• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.3-10
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• 2004

The earthquake-resistant structural systems have to ensure the sufficient stiffness and ductility for the stability. For those purposes, recently, the performance design concept to increase the degree of absorbed energy level of structures has been proposed. One practical way of the performance design in the spatial structures is to apply the isolation system to boundary parts of roof system and sub-structure to obtain the target performance. So, it is necessary to examine the characteristics of dynamic behavior of spatial structures governed by higher modes rather than lower modes different from the cases of high rise buildings. The objectives of this paper are to develop the equivalent lumped mass model to simplify the analytical processes and to investigate the dynamic behavior of roof system according to the mass and the stiffness of sub-structures as a fundamental study of performance design for the spatial structures.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.385-390
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• 2000

In this study we propose the computational model for the coronary circulation. The bypass from left ventricle is also considered. Lumped parameter model with three compartments in the coronary circulation is implemented in this study. We connected the coronary artery compartment with left ventricle to explain the bypass procedure from left ventricle. The asymmetric resistance is assumed in the bypass line from left ventricle. The present numerical method is tested for normal coronary circulation and the results are compared with the existing computational work. The bypass simulation is conducted and the flow pattern is delineated. The effect of shunt resistance and coronary compliance to circulation is investigated for the better design of the bypass shunt.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.438-443
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• 2009

This paper proposes a new method for dynamic modeling of electrorheological (ER) damper considering fluid compressibility. After describing configuration and operating principle of the ER damper, a quasi-static modeling of the ER damper is conducted on the basis of Bingham model of ER fluid. Subsequently, the dynamic model for describing the ER damper considering compressibility of ER fluid and gas chamber is obtained using the lumped parameter method. This method includes dynamic motions of annular duct, upper chamber, lower chamber and connecting pipe. The hysteresis behavior of the ER damper is evaluated through computer simulations and compared with experimental results. In addition, the hysteresis behavior due to the compressibility of ER fluid and gas chamber is investigated through computer simulations.

• 대한기계학회논문집A
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• 제25권3호
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• pp.495-501
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• 2001

In this paper, a new technique which models the joints characteristics through reduction of DOFs of structures with joints using component mode synthesis (CMS) method is proposed. Bolt joints are modeled by mass-spring systems. Also generalized mass and stiffness matrices for this models are introduced. Because bolt joints have influence on eigenvalues of structures, exact eigenvalues from modal test are used. The results show that the behaviors of structures with bolt joints depend to a large extent on the translational DOFs and not on rotational DOFs of mass and stiffness matrices of bolts. Furthermore it is confirmed that lumped mass-spring systems as models of bolt joints are effective models considering the facts that joint characteristics converged to constant values in some iterations and eignevalues from proposed method are in good agreement with ones from modal test.

• 한국소음진동공학회논문집
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• 제15권2호
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• pp.219-224
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• 2005

Vibration response of the tower structure of a 750kW wind turbine (W/T) generator is investigated by measurement and analysis. Acceleration response of the W/T tower under various operation condition is monitored in real time by the vibration monitoring system using LabVIEW. Resonance state of the tower structure is diagnosed in the operating speed range. Resonance frequency range of the test model is investigated with the wind speed data of the test site. To predict the tower resonance frequency, tower is modeled as an equivalent beam with a lumped mass and Rayleigh energy method is applied. Calculated tower bending frequency is in good agreement with the measured value and the result shows that the simplified model can be used in the design stage of the W/T tower.

• 한국정밀공학회지
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• 제17권7호
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• pp.189-195
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• 2000

For free motions, vibration suppression of flexible manipulators has been one of the hottest research topics. However, for constrained motions, a little effort has been devoted for vibration suppression control. Using the dependency of elastic deflections of links on contact force under static conditions, vibrations for constrained planar two-link flexible manipulators have been suppressed successfully by controlling the contact force. However, for constrained spatial multi-link flexible manipulators, the vibrations cannot be suppressed by only controlling the contact force. So, the aim of this paper is to clarify the vibration mechanism of a constrained, multi-DOF, flexible manipulator and to devise the suppression method. We apply a concise hybrid position/force control scheme to control a flexible manipulator modeled by lumped-parameter modeling method. Finally, a comparison between simulation and experimental results is presented to show the performance of our method.

• 한국철도학회논문집
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• 제6권3호
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• pp.163-168
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• 2003

This paper considers the sound radiation characteristics of a cracked rectangular vibrating plate, varying the orientation angle of a line crack. The vibration response of the cracked vibrating plate is obtained by using ANSYS, the acoustic theory based on the lumped parameter model is used to calculate radiated sound power. The radiated sound powers are computed with varying the orientation angle of the crack: i.e, 0$^{\circ}$, 45$^{\circ}$, and 90$^{\circ}$. It is found that characteristics of the radiated sound power are very closely related to the crack orientation, vibration mode and crack location.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.429-434
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• 2004

Vibration response of the tower structure of a 750kW wind turbine generator is investigated by measurement and analysis. Acceleration response of the tower under various operation condition is monitored in real time by vibration monitoring system using LabVIEW. Resonance state of the tower structure is diagnosed in the operating speed range. To predict the tower resonance frequency, tower is modeled as an equivalent beam with a lumped mass and Rayleigh energy method is applied. Calculated tower bending frequency is in good agreement with the measured value and the result shows that the simplified model can be used in the design stage of the wind turbine tower.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.670-676
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• 2004

In this paper, a modeling method for the vibration analysis of rotating structures composed of beams and shells employing multi-reference frames is presented. The rotary inertia effect and the geometric stiffening effect that results from centrifugal inertia force we considered for beams and shells with lumped mass model. In most previous studies, single reference frame has been employed for the vibration analysis. In the present study, a modeling method employing multi-reference frames is presented and the effects of employing multi-reference frames on the analysis accuracy are investigated through solving numerical examples.

• 대한토목학회논문집
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• 제33권5호
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• pp.2125-2133
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• 2013

최근 콘크리트궤도 공법이 증가함에 따라 인접한 슬래브를 연결하는 방법에 대한 관심이 높아지고 있다. 슬래브의 연결부는 효과적인 하중전달, 변형 연속화, 응력 분산을 위해서 다웰 시스템이 다수 적용된다. 본 연구에서는 콘크리트 슬래브 다웰연결부를 효율적으로 이상화할 수 있는 연결부의 집중 전단스프링 (Lumped shear spring) 모델을 제안한다. 전단 스프링 모델의 강성은 다웰바의 강성과 유격을 고려하였으며, 강도는 연결부의 전단파괴에 근거한 Concrete Capacity Design(CCD) 방법에 의해 산정되었다. 해석모델의 타당성을 검증하기 위하여 다웰로 연결된 슬래브 실험체를 제작하고 재하실험을 수행하였다. 제안된 해석모델은 다웰과 콘크리트 간의 유격으로 인한 초기 비선형성 및 콘크리트 재료 비선형성을 합리적으로 반영하고 있는 것으로 분석되었다. 따라서 향후 슬래브 다웰 조인트로 연결된 콘크리트궤도의 파괴 시까지의 비선형 거동을 합리적으로 예측함으로써 철도 궤도의 설계 시 효과적으로 활용될 수 있을 것이다.