• Title/Summary/Keyword: Force Balance

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Design of tall residential buildings in Singapore for wind effects

  • Balendra, T.;Ma, Z.;Tan, C.L.
    • Wind and Structures
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    • v.6 no.3
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    • pp.221-248
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    • 2003
  • The design of high-rise building is often influenced by wind-induced motions such as accelerations and lateral deflections. Consequently, the building's structural stiffness and dynamic (vibration periods and damping) properties become important parameters in the determination of such motions. The approximate methods and empirical expressions used to quantify these parameters at the design phase tend to yield values significantly different from each other. In view of this, there is a need to examine how actual buildings in the field respond to dynamic wind loading in order to ascertain a more realistic model for the dynamic behavior of buildings. This paper describes the findings from full-scale measurements of the wind-induced response of typical high-rise buildings in Singapore, and recommends an empirical forecast model for periods of vibration of typical buildings in Singapore, an appropriate computer model for determining the periods of vibration, and appropriate expressions which relate the wind speed to accelerations in buildings based on wind tunnel force balance model test and field results.

Applications of Force Balance Method to Several Metal Forming Problems (성형가공문제에 대한 힘 평형법의 응용)

  • 최재찬;김진무
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.5
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    • pp.653-660
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    • 1986
  • Two uppor bound solutions, by the force balance method and by a kinematically admissible velocity field, are compared for the metal forming problems in plane strain. It is concluded that these two approaches always give identical results when the geometrical configurations of the deformation model reman the same. By detailed derivations for plastic bending of a notched bar, closed die forging, compression of a rectangular block, machining with a restricted contact tool and plane strain backward extrusion, the identity of both approaches is verified.

The Sectional Analysis of Trunk-lid using the Equilibrium Approach and Three-Dimensional Shape Composition (평형해법을 이용한 트렁크 리드의 단면해석과 3차원 형상합성)

  • 정동원
    • Journal of Ocean Engineering and Technology
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    • v.15 no.2
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    • pp.66-71
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    • 2001
  • A sectional analysis of trunk-lid carried out by using the equilibrium approach based on the force balance together with geometric relations and plasticity theory. In computing a force balance equation, it is required to define a geometric curve approximating the shape of sheet metal at any step of deformation from the interaction between the die and the deformed sheet. The trunk-lid panel material is assumed to possess normal anisotropy and to obey Hill's new yield criterion. Deformation of each section of trunk-lid panel is simulated and composed to get the three-dimensional shape by using CAD technique. It was shown that the three-dimensional shape composition of the two-dimensional analysis.

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Element Design of Balancing Shaft for Reducing the Vibration in Engine Module (엔진진동 저감을 위한 밸런싱샤프트의 요소설계 기법 연구)

  • Lee, Bong-Hyun;Kim, Dong-Chul;Jung, In-Oh;Kim, Chan-Jung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.11 s.104
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    • pp.1268-1275
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    • 2005
  • Vibration in Engine module could be reduced by introducing a balance shaft module which has one or more unbalanced rotors. Since the unbalanced rotor is installed in an opposite direction of the free force or unbalance moment by engine component, the unexpected vibration could be decreased kinematically. The essential equation of the unbalanced rotor was Presented for two cases, 3 in-line and 4 in-line cylinder engine type, And the efficiency of the balance shaft is investigated by the vehicle testing that is focused on measuring the reduced vibration level when adapting a balancing module. With the signal processing of measured signals, some important issues on design the balancing shaft could be derived and the overall design process is explained in the final part including the peripheral component, i.e. housing and bush.

On the Physical Meaning of Maxwell Stress Tensor (맥스웰 응력텐서의 물리적 의미의 고찰)

  • Choi, Hong-Soon;Park, Il-Han;Moon, Won-Kyu
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.4
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    • pp.725-734
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    • 2009
  • Maxwell stress tensor is one of the methods which are generally used for electromagnetic force calculation. In this paper, it is presented that Maxwell stress tensor T and n${\cdot}$T have no physical meaning and therefore should not be used as sources of mechanical force for deformations or dynamics. The divergence of Maxwell stress tensor ${\nabla}{\cdot}T$ is the one which can acquire a physical identity and is electromagnetic body force density by an action at a distance like a gravity. This result can be derived from the principle of power balance, and also verified by some thought experiments. The virtual air-gap approach is proposed as a valid solution for the calculation of the body force.

An experimental study on friction measurement of piston-ring assembly of a SI engine (가솔린 기관의 피스톤-링 결합체 마찰력 측정에 관한 실험적 연구)

  • 이동원;윤정의;김승수
    • Journal of the korean Society of Automotive Engineers
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    • v.12 no.4
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    • pp.66-74
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    • 1990
  • Friction between piston-ring assembly and cylinder wall of a spark ignition engine was evaluated under various engine operating conditions utilizing a grasshopper linkage system. The friction force was estimated by the force balance relation at the small end of connecting rod. Three forces were chosen to be measured for the objective. They were gas pressure inside the cylinder, inertia force of the piston-ring assembly, and the force exerted by the connecting rod. These forces were measured by a piezo type pressure sensor, an accelerometer and strain gauges, respectively. Comparisons were made with the frictional force evaluated by the conventional method where the assumption of constant rotational speed of engines was adopted. Due to the variation of rotational speed of engines, the conventional method was found to lead to a large error in the evaluation of the frictional force.

