사각개구부가 있는 회전 복합재료 원통쉘의 자유진동해석

김영완 여수대학교 1997 論文集 Vol.11 No.2

The free vibration analysis of the rotating composite cylindrical shells with a rectangular cutout is investigated by theoretical method. The Love's thin shell theory is used to derive the frequency equation. The theoretical results are obtained by application of the energy method employing the Rayleigh-Ritz procedure. The used circumferential vibration modes are trigonometric functions, the axial modes are the beam modal functions chosen to satisfy the prescribed boundary conditions. To check the validity, the theoretical results are compared with experimental and FEM results.

링보강이 원통셸의 진동특성에 미치는 영향

김영완 여수대학교 1998 論文集 Vol.12 No.2

The Rayleigh-Ritz method is used to investigate the natural frequencies and mode shapes of thin-walled cylindrical shells with ring stiffeners. The Love's thin shell theory combined with the discrete stiffener theory is adopted to formulate the analytical model. The effect of stiffener eccentricity, number, size, and position on vibration characteristics of the shell is examined. By comparison with previously published experimental, FEM and new FEM results, it is shown that natural frequencies and mode shapes can be determined with adequate accuracy.

사각개구부가 복합재료 원통셸의 진동특성에 미치는 영향

김영완 여수대학교 1998 論文集 Vol.13 No.2

The vibration characteristics(frequencies, mode shapes) of the simply supported isotropic and composite cylindrical shells with a rectangular cutout is investigated using the theoretical method based on the Rayleigh-Ritz technique. The Love's shell theory is used to derive the governing equation of the shell. The rectangular cutout is located on the center of the shell. In this study, only the symmetric mode is considered for the circumferential vibration mode. Mainly, the effect of cutout sizes on the frequencies and mode shapes is examined and discussed. The mass and frequency variation of the weakened shell by a cutout are compared. Comparisons of results from this method with those from the available literature or finite element method are made and a good agreement is observed.

디버터의 열유동 및 열응력 해석

김영완,이상윤,김홍배 여수대학교 1998 論文集 Vol.13 No.2

For the optimal design of plasma facing components of a fusion reactor, the thorough understanding of thermal behavior of high heat flux components are required. The purpose of this research is to investigate the characteristics of heat flow and thermal stress in divertors which are exposed to high heat load varying with time and space. Numerical simulations of heat flow and thermal stress for three types of divertor are performed using finite volume method and finite element method. Respectively, commercial FLUENT code are used in the heat flow simulation, and maximum surface temperature, temperature distribution and cooling rate are calculated. Commercial ABAQUS code are used for calculating temperature distribution, thermal stress, strain and displacement. Through this computer simulation, design data for cooling system and structural are provided.

자동차용 핀-관 열교환기의 제작 및 열성능 향상에 관한 연구

김영완,김홍배,이상윤 여수대학교 1998 論文集 Vol.13 No.2

Naphthalene sublimation technique is employed to investigate the heat transfer enhancement of fin-tube heat exchangers using vortex generators. Experiments are performed for the fin-circular tube heat exchanger with and without vortex generators, and fin-flat tube heat exchanger with and without vortex generators. Local and spanwise averaged heat transfer coefficients are measured on the surface of fin, and compared with those obtained without vortex generator. Average heat transfer coefficients of fin-flat tube heat exchanger are much lower than those of fin-circular tube heater exchanger. On the other hand, fin-flat tube heat exchanger with vortex generators has a little higher heat transfer value than fin-circular tube with vortex generators. Friction loss for four types of heat exchanger are also measured and compared.

Vibration Characteristics of a Passenger Car Steering Column

Young-Shin Lee,Sun-Young Song,Myoung-Hwan Choi,Chung-Hyun Ryu,Young-Wann Kim 한국자동차공학회 2000 한국 자동차공학회논문집 Vol.8 No.6

The vibration characteristics of a passenger car steering column are studied by using a modal test and a finite clement (FE) analysis. To verify the FE model and the results, an experiment using the impact exciting method is performed. Two types of the steering column in this study are considered as follows; (i) the non-tilt type steering column and (ii) the upper-tilt type steering column. The experimental results are compared with those of the FE analysis, and it is shown that the results agree with each other. The effects of various design parameters such as the bracket thickness, the column thickness and the column diameter on the natural frequencies are also investigated by FE analysis.

중간 지지된 유체 유동 외팔형 원통셸의 임계유속

김영완(Kim, Young-Wann) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.5

The critical fluid velocity of cantilevered cylindrical shells subjected to internal fluid flow is investigated in this study. The fluid-structure interaction is considered in the analysis. The cantilevered cylindrical shell is supported intermediately at an arbitrary axial position. The intermediate support is simulated by two types of artificial springs: translational and rotational spring. It is assumed that the artificial springs are placed continuously and uniformly on the middle surface of an intermediate support along the circumferential direction. The steady flow of fluid is described by the classical potential flow theory. The motion of shell is represented by the first order shear deformation theory (FSDT) to account for rotary inertia and transverse shear strains. The effect of internal fluid can be considered by imposing a relation between the fluid pressure and the radial displacement of the structure at the interface. Numerical examples are presented and compared with existing results.

첩릿변환을 이용한 비틀림 유도파 모드분리

김영완(Young-Wann Kim),박경조(Kyung-Jo Park) 한국소음진동공학회 2014 한국소음진동공학회 논문집 Vol.24 No.4

유체 유동을 고려한 경사기능재료 원통셸의 연성진동

김영완(Kim, Young-Wann),김규호(Kim, Kyu-Ho),위은중(Wi, Eun-Jung) 한국소음진동공학회 2009 한국소음진동공학회 논문집 Vol.19 No.11

The coupled fluid-structure interaction problem is analyzed using the theoretical method to investigate the coupled vibration characteristics of functionally graded material(FGM) cylindrical shells conveying an incompressible, inviscid fluid. Material properties are assumed to vary continuously through the thickness according to a power law distribution in terms of the volume fraction of the constituents. The steady flow of fluid is described by the classical potential flow theory. The motion of shell represented by the first order shear deformation theory(FSDT) to account for rotary inertia and transverse shear strains. The effect of internal fluid can be taken into consideration by imposing a relation between the fluid pressure and the radial displacement of the structure at the interface. Numerical examples are presented and compared with exiting results.

경사기능재료 사각판의 열탄성 및 동적해석

김영완(Kim, Young-wann) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.4

A theoretical method is presented to investigate the thermoelastic and dynamic response of functionally graded material (FGM) rectangular plates made up of metal and ceramic. The temperature is assumed to be constant in the plane of the plate and to vary in the thickness direction only. Material properties are assumed to be temperature-dependant, and vary continuously through the thickness according to a power law distribution in terms of the volume fraction of the constituents. The third order shear deformation theory (TSDT) to account for rotary inertia and transverse shear strains is adopted to formulate the theoretical model. The modal analysis technique is used to develop the analytic solutions of the dynamic problem. The effect of material compositions and temperature fields is examined. The present theoretical results are verified by comparing with those from finite element analysis by ANSYS.