• Title/Summary/Keyword: 코리올리력

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Model Order Reduction for Piezoelectric-Structural Systems with Coriolis Effect (코리올리 효과를 가진 압전-구조계의 모델차수축소법)

  • Han, Jeong-Sam
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2010.04a
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    • pp.713-716
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    • 2010
  • 본 논문에서는 코리올리 효과를 가진 압전-구조 시스템의 주파수응답 해석을 효율적으로 수행하기 위한 크리로프 부공간 모델차수축소법을 제안하였다. 이 방법은 초기 유한요소모델과 축소모델의 전달함수의 계수인 모멘트를 일치시키는 방법을 이용하는 축소기법으로 이미 대형 유한요소모델의 주파수응답 해석에 효과적으로 이용되고 있다. 예제로 고려된 압전형 미소 각속도계의 해석에는 압전구동 하중과 구조체의 회전에 따른 원심력이 동시에 입력하중으로 고려되는 다중입력의 경우이므로 변환행렬 V의 생성시, block Arnoldi 과정을 이용하여 두 하중의 효과를 축소모델에 함께 고려한다. 본 문제에 제안된 축소기법을 이용한 결과, 축소모델을 이용하여 원래 시스템의 관심영역의 주파수응답을 작은 차수의 모델로도 정확하게 계산할 수 있음을 확인하였다. 본 논문에서 제안된 방법을 이용하면 다양한 가진조건과 각속도 입력 하에서의 주파수응답을 정확하고 더욱 효율적으로 계산할 수 있을 것이다.

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A Study on the Coriolis Force Technique and the Flat Bottom Foot Using Ceramic Electric Wheel (도자기 전기물레를 이용한 코리올리힘 기법과 평저굽 융합에 관한 연구)

  • Kim, Seung-Man
    • 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.

Measurement of Developing Turbulent Flows in a Rotating 90 Degree Bend with Square Cross-Section (회전하는 정사각 단면 $90^{\circ}$ 곡덕트 내의 발달하는 난류유동의 측정)

  • Kim, Dong-Chul;Chun, Kun-Ho;Choi, Young-Don
    • 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.

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Model Parametrization on the Mixing Behavior of Coastal Discharges

  • Kim, Jong-Kyu
    • Journal of Ocean Engineering and Technology
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    • v.17 no.2
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    • pp.1-7
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    • 2003
  • A common feature in the three-dimensional numerical model experiments of coastal discharge with simplifed model and idealized external forcings is investigated. The velocity fields due to the buoyancy and flow flux, are spreaded radiately and the surface velocites are much greater than homegeneous discharges. The coastal dischargd due to the Coriolis force and flow flux are shaped a anticyclical gyre (clockwise) and determined the scale of the gyre in the coastal zone, respectively. The bottom topography restricts a outward extention of the coastal fronts and it accelerates a southward flow.

Effect of channel height on the heat transfer coefficient of a rotation dimpled channel (딤플이 설치된 회전 유로의 높이가 열전달 계수에 미치는 영향에 대한 실험적 연구)

  • Kim, Seok-Beom;Lee, Yong-Jin;Choi, Eun-Yeong;Jeon, Chang-Soo;Kwak, Jae-Su
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.3
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    • pp.30-36
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    • 2010
  • The detailed heat transfer coefficients on a rotating dimpled channel were measured by the hue detection based the transient liquid crystal technique. The dimples were fabricated on the one side of the channel and the tested channel aspect ratio was 4, 6, and 12 with fixed channel width. Tested Reynolds number based on the channel hydraulic diameter was varied from 21,000 to 47,000. A stationary case and two different rotating conditions were tested so that the dimple fabricated surface became leading or trailing surface. For all rotating conditions, the minimum averaged heat transfer coefficient was measured for the channel aspect ratio of 6. Generally, the highest averaged heat transfer coefficient was observed for the highest aspect ratio cases due to increased dimple induced vortex strength.

