• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.107-121
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• 2003

When the seismic stability of quay walls is analyzed, the magnitudes of force components acting on quay walls during earthquakes and the phase relations among these force components must be properly evaluated. In general, force components include inertia force of the quay wall, lateral earth force, and water force. The magnitude and the phase relation of each force component vary according to the magnitude of the excess pore pressures developed in backfill soils of the quay wall. The dynamic thrust mobilized at the contact surface between the backfill soil and the wall develops as a result of the interactions among these force components. We propose a simple model to evaluate the magnitude and phase variation of the dynamic thrust on the back of the wall in terms of the excess pore pressure. The proposed model can predict the dynamic thrust by summing the magnitudes of farce components calculated from design equations for seismic pressures on the wall. The proposed model was verified by comparing its results with the results from a series of shaking table tests.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.883-898
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• 2019

This paper employs computational tools to predict power increase (or speed loss) and propulsion performances in waves of KVLCC2. Two-phase unsteady Reynolds averaged Navier-Stokes equations have been solved using finite volume method; and a realizable k-ε model has been applied for the turbulent closure. The free-surface is obtained by solving a VOF equation. Sliding mesh method is applied to simulate the flow around an operating propeller. Towing and self-propulsion computations in calm water are carried out to obtain the towing force, propeller rotating speed, thrust and torque at the self-propulsion point. Towing computations in waves are performed to obtain the added resistance. The regular short head waves of λ/LPP = 0.6 with 4 wave steepness of H/λ = 0.007, 0.017, 0.023 and 0.033 are taken into account. Four methods to predict speed-power relationship in waves are discussed; Taylor expansion, direct powering, load variation, resistance and thrust identity methods. In the load variation method, the revised ITTC-78 method based on the 'thrust identity' is utilized to predict propulsive performances in full scale. The propulsion performances in waves including propeller rotating speed, thrust, torque, thrust deduction and wake fraction, propeller advance coefficient, hull, propeller open water, relative rotative and propulsive efficiencies, and delivered power are investigated.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.337-342
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• 2003

In this paper, in order to analyzing the thrust force of LDM, it was divided by the vertical force(Fx)and the horizontal force(Fy). The magnet and winding width was determined by analyzing the magnetic flux distribution throughout the airgap of LDM. Using finite-element analysis(FEA), which is the magnetic field analysis, and Proved the validity of design process, also the characteristics of LDM according to the variation of the design parameters of LDM was almost in accord with th experiment results.

• Advances in aircraft and spacecraft science
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• v.9 no.1
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• pp.39-57
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• 2022

Instead of developing new guided missiles, converting unguided missile into guided ones by adding guidance and controlkits hasbecome aglobaltrend.Ofthemost efficient andwidelyused thrust vector control(TVC) techniquesin rocketry isthe jet vanes placed inside the nozzle divergentsection. Upon deflecting them, lift created on the vanesistransferred to the rocket generating the desired control moment. The presentstudy examinesthe concept of using an add-on jet vaneTVC kit to a plain nozzle.The impact of adding the kit with different vaneslocations and deflectionanglesisnumericallyinvestigatedbysimulatingtheflowthroughthenozzlewiththekit.Twohingelocations are examined namely, at 24% and 36% of nozzle exit diameter. For each location, angles of deflection namely 0°, 5°, 10°, and 15° are examined. Focus is made on variation of control force, thrust losses, lift and drag on vanes, jet inclination, and jetflow structure withTVCkit design parameters.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.4
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• pp.119-125
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• 1997

The drilling experiment of carbon fiber epoxy composite material with WC-drill has been done under the various cutting conditions in order to minimize the problems occurred in the material while being drilled. It has been confirmed by a frequency analysis of the cutting force signals that the variation of cutting force resulted from the periodic variation of the angle between the ortating drill and the stacking angle of the carbon fiber. By the drilling experiment with several drills having different point angles, the drilling char- acteristics, which show the relations between the change in the point angle and cutting force or external surface condition, were analyzed.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.1
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• pp.40-48
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• 2021

Through a series of bollard pull tests of a propeller in partially submerged condition, thrust, torque, and shaft excitation force of a conventional propeller model were measured using a six-component load cell. By variation of the Weber number and Reynolds number, a consistent towing tank model test condition was derived. The effects of propeller immersion depth on the ventilation behavior and change of force and moment acting onto the propeller shaft were investigated. The decrease in thrust owing to the inception of ventilation was confirmed, and a large degree of dispersion of the thrust and torque coefficients were also observed in the transition region where the blade tip was under the water surface. The shaft excitation force was derived from the force and moment onto the propeller shaft.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.9
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• pp.723-730
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• 2014

Experimental study for supersonic co-flowing fluidic thrust vectoring control utilizing the secondary flow is performed. The characteristics of the thrust vectoring of two dimensional supersonic flow (Mach 2.0) are studied by Schlieren flow visualization and highly-accurate multi-component force measurements using the load cells. It is observed that the thrust deflection angle initially decreases and increases again forming a V-shaped variation as the pressure of the secondary flow increases. Characteristics of the performance coefficients of the system are also studied, and the detailed operating conditions for higher performance of the technique are suggested.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.3
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• pp.153-162
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• 1987

The purpose of this paper is to analysis and develop theoretically the characteristics of tubular linear induction motor, which is a special industrial motor that generates directly thrust force from electrical power. The Poisson equation about vector potential which is created by the application of Maxwell electromagnetic equation with the speed considered, results in modified Bessel equation by the assumption that is applied to each region of the experimental motor. Vector potential, magnetic flux density, secondary current, and thrust force according to its region respectively were found out by substituting boundary condition for this equation and rearranging. Besides, a attendant materials, that is, thermal characteristic, which is one of the characteristics under the operation of experimental motor each part's magnetic flux distribution characteristics within active zone, the required time for reciprocating motion, and variation of power factor vs. a slip were found.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.38-41
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• 1997

As the LPM is used for position accuracy decision device it is required that both the reason of posion error and the definition of position itself should be cleared. In this study, the precision of the position decision of LPM is affected by the geometrical shape such as tooth shape or processing accuracy. By using the analysis of magnetic circuit, we calculated the permeance come up with the gap. Once the thrust force has been obtained, the permeance due to the mechanical error of the pole pitch and the tooth pitch becomes the error of thrust force. We confirmed as well that it is being affected by the difference due to the variation of the airgap permeance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2467-2474
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• 1993

This paper deals with the cantilever subjected to a follower force which is generated by real rocket motor which has linearly decreasing thrust. The cantilever is assumed to be uniform and elastic one, In the theoretical analysis, the tip mass of rocket motor is considered as a rigid body and effects of its dynamic parameters are shown and compared with the experimental results. Particularly, the variation of the 2nd natural frequency due to the decreasing thrust is measured in the experiments and compared with the theoretical estimations. Approximate method is adopted in the theoretical analysis using Galerkin method by introducing 3-element modified operator and modified variable which represent eqation of motion and natural boundary conditions. In general, structural damping effects can be neglected and all the rigid body parameters must be taken into account in case of the short action time of the follower force and the relatively big tip mass like the system of this paper according to the experiment. Good agreement was obtained between the theoretical estimations and the experimental results by neglecting structural damping and considering all the rigid bidy parameters of the tip mass.