• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1928-1933
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• 2005

This Paper is about landing control of legged robot. Body stiffness and damping is used as landing strategy of a legged robot. First, we only used stiffness control method to control legged robot landing. Second control method,sliding mode controller and feedback linearization controller is applied to enhance position control performance. Through these control algorithm, body center of gravity behaves like mass with spring & damping in vertical direction on contact regime.

• Nuclear Engineering and Technology
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• 제27권5호
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• pp.760-766
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• 1995

Young's Modulus와 단지 기하학적 테이타를 이용하여 흘드다운스프링의 탄성강성도를 해석하는 방법을 제시하였다. 제시된 이 방법은 엔지니어링 빔이론과 카스티릴아노 이론을 이용하여 판형흘드다운스프링의 탄성강성도 해석에 적용하였다. 이러한 방법의 효율성과 신뢰성을 보여주기 위하여 제안된 방법으로 부터의 탄성강성도를 여러가지 형태의 홀드다운스프링의 시험결과와 비교하였다. 이러한 결과비교에 의해 제안된 방법이 판형홀드다운스프링의 탄성강성도를 구하는데 있어서 효과적임을 입증하였다.

• 한국시뮬레이션학회논문지
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• 제8권3호
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• pp.39-48
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• 1999

A finite element model of geared rotor system with flexible bearings were used to simulate the critical speeds and to investigate the effects of bearing coefficients on the dynamic behaviors of the systems. The finite element model includes the effects of tooth mesh stiffness, gyroscopic moment, rotary inertia, shear, and torque of the shaft. The gear mesh was modelled as a pair of rigid disks connected by a spring of time varying stiffness. The time varying mesh stiffness results in the abrupt change of the critical speeds of spur geared systems. As the bearing stiffness increases, critical speeds increase rapidly in case of stiff shafts, compared with flexible shafts.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.421-429
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• 2019

This paper presents an analytical model for the estimation of initial lateral stiffness of steel moment resisting frames with masonry infills. However, rather than focusing on the single bay-single storey substructure, the developed model attempts to estimate the global stiffness of multi-storey and multi-bay frames, using an assembly of equivalent springs and taking into account the shape of the lateral loading pattern. The contribution from each infilled frame panel is included as an individual spring, whose properties are determined on the basis of established diagonal strut macro-modeling approaches from the literature. The proposed model is evaluated parametrically against numerical results from frame analyses, with varying number of frame stories, infill openings, masonry thickness and modulus of elasticity. The performance of the model is evaluated and found quite satisfactory.

• 한국정밀공학회지
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• 제26권2호
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• pp.94-100
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• 2009

In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. The sleeve spring type damper is one of the preventive measures for reducing the torsional vibration. In this study, a closed form equation to predict spring constant of the sleeve spring and torsional characteristic of the torsional vibration damper was proposed to calculate stiffness of the damper and verified their availability through the finite element analysis. The theoretical values have a good agreement with the results obtained by the finite element analysis. The results obtained from the equation derived enable the designers in actual fields to be more efficient.

• 한국소음진동공학회논문집
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• 제16권12호
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• pp.1215-1223
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• 2006

A leaf spring suspension has been widely used since it can carry big load and its simplicity. But one major drawback is the poor ride performance because of the friction in the system and the high stiffness coefficient. To overcome these, an air spring suspension can be used. The air spring suspension system can improve the ride of the heavy vehicle significantly and also it can adjust the height to the loading and unloading. The road tests for the truck with the leaf spring suspension and air spring suspension are performed to compare the ride quality of the two systems. To develop the air spring suspension system tailored to the target truck, chassis development procedure using CAE has been applied.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
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• pp.197-200
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• 1995

Corrugation of railway track can be caused by the various dynamic behavior of travelling wheels and track. In this paper, the coupled vibrations of travelling wheel and railway track are analyzed as the cause of corrugations. To analyze the coupled vibrations, the track supported by the sleepers and the traveling wheel are identified to the elastically supported infinite beam and the spring-mass system which runs at constant speed. The Hertzian contact spring is considered betwen the infinite beam and spring-mass system. The dynamic responses of elastically supported infinite beam and spring-mass system are calculated. The cause and development of rail corrugation are discussed in the view point of contact force fluctuation affected by the elastic supports and the corrugated surface profile of the track. By the obtained results, the possibilities of resonance are checked between the excitation by the corrugated surface profile and the natural frequency of contact spring-moving mass system. It may be thought to a development of railway corrugation.

• 한국군사과학기술학회지
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• 제21권3호
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• pp.331-341
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• 2018

This study proposes an integrated serial spring-damper mechanism as a dual pulse generation system. Compared to the traditional dual pulse generation system, which used multiple springs and a damper to generate a dual pulse critical for impact testing of naval equipments, currently used separated serial spring-damper mechanism is comprised of two components: an air spring, and a damper. The proposed mechanism combines the two components into one integrated system with a unique design that lets simply changing the volume and the pressure of the air tank, and the length of the annular pipe adjust the stiffness and damping constants for testing, eliminating the need to have multiple sets of air springs and dampers. Simulations using MatLab and Simulink were conducted to verify the feasibility of this design. The results show the potential of an integrated serial spring-damper mechanism as a more convenient and flexible mechanism for dual pulse generation system.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.157-161
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• 2013

It is well known that the targeted fuel efficiency could only be achieved by more than 40% reduction of the vehicle weight through improved design and extensive utilization of lightweight materials. In order to obtain the goal of the weight reduction of automobiles, the researches about lighter and stronger spring link have been studied without sacrificing the safety of automotive components. In this study, the weight reduction design process of spring link could be proposed based on the variation of von-Mises stress contour by substituting an aluminum alloys (A356) having tensile strength of 245 MPa grade instead of SAPH440 steels. In addition, the effect of the stress and stiffness on shape variations of the spring link were examined and compared carefully. It could be reached that this approach could be well established and be contributed for light-weight design guide and the safe design conditions of the automotive spring link development.

• Geomechanics and Engineering
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• 제25권3호
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• pp.221-231
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• 2021

A two dimensional model of linearly elastic soil spring used for the settlement analysis of the flexible mat foundation is suggested in this study. The spring constants of the soils underneath the foundation were modeled assuming uniformly vertical load applied onto the foundation. The soil spring constants were back calculated using the three-dimensional finite element analysis with Midas GTS NX program. Variation of the soil spring constants was modeled as a two-dimensional polynomial function in terms of the normalized spatial distances between the center of foundation and the analytical points. The Lysmer's analog spring for soils underneath the rigid foundation was adopted and calibrated for the flexible foundation. For validations, the newly proposed soil spring model was incorporated into a two dimensional finite difference analysis for a square mat foundation at the surface of an elastic half-space consisting of soft clays. Comparative study was made for elastic soils where the shear wave velocity is 120~180 m/s and the Poisson's ratio varies at 0.3~0.5. The resulting foundation settlements from the two dimensional finite difference analysis with the proposed soil springs were found in good agreement with those obtained directly from three dimensional finite element analyses. Details of the applications and limitations of the modified Lysmer's analog springs were discussed in this study.