• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.3
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• pp.231-236
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• 2015

In this study, we propose a non-contact circular eddy current load brake using permanent magnet that can be applied to the rehabilitation exercise equipment. The circular eddy current load brake is manufactured and is evaluated for performance. This has the torque value of 49% compared to a "ㄷ" type eddy current load brake having a fixed load. And we confirmed that load is regulated due to the conductivity and air gap. Proposed load brake is adjustable according to the user's condition and can be applied to the equipment having advantages such as miniaturization and cost reduction.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.264-268
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• 2005

Most of the train brakes depends on friction between wheels and tracks. This requires braking force reduced in order not to cause wheel slides since the friction decreases as the train speed increases and consequently results in extension of braking distance. The braking system called 'Linear eddy current brake' or simply' Eddy current brake' is a braking system for making a brake independent from friction, which consists in creating electromagnet by coiling around shoes attached. to bogies; having the shoes above the tracks approached to the tracks upon acknowledgement of a braking command; and authorizing braking force that is irrelevant to friction through magnetic repulsion between electromagnet attached to the tracks and train set by the use of the electromagnet's magnet field characteristics. An electromagnetic attraction braking system that consists in pressing pole shoes attached to bogies against the tracks by using electromagnet's attraction force is called 'Electromagnetic track brake' or simply 'Track brake'. This paper has been prepared in purpose of studying technological tendencies of the eddy current brake and the track brake so that it can be utilized as fundamental data for commissioning Korean high-speed trains with the eddy current brake hereafter.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.225-235
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• 2010

There are many types of the geometric transitions such as dent, bulge, protrusion, expansion, etc, on the inner and outer surfaces of heat exchanger tubes, steam generator tubes, and condenser tubes of nuclear power plants. Such geometric transition causes a local residual stress in heat exchanger tubes and acts as a structural factor accelerating the evolution of defects, in particular stress corrosion cracks. In the conventional eddy current test methods, the bobbin coil profilometry can provide 2-dimensional geometric information on the variation of the average inner diameter along the tube length, but the 3-dimensional distribution and the quantitative size of a local geometric transition existing in the tube cannot be measured. In this paper, a new eddy current probe, developed for the 3-dimensional profile measurement, is introduced and its superior performance is compared with that from the conventional bobbin coil profilometry for the various types of geometric transition. Also, the accuracy of the probe for the quantitative profile measurement is verified by comparing the results with that from the laser profilometry. It is expected that the new eddy current probe and techniques can be effectively used for an optimization of the tube expansion process, and the management of tubes with geometric transitions in service.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.935-942
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• 2019

This paper descries the operation of a heater which was designed to control a motor that generates an eddy current. As the motor drives the rotor of an eddy current heater, magnetic fields are provided within the air gap between an eddy current heater's rotor and stator. Throughout the research, a rotor composed of 8 and 16 pieces of magnets was used to analyze which are the factors that affect the efficiency of this equipment. Test results showed that the magnetic fields are influenced by variable functions including the velocity of a motor and the quantity of magnets composing a rotor.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.513-518
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• 2019

The non-destructive testing equipment using an eddy current was developed to check for defect in the vehicle transmission component. A defect master sample was made to test all types of defects that occur in the component and also an eddy current detector was manufactured and used to test and detect all kinds of defects. In addition, testing was held against the actual defective items to investigate the cause and type of defects, and a comparative study was conducted based on results from the examination. The software system of the eddy current detector was developed so that even a non-specialist can make assessment of detect in the component from the test results displayed on the monitor.

• Journal of Ocean Engineering and Technology
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• v.33 no.5
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• pp.387-393
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• 2019

In this study, the free motion of a riser due to vortex shedding was numerically simulated with Large Eddy Simulation (LES) and Detached Eddy Simulation (DES) turbulence models. A numerical simulation program was developed by applying the Rhie-Chow interpolation method to the pressure correction of the OpenFOAM standard solver pimpleDyMFoam. To verify the developed program, the vortex shedding around the fixed riser at Re = 3900 was calculated, and the results were compared with the existing experimental and numerical data. Moreover, the vortex-induced vibration of a riser supported by a linear spring was numerically simulated while varying the spring constant. The results are compared with published direct numerical simulation (DNS) results. The present calculation results show that the numerical method is appropriate for simulating the vortex-induced motion of a riser, including lock-in phenomena.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.7
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• pp.434-441
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• 1988

This paper proposes a new invention of the integrated generator converter system for the HVDC transmission. And it analyses the general formula for eddy currents in the rotor iron using the double Fourier series in order to trace the smallest eddy current losses of the system which connects a new designed synchronous generator windings or conventional synchronous generator windings with the v Graetz bridges.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.E1
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• pp.37-39
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• 2005

It is well perceived that micrometeorological approach is one of the most reliable method for the quantification of vertical fluxes of trace components in the atmosphere. In this study, the feasibility of relaxed eddy accumulation (REA) method is discussed with respect to its reliability in the field application. Knowing that the use of micrometeorological approaches requires validation of analytical uncertainties involved, the problems and issues associated with its application are discussed to stimulate the proper employment of such technique in the field study.

• Fisheries and Aquatic Sciences
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• v.4 no.3
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• pp.101-111
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• 2001

In an attempt to demonstrate the seasonal variation of the Ulleung Warm Eddy (UWE), in which the UWE changes its shape from a warm core ring in early spring to a warm lens in late summer under the effect of surrounding East Korean Warm Current (EKWC) Water, a simple geostrophic adjustment model is considered. Model results indicate that the buoyancy increase of the EKWC Water and the strengthening of the EKWC towards summer, both of which are typical of this region, are the major factors governing the seasonal variation of the UWE.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.133-137
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• 2004

The present study is focused on the small scale turbulent mixing processes in the scalar field. In order to deal with molecular mixing in turbulent flow, the linear eddy model is addressed. In each realization, the molecular mixing term is implemented deterministically, and turbulent stirring is represented by a sequence of instantaneous, statistically independent rearrangement event called by triplet map. The LEM approach is applied with relatively simple conditions. The characteristics of scalar mixing and PDF profiles are addressed in detail.