• 제목/요약/키워드: force integration

검색결과 359건 처리시간 0.02초

A Study on Competitiveness Improvement and Countermeasure of Export Promotion in Korean Industry

  • Jae-Sung LEE
    • 동아시아경상학회지
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    • 제12권3호
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    • pp.11-23
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    • 2024
  • Purpose: The plant industry is a key order-taking industry that leads national industrial development through convergence and integration with various industries in all value chains from planning and marketing to financing, design and engineering, purchasing, construction, and operation and maintenance (O&M). Research design, data and methodology: The Korea government has been actively promoting overseas plant market development support projects to support large and public enterprises and medium and small enterprises. Results: The Korea government are working with the industry and the government so that the Korean plant industry can establish itself as a key driving force that provides the foundation for low-carbon and energy transition that our times demand and makes our world a better place to live. Conclusion: A high value-added industry that brings enormous profits and international fame to exporting countries. Korea is highly dependent on trade, should recognize the plant industry as a key national export sector.

환경 하중을 고려한 침몰 선체의 물리 기반 인양 시뮬레이션 (Physics-based Salvage Simulation for Wrecked Ship Considering Environmental Loads)

  • 함승호;노명일;김주성;이혜원;하솔
    • 대한조선학회논문집
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    • 제52권5호
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    • pp.387-394
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    • 2015
  • Before salvaging a wrecked ship, the physics-based simulation is needed to predict lifting force before real operation by floating crane or barge. Procedures affecting lifting force for the salvage can be divided into three stages. At the first stage, the bottom breakout force for the wrecked ship to escape from seabed sediment should be calculated. At the second step, the current force acting on the wrecked ship while lifting from the seabed to near sea surface should be considered. Finally, buoyancy change near at the sea surface when the wrecked ship start to escape from the water should be considered. In the previous studies, only the breakout force at the first stage was calculated based on simple assumption of embedment depth and contact area of the wrecked ship. Therefore, we develop a program for salvage simulation including whole stages. It is composed of four modules such as the equations of motion, time integration, force calculation, and visualization. As a result, it is applied to simulate lifting the wrecked ship according to various environmental loads including seabed sediments.

Pressure distribution and aerodynamic forces on stationary box bridge sections

  • Ricciardelli, Francesco;Hangan, Horia
    • Wind and Structures
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    • 제4권5호
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    • pp.399-412
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    • 2001
  • Simultaneous pressure and force measurements have been conducted on a stationary box deck section model for two configurations (namely without and with New Jersey traffic barriers) at various angles of incidence. The mean and fluctuating aerodynamic coefficients and pressure coefficients were derived, together with their spectra and with the coherence functions between the pressures and the total aerodynamic forces. The mean aerodynamic coefficients derived from force measurements are first compared with those derived from the integration of the pressures on the deck surface. Correlation between forces and local pressures are determined in order to gain insight on the wind excitation mechanism. The influence of the angle of incidence on the pressure distribution and on the fluctuating forces is also analysed. It is evidenced how particular deck section areas are more responsible for the aerodynamic excitation of the deck.

고성능 원심펌프에서 임펠러 시라우드 및 마모 시일의 유체가진력 해석 (Hydrodynamic forces of impeller shroud and wear-ring seal on centrifugal pump)

  • 하태웅
    • 대한기계학회논문집A
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    • 제22권1호
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    • pp.102-110
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    • 1998
  • The analysis of lateral hydrodynamic forces in the leakage path between a shrouded pump impeller through wear-ring seal and its housing is presented. Governing equations are derived based on Bulk-flow and Hirs' turbulent lubrication model. By using a perturbation analysis and a numerical integration method, governing equations are solved to yield leakage and rotordynamic coefficients of force developed by the impeller shroud and wear-ring seal. The variation of rotordynamic coefficients of pump impeller shroud and wear-ring seal is analyzed as parameters of rotor speed, pressure difference, shroud clearance, wear-ring seal clearance, and circumferential velocity at the entrance of impeller shroud for a typical multi-stage centrifugal pump.

기어이의 변동물림강성을 고려한 비틀림진동해석 (Torsional Vibration Analysis of a Spur Gear Pair with the Variable Mesh Stiffness)

  • 류재완;한동철;최상현
    • 한국정밀공학회지
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    • 제16권12호
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    • pp.99-108
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    • 1999
  • A four-degree-of-freedom non-linear model with time varying mesh stiffness has been developed for the dynamic analysis of spur gear trains. The model includes a spur gear pair, two shafts, two inertias representing load and prime mover. In the model, developed several factors such as time varying mesh stiffness and damping, separation of teeth, teeth collision, various gear errors and profile modifications have been considered. Two computer programs are developed to calculate stiffness of a gear pair and transmission error and the dynamic analysis of modeled system using time integration method. Dynamic tooth and mesh forces, dynamic factors are calculated. Numerical examples have been given, which shows the time varying mesh stiffness ha a significant effect upon the dynamic tooth force and torsional vibrations.

