• Journal of Institute of Convergence Technology
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• v.6 no.1
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• pp.37-41
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• 2016

The serpentine internal passage is located in turbine blade and it shows the variety heat transfer distribution. Especially, the Coriolis force, which is induced by blade rotation, makes different heat transfer distribution of the leading and trailing surfaces of serpentine internal passage. The different heat transfer is one of the reasons why the serpentine cooling passage shows low cooling performance in the rotating condition. So, this study tried to design the advanced the serpentine passage to consideration of the Coriolis force. The design concept of advanced serpentine cooling is maximizing cooling performance using the Coriolis force. So, the flow turns from leading surface to trailing surface in advanced serpentine passage to match the direction of Coriolis force and rotating force. We performed numerical analysis using CFX and compared the existing and advanced serpentine internal passage. This design change is induced the high heat transfer distribution of whole advanced serpentine internal passage surfaces.

• Journal of The Korean Association For Science Education
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• v.36 no.3
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• pp.423-434
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• 2016

The purpose of this study is to investigate preservice earth science teachers' mental models through applications of Coriolis force experiment apparatus. After the root of preconception was examined by face to face interviews based on the questionnaire, five preservice earth science teachers were finally selected for this study. The mental models about concept of Coriolis force was classified into naive mental model, static unstable mental model, dynamic unstable mental model, and scientific mental model through the result of individual interviews and their drawings. According to the mental model analysis about Coriolis' force conception, students C and M showed naive mental model about concept of Coriolis force before experiment. After the experiment, student M's model changed to static unstable mental model. Student C's model improved to dynamic unstable mental model. In adiition, students D and O's model improved from static unstable mental model to dynamic unstable mental model. In the case of student B, the dynamic unstable mental model was maintained after the experiment, however, student B's preconception changed to scientific concept. It turned out that a change occurred from low mental model level to integrated mental model after the application of the developed Coriolis' force experiment apparatus. According to the results, national curriculum is similar to static unstable mental model and the result of developed Coriolis' force experiment apparatus is similar to dynamic unstable mental model. It is suggested that it become the theoretical foundation to develop more comfortable and advanced Coriolis force experiment apparatus by improving the experiment apparatus.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.441-451
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• 2018

The main point of this study is to use the principle of Coriolis force and the sense of fingertips to scratch the surface of the wall by high-speed rotation (RPM) to push the texture of the stripe from the inside to the outer wall, and to express the beautiful, dynamic and distinctive outer wall texture that is diversified by Coriolis force (centrifugal force). This is designated as Coriolis force technique. In addition, instead of the traditional flat bottom foot onggi molding technique, a new type of flat bottom foot that uses the electric wheel to push the cylinder from inside to out to expand the outer wall and to spread the bottom of foot flatly. The purpose of this study is to create a modernized, distinctive, new interior work by fusing these techniques.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.819-824
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• 2001

Mean velocity and Reynolds stress components of the developing turbulent flows in a rotating 90 degree bend with square cross-section were measured by a hot-wire anemometer. Effects of the centrifugal and Coriolis forces generated by the curvature and rotation of bend on the mean motion and turbulence structures are investigated experimentally. Results show that the Coriolis force associated with the rotation of the bend may act both through the mean motion and turbulent structures, thereby changing the pressure fields, mean and turbulent velocities distributions.

• Journal of the Korean earth science society
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• v.32 no.1
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• pp.73-83
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• 2011

A new method was developed to better understand the principle of Coriolis force. We also investigated the understanding of 5 10th grade students and analyzed their responses. Since no clear explanation about the nature of a rotating disk is provided in school textbooks, it tends to be misunderstood as the earth surface revolving on its axis pointing to the North Pole. This study was carried out focusing on the fact that a rotating disk is the tangential plane at arbitrary latitude. Results showed that there are changes in students' conceptions on the principle of Coriolis force with a new understanding of the rotating disk. In conclusion, a new method used in this study helped students better understand the link between Coriolis force and rotating disk. The method would be helpful to clarify the principle of Coriolis force in school science.

