• 한국해양공학회지
• /
• 제13권4호통권35호
• /
• pp.132-142
• /
• 1999

A three-dimensional linearised potential theory is presented for the prediction of motions and dynamic structural responses of twin-hull ships travelling with forward speed in regular waves. Comparisons between theoretical and experimental results are shown for the motion responses and lateral wave loads of an ASR(anti-submarine rescue) catamaran. In general, good agreement between theory and experiment is found except for some discrepancies that are believed to be caused by neglect of forward speed effects on free surface.

• 대한기계학회논문집A
• /
• 제26권11호
• /
• pp.2436-2441
• /
• 2002

Finite element technique considering adhesive forces is proposed and applied to analyze the behavior of elastic hemispherical asperity adhesively contacting the plane surface of semi -infinite rigid body. It is demonstrated that the finite element model simulates interfacial phenomena such as jump -to-contact and adhesion hysteresis that cannot be simulated with the currently available adhesive contact continuum models. This simulation aiso provides valuable information on contact pressure, contact region and stress distributions. This technique is anticipated to be utilized in designing a low-adhesion surface profile for MEMS/NEMS applications since various contact geometries can be analyzed with this technique.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1337-1340
• /
• 2005

A rheology casting technology has some advantages compared with conventional forming processes such as die casting, squeeze casting and hot/cold forming. The liquid segregation is important on mechanical properties of materials using rheology casting. In this study, so, molecular dynamics simulations were performed for the control of liquid segregation. Because the dynamics of fluid flow about nano-scaled materials is completely different from continuum, molecular dynamics simulations were used. The behavior of particles was far from the truth according to boundary conditions in simple flow. But various movement of particles appear at two or more molecular simulations.

• 한국해양공학회지
• /
• 제16권3호
• /
• pp.1-7
• /
• 2002

In this paper, a numerical model to analyze the performance of a vertical slit-type wave absorber is developed under the assumption of inviscid water waves. The formulation combines the linear potential theory with a semi-empirical description of the eddy-shedding at a slit-type wave absorber. We investigated the reflection coefficients over a wide frequency range for a vertical slit-type wave absorber both with and without a solid rear wall. Model test was conducted at KRISO' s two dimensional wave tank to validate the theoretical results. It is found that the agreement between theoretical results and experimental data is surprisingly good. We found that the wave absorbing system using a vertical slit plate has sufficient potentials for breakwaters for ocean development.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2007년도 춘계학술대회
• /
• pp.414-419
• /
• 2007

This paper describes the prediction of aerodynamic performance and wake of HAWT in normal and yawed flow operation using potential based methods. In order to analyze aerodynamic performance of wind turbine WINFAS program is used, which is based on VLM(Vortex Lattice Method) and CVC(Constant vorticity contour) Free wake model. Some problems of CVC vortex filament method are investigated arid to improve these problems vortex ring wake are introduced in behalf of CVC vortex filament. The prediction results using the vortex lattice wake are compared to experimental data.

• 대한기계학회논문집A
• /
• 제28권7호
• /
• pp.930-939
• /
• 2004

Constitutive models for final stage densification of metal powder compacts with power-law creep deformation were investigated. The constitutive models were implemented into a finite element program (ABAQUS) by using user subroutine CREEP and, from FEM results, useful densification curves were obtained when hydrostatic and uniaxial stress were applied to the powder compacts at various pressures and temperatures. Because the densification behavior varied as the constitutive models, the equivalent stress surface on each constitutive equation was investigated to analyze the difference of densification behavior.

• 대한기계학회논문집A
• /
• 제21권10호
• /
• pp.1666-1673
• /
• 1997

In order to investigate the characteristics of sound-structure interaction plate having a cut-out, we modeled a rectangular cavity and the flexible plate of the cavity. Because the particle velocity of air is the same as that of plate on the plate, we could easily redefine vibration equation using the velocity potential. We calculated the natural frequencies of plate using orthogonal polynomial functions which satisfy the boundary conditions in the Rayleigh-Ritz method. For the change of vibration characteristics, the effect of sound-structure interaction is more dominant than that of cut-out size.

• 대한기계학회논문집
• /
• 제15권5호
• /
• pp.1530-1537
• /
• 1991

본 연구에서는 반무한 직선 계면균열의 상하면에 임의로 분포하는 어떠한 하 중에 대해서도 그 해석이 가능한 그린함수(Green's function)를 구하고자 한다. 이 를 위하여 반무한 직선 계면균열상의 임의의 한 점에 평면 집중하중이 작용하는 문제 와 비평면 집중전단하중이 작용하는 문제를 각각 택하였고, 이때 계면균열의 선단은 열려있다고 가정하였다. 이 문제를 풀므로써 균열선단부근의 응력성분을 결정하고 이로부터 그린함수의 의미를 지니는 응력강도계수에 대한 폐형해를 얻었다.

• 대한기계학회논문집B
• /
• 제30권6호
• /
• pp.578-586
• /
• 2006

Numerical simulations are carried out to investigate the thermal effects of the gravitational potential on the centrifugal instability of a Taylor-Couette flow, and to further study the detailed flow fields and flow bifurcations to spiral vortices. The effects of centrifugal potential on the centrifugal instability are also investigated in the current study. Spiral vortices have various types of mode depending on Grashof number and Reynolds number. The correlation of Richardson number with the spiral angle of the spiral vortices shows that the structure of the spiral vortices strongly depends on the Richardson number. The heat transfer rate of the inner cylinder increases with increasing Grashof number. It is also confirmed that the torque required to rotate the inner cylinder increases as Grashof number increases.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1004-1009
• /
• 2003

Electroosmotic flow induced by an applied electrostatic potential field in microchannel is analyzed in this study. The electroosmotic flow is an alternative to pressure driven flow in microchannels, but the usage has been limited to the simple cases. In this study, We analyze electroosmotic flow driven by inhomogeneous surface charge on the channel wall. The surface charge varies along a direction perpendicular to the electric field in order to generate the electroosmotic flow. A numerical results substantiate the highly efficient mixing performance. It is highly the beneficial to fabrication process since only straight microchannel rather than complex geometry is enough to yield efficient mixing.