• Title/Summary/Keyword: 원판

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A Study on the Performance Characteristics of a Disk-type Drag Pump (원판형 드래그펌프의 성능특성에 관한 연구)

  • Hwang, Young-Kyu;Heo, Joong-Sik
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.643-648
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    • 2001
  • The direct simulation Monte Carlo(DSMC) method is applied to investigate steady and unsteady flow fields of a single-stage disk-type drag pump. Two different kinds of pumps are considered: the first one is a rotor-rotor combination, and the second one is a rotor-stator combination. The pumping channels are cut on a rotor and stator. The rotor and stator have 10 Archimedes' spiral blades, respectively. In the present DSMC method, the variable hard sphere model is used as a molecular model, and the no time counter method is employed as a collision sampling technique. For simulation of diatomic gas flows, the Borgnakke-Larsen phenomenological model is adopted to redistribute the translational and internal energies. The DSMC results are in good agreement with the experimental data.

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Effect of viscous damping force subjected to a rotating flexible disk (점성감쇠력이 회전탄성원판에 미치는 영향)

  • Kong, Dae-Wee;Joo, Won-Gu
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.185-190
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    • 2001
  • Rotating disks are used in various machines such as floppy disks, hard disk, turbines and circular sawblades. The problems of vibrations of rotating disks are important in improving these machines. Many investigators have dealt with these problem. Specially, vibrations of a rotating flexible disk taking into account the effect of air is difficult problem in simulation. The governing equation of a rotating flexible disk coupled to the surrounding fluid is investigated by a simple mathematical model. And several important parameters concerned with the stability of a rotating flexible disk are defined. Coupling strength between air and rotating flexible disk is proportional to square of disk radius directly and square root of the all of bending rigidity, disk density and thickness inversely. Lift-to-damping coefficient has relation to the onset of disk flutter.

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Residual Stress Measurement for Circular Disk Using Fraction Mechanics Approach (파괴역학을 이용한 원판형 부재의 잔류응력 측정)

  • 강기주;최성렬
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.5
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    • pp.1218-1226
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    • 1993
  • A method, so called 'successive cracking method,' for measuring residual stresses in a circular disk is proposed. In this method residual stresses are evaluated using a fracture mechanics approach, that is, the strains measured at a point on a edge of the disk as a crack is introduced and extended from the edge are used to deduce the residual stress distribution which existed in the uncracked disk. Through finite element analysis and comparative experiments with generally used sectioning method, the successive cracking method is shown to be valid, simple and effective to measure 2-dimensional residual stress distribution in a circular disk.

In-plane Stress Analysis of Rotating Composite Disks (복합재료 회전원판의 면내응력 해석)

  • Koo, Kyo-Nam
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.176-179
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    • 2005
  • Rotating annular disks are widely used in data storage devices such as CDs, DVDs(digital versatile disks), and HDs(hard disks) as well as in traditional industrial machines like sawing machines, turbines, brake disks. The exact stress distribution of rotating polar orthotropic disk is derived by solving directly the equilibrium equation instead of using stress function. Stress distributions for typical GFRP and CFRP disks are presented in addition to polycarbonate disk. The results show that the application of CFRP to rotating disk can increase the maximum allowable rotating speed but this may not be applicable to GFRP disk.

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Effect of Clearance between a Rotor and Stator of a Disk-Type Drag Pump on the Pumping Performance (고속 회전하는 원판형 드래그펌프 회전익과 고정익 사이 간극이 배기 성능에 미치는 영향)

  • Kwon, Myoung-Keun;Lee, Soo-Yong;Hwang, Young-Kyu
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1640-1645
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    • 2004
  • The pumping characteristics of a single-stage disk-type drag pump ( DTDP ) are calculated,for the variation of the vertical clearance between a rotor and stator and of the radial clearance between a rotor and casing wall, by the three-dimensional direct simulation Monte Carlo (DSMC)method. The gas flow mainly belongs to the molecular transition flow region. Spiral channels of a DTDP are cut on the both the upper and lower sides of a rotating disk, but the stationary disks are planar. As a consequence of results, the vertical and radial clearances have a significant effect on the pumping performance. Experiments are performed under the outlet pressure range of 0.4 $^{\sim}$ 533 Pa. When the numerical results are compared to the experimental data, the numerical results agree well qualitatively.

