• 한국전산구조공학회논문집
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• 제27권4호
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• pp.223-230
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• 2014

본 논문에서는 FSI해석을 이용하여 비정형 초고층 빌딩의 풍응답 특성을 연구하였다. 해석모델은 Twist모델이며, 뒤틀림 각도와 풍가속도의 상관관계에 대해 연구 중점을 두었다. 먼저 단방향 해석을 수행하여 100년 재현주기 풍속에 대한 최대 횡 변위를 구하고, 제한조건을 만족하는 탄성계수를 산출한다. 그리고 양방향 해석을 수행, 시간이력해석을 통해 산출된 탄성계수와 임의의 밀도를 가지는 풍가속도를 예측하게 된다. 정방형 모델은 높이 400m, 변장비 1:1, 세장비 8로 설정, 뒤틀림 모델은 0도에서 90도까지 15도 간격으로, 90도에서 360도까지 90도 간격으로 비틀어 회전시켰다. 형상에 따른 풍가속도 예측 결과, 정방형 모델이 뒤틀림 모델보다 크게 산출되어 풍진동 영향에 더 민감한 것을 검증하였다.

• 한국전산구조공학회논문집
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• 제33권1호
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• pp.45-53
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• 2020

액체저장탱크의 지진 거동은 유체-구조물 상호작용에 의해 복잡하게 나타나므로, 이 시스템의 지진응답과 피해를 정확하게 예측하기 위해서는 이를 엄밀히 고려하여야 한다. 이 연구에서는 유체-구조물 상호작용을 엄밀히 고려하여 양방향 수평 지반운동이 작용하는 직사각형 액체저장탱크의 지진응답 해석을 수행하고 그 응답 특성을 분석하고자 한다. 이를 위해 지진하중 작용 시 발생하는 유체 동수압을 유한요소 기법을 사용하여 산정하고, 이 동수압을 구조물의 유한 요소에 작용하여 전체 시스템의 동적 거동을 모사한다. 예제 직사각형 액체저장탱크의 지진응답 해석을 통하여 대상 시스템의 동적 거동은 양방향 수평 지반운동이 작용하는 방위각에 의해 유의미한 영향을 받음을 확인할 수 있다. 그러므로 직사각형 액체저장탱크의 내진설계를 수행하거나 내진성능을 검토할 때는 이러한 특성을 고려하여야 할 것이다.

• Structural Engineering and Mechanics
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• 제76권3호
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• pp.355-365
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• 2020

In this study, considering the hydroelastic response represented by the springing and whipping phenomena, we propose a method of estimating the fatigue damage in the longitudinal connections of ships. First, we screened the design sea states using a load transfer function based on the frequency domain. We then conducted a time domain fluid-structure interaction (FSI) analysis using WISH-FLEX, an in-house code based on the weakly nonlinear approach. To obtain an effective and robust analytical result of the hydroelastic response, we also conducted an experimental model test with a 1/50-scale backbone-based model of a ship, and compared the experimental results with those obtained from the FSI analysis. Then, by combining the results obtained from the hydroelastic response with those obtained from the numerical fatigue analysis, we developed a fatigue damage estimation method. Finally, to demonstrate the effectiveness of the developed method, we evaluated the fatigue strength for the longitudinal connections of the real ship and compared it with the results obtained from the model tests.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2014년도 춘계학술대회
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• pp.36-37
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• 2014

It is necessary to develop highly sophisticated Modeling & Simulation (M&S) system for the scientific investigation of marine accident causes and for the systematic reproduction of accidental damage procedure. To ensure an accurate and reasonable prediction of marine accidental causes, such as collision, grounding and flooding, full-scale ship M&S simulations would be the best approach using hydrocode, such as LS-DYNA code, with its Fluid-Structure Interaction (FSI) analysis technique. The objectivity of this paper is to present three full-scale ship collision, grounding and flooding simulation results of marine accidents, and to show the possibility of the scientific investigation of marine accident causes using highly sophisticated M&S system.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.524-529
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• 2010

In the present study, a CFD program is developed for the Fluid-Structure Interaction(FSI) analysis. The non-staggered, non-orthogonal, and unstructured grid system was also used to handle the complicated geometries in the program. In order to validate the capabilities of the developed CFD program, various models are investigated by using unstructured and nonorthogonal meshes. The predicted results are a good agreement with analytic solution, experimental data and commercial software. And also PISO algorithm is applied for transient flow analysis. The cyclic boundary condition and baffle cell are developed in order to improve the effectiveness of the calculation for complex geometry.

