• 한국가스학회지
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• 제14권6호
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• pp.44-50
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• 2010

내진 평가에서 동적 해석이 필요한 원심펌프에 대하여, 시간 이력 해석에 비해 간편한 스펙트럼 해석을 이용하여, 진동 응답을 산출하였다. 유한요소법에 의하여 모드 해석을 하였으며, 모드 해석 결과에 입각하여 스펙트럼 해석을 수행하였다. 스펙트럼 해석에 의해 구해진 진동 응답은 시간 이력 해석의 결과보다 보수적으로 산출되어 안전하게 설계할 수 있음을 알 수 있었다. 본 연구에서의 펌프는 IEEE 344-1987에서 요구되는 조건에 따라 내진 구조 건전성이 평가 되었다. 각 부재의 최대 응력은 허용 응력이하로 산출되었으며, 펌프는 주어진 지진 입력에 대하여 요구되는 안전 조건을 구비하고 있음이 판명되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.489-493
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• 2000

Turbine blade has trouble of cracking at root region. Fracture surface of blade root is surveyed by SEM and AFM to clear relation between fracture mechanical parameter and surface parameter (striation width and surface roughness). Service stress is predicted by maximum height roughness $R_{max}$, on fractured surface and stress analysis on turbine blade. It is to thought that turbine blade is fractured by abnormal condition such as incorrect fittings between pin and pin hole but isn't fractured by normal service conditions such as steam pressure, centrifugal force and torsional force.

• 대한기계학회논문집
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• 제19권7호
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• pp.1665-1674
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• 1995

An optimum design has been performed to maximize specific energy (SED) of composite flywheel rotor for energy storage system. The flywheel rotor is assumed to be an axisymmetric thick laminated shell with a plane strain state for structural analysis. For the structural analysis the centrifugal force is considered and the stiffness matrix equation was derived for each ring considering the interferences between the rings. The global stiffness matrix was derived by integrating the local stiffness matrix satisfying the conditions of force and displacement compatibilities. Displacements are then calculated from the global stiffness matrix and the stresses in each ring are also calculated. 3-D intra-laminar quadratic Tsai-Wu criterion is then used for the strength analysis. An optimum procedure is also developed to find the optimal interferences and lay up angle to maximize SED using the sensitivity analysis.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.361-370
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• 2015

There will inevitably be errors and uncertainties in tire yaw mark related critical speed formula, which is derived merely from the relationship between the centrifugal force and the friction force acting on the point-mass vehicle. Constructing and measuring yaw marks through appropriate simulation works have made it possible to perform uncertainty analysis in calculation of critical speeds under variation of variety of conditions and parameters while existing yaw mark experimental tests have not performed properly. This paper does not present only the critical speed analysis results for parametric sensitivity and uncertainty of chord and middle ordinate, coefficient of friction and road grade, but also modeling uncertainty such as variation of braking level during turning and vehicle size. The yaw mark analysis methods and results may be now applied in practice of traffic accident investigation.

• 대한기계학회논문집A
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• 제20권3호
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• pp.968-977
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• 1996

The linear/nonlinear vibration response of the rotating hybrid cylindrical shell with simply supported boundary condition is studied. The Ritz-Galerkin method is applied to obtain the nonlinear frequency equation, which excludes in-plane and rotatory inertia but includes bending stretching coupling terms. The bifurcation phenomena for the linear frequency and the frequency ratio(nonlinear/linear frequency ratio) are presented. The hybrid cylindrical shells are composed of composite(GFRP, CFRP) metal(aluminium, steel) with symmetric and antisymmetric stacking sequence. The effects of the Coriolis and centrifugal force are considered The results also present the effects of length-to- radies ratio, radius-to-thickness ratio, the circumferential wave number, the stacking sequence, the material property, the initial excitation amplitude and the rotating speed. The present linear frequency results are compared with those of the available literature.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.810-814
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• 2009

