior analysis of the offshore wind turbine can be expected to take less time.
DEVS 형식론 기반의 Dynamic Reliability Block Diagram과 GPU 가속 기술을 이용한 신뢰도 분석 방법
하솔,구남국,노명일,Ha, Sol,Ku, Namkug,Roh, Myung-Il 한국시뮬레이션학회 2013 한국시뮬레이션학회 논문지 Vol.22 No.4
전통적으로 신뢰도 분석에 사용되는 Fault Tree Analysis의 경우 관련 분야의 전문가가 필요하고 작성자의 판단에 따라 신뢰도 분석 결과가 달라진다. 반면, Reliability Block Diagram의 경우 시스템 구성도나 Process Flow Diagram (PFD), Piping and Instrument Diagram (P&ID)을 기반으로 하기에 작성에 필요한 비용과 시간이 절감되는 장점이 있다. 본 논문에서는 Dynamic Reliability Block Diagram과 이산 사건 시뮬레이션에 널리 사용되는 DEVS 형식론을 이용하는 신뢰도 분석 방법을 제안한다. 또한 시스템 모델링 방법론 중 하나인 System Entity Structure/Model Base의 개념을 도입함으로써 다양한 설계 대안에 대한 신뢰도 분석 모델을 자동으로 생성할 수 있도록 하였다. 그리고 Reliability Block Diagram을 이용한 신뢰도 분석 시 오래 소요되는 계산 시간을 단축시키기 위해 GPU 가속 기술을 신뢰도 분석 시뮬레이션에 접목하였다. 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.
수중운동체 교전 시뮬레이션을 위한 이산 사건 및 이산 시간 혼합형 시뮬레이션 모델 구조 기반의 전투 공간 모델 개발
하솔,구남국,이규열,노명일,Ha, Sol,Ku, Namkug,Lee, Kyu-Yeul,Roh, Myung-Il 한국시뮬레이션학회 2013 한국시뮬레이션학회 논문지 Vol.22 No.2
본 논문에서는 전장 환경 요소 및 플랫폼 모델 간 상호 교환 정보를 통합하여 관리하는 전투 공간 모델(Battle Space Model)을 제안한다. 전투 공간 모델은 전장의 지형 정보와 환경 요소를 저장하는 Geographic Information System(GIS) Model, 플랫폼 모델 간 상호 교환 정보에 전장 환경 요소의 영향을 고려하는 Propagator Model, 플랫폼 모델 간 상호 교환 정보를 저장하는 Logger Model, 그리고 플랫폼 모델 간의 상호 작용(encounter) 시점을 예측하고 상호 작용 시점까지 시간을 건너뛰는 Spatial Encounter Predictor(SEP) Model로 구성된다. 또한 이산 사건 및 이산 시간 혼합형 시뮬레이션 모델 구조로 구성되어 있는 플랫폼 모델과 추가 작업 없이 직접 연결하기 위해, 전투 공간 모델 또한 이산 사건 및 이산 시간 혼합형 시뮬레이션 모델 구조로 구성하였다. 본 연구에서는 전투 공간 모델을 적용하여 수중운동체 교전 시뮬레이션을 수행하였다. 이를 통해 플랫폼 모델 각자가 반영하던 전장 환경 요소를 전투 공간 모델이 일괄적으로 반영함으로써 플랫폼 모델 개발을 단순화 할 수 있었다. 또한 각 플랫폼 모델은 다른 플랫폼 모델과의 정보 교환을 고려하지 않고 전투 공간 모델과의 정보 교환만을 고려하면 되므로, 플랫폼 모델을 중립적으로 구성할 수 있었다. 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. 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.
다물체계 동역학을 이용한 해양 플랜트의 라이저 인장 장치의 동적 거동 해석
이혜원(Hyewon Lee),구남국(Namkug Ku),하솔(Sol Ha),노명일(Myung-il Roh) (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.2
In this study, dynamic response analysis of the riser tensioner system for offshore plant was performed. The main function of riser tensioner system is to provide enough tension to riser which become much heavier at deep sea to support itself. The riser tensioner also required to maintain same tension regardless of the motion of the drilling unit. The riser tensioner system includes pressure system which composed of hydraulic cylinders, and it reduce motion of riser caused by motion of drilling unit. In this study, the simple springdamper model of the riser tensioner, platform and riser was constructed. Three masses are linked with springs and dampers, and dynamic response of riser followed by the motion of platform was analyzed using the Simulink as a tool. Further study will be done with multi-body systems dynamics.
이중선체 작업환경 센싱을 위한 포인트 클라우드 데이터 취득 시스템 프로토타입 개발
이정우(Jungwoo Lee),구남국(Namkug Ku),이재용(Jaeyong Lee) (사)한국CDE학회 2022 한국CDE학회 논문집 Vol.27 No.4
When work such as blasting starts inside the double hull block, it becomes a poor environment to the extent that sensing is impossible due to the cause of dust. Accordingly, in this study, a point cloud acquisition system that can be used independently of an automated device was developed. Various pre-tests were performed to select the sensor, and hardware that enables the lidar sensor to rotate 360 degrees was developed. The test was first conducted in a small laboratory, and it was confirmed that the point cloud clearly depicts the target object.
연성된 과대 경사 각도를 고려한 부유식 구조물의 비선형 유체정역학 힘과 자세
차주환(Ju-Hwan Cha),구남국(Namkug Ku),박광필(Kwang-Phil Park) (사)한국CDE학회 2016 한국CDE학회 논문집 Vol.21 No.1
When ships and offshore plants are flooded or the floating crane is equipped with a heavy object, these floating structures are excessively inclined. In this case, immersion, heel, and trim affecting the hydrostatic restoration performance are very large and are coupled each other. In this paper, in order to calculate a static equilibrium position of floating structures with excessive inclination, the nonlinear governing equations were constructed by sequential linearization. In the governing equation, the immersion, heel, and trim are fully coupled, and the equations are represented using a plane area, a primary moment, and a moment of inertia of the water plane area. Therefore, it is possible to calculate the additional factor related the water plane area for estimating stability. Position and orientation of the floating structure are obtained by iterative calculation. The calculated results are compared with the previous studies in the aspect to the performance and the accuracy.