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The Effects of Training Using Pedalo Equipment on Balance of Post-Stroke Patients: Pilot Study (페달로 도구를 이용한 훈련이 만성 뇌졸중 환자의 균형에 미치는 영향: 예비 실험)

  • Lee, Yun-Bok;Kim, Jin-Beom;Lee, Gyu-Chang
    • Journal of the Korean Society of Physical Medicine
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    • v.8 no.3
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    • pp.387-395
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    • 2013
  • PURPOSE: The purpose of the present study was to investigate the effect of the training using Pedalo equipment on balance function in post-stroke patients. METHODS: The present study was case-series. Ten post-stroke patients participated in the study. Participants performed the training using Pedalo equipment. The training using four Pedalo equipment lasted 30 minutes, 3 times a week for 6 weeks. Force platform, Berg Balance Scale(BBS), and Timed Up and Go(TUG) test were used to assess balance ability before and after training. RESULTS: After training using Pedalo equipment, there were significantly improved on path length and sway velocity of post-stroke patients in the both of eye open and - close conditions comparing with baseline. Also, on the BBS and TUG, there were significant improvements after training. CONCLUSION: The results of this study showed that the training using Pedalo equipment may be effective on improving the balance ability in the post-stroke patients. Through this study, we were able to confirm the potential of training using Pedalo equipment as an intervention in the rehabilitation of post-stroke patients.

The Fluxless Wetting Properties of TSM-coated Glass Substrate to the Pb-free Solders (TSM(Top Surface Metallurgy)이 증착된 유리기판의 Pb-free 솔더에 대한 무플럭스 젖음 특성)

  • 홍순민;박재용;박창배;정재필;강춘식
    • Journal of the Microelectronics and Packaging Society
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    • v.7 no.2
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    • pp.47-53
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    • 2000
  • The fluxless wetting properties of TSM-coated glass substrate were evaluated by the wetting balance method. We could estimate the wettability of the TSM with new parameters obtained from the wetting balance test for one side-coated specimen. It was more effective in wetting to use Cu as a wetting layer and Au as a protection layer than to use Au itself as a wetting layer. The SnSb solder showed better wettability than SnAg, SnBi, and SnIn solders. The contact angle of the one side-coated glass substrate to the Pb-free solders could be calculated from the farce balance equation by measuring the static force and the tilt angle.

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The Effect of Gluteus Medius Taping on Balance and Walking in Chronic Stroke Patients (만성 뇌졸중 환자의 마비측 중간볼기근 테이핑이 균형과 보행에 미치는 영향)

  • Lee, Yangjin;Cho, Namjeong
    • Journal of The Korean Society of Integrative Medicine
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    • v.6 no.3
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    • pp.17-24
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    • 2018
  • Purpose : Kinesio taping is a therapeutic method used in the treatment of various musculoskeletal and neuromuscular deficits limited evidence the effects of gluteus medius kinesio taping in neurologic patients. Therefore, this study aimed to determine the effects of gluteus medius kinesio taping on balance ability and gait function in after a stroke. Methods : Twenty-four post-stroke patients were included in this study. Gluteus medius taping group and sham gluteus medius taping group were divided into intervention. Kinesio tape was applied the gluteus medius muscles. In all the subjects, the balance ability was measured using the force plate and timed up & go test (TUG) and gait function was assessed using the 10-meter walking test at time points of both before and after the taping. Result : There was a significant difference in balance ability and gait function between the two groups before and after gluteus medius taping group (p<.05). The gluteus medius taping group showed a significant difference between the groups (p<.05). Conclusion : The results suggest that taping may be a useful method during rehabilitation programs for stroke patients. Application of Kinesio taping to the gluteus medius muscles was found to be useful especially in improving balance ability.

Location Issue of Bearing and Unbalance Mass on the Balance Shaft for a Inline 4-Cylinder Engine (직렬 4기통 엔진용 밸런스 샤프트의 베어링 및 불평형 질량 위치 결정 문제)

  • Bae, Chul-Yong;Kim, Chan-Jung;Lee, Dong-Won;Kwon, Seong-Jin;Lee, Bong-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.3
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    • pp.277-283
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    • 2008
  • Balance shaft module contributes to reduce the engine-born vibration by compensating it from a unbalance mass with opposite phase but practically, this device has some problems during the operation in a high speed owing to the considerable amount of unbalance mass that leads to the large quantity of bending deformation as well as torque fluctuation at the balance shaft. To tackle two main problems, the design strategy on balance shaft is suggested by addressing the optimal location of unbalance mass and supporting hearing based on the formulation of objective function that minimizes critical issues, both bending deformation as well as torque fluctuation. The boundary condition of balance shaft assumes to be free such that any external force or contact component is not taken into consideration in this study.