• 한국기계가공학회지
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• 제13권3호
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• pp.83-88
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• 2014

FSI (Fluid Structure Interaction) method, in this study, has been applied to analyzing thermal characteristics of a high speed machine tool spindle system. The spindle is composed of angular contact ceramic ball bearings, a high speed built-in motor, a cooling jacket, and so on. The cooling jacket has three inlets and outlets. Using the FSI method, temperature distributions and thermal displacements of the spindle system were computed considering the heating of the front and rear bearings and the built-in motor. The results computed using the FSI method were compared with those determined by experiment and using the conventional numerical approach. The results determined using the FSI method were similar to those from the conventional numerical approach but showed better agreement with the experimental results. Therefore, it is concluded that the FSI method is useful for analyzing the thermal characteristics of high speed spindles and can be applied to the design of high speed spindles.

• 설비공학논문집
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• 제16권8호
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• pp.707-713
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• 2004

A numerical analysis has been conducted for flow characteristics of piezoelectric micropumps. In the present study, FSI (Fluid-Structure Interaction) model and grid deform model have been employed for each of two different geometries of the micropumps with two different frequencies in the piezoelectric diffuser/nozzle based micropumps. The displacement of piezo disk and flow rates have been closely examined at the inlet and outlet. It has been found that the motion of the piezo disk investigated with FSI model is not in accordance with that with grid deform model. The results show that the time averaged flow rate calculated with FSI model is larger than that with grid deform model. This study presents the performance analysis of piezoelectric micropumps with two different numerical models for different types of pumps.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.275-282
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• 2007

In this study, a fluid-structure interaction (FSI) analysis system has been developed in order to evaluate the turbine cascade performance with blade structural deformation effect. Relative movement of the rotor with respect to stator is reflected by modeling independent two computational domains. To consider the deformed position of rotor airfoil, dynamic moving grid method is applied. Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation SST $k-{\varepsilon}$ turbulence models are solved to predict unsteady fluid dynamic loads. A fully implicit time marching scheme based on the Newmark direct integration method with high artificial damping is used to compute the fluid-structure interaction problem. Cascade performance evaluations for different elastic axis positions are presented and compared each other. It is importantly shown that the predicted aerodynamic performance considering structural deformation effect of blade can show some deviations compared to the data generally computed from rigid blade configurations and the position of elastic axis also tend to give sensitive effect.

• Tribology and Lubricants
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• 제38권3호
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• pp.109-114
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• 2022

This paper reports the development of an oil flushing system combined with a microbubble generator. Oil flushing plays a crucial role in regulating the lubricant's performance during the lubricant replacement process. Moreover, harmful contaminants, such as sludge, wear particles, and rust, from piping systems or lubrication system can be removed by oil flushing. Oil flushing aims to increase the system's efficiency using a dedicated flushing oil, increasing of the supply pressure and generating a vortex. In addition, it helps the mechanical system or equipment achieve peak performance and reduces the potential for premature failure. However, the contaminant-removal applications of existing oil flushing system are limited. In this research, we aim to improve the performance of oil flushing system by incorporating a microbubble generator, which uses the venture effect to generate microbubbles and mixes them with lubricant. The microbubbles in the blended lubricant remove contaminants from the lubrication system more effectively. Structural mechanics and fluid dynamics are analyzed through fluid-structure interaction (FSI) analysis, and the numerical analysis results are used for the designing the system. The magnitude of the maximum stress is investigated based on the pressure results obtained by the CFD analysis; through the CFD analysis, the mixing ratio of air (bubble) and lubricant is evaluated using the volume of fluid (VOF) model according to the working conditions.

• 한국항해항만학회지
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• 제41권6호
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• pp.451-466
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• 2017

원양어선 제501 오룡호는 황천 중인 베링해에서 조업 후 피항하던 중 개구부를 통한 침수로 인하여 침몰하였으며 많은 선원들이 사망하고 실종되었다. 본 연구에서는 유체-구조 연성(Fluid-Structure Interaction, FSI) 해석기법의 고도 정밀 M&S(highly advanced Modeling & Simulation) 시스템을 사용하여 실선 침수 침몰 시뮬레이션을 수행하여 침몰사고의 과정을 정확하고 과학적으로 분석하고자 하였다. 베링해 침몰사고 시의 기상 및 해상상태를 객관적으로 확보하기 위하여 침몰사고 지역의 시간대별 기상 및 해상 시뮬레이션을 수행하여 침몰사고 당시 파랑과 강풍 등을 분석하고, 불규칙 파랑과 강풍 스펙트럼을 사용하여 구현하였다. 사고선박의 선체 도면 등을 통하여 선박의 선형, 배치 및 중량 분포와 외부 해수 침수 개구부 및 선내 침수 경로를 분석하고 주요 탱크들의 용적과 그들의 중량 분포를 추정하여 침수 침몰 시뮬레이션을 위한 시나리오를 작성하고, 사고선박의 전선과 유체(공기 및 해수)를 상세 모델링을 하였다. 본 연구를 통하여 침수 침몰사고는 단순한 복원성의 부족으로 인한 일반적인 전복 침몰사고와는 다소 차이가 있다는 것도 확인할 수 있었다.