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  • Title/Summary/Keyword: 모멘트방정식

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Study on the Suitability of Composite Materials for Enhancement of Automotive Fuel Economy (자동차 연비향상을 위한 복합재료 적용 타당성에 관한 연구)

  • Ju, Yeon Jin;Kwon, Young-Chul;Choi, Heung Soap
    • Composites Research
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    • v.32 no.5
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    • pp.284-289
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    • 2019
  • In the present paper, the dynamic force-moment equilibrium equations, driving power and energy equations are analyzed to formulate the equation for fuel economy(km/liter) equivalent to the driving distance (km) divided by the fuel volume (liter) of the vehicle, a selected model of gasoline powered KIA K3 (1.6v). In addition, the effects of the dynamic parameters such as speed of vehicle (V), vehicle total weight(M), rolling resistance (Cr) between tires and road surface, inclined angle of road (θ), as well as the aerodynamic parameters such as drag coefficient (Cd) of vehicle, air density(ρ), cross-sectional area (A) of vehicle, wind speed (Vw) have been analyzed. And the possibility of alternative materials such as lightweight metal alloys, fiber reinforced plastic composite materials to replace the conventional steel and casting iron materials and to reduce the weight of the vehicle has been investigated by Ashby's material index method. Through studies, the following results were obtained. The most influencing parameters on the fuel economy at high speed zone (100 km/h) were V, the aerodynamic parameters such as Cd, A, ρ, and Cr and M. While at low speed zone (60 km/h), they are, in magnitude order, dynamic parameters such as V, M, Cr and aerodynamic ones such as Cd, A, and ρ, respectively.

A Development of Torsional Analysis Model and Parametric Study for PSC Box Girder Bridge with Corrugated Steel Web (복부 파형강판을 사용한 PSC 복합 교량의 비틀림 해석모델의 제안 및 변수해석)

  • Lee, Han-Koo;Kim, Kwang-Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.2A
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    • pp.281-288
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    • 2008
  • The Prestressed Concrete (hereinafter PSC) box girder bridges with corrugated steel webs have been drawing an attention as a new structure type of PSC bridge fully utilizing the feature of concrete and steel. However, the previous study focused on the shear buckling of the corrugated steel web and development of connection between concrete flange and steel web. Therefore, it needs to perform a study on the torsional behavior and develop the rational torsional analysis model for PSC box girder with corrugated steel web. In this study, torsional analysis model is developed using Rausch's equation based on space truss model, equilibrium equation considering softening effect of reinforced concrete element and compatibility equation. Validation studies are performed on developed model through the comparison with the experimental results of loading test for PSC box girder with corrugated steel webs. Parametric studies are also performed to investigate the effect of prestressing force and concrete strength in torsional behavior of PSC box girder with corrugated steel web. The modified correction factor is also derived for the torsional coefficient of PSC box girder with corrugated steel web through the parametric study using the proposed anlaytical model.

Analytical Models for the Prediction of the Flexural Behavior for Thermal Bridge Breaker Systems embedded in Reinforced Concrete Slabs (열교차단장치가 적용된 철근 콘크리트 슬래브의 휨거동 예측을 위한 해석모델)

  • Shin, Dong-Hyeon;Kim, Hyung-Joon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.3
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    • pp.325-333
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    • 2015
  • Recently, thermal bridge breaker systems(TBBSs) applicable to RC slab-wall connections have been increasingly studied and proposed. This study also aims at proposing an analytic model which is applicable to predicting the flexural behavior of TBBS embedded in slabs from the initial elastic stages, yield states to ultimate conditions. The analytic models are developed by considering strain compatibility, force equilibrium and the constitutive law obtained from material test results. To verify the accuracy of the proposed analytic model, the moment-curvature relationship and change of neutral axis according to the loading states are compared with those of experimental results. Based on the comparison, it is verified that the proposed analytic model provides well predict the flexural behavior of TBBS embedded in slabs.

