• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.316-325
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• 1993

The forces acting on tractor three-point linkage were analyzed including the rear cover action of a rotary tiller which is ignored usually. The relation of link force and tillage resistance is expressed as a linear form. The link forces vary with tilling torque from negative force to positive in the free-link, though in the fixed-link they increase without change of force sign. The effects of the rear cover resistance appeared in the link forces in the fixed-link.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.11a
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• pp.27-41
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• 1996

In this study the heat transfer and fluid flow of the molten pool in stationary gas tungsten arc welding using argon shielding gas were investigated. Transporting phenomena from the welding arc to the base material surface, such as current density, heat flux, arc pressure and shear stress acting on the weld pool surface, were taken from the simulation results of the corresponding welding arc. Various driving forces for the weld pool convection were considered, self-induced electromagnetic, surface tension, buoyancy, and impinging plasma arc forces. Furthermore, the effect of surface depression due to the arc pressure acting on the molten pool surface was considered. Because fusion boundary has a curved and unknown shape during welding, a boundary-fitted coordinate system was adopted to precisely describe the boundary for the momentum equation. The numerical model was applied to AISI 304 stainless steel and compared with the experimental results.

• 한국기계연구소 소보
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• v.4 no.2
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• pp.49-63
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• 1982

In this paper, a classical gust problem is treated by using the numerical lifting¬-surface theory to verify the effect of gust-a sudden fluctuating fluid velocity around an object, which is normal to the main stream direction-on the hydrody¬namic forces, especially the mean thrust in upstream direction, acting on the two¬-dimensional flat plate. In this case, the mean thrust wholly resorts to the leading edge suction, and it is the same situation to the case of the heaving plate in uniform flow. The ph¬enomenon of leading edge suction is very important for the flapping propulsion of animals, typical to fish and birds, and can be related to the prediction of the hydrodynamic forces acting on marine propellers operating in gustlike wakes of ships. The results of this paper can be easily superposed to those of the reference [1J in order to solve the problem of the two-dimensional oscillacting plate in gust

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.203-207
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• 2004

In this study, we focus on the submerged plate built into the Very Large Floating Structure with the partial openings of 5m long, which enables the reverse flow of incident wave to generate the wave breaking. The purpose of this study is to investigate the characteristics of wave exciting forces acting on the submerged plate. Firstly, we have carried out the extensive experiments to understand the characteristics of the wave exciting forces. Then we have performed the numerical simulations by applying the Marker and Cell method and compare with the experimental results. We discuss the validity of MAC method and the effects of the submerged plate on the motion of VLFS.

• Journal of Navigation and Port Research
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• v.27 no.6
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• pp.625-630
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• 2003

In order to keep the safety of maneuverability under the lateral berthing, it is necessary to estimate the magnitudes and properties of the hydrodynamic forces acting on ship hull quantitatively. In this paper, CFD technique is used to calculate the steady lateral force according to the water depth for Wigley model under the unsteady lateral berthing. The numerical results are analysed into the steady lateral force and the transitional lateral force, and some of reviews for the safety of maneuverability relating to the lateral berthing are discussed based on the computed hydrodynamic forces.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.19-21
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• 2017

Ship maneuvering performance is usually estimated in calm water conditions which provide valuable information about the ship maneuvering characteristics at the early design stage. However, the course-keeping ability and the maneuvering performance of a ship can be significantly affected by the presence of waves when ship maneuvers in real sea condition. Therefore, it is necessary to understand the maneuvering behavior of a ship in waves in the viewpoint of ship safety in the design stage. In this study, the force and yaw moment acting on a moving ship in regular waves with different wave length and wave direction will be performed in the square wave tank in Changwon National University. The results of this study can be used to help a person to design a ship hull with the best ship maneuverability in waves and disseminate knowledge on predicting ship maneuvering in regular waves in various wave directions.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1451-1453
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• 2007

The electrical and the optical properties of organic light-emitting devices (OLEDs) with or without multiple heterostructures acting as a hole transport layer were investigated. The efficiency enhancement mechanism in the OLEDs with multiple heterostructures is described on the basis of the electrical and the optical results.

• Water for future
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• v.27 no.4
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• pp.155-160
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• 1994

External foces acting on a pipe bend change when a transient pressure wave propagates through the bend. Analytical expressions are derived to compute the changes of these forces when the instantaneous pressure wave passes through the bends. This analysis reveals that these forces depend mainly on static pressure rather than fluid momentum. The analysis also reveals that the change of the vertical component of the force acting on a pipe bend with an angle larger than 90$^{\circ}$ may reverse in direction during the passage of a pressure wave through the bend.

• Tribology and Lubricants
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• v.14 no.1
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• pp.79-84
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• 1998

This paper presents the experimental study of the dynamic internal pressure within a vane pump. The measurement of the dynamic internal pressure acting on the line contact between the vane and the camring in a vane pump with intravanes have been investigated. The variations of the radial acting force of a vane are calculated from previously measured results of dynamic internal pressure in four chambers surrounding a vane, and the variations of the film thickness are estimated in both the rotational speed ranges from 600 to 1200 rpm and the delivery pressure ranges from 1 to 14 MPa. The experimental technic has been established to obtain the data for performance analysis, such as reaction forces between vane and camring, friction wear at the contact regions, leakage characteristics and net forces upon the pump shaft in case of the unsteady load which is forced to the intravane pressure balance type vane pump.

• Tribology and Lubricants
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• v.13 no.4
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• pp.53-59
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• 1997

The camshaft locus at camshaft beating in a direct acting OHC valve train system has been investigated using the transient method. Forces applied to the camsfiaft are composed of two components, one is the transfer force between the cam and the tappet, the other is the frictional force. These forces have been calculated using the lumped mass model and the elastohydrodynamic lubrication theory. The alternating direction implicit method has been used for the numerical analysis of Reynolds equation, and 4th order Runge-Kutta method has been used for the transient journal locus analysis. The effects of various load conditions are presented in the form of journal locus. As a result of the analysis, it has been found that camshaft bearings were mainly in the hydrodynamic lubrication condition.