• 제목/요약/키워드: Force Balance

검색결과 600건 처리시간 0.027초

T-50 항공기모델 풍동시험에서의 항력측정 연구 (Analysis of Drag Measurements on T-50 Aircraft Model Wind Tunnel Testing)

  • 김형국;양희돈;이일우
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 추계학술대회
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    • pp.1564-1568
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    • 2004
  • The requirements of internal balance were studied that should be considered on performing force & moment transonic wind tunnel testing to develop combat aircraft. In many insecure factors of test condition, uncertainty analysis was conducted to verify one drag count measurements. The analysis result was applied to T-50 aircraft model and compared for data verifaction. In conclusion, the aerodynamicist should estimate the validation and accuracy of test data by having an overall grasp of system components including internal balance. It will help him get high productivity of testing and effective validated data at tunnel.

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Orthotics 착용에 따른 정상, 요족, 평발의 생체역학적 보행분석 및 시뮬레이션 (Biomechanical Gait Analysis and Simulation on the Normal, Cavus and Flat Foot with Orthotics)

  • 이중현;이재옥;박성하;이영신
    • 대한기계학회논문집A
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    • 제31권11호
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    • pp.1115-1123
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    • 2007
  • The foot plays an important role in supporting the body and keeping body balance. An abnormal walking habit breaks the balance of the human body as well as the function of the foot. The foot orthotics which is designed to consider biomechanics effectively distributes the load of the human body on the sole of the foot. In this paper, gait analysis was performed for three male subjects wearing the orthotics. In this study, three male subjects were selected. The experimental apparatus consists of a plantar pressure analysis system and digital EMG system. The gait characteristics are simulated by ADAMS/LifeMOD. The COP (Center of Pressure), EMG and ground reaction force were investigated. As a result of gait analysis, the path of COP was improved and muscle activities were decreased with orthotics on the abnormal walking subjects.

Self-Regulation of Star Formation Rates: an Equilibrium Vieww

  • Kim, Chang-Goo;Ostriker, Eve C.
    • 천문학회보
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    • 제41권2호
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    • pp.55.2-55.2
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    • 2016
  • In this talk, I will present a theoretical and numerical framework for self-regulation of the star formation rates (SFRs) in disk galaxies. The theory assumes (1) force balance between pressure support and the weight of the interstellar medum (ISM), (2) thermal balance between radiative cooling in the ISM and heating via FUV radiation from massive young stars, and (3) turbulent energy balance between dissipation in the ISM and driving by momentum injection of SNe. Numerical simulations show vigorous dynamics in the ISM at all times, but with proper temporal and spatial averages, all the expected balances hold. This leads to a scaling relation between mean SFRs and galactic gas and stellar properties, arising from the fundamental relationship between SFR surface density and the total midplane pressure.

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출력 소음을 고려한 직접방사형 라우드스피커의 비선형 매개변수 규명 (Identification of Nonlinear Parameters of Electrodynamic Direct-Radiator Loudspeaker with Output Noise)

  • 박석태;홍석윤
    • 소음진동
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    • 제8권5호
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    • pp.887-899
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    • 1998
  • It has been resulted that Lagrange multiplier method with statistical approach was superior to traditional harmonic balance method in identifying the nonlinear loudspeaker parameters when output signals were contaminated with Gaussian random noise. We have known that the displacement-dependent characteristic values of nonlinear parameters identified by traditional harmonic balance method were estimated less than original values by the increase of output noise and the stiffness coefficients were very sensitive to output noise. Also, by the sensitivity analysis we have verified that the harmonic distortions in acoustic radiation was mainly due to nonlinearity of force factor caused by uneven magnetic fields and that reducing the nonlinearity of damping coefficients were very effective for improving second harmonic distrotion of acoustic radiation.

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사료중 Casein 및 대두단백질의 아미노산 균형이 병아리의 혈액 및 간조직내의 Cholesterol함량에 미치는 영향 (Effects of Amino Acid Balance of Dietary Casein and Soy Protein on the Plasma and Liver Cholesterol Levels in Young Chicks)

  • 김현숙;지규만;최인숙
    • 한국가금학회지
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    • 제22권1호
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    • pp.43-54
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    • 1995
  • Effects of dietary protein sources and their amino acid compositions on the liver and plasma cholesterol levels in growing Single Comb white Leghorn male chicks were studied. A diet containing isolated soy protein (21% cp) was supplemented with 0.5% DL-methionine and 0.3% L-glycine. and another diet containing casein(21% cp) was supplemented with 1.5% L-arginine HCl, 0.4% DL-methionine. and 1.0% L-glycine. Plasma cholesterol level was markedly lower in groups force-fed the diets containing either soy protein or casein supplemented with amino acids compared to those found in birds fed corresponding diets without amino acids supplementation. The cholesterol lowering effect of the casein diet. when balanced with various supplemental amino acids appeared to be due to arginine instead of methionine or glycine. It is likely that amino acid balance rather than the composition of a specific amino acid is one of the major factors determining the effect of dietary protein sources on the blood cholesterol levels in chicks.