Two dimensional steady and unsteady numerical models are applied to bend reaches of the Lower Han River and the superelevation at the Ichon-Banpo bend area of Han River was observed. The flow characteristics in the meandering river are complicated due to the effects of the centrifugal force. The centrifugal force makes the outside water surface level increase and the outside velocity decrease. To study this complex flow studying two dimensional flow is important and useful to design flood control countermeasures, the analysis of sedimentation and the site selection of intake structures. Especially, the superelevation between inside and outside of the bend should be considered to determine the height of embankment. In this study, the water surface elevations in both bank sides of the bend were measured in two reaches during floods in 2007 and 2008. And then the two-dimensional simulation using RMA-2 model was carried out. The upstream and downstream boundary conditions on bend reaches were determined by FLDWAV which is one-dimensional unsteady model. Finally, the observed data are compared with simulation results and the results of the several superelevation formulas, and the flow characteristics of the bend are discussed.

• 동력기계공학회지
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• 제8권2호
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• pp.31-38
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• 2004

The main purpose of this study is to investigate the characteristics of hybrid collection system combined with centrifugal force of cyclone and filtration of bag filter in one unit system. The experiment and numerical simulation are executed for the analysis of collection efficiency and pressure drop characteristics of hybrid system in comparison with those of a general fabric bag filter with the various experimental parameters such as inlet velocity(filtration velocity), dust concentration and dust type, etc.. In present system, dust particles tangentially coming into the system body are controlled by the centrifugal force effect, and the next collection is made out by the filtration mechanism in the fabric filter media. Therefore, the effective first collection causes the decrease of dust loading on the fabric filter, and it presents quite a lower pressure drop of fabric filter than that of a general fabric filter. At the inlet velocity, $21{\sim}27m/sec$ and inlet concentration(fly ash) $300mg/m^3$, pressure drops through the filter media of hybrid system are shown lower as $10{\sim}22mmH_2O$ comparing to those($17{\sim}33mmH_2O$) of a general fabric bag filter.

• 한국정밀공학회지
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• 제28권6호
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• pp.738-744
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• 2011

The reliability of blade root fixing section is required to endure the centrifugal force and vibration stress for the last stage blade of steam turbine in thermal power plant. Most of the domestic steam turbine last stage blades have finger type roots. The finger type blade is very complex, so the inspection had been performed only on the exposed fixing pin cross-section area due to the difficulty of inspection. But the centrifugal force and vibration stress are also applied at the blade root finger and the crack generates, so the inspection method for finger section is necessary. For the inspection of root finger, inspection points were decided by simulating ultra-sonic path with 3D modeling, curve-shape probe and fixing jig were invented, and the characteristics analysis method of ultrasonic reflection signal and defect signal disposition method were invented. This invented method was actually executed at site and prevented the blade liberation failure by detecting the cracks at the fingers. Also, the same type blades of the other turbines were inspected periodically and the reliability of the turbine increased.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2713-2716
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• 2003

This paper presents a dynamic manipulability analysis method of the limb moving in viscous fluid. The key idea of the presented method is that the boundary of joint velocity can be converted to the velocity-dependant dynamic manipulability polytope through the coriolis, centrifugal and drag terms in dynamic equation. The velocity-dependant dynamic manipulability polytope is added to the inertial and restoring force manipulability polytope to get overall manipulability polytope of the limb moving in the fluid Each of the torque and velocity bounds arc considered in the infinite norm sense in joint space, and the drag force of a limb moving in fluid viscous is modeled as a quadratic form An analysis example with proposed analysis scheme is presented to validate the method.

• 한국생산제조학회지
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• 제8권3호
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• pp.107-113
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• 1999

The purpose of this study is to analyze multi-size power chuck which can chuck work pieces having various sizes automatically and be used suitably to an exclusive product line in the field of automotive industry. Gripping force, accuracy, and stiffness about the chuck are especially considered for the analysis. MSC/NASTRAN software is used for FEM analysis. Also, the effects of centrifugal force which occurs when chuck body rotates and compressive stresses which occur at contacting area in between chuck body and collet are estimated.