• Journal of Astronomy and Space Sciences
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• v.31 no.1
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• pp.91-99
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• 2014

The atmospheric flow in the 3-Cell model of global atmosphere circulation is described by the Lagrange's equation of the non-inertial frame where pressure force, frictional force and fictitious force are mixed in complex form. The Coriolis force is an important factor which requires calculation of fictitious force effects on atmospheric flow viewed from the rotating Earth. We make new Mathematica platform to solve Lagrange's equation by numerical analysis in order to analyze dynamics of atmospheric general circulation in the non-inertial frame. It can simulate atmospheric circulation process anywhere on the earth. It is expected that this pedagogical platform can be utilized to help students studying the atmospheric flow understand the mechanisms of atmospheric global circulation.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.544-553
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• 2012

A simple experimental method was developed to help students understand the effect of the Coriolis force on typhoon genesis and movement. It consists of rotating tanks with and without a sloping bottom, and a small stirrer to produce cyclonic typhoon-like vortices by locally stirring the water. Vortices were able to last for more than 3 minutes without dissipation in the rotating tank. However, vortices were hardly maintained without rotation, and would rather disappear as soon as the stirrer stopped mixing. Since the dynamical properties of the rotating water are similar to those of the atmosphere influenced by the Coriolis force, the experiments show that the Coriolis force is indispensable to the typhoon genesis. When the tank had both the sloping bottom and rotation, vortices would move in a particular direction. Considering the topographical beta effect, this result indicates that typhoons are drifted not only by the steering wind but also by the meridional gradient of the Coriolis force. The methodology developed in this study, would be useful for both students and teachers to better the relationship between the Coriolis force and the typhoon genesis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.850-858
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• 2002

The present study investigates in detail the combined effects of the Coriolis force and centrifugal force on the development of turbulent flows in a square-sectioned U-bend rotating about an axis parallel to the center of bend curvature. When a viscous fluid flows through a curved region of U-bend, two types of secondary flow occur. One is caused by the Coriolis force due to the rotation of U-bend and the other by the centrifugal force due to the curvature of U-bend. For positive rotation, where the rotation is in the same direction as that of the main flow, both the Coriolis force and the centrifugal force act radially outwards. Therefore, the flow structure is qualitatively similar to that observed in a stationary curved duct. On the other hand, under negative rotation, where these two forces act in opposite direction, more complex flow fields can be observed depending on the relative magnitudes of the forces. Under the condition that the value of Rossby number and curvature ratio is large, the flow field in a rotating U-bend can be represented by two dimensionless parameters : $K_{TC}$ =Re $\sfrac{1}{4}$√λand a body force ratio F=λ/Ro. Here, $K_{TC}$ has the same dynamical meaning as $K_{TC}$ =Re√λ for laminar flow.

• Structural Engineering and Mechanics
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• v.47 no.4
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• pp.455-470
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• 2013

This paper presents a theory concerning the beam element subjected to an eccentric rolling disk (or simply called the eccentric-disk-loaded beam element) such that the dynamic responses of a beam subjected to an eccentric rolling disk with its inertia force, Coriolis force and centrifugal force considered can be easily determined. To this end, the property matrices of an eccentric-disk-loaded beam element are firstly derived by means of the Lagrange's equations. Then, the overall property matrices of the entire vibrating system are determined by directly adding the property matrices of the eccentric-disk-loaded beam element to the overall ones of the entire beam itself. Finally, the Newmark direct integration method is used to solve the equations of motion for the dynamic responses of a beam subjected to an eccentric rolling disk. Some factors relating to the title problem, such as the eccentricity, radius and rotating speed of the rolling disk, and the Coriolis force and centrifugal force induced by the rolling disk are investigated. Numerical results reveal that the influence of last factors on the dynamic responses of the pinned-pinned beam is significant except the centrifugal force.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2206-2222
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• 1995

In this study, the characteristics of the three-dimensional turbulence flow in a rotating square sectioned 90.deg. bend were investigated by numerical simulation. And a dimensionless number, Coriolis force ratio, primarily subjected to the feature of the flow in the rotating 90.deg. bend was obtained as a result of one-dimensional theory. In the simulation study, low Reynolds number ASM developed by Kim(1991) in the square sectioned 180.deg. bend flow was modified in order to consider the rotational effects in the testing flows. In the near wall region of low Reynolds number, four turbulence models were employed and compared in order to find the most appropriate model for the analysis of the rotating 90.deg. bend flow. By comparison of the results with the experimental data, it is shown that low Reynolds number Algebraic Stress Model with rotating terms reflects most correctly the rotational effects. As the results of this study, centrifugal forces associated with the curvature of the bend and Coriolis forces and centripetal forces associated with the rotation affect directly both the mean motion and the turbulent fluctuations. Their actions on the mean flow are to induce a secondary motion while their effects on turbulence are to modify the pressure strain.