• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.2
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• pp.155-159
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• 2016

Eddy current testing (ECT) is an important nondestructive testing technology for the inspection of flaws in conductive materials. However, this widely used technology is not suitable for inspecting lamination when a conventional pancake coil is used because the eddy current (EC) generated by the pancake coil is parallel to the lamination and will not be perturbed. A new method using a rectangular coil placed vertical to the work piece is proposed for lamination detection. The vertical sections of the rectangular coil induce ECs that are vertical to the lamination and can be perturbed by the lamination. A parametric study of a rectangular coil by finite element analysis was performed in order to examine the capability of generating vertical EC.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.77-79
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• 1995

This paper investigates the force on a rectangular AC supercoducting coil moving above and parallel to a conducting plate of finite thickness. Expressions are developed for the levitation and drag forces on the coil a a function of speed and frequency. The levitation force are generated at all speed including stand still in a AC supercoducting coil. The levitation and drag forces on a rectangular AC supercoducting coil are compared with those on a rectangular DC supercoducting coil moving above and parallel to a conducting plate.

• Journal of Magnetics
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• v.21 no.3
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• pp.348-355
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• 2016

Precision motion stages used in the manufacturing process of flat-panel displays have inevitably low settling performance due to their huge mass and bulky structures. In order to improve the settling performance, several methods of frame vibration compensation have been developed so far. These methods are used to cancel the vibration by imposing a counter force or modifying the resonance mode of the frame of the stage. To compensate the frame vibration, high force actuators are required. In this paper, a mighty voice coil actuator is proposed to generate the counter force against the frame vibration. The proposed voice coil actuator has an axis-symmetric rectangular structure to achieve a large force with simple and low cost fabrication. Also, the voice coil actuator allows radial clearance up to ${\pm}4mm$. Using an optimized design process and a magnetic circuit model, the power consumption is minimized while the required force is obtained. With a power of 322 W, the VCA has been designed to have a maximum force of 574 N with a force constant of 164 N/A. Experimental results verified the force constant of the fabricated voice coil actuator is well matched with the designed value.

• 연구논문집
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• s.34
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• pp.87-99
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• 2004

A spring tension control device is used as a very important part of an twister system. The friction force of tensioner must keep same friction force during winding in package. For satisfy this function, many device used common compression coil spring. In this paper, by using the case-building technique which was based on simple theory that unknown design variables are induced by given input design variables by the designer, design automation algorithm about rectangular section compression springs with elastic characteristic is developed. Four design equation are justified in using of analysis of torsion of straight bar of rectangular section and geometrical condition of coil spring. Four design equation and nine design variables are computed by case-building technique.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.174-174
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• 2001

Purpose： Dimensions of body RF coil composed of 4 rectangular loops for low field open MRI hav been optimized. The design result shows the field inhomogeneity of B1 field below 1.5 dB in the 25 cm DSV can be achieved. Method： Our low field RF coil is composed of 4 rectangular strip loops that assumed to b located at both the bottom and top sides of permanent magnet. All the loops have identica dimensions and current amplitude. First, the inductance of a loop is calculated. Second, the current distribution on the coil strip is calculated by using finite difference time doma method (FDTD). It takes as much as 4 days in FDTD simulation for low frequency RF field That's why the electrical dipole radiation method is used for simulation. With the curren distribution obtained using the FDTD simulation, for various dimensional parameters th magnetic field has been calculated by electric dipole radiation method, where the curren elements are regarded as electric dipole radiation sources. The field pattern from electri dipole radiation is almost same as that from FDTD simulation. Also, it is same as that fro the result using the Viot-Savart equation, for far tone radiation term becomes zero and th Bl field amplitude of near one radiation is the same as the B field due to static current The field homogeneity is calculated in the 25 cm BSV.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.461-464
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• 1999

Planar type thin film inductors have a potential for the application of miniaturized DC-DC converters. For those high current applications, the magnetic film with high current capability is required. The current capability of magnetic films is mainly determined from high saturation magnetization (4$\piM_s$) as well as large anisotropy field $(H_k)$. We fabricated a double rectangular spiral thin film inductor which consist of magnetic layer, coil and insulator. Highest inductance values as well as best frequency characteristics can be obtained from 5 MHz and quality factor exhibit about 7.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.278-280
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• 1998

A voice-coil-type LOA consists of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure, and an iron core as a pathway for magnetic flux. When applying a voice-coil-type LOA to the control system, we have to obtain the control parameters and circuit parameters, such as mass, coil inductance, coil resistance, thrust voltage & stroke, frequency & stroke and so on. Therefore, these parameter were determined from the analytical and experimental method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.7
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• pp.307-314
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• 2001

A moving coil linear oscillatory actuator is consisted of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure and an iron core as a pathway for magnetic flux. The variation of mover position and the consequent changes of coil flux path affect the coil inductance, because coil flux leaks at the open region of LOA stator. The interaction between permanent magnet and armature field is to shift the airgap flux density variation due to the magnet alone by a certain amount. The unbalanced reciprocation force due to armature reaction field decreases the advantage of moving coil LOA, such as a high degree of linearity and controllability in the force ad motion control. This paper firstly describes the coil inductance, the deviation of flux density, and the unbalanced reciprocation force, which are derived form the permeance model of LOA. Secondly, the analytical method are verified using the 2D finite element method and tests. Finally, the dynamic simulation algorithm taking the armature reaction effect and variable inductance into account, is proposed and confirmed through the experiment.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.22-31
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• 2006

When ironwork, especially steel roll coil, is transported to customers, land transportation and sea transportation are usually used. To transport steel roll coil fast and safe without damaging it, it is necessary that the steel roll coil has to be in stable condition. These days, apitong, which is all imported from overseas, is being used to support the steel roll coil, but because of apitong's rigidity, it damages the coil and when the coil is damaged, it is hard to fix. Due to the fact that recovering damage of the coil is almost impossible, we have to find the new type of dunnage that can substitute the apitong. In this paper, the arrays and the kinds of reinforcements, and rectangular type and trapezoid of dunnage will be talked about. The phenomenon of rolling and the impact when the carrier start moving and stop will be talked about as well. Therefore, we are going to develop a dunnage that does not damage ironwork and has better recovery and softness than existing apitong dunnage.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.231-234
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• 2016

The AC insulation breakdown voltage was investigated for seven types of winding coils made of polyamideimide (PAI), flexural PAI (nanosilica 5 wt%) and anti-corona PAI (nanosilica 15 wt%) wires with various winding coil diameters of φ5, φ15 and φ25 mm. The winding coil was made of enameled wire with an enamel thickness of 30~50 μm, and the rectangular copper wire had a thickness of 0.77~ to 0.83 mm and width of 1.17~ to 1.23 mm, respectively. The insulation breakdown voltages of the original PAI coils with diameters of φ5, φ15 and φ25 mm were 7.30, 6.58, and 5.95 kV, respectively, and those values decreased as the winding coil diameter increased, regardless of the wire types.