Effect of Inlet Velocity Distribution on the Heat Transfer Coefficient in a Rotating Smooth Channel (입구 속도 분포가 매끈한 회전유로 내 열전달계수에 미치는 영향)

  • Choi, Eun-Yeong;Lee, Yong-Jin;Jeon, Chang-Soo;Kwak, Jae-Su
    • The KSFM Journal of Fluid Machinery
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    • v.14 no.6
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    • pp.76-84
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    • 2011
  • The effect of inlet velocity profile on the heat transfer coefficient in a rotating smooth channel was investigated experimentally. Three simulated inlet flow conditions of fully developed, uniform, and distorted inlet conditions were tested. The Reynolds number based on the channel hydraulic diameter was ranged from 10,000 to 30,000 and the transient liquid crystal technique was used to measure the distribution of the heat transfer coefficient in the rotating channel. Results showed that the overall heat transfer coefficient increased as the Reynolds number increased. Also, the distribution of the heat transfer coefficient was strongly affected by the inlet flow condition. Generally, the fully developed flow simulated condition showed the highest heat transfer coefficient.

A numerical study of natural convection for low Pr liquids in enclosures with rocking (요동이 있는 밀폐용기내 낮은 Pr 액체의 자연대류에 관한 수치적 연구)

  • Mo, Jeong-Ha
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.3
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    • pp.360-372
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    • 1998
  • This study deals with the interaction between buoyancy-induced convection and externally imposed excitation in the form of harmonic rocking and the effect of the interaction upon heat transfer in low-Pr liquids. A wide array of system responses are discussed using the spectral collocation numerical technique. The superposition of buoyancy and Coriolis forces leads to complex fluid flow and heat transfer. The transition to chaotic convection is accelerated, and heat transfer rates are reduced as the enclosure is excited at the fundamental frequency of oscillation associated with the pure buoyancy-driven case. Average heat transfer rates are correlated for Pr=0.02 and 0.03. The heat transfer is affected more in the Pr=0.03 liquid than the case of Pr=0.02.

Study on the Similarity of Flows in an Orthogonally Rotating Square Duct and a Stationary Curved Square Duct (수직축을 중심으로 회전하는 직관과 정지한 곡관내의 유동 유사성에 관한 연구)

  • Lee, Gong-Hee;Baek, Je-Hyun
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.825-830
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    • 2001
  • A numerical study on a quantitative analogy of the fully developed flow between in a straight square duct rotating about an axis perpendicular to that of the duct and a stationary curved duct of square cross-section is carried out. In order to clarify the similarity of two turbulent flows, the dimensionless parameters $K_{TR} = Re^{1/4}/\sqrt{Ro}$ and the Rossby number, Ro, in a rotating straight duct flow were used as a set corresponding to $K_{TC} = Re^{1/4}/\sqrt{{\lambda}}$ and curvature ratio, ${\lambda}$, in a stationary curved duct flow so that they have the same dynamical meaning as $K_{LR} = Re/\sqrt{Ro}$ and $K_{LC} = Re/\sqrt{{\lambda}}$ of the fully developed laminar flows. For the large values of Ro or A, it is shown that the flow field satisfies the asymptotic invariance property: there are strong quantitative similarities between the two flows such as flow patterns and friction factors for the same values of $K_L$ and $K_T$.

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A Numerical Study on the Similarity of Laminar Flows in Orthogonally Rotating Rectangular Ducts and Stationary Curved Rectangular Ducts of Arbitrary Aspect Ratio (임의의 종횡비를 가지는 수직축을 중심으로 회전하는 직관과 정지한 고고간 내부의 층류 유동의 유사성에 관한 수치적 연구)

  • Lee, Gong-Hee;Baek, Je-Hyun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.6
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    • pp.842-849
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    • 2002
  • The present study showed that a quantitative analogy of the fully developed laminar flows inorthogonally rotating rectangular ducts and stationary curved rectangular ducts of arbitrary aspect ratio could be established. In order to clarify the similarity of the two flows, the dimensionless parameters $K_{LR}$ =Re/√Ro and Rossby number Ro= $w_{m}$/$\Omega$d in a rotating strait duct were used as a set corresponding to Dean number $K_{LC}$ =Re/√λand curvature ratio λ=R/d in a stationary curved duct. Under the condition that the value of Rossby number and curvature ratio was large enough, the flow field satisfied the ‘asymptotic invariance property’: there were strong quantitative similarities between the two flows such as friction factors, flow patterns, and maximum axial velocity magnitudes for the same values of $K_{LR}$ and $K_{LC}$ .