Stability Evaluation Methods of Agricultural Reservoir by Field Monitoring (현장계측에 의한 농업용저수지 제체의 안정관리기법)

  • Lee, Dal-Won;Oh, Beom-Hwan
    • Korean Journal of Agricultural Science
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    • v.30 no.2
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    • pp.164-174
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    • 2003
  • This study was performed to suggest a rational method for the stability evaluation of agricultural reservoir in the very soft ground. The stability methods for agricultural reservoir was used to compare and analyze with various condition by limit equilibrium method. The behavior of settlement-displacement obtained by field monitoring system was used to compare and analyze with various stability methods, and to investigate the applicability of the methods for stability evaluation of agricultural reservoir. The horizontal displacement was abruptly increased when physical properties of soft clay reached its maximum values and therefore, the values of these properties could be used to the fundamental data for stability evaluation. The evaluation of the stability of agricultural reservoir was suggested to use the inclination of curve rather than critical line.

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Theoretical Formulation of Porous Medium Behavior Depending on Degree of Saturation (포화도에 따른 다공질 매체 거동의 이론적 정식화)

  • Park, Tae Hyo;Jung, So Chan;Kim, Won Cheul
    • Journal of the Korean GEO-environmental Society
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    • v.2 no.3
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    • pp.81-88
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    • 2001
  • The behavior of porous medium is modeled by linear thermoporoelastic behavior, linear poroviscoelastic behavior, poroplastic behavior, and poroviscoplastic behavior, etc. The behavior has, in general, a complicated aspect which makes a mechanical description of the problem with time. Constitutive modeling for deformation behavior of porous medium with coupling effects is needed since there is interaction between the constituents in pores with a relative velocity to each other. In this work, it is explained 3-dimensional behavior depending on degree of saturation for porous medium composed of homogeneous, isotropic materials. It is obtained the governing equations based on continuum porous mechanics. In addition, it is developed constitutive model which can be understood of behavior for porous medium which can be understood, analysed behavior of porous medium. It can be accomplished exact analysis and prediction of behavior in porous medium. The behavior for porous medium is analysed exactly, and the prediction of deformation behavior is accomplished. Consequently, it will be basis to analyze 3-dimensional behavior in municipal solid waste landfill, and the practical using of porous medium ground which are composed of nonhomogeneous, anisotropic materials can be done widely.

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Antenna Factor Characteristics of EMI Dipole Antennas with Coaxial Cable Balun for Frequencies between 30 and 1,000 MHz (동축 케이블 밸런이 부착된 30~1,000 MHz 대역용 EMI 다이폴 안테나의 안테나 인자 특성)

  • Ju Chang-Hyun;Kim Ki-Chai
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.7 s.110
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    • pp.623-628
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    • 2006
  • This paper presents the characteristics of an antenna factor of two kinds of EMI dipole antennas with a coaxial cable balun used in the frequency range between 30 and 1,000 MHz. The integral equation for unknown current distribution is solved by the Galerkin's method of moments with piecewise sinusoidal functions. An antenna factor for EMI dipole antennas with the coaxial cable balun is derived by using the power loss concepts. We can realize two kinds of EMI dipole antennas with appropriate antenna factors in the frequency range from 30 to 1,000 MHz: 150-cm dipole length(30300MHz) and 30cm dipole length(3001,000MHz). To check th ε validity of the theoretical analysis, the complex antenna factor was measured using by reference antenna methods. It is shown that the calculated complex antenna factor is good agreement with experimental results.