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Determination of shear stiffness for headed-stud shear connectors using energy balance approach

  • Ye, Huawen;Huang, Ruosen;Tang, Shiqing;Zhou, Yu;Liu, Jilin
    • Steel and Composite Structures
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    • 제42권4호
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    • pp.477-487
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    • 2022
  • The shear stiffness of headed-stud shear connectors has no unified definition due to the nonlinear characteristics of its load-slip relationship. A unified framework was firstly adopted to develop a general expression of shear load-slip equation for headed-stud shear connectors varying in a large parameter range based on both force and energy balance. The pre- and post-yield shear stiffness were then determined through bilinear idealization of proposed shear load-slip equation. An updated and carefully selected push-out test database of 157 stud shear connectors, conducting on studs 13~30mm in diameter and on concretes 30~180 MPa in cubic compressive strength, was used for model regression and sensitivity analysis of shear stiffness. An empirical calculation model was also established for the stud shear stiffness. Compared with the previous models through statistical analysis, the proposed model demonstrates a better performance to predict the shear load-slip response and stiffness of the stud shear connectors.

Aerodynamic force characteristics and galloping analysis of iced bundled conductors

  • Lou, Wenjuan;Lv, Jiang;Huang, M.F.;Yang, Lun;Yan, Dong
    • Wind and Structures
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    • 제18권2호
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    • pp.135-154
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    • 2014
  • Aerodynamic characteristics of crescent and D-shape bundled conductors were measured by high frequency force balance technique in the wind tunnel. The drag and lift coefficients of each sub-conductor and the whole bundled conductors were presented under various attack angles of wind. The galloping possibility of bundled conductors is discussed based on the Den Hartog criterion. The influence of icing thickness, initial ice accretion angle and sub-conductor on the aerodynamic properties were investigated. Based on the measured aerodynamic force coefficients, a computationally efficient finite element method is also implemented to analyze galloping of iced bundled conductors. The analysis results show that each sub-conductor of the bundled conductor has its own galloping feature due to the use of aerodynamic forces measured separately for every single sub-conductors.

전자기력에 의한 자성유체의 2차원 자유표면 형상 제어에 관한 연구 (A Study on the Two-dimensional Formation Control of Free Surface of Magnetic Fluid by Electromagnetic Force)

  • 배형섭;양택주;이육형;주동우;박명관
    • 한국정밀공학회지
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    • 제22권3호
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    • pp.29-37
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    • 2005
  • In this study, the control of the free surface deformation of a magnetic fluid for the change in electromagnetic force is discussed. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. Magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. Thus, the device of a magnetic fluid proposed the complete zero-leakage sealing, oscillator for surface control, boundary layer control, MHD, flow control, flow using magnetic levitation system and surface actuator. This study show the deformation of surface rise due to the intensity of the magnetic field and possibility of two-dimensional control of magnetic fluid through the feedback data of hall sensor.

MAGNETIC FLUX-CURRENT SURFACES OF MAGNETOHYDROSTATIC EQUILIBRIA

  • Choe, G.S.;Jang, Minhwan
    • 천문학회지
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    • 제46권6호
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    • pp.261-268
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    • 2013
  • Magnetohydrostatic equilibria, in which the Lorentz force, the plasma pressure force and the gravitational force balance out to zero, are widely adopted as the zeroth order states of many astrophysical plasma structures. A magnetic flux-current surface is a surface, in which both magnetic field lines and current lines lie. We for the first time derive the necessary and sufficient condition for existence of magnetic flux-current surfaces in magnetohydrostatic equilibria. It is also shown that the existence of flux-current surfaces is a necessary (but not sufficient) condition for the ratio of gravity-aligned components of current density and magnetic field to be constant along each field line. However, its necessary and sufficient condition is found to be very restrictive. This finding gives a significant constraint in modeling solar coronal magnetic fields as force-free fields using photospheric magnetic field observations.

부유금형을 가진 냉간단조 공정의 유한요소해석 (Finite Element Analysis of a Cold forging Process Having a Floating Die)

  • 전만수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1999년도 춘계학술대회논문집
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    • pp.103-107
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    • 1999
  • In this paper, a computer simulation technique for the forging process having a floating die is presented. The penalty rigid-plastic finite element method is employed together with an iteratively force-balancing method, in which the convergence is achieved when the floating die part is in force equilibrium within the user-specified tolerance. The force balance is controled by adjusting the velocity of the floating die in an automatic manner. An application example of a three-stage cold forging process is given.

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