• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 1998년도 하계 학술대회 논문집
• /
• pp.191-196
• /
• 1998

• 교육시설
• /
• 제9권2호
• /
• pp.126-129
• /
• 2002

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2001년도 춘계학술발표대회 개요집
• /
• pp.23-26
• /
• 2001

• 대한기계학회논문집B
• /
• 제23권3호
• /
• pp.408-418
• /
• 1999

Incompressible flow inside a circular cylinder Including periodically oscillating free surface waves was studied primarily by using a numerical method. We developed a finite difference scheme based on the MAC method applicable to three-dimensional free-surface flows, and applied it to the present flow model to study tho flow characteristics as well as the fluid stirring. To verify the validity of our scheme, we performed a simple experiment for flow visualization. We found that the numerical results show a reasonable agreement with the observed flow patterns.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2002년도 춘계학술대회 논문집
• /
• pp.215-219
• /
• 2002

In this study, we show the numerical and the experimental results for fluid motions inside a rectangular container subjected to a background rotation added by a rotational oscillation. In the numerical computation, we used a parallel computer system of PC-cluster type. Attention is given to dependence of the flow patterns on the parameter change. It shows that the flow becomes in a periodic state at low Reynolds numbers and undergoes a transition to a chaotic motion at high Reynolds numbers. It also shows that the fluid motion tends to be depth-independent at ${\epsilon}$ up to 0.3 for Re lower than 5235.

• 한국공작기계학회논문집
• /
• 제14권3호
• /
• pp.103-109
• /
• 2005

Since fretting fatigue damage accumulation occurs over relatively small volumes, the role of the microstructure is quite significant in fretting fatigue analysis. The heterogeneity of discrete grains and their crystallographic orientation can be accounted for using continuum crystallographic cyclic plasticity models. Such a constitutive law used in parametric studies of contact conditions may ultimately result in more thorough understanding of realistic fretting fatigue processes. The primary focus of this study is to explore the influence of microstructure as well as the magnitude of the normal force and tangential force amplitude during the fretting fatigue process. Fretting maps representing cyclic plastic strain behaviors are also developed to shed light on the cyclic deformation mechanisms.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 1998년도 추계 학술대회논문집
• /
• pp.133-140
• /
• 1998

A Navier-Stokes code based on a unstructured finite volume method is used to simulate the MIT flapping foil experiment. A low Reynolds number $k-{\varepsilon}$ turbulence model is used to close the Reynolds averaged Navier-Stokes equations. Computations are carried out for a domain involving two flapping foils and a downstream hydrofoil. The computational domain is meshed with unstructured quadrilateral elements, partly structured. Numerical solutions show good agreement with experiment. Unsteadiness inside boundary layer is entrained when a unsteady vortex impinge on the blade surface. It shoves that local peak value inside the boundary layer and also local minimum near the edge of boundary layer as it developes along the blade surface. The unsteadiness inside the boundary layer is almost isolated from the free stream unsteadiness and being convected at local boundary layer speed, less than the free stream value.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1682-1687
• /
• 2003

Die polishing technology is very critical to determine quality and performance of the final products. Generally, the rotation-type tool is used most widely in the polishing process. However it is difficult to make the mirror surface, because the method using the rotation-type tool causes a lot of tiny scratch on the polished surface. This paper proposes a new method using the oscillation-type tool that reduces the scratch and improves the surface roughness. As result. the mirror surface was able to obtain by using the oscillation-type tool. AE is known to be closely related to material removal rate(MRR). As the surface is rougher, MRR gets larger and AE increase. The surface roughness can be indirectly estimated using the AE signal measured during automatic die polishing process. In this study. an AE sensor based monitoring system was developed to investigate the relation the level of AE RMS with the surface roughness during polishing process.

• 대한기계학회논문집B
• /
• 제20권12호
• /
• pp.3960-3969
• /
• 1996

A fluid flow inside a circular cylinder subject to horizontal and circular oscillation is analyzed theoretically. Under the assumption of small-amplitude oscillation, the governing equations take linear forms. The velocity field is obtained in terms of the first kind of Bessel function of order 1. It was found that a particle describes an orbit close to a circle in the central region and an arc near the side wall. We also obtained the Stokes' drift velocity induced by the traveling wave along the circumferential direction. The Eulerian streaming velocities at the edge of the bottom and side boundary layers were also obtained. It was shown that the vertical component of the steady streaming velocity on the side wall is almost proportional to the amplitude of the free surface motion.

• 대한기계학회논문집B
• /
• 제24권6호
• /
• pp.845-851
• /
• 2000

In this paper, we show the numerical and the experimental results of two-dimensional fluid motions inside a rectangular container subjected to a background rotation added by a rotational oscillation. In the PlY experiment we apply a new algorithm, new three step search(NTSS), to the velocity calculation. In the numerical computation, the linear Ekman-pumping model was used to take the bottom friction effect into account. It was found that it well produces the experimental results at low e number.