Electromagnetic Transmission through Slits in Two Adjacent Conducting Parallel-Plates (근접하는 도체 평행 평판의 슬릿을 통한 전자파 투과)

  • Lee, Jong-Ig;Ko, Ji-Hwan;Cho, Young-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.1
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    • pp.83-90
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    • 2009
  • In this paper, the problem of electromagnetic transmission through slits in two parallel conducting plates which separate two half spaces is considered. The coupled integral equations for the electric field distributions over the slits are developed for the case that the TM polarized plane wave is incident on the slit and solved by the method of moments. The transmitted power beyond the slit-perforated conducting parallel plates is computed in order to check the variations of the coupled power through slits against some parameters such as the incident angle of the TM polarized wave, slit width, lateral distance between two slits, and distance between the conducting plates. When the lateral distance between two slits approaches near the multiples of half wavelengths, the transmission resonance (maximum power transmission) is observed. If the slit width in the incident side is narrow and the distance between conducting plates is small compared to the wavelength, the maximum of transmitted power is observed to be nearly independent of the incident angle and slit width. In addition, the mechanism of the transmission resonance in the present geometry is explained using a simplified geometry and its equivalent circuit.

Dynamic Balancing in a Link Motion Punch Press (링크모션 펀치프레스의 다이나믹 발란싱)

  • Suh, Jin-Sung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.5 s.122
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    • pp.415-426
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    • 2007
  • In a link motion punch press, numerous links are interconnected and each link executes a constrained motion at high speed. As a consequence, dynamic unbalance force and moment are transmitted to the main frame of the press, which results in unwanted vibration. This degrades productivity and precise stamping work of the press. This paper presents an effective method for reducing dynamic unbalance in a link motion punch press based upon kinematic and dynamic analyses. Firstly, the kinematic analysis is carried out in order to understand the fundamental characteristics of the link motion mechanism. Then design variable approach is presented in order to automate the model setup for the mechanism whenever design changes are necessary. To obtain the inertia properties of the links such as mass, mass moment of inertia, and the center of mass, 3-dimensional CAD software was utilized. Dynamic simulations were carried out for various combinations of design changes on some links having significant influences on kinematic and dynamic behavior of the mechanism.

The Influence of the Aspect Ratio on the Natural Frequency of the Composite Laminated Plates (복합적층판의 고유진동수에 대한 형상비의 영향)

  • Han, Bong-Koo;Suck, Ju-Won
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.1 no.2
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    • pp.14-19
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    • 2010
  • Theories for advanced composite structures are too difficult for such design engineers for construction and some simple but accurate enough methods are necessary. The senior author has reported that some laminate orientations have decreasing values of D16, B16, D26 and B26 stiffnesses as the ply number increases. For such plates, the fiber orientations given above behave as specially orthotropic plates and simple formulas developed by the senior author. Most of the bridge and building slabs on girders have large aspect ratios. For such cases further simplification is possible by neglecting the effect of the longitudinal moment terms(Mx) on the relevant partial differential equations of equilibrium. In this paper. the influence of the aspect ratio on the natural frequency of the composite laminated plates is studied and it is concluded that the method used is sufficiently accurate for engineering purposes.

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Simplified Static Analysis of Superstructure on Very Large Floating Structures subjected to Wave Loads (파랑하중을 받는 초대형 부유식 구조물 상부구조체의 실용정적해석법)

  • Song, Hwa-Cheol;Park, Hyo-Seon;Seo, Ji-Hyun
    • Journal of Navigation and Port Research
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    • v.27 no.5
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    • pp.519-526
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    • 2003
  • For preliminary structural analysis of superstructures on very large floating structures(VLFS), superstructures are analyzed considering elastic deformations of barge type lower-structures subjected to wave loads. In this case, to consider the effect of wave loads on the superstructure, initial displacements at the support points of superstructures are evaluated as input data for the analysis. However, the evaluation and application of displacement loads are tedious and very time-consuming processes. Therefore, this paper proposes a simplified static analysis method to analyze the structural behaviors of superstructures on very large floating structures subjected to wave loads. In this study, the member forces due to the variation of beam span and the amplitude and period of wave load are analyzed by using an example 4 span -3 story structure and the amplification factors for beam moments are represented by the specific regression equation.