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Free Vibration Analysis of Fluid Vessel with Annular and Circular Plates (환형평판과 원판으로 구성된 유체용기의 고유진동 해석)

  • Jeong, Kyeong-Hoon;Kim, Jong-In;Park, Keun-Bae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.295-300
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    • 2005
  • An analytical method for the hydroelastic vibration of a vessel composed of an upper annular plate and a lower circular plate is developed by the Rayleigh-Ritz method. The two plates are clamped along a rigid cylindrical vessel wall. It is assumed that the fluid bounded by a rigid cylindrical vessel is incompressible and non-viscous. The wet mode shape of the plates is assumed as a combination of the dry mode shapes of the plates. The fluid motion is described by using the fluid displacement potential and determined by using the compatibility conditions along the fluid interface with the plate. Minimizing the Rayleigh quotient based on the energy conservation gives an eigenvalue problem. It is found that the theoretical results can predict well the fluid-coupled natural frequencies comparing with the finite element analysis result.

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Free Vibration Analysis of Fluid Vessel with Annular and Circular Plates (환형평판과 원판으로 구성된 유체용기의 고유진동 해석)

  • Jeong, Kyeong-Hoon;Kim, Jong-In;Park, Jin-Seok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.8 s.101
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    • pp.968-974
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    • 2005
  • An analytical method for the hydroelastic vibration of a vessel composed of an upper annular plate and a lower circular plate is developed by the Rayleigh-Ritz method. The two plates are clamped along a rigid cylindrical vessel wall. It is assumed that the fluid bounded by a rigid cylindrical vessel is incompressible and non-viscous. The wet mode shape of the plates is assumed as a combination of the dry mode shapes of the plates. The fluid motion is described by using the fluid displacement potential and determined by using the compatibility conditions along the fluid interface with the plate. Minimizing the Rayleigh quotient based on the energy conservation gives an eigenvalue problem. It is found that the theoretical results can predict well the fluid-coupled natural frequencies comparing with the finite element analysis result.

Semi-finite Element Analysis of Rotating Disks Reinforced at Rim (테두리가 보강된 회전 원판의 반-유한요소해석)

  • Koo, Kyo-Nam
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.5
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    • pp.537-544
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    • 2009
  • In order to increase the critical speed of rotating disks of which functional material could not be changed such as in optical and magnetic data storage disks, a new disk with a rim reinforced by composite material is proposed and its concept is verified by numerical analysis. Stress distributions are found for the rotating disk composed of two annular disks of which materials are isotropic inside and orthotropic outside. Dynamic equation is formulated in order to calculate the natural frequency and critical speed. For the solution of lateral vibration, a rotational symmertry condition is applied along circumferential direction and a finite element interpolation with Hermite polynomial is performed along the radial direction to obtain a proper solution. According to the results, reinforcing a disk at rim makes critical speeds drastically increased, and induces a buckling phenomenon in mode (0,0) which occurs over the lowest critical speed.

The Effect of Constant Excitation on Nonlinear Interactions in Vibrating Modes of Circular Plates - Part 1. The Equations of Motion (상수 가진력항이 원판의 진동모드사이의 비선형 상호작용에 미치는 영향 - 제 1 보 운동방정식)

  • Lee, Won-K.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.716-720
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    • 2006
  • In order to examine the effect of constant excitation on nonlinear interactions in vibrating modes of circular plates, we added a constant term to a harmonic excitation. A two-degree-of freedom system is derived by using the Galerkin's procedure. The system is shown to have quadratic and cubic nonlinearities subjected to a harmonic excitation.

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A study on the sound amplification and delay by rim's depth of Jing (징악기의 RIM 깊이에 따른 음향 증폭 및 음향 지속 시간에 관한 연구)

  • Sohn Jung-Ho;Choi Seoung-Ypung;Bae Myung-Jin
    • Proceedings of the Acoustical Society of Korea Conference
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    • autumn
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    • pp.265-268
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    • 2004
  • 한국의 전통국악기 가운데 대중들에게 가장 친근한 악기 가운데 사물놀이 악기이다. 징, 장구, 꽹과리, 북, 이 사물 악기 가운데도 특히 징악기는 소리가 웅장하고 부드러우며 감싸주는 멋이 있다. 징의 구조는 직경 $39\~40cm$인 둥근 원판과 림(Rim:전두리)으로 되어 있다. 재질은 동과 주석을 78:22의 비율로 합금한 유기(놋쇠) 제품으로 만들 때는 방짜유기로 만든다. 본 논문에서는 우선 파동방정식에 의해서 수리적으로 징의 기본 주파수를 구하고, 만곡 면으로 된 원판을 지지하고 있는 징의 Rim 두께와 깊이에 따라 징악기 소리의 세기를 나타내는 진폭과 소리 여운의 지속 시간을 변동 시키는 관계를 본 연구 논문에서 밝히고자 한다.

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