• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1998년도 한국우주과학회보 제7권1호
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• pp.15.1-15
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• 1998

No Abstract.See Full-text

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1997년도 한국우주과학회보 제6권2호
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• pp.16.2-16
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• 1997

No Abstract.See Full-text

• 천문학회보
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• 제20권
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• pp.10.2-10.2
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• 1995

• 천문학회보
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• 제24권1호
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• pp.36-36
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• 1999

• Geomechanics and Engineering
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• 제8권3호
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• pp.323-359
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• 2015

This paper presents an elasto-plastic model for determination of the ground response curve of a circular underwater tunnel excavated in elastic-strain softening rock mass compatible with a nonlinear Hoek-Brown yield criterion. The finite difference method (FDM) was used to propose a new solution to calculate pore water pressure, stress, and strain distributions on periphery of circular tunnels in axisymmetric and plain strain conditions. In the proposed solution, a modified non-radial flow pattern, for the hydraulic analysis, is utilized. To evaluate the effect of gravitational loads and variations of pore water pressure, the equations concerning different directions around the tunnel (crown, wall, and floor) are derived. Regarding the strain-softening behavior of the rock mass, the stepwise method is executed for the plastic zone in which parameters of strength, dilatancy, stresses, strains, and deformation are different from their elasto-plastic boundary values as compared to the tunnel boundary values. Besides, the analytical equations are developed for the elastic zone. The accuracy and application of the proposed method is demonstrated by a number of examples. The results present the effects of seepage body forces, gravitational loads and dilatancy angle on ground response curve appropriately.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4291-4296
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• 2011

Gravitational SPLITT fractionation (GSF) provides separation of colloidal particles into two subpopulations in a preparative scale. Conventionally, GSF is carried out in a thin rectangular channel having two inlets and two outlets at the top and bottom of the channel, respectively. And the channel is equipped with two flow-splitters, one between the top and bottom inlets and another between the top and bottom outlets. A large scale splitter-less GSF system had been developed, which was designed to operate in the full feed depletion (FFD) mode. In the FFD mode, there is only one inlet through which the sample is fed, thus preventing the sample dilution. In this study, the effect of the sample-loading (in the unit of g/hr) on the fractionation efficiency (FE, number% of particles in a GSF fraction that have the sizes expected by theory) of the new large scale splitter-less FFD-GSF system was investigated. The system was tested in the sample-loading range of 3.0-12.0 g/hr with polyurethane latex beads (PU) and sea-sediment. It was found that there is an optimum range in the sample-loading for a FFD-GSF separation. It was also found that there is a general tendency of FE decreasing as the concentration of the sample suspension increases.

• International Journal of Aeronautical and Space Sciences
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• 제4권1호
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• pp.99-109
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• 2003

Attitude control law synthesis for the three-axis attitude maneuver of a flexible spacecraft model is presented in this study. The basic idea is motivated by previous works for the extension into a more general case. The new case includes gravitational gradient torque which has significant effect on a wide range of low earth orbit missions. As the first step, the fully nonlinear dynamic equations of motion are derived including gravitational gradient. The control law design based upon the Lyapunov approach is attempted. The Lyapunov function consists of a weighted combination of system kinetic and potential energy. Then, a set of stabilizing control law is derived from the basic Lyapunov stability theory. The new control law is therefore in a general form partially validating the previous work in some sense.

• Steel and Composite Structures
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• 제46권5호
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• pp.669-672
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• 2023

In this research, the researcher has examined the factors affecting the movement of the soccer ball and will show that the effects such as air resistance, altitude above sea level, wind, air pressure, air temperature, air humidity, rotation of the earth, changes in the earth's gravitational acceleration in different areas. It, the geographical length and latitude of the launch point, the change of gravitational acceleration with height, the change of pressure with height, the change of temperature with height and also the initial spin (Magnus effect) affect the movement of projectiles (especially soccer ball). We modelled th ball based on shell element and derive the motion equations by energy method. Finally, using numerical solution, the wave of the ball is studied. The influences of various parameters are investigated on wave propagation of the ball. Therefore, in short, it can be said that the main factors that play a major role in the lateral deviation of the hit ball are the initial spin of the ball and the wind.

• Advances in materials Research
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• 제12권2호
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• pp.101-118
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• 2023

The purpose of this paper is to study the effects of magnetic field and gravitational field on fiber-reinforced thermoelastic medium with memory-dependent derivative. Three-phase-lag model of thermoelasticity (3PHL) is used to study the plane waves in a fiber-reinforced magneto-thermoelastic material with memory-dependent derivative. A gravitating magneto-thermoelastic two-dimensional substrate is influenced by both thermal shock and mechanical loads at the free surface. Analytical expressions of the considered variables are obtained by using Laplace-Fourier transforms technique with the eigenvalue approach technique. A numerical example is considered to illustrate graphically the effects of the magnetic field, gravitational field and two types of mechanical loads(continuous load and impact load).

• 한국산학기술학회논문지
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• 제7권3호
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• pp.291-297
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• 2006

매우 작은 브릿지 형상을 무수히 지닌 용융탄산염 연료전지용 쉴드슬롯판이 생산 과정 중 일정한 곡률을 가지게 되는데, 자중으로 인해 본래의 곡률을 알 수 없게 되어 교정 작업에 지장을 초래한다. 본 연구에서는 이러한 쉴드슬롯판의 유효 물성치를 실험을 통하여 구하고, 이를 바탕으로 수치해석을 통해 쉴드슬롯판의 원래 곡률을 추정하였다. 구한 유효 물성치를 검증하기 위하여 정방향 및 역방향으로 놓인 쉴드슬롯판의 자중 처짐 형상을 계산을 통해 구하여 실험 결과와 비교하였다. 비교 결과 추정된 유효 물성치는 매우 타당하였고 이로부터 쉴드슬롯판의 원래 곡률을 추정할 수 있었다. 본 연구에서 추정된 유효 물성치는 추후 쉴드슬롯판의 편평도 향상에 대한 연구에서 유용한 자료로 활용될 수 있다.