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류경중(Gyeong-Joong Ryu),김동현(Dong-Hyun Kim),김명환(Myung-Hwan Kim),이장호(Jang-Ho Lee) 한국자동차공학회 2012 한국자동차공학회 지부 학술대회 논문집 Vol.2012 No.5-1
In this study, a low-drag electric car configuration is presented based on the similar design concept of an aircraft body. Also, numerical drag tests using advanced computational fluid dynamics (CFD) technology has been conducted considering high-order turbulent models in order to investigate its drag characteristics. It is importantly shown that the present electric car model can significantly reduce the total drag and can achieve the very low drag coefficient such as 0.17~0.18.
김동현(Dong-Hyun Kim),류경중(Gyeong-Joong Ryu),김요한(Yo-Han Kim),김성복(Sung-Bok Kim),김광원(Kwang-Won Kim),남효우(Hyo-Woo Nam),이명구(Myoung-Goo Lee) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.4
In this study, the design and verification of 6 kW class lift-type vertical-axis wind turbine (VAWT) has been conducted using advanced CAE technique based on computational fluid dynamics (CFD), finite element method (FEM), and computational structural dynamics (CSD). Designed aerodynamic performance of the VAWT model is tested using unsteady CFD method. Designed structural safety is also tested through the evaluation of maximum induced stress level and resonance characteristics using FEM and CSD methods. It is importantly shown that the effect of master eccentricity due to rotational inertia needs to be carefully considered to additionally investigate dynamic stress and deformation level of the designed VAWT system.
김동환(Dong Hwan Kim),김동현(Dong Hyun Kim),류경중(Gyeong Joong Ryu),이승민(Seung Min Lee),송지관(Ji Kwan Song),서정권(Jeoung Kwon Seo) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.4
본 연구에서는 고온, 고압 조건에 온도 변화에 따른 바이메탈의 접촉, 기하 비선형 및 대변형을 고려한 전산구조 해석을 수행하였다. 스팀 트랩의 주목적은 고온, 고압 증기의 배관 중에 발생한 응축수를 분리 배출하여 발전 효율 및 열 회수 효율을 높이는 데 있다. 온도 변화에 따른 바이메탈의 변형 수준과 응력 발생 수준 및 하우징(housing)의 변형과 응력 발생 수준을 정확하게 예측하기 위해 사면체 격자(tetrahedron parabolic order mesh)를 활용한 전산구조해석(computer applied engineering) 기법이 적용되었다. 바이메탈의 적층 방법과 각 바이메탈과 레귤레이터(regulator) 간의 접촉 조건을 고려하였으며, 온도 변화에 따른 바이메탈의 변형 수준을 시뮬레이션하였다. In this study, structural thermal analyses for steam trap valve considering contact boundary condition have been conducted for high temperature and pressure conditions using nonlinear finite element method. Full steam trap model also including regulator and housing structures is considered in order to accurately simulate the complex valve mechanism and investigate thermal stress levels and behaviors of core structural parts. It is typically shown that the present computational approach can give very useful results for design engineers so that they can verify the operating performance and structural safety of the steam trap valve in the design process.
김동환(Dong-Hwan Kim),김동현(Dong-Hyun Kim),류경중(Gyeong-Joong Ryu),김수현(Su-Hyun Kim),송지관(Ji-Kwan Song),서정권(Jeoung-Kwon Seo) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7
In this study, structural thermal analyses for steam trap valve considering contact boundary condition have been conducted for high temperature and pressure conditions using nonlinear finite element method. Full steam trap model also including regulator and housing structures is considered in order to accurately simulate the complex valve mechanism and investigate thermal stress levels and behaviors of core structural parts. It is typically shown that the present computational approach can give very useful results for design engineers so that they can verify the operating performance and structural safety of the steam trap valve in the design process.
공탄성 변형효과를 고려한 10MW급 풍력발전기 블레이드의 성능해석
김동현(Dong-Hyun Kim),김요한(Yo-Han Kim),류경중(Gyeong-Joong Ryu),김동환(Dong-Hwan Kim),김수현(Su-Hyun Kim) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.4
In this study, aeroelastic performance analyses have been conducted for a 10MW class wind turbine blade model. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate detailed dynamic responsed of wind turbine blade. Reynolds-averaged Navier-Stokes (RANS) equations with k-ω SST turbulence model are solved for unsteady flow problems of the rotating turbine blade model. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D turbine blade for fluid-structure interaction (FSI) problems.
오일로 방정식 및 저차모델링 기법을 활용한 천음속 플러터 해석
김동현(Dong-Hyun Kim),김요한(Yo-Han Kim),김명환(Myung-Hwan Kim),류경중(Gyeong-Joong Ryu),황미현(Mi-Hyun Hwang) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.4
In the past much effort has been made to utilize advanced computational fluid dynamic (CFD) programs for aeroelastic simulations and analysis. However, it is limited in the field of unsteady aeroelasticity due to enormous size of computer memory and unreasonably long CPU time. Recently, AAEMS(Aerodynamics is Aeroelasticity minus Structure) was developed for linear time-invariant, coupled fluid-structure systems. In this paper, to demonstrate further the efficiency and accuracy of the new model reduction method, we successfully examine AGARD 445.6 wing modeled by FLUENT CFD, FSIPRO3D and NASTRAN FEM(Finite Element Method) programs. Using the ROM(Reduced Order Modeling) one can predict flutter boundary as a function of the dynamic pressure.
타워강성 효과를 고려한 소형 수직축 풍력발전기 운전 진동실험 및 해석
추헌호(Heon Ho Choo),심재박(Jae Park Sim),류경중(Gyeong Joong Ryu),김동현(Dong Hyun Kim),김봉영(Bong-Yung Kim) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.10
In this study, operational vibration experiment and analysis have been conducted for the 4-blade small vertical-axis wind turbine (VAWT) including the effect of tower elastic behavior. Computational structural dynamics analysis method is applied to obtain Campbell diagram for the VAWT with elastic tower. An open type wind-tunnel is used to change and keep the wind velocity during the ground test. Equivalent reduced elastic tower is supported to the VAWT so that the elastic stiffness effect of the tower can be reflected to the present vibration experiment. Various excitation sources with aerodynamic forces are considered and the dominant operating vibration phenomena are physically investigated in detail.
김동환(Dong Hwan Kim),김동현(Dong Hyun Kim),류경중(Gyeong Joong Ryu) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.11
In this study, structural thermal analyses for steam trap valve considering contact boundary condition have been conducted for high temperature and pressure conditions using nonlinear finite element method. Full steam trap model also including regulator and housing structures is considered in order to accurately simulate the complex valve mechanism and investigate thermal stress levels, and structural behaviors of core structural parts. It is typically shown that the present computational approach can give very useful results for design engineers so that the operating performance and structural safety of the steam trap valve can be verified in the design process.