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고차전단변형과 대처짐을 고려한 복합적층판의 저속충격거동 해석 (Low-Velocity Impact Response Analysis of Composite Laminates Considering Higher Order Shear Deformation and Large Deflection)

  • 최익현;홍창선
    • 대한기계학회논문집
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    • 제17권12호
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    • pp.2982-2994
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    • 1993
  • Low-velocity impact responses of composite laminates are investigated using the finite element method based on various theories. In two-dimensional nonlinear analysis, a displacement field considering higher order shear deformation and large deflection of the laminate is assumed and a finite element formulation is developed using a C$^{o}$-continuous 9-node plate element. Also, three-dimensional linear analysis based on the infinitesimal strain-displacement assumptions is performed using 8-node brick elements with incompatible modes. A modified Hertzian contact law is incorporated into the finite element program to evaluate the impact force. In the time integration, the Newmark constant acceleration algorithm is used in conjuction with successive iterations within each time step. Numerical results from static analysis as well as the impact response analysis are presented including impact force histories, deflections, strains in the laminate. Impact responses according to two typical low-velocity impact conditions are compared each other.

Nonlinear Finite Element Analysis of Composite Shell Under Impact

  • Cho, Chong-Du;Zhao, Gui-Ping;Kim, Chang-Boo
    • Journal of Mechanical Science and Technology
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    • 제14권6호
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    • pp.666-674
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    • 2000
  • Large deflection dynamic responses of laminated composite cylindrical shells under impact are analyzed by the geometrically nonlinear finite element method based on a generalized Sander's shell theory with the first order transverse shear deformation and the von-Karman large deflection assumption. A modified indentation law with inelastic indentation is employed for the contact force. The nonlinear finite element equations of motion of shell and an impactor along with the contact laws are solved numerically using Newmark's time marching integration scheme in conjunction with Akay type successive iteration in each step. The ply failure region of the laminated shell is estimated using the Tsai- Wu quadratic interaction criteria. Numerical results, including the contact force histories, deflections and strains are presented and compared with the ones by linear analysis. The effect of the radius of curvature on the composite shell behaviors is investigated and discussed.

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미끄러지는 벨트 장치를 이용한 난류 항력 감소 (Turbulent Drag Reduction Using the Sliding-Belt Device)

  • 최병귀;최해천
    • 대한기계학회논문집B
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    • 제23권11호
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    • pp.1481-1489
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    • 1999
  • The sliding-belt concept introduced by Bechert et al. (AIAA J., Vol. 34, pp. 1072~1074) is numerically applied to a turbulent boundary layer flow for the skin-friction reduction. The sliding belt is moved by the shear force exerted on the exposed surface of the belt without other dynamic energy input. The boundary condition at the sliding belt is developed from the force balance. Direct numerical simulations are performed for a few cases of belt configuration. In the ideal case where the mechanical losses associated with the belt can be ignored, the belt velocity increases until the integration of the shear stress over the belt surface becomes zero, resulting in zero skin friction on the belt. From practical consideration of losses occurred In the belt device, a few different belt velocities are given to the sliding belt. It is found that the amount of drag reduction is proportional to the belt velocity.

엔진 연결봉 베어링의 운동 궤적 해석 (Analysis of Journal Locus in a Connecting Rod Bearing)

  • 조명래;정진영;한동철
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1997년도 제25회 춘계학술대회
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    • pp.183-189
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    • 1997
  • This paper presents the motion of dynamically loaded journal in the connecting rod bearing of reciprocating internal combustion engine. Journal motions in engine bearings have been composed of two components, which was rotational and translational motion. Early study of journal locus in engine bearing had been performed on each motion. This paper has been considered two motions simultaneously. Reynolds equation including the squeeze effect has been analyzed using the ADI method, and real engine bearing and crankshaft system has been considered to calculate the cyclic external force. The equations of journal motion have been derived and then the numerical integration of these equations performed by 4th order Runge-Kutta method. This paper gives various journal orbits in connecting rod bearing depending on cyclic external forces, rotating speeds, and bearing parameters.

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3차원 셸 요소를 이용한 섬유보강 고무모재 공기 스프링의 유한요소해석 (Finite Element Analysis of Air Springs with Fiber-Reinforced Rubber Composites Using 3-D Shell Elements)

  • 이형욱;허훈
    • 대한기계학회논문집A
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    • 제25권4호
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    • pp.602-609
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    • 2001
  • This paper is concerned with the orthotropic problem of diaphragm-type air springs which consist of rubber linings, nylon reinforced rubber composite and bead ring. The analysis is carried out with a finite element method developed to consider the orthotropic properties, geometric nonlinearity using four-node degenerated shell element with reduced integration. Physical stabilization scheme is used to control the zeroenergy mode of the element. The analysis includes an inflation analysis and a lateral analysis of an air spring for the deformed shape and the spring load with respect to the vertical and l ateral deflection. Numerical results demonstrate the variation of the outer diameter, the fold height, the vertical force and the lateral force with respect to the inflation pressure and the lateral deflection.