• Journal of the Korean Society of Visualization
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• v.14 no.2
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• pp.46-51
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• 2016

In this study, a Masked Omni-Directional Integration(MODI) method for pressure calculation is proposed using the Particle Image Velocimetry (PIV) data. To obtain the velocity field, the Affine PIV method was adopted. Synthetic images were generated for a solid body rotation. Calculation on the pressure was based on the Navier-Stokes equation. The results obtained by the MODI were compared with those obtained by theoretical pressure and by the Omni-Directional Integration(ODI) method. It was shown that the minimum error by the proposed MODI method was attained when the mask size was 1.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.18-20
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• 1995

In this paper we presented a calculation method of leakage inductance in electrical machines. For its accurate calculation the finite element method is applied to the analysis of magnetic field distribution. The self and mutual inductances are derived using the results of the magnetic field analysis and the leakage inductance is easily obtained from these inductances. As numerical examples, we tread a single phase transformer and a rotor slot model of induction motor. In the finite element analysis we used the 2D linear magnetostatic formulation with the first-order triangular element.

• Progress in Superconductivity and Cryogenics
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• v.13 no.4
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• pp.26-29
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• 2011

In a High temperature superconducting (HTS) tape with high aspect ratio, the magnetic field applied to the HTS tape can be different considerably within the HTS tape. The current distribution in the HTS tape is generally non-uniform because the current distribution is strongly dependent on the applied magnetic field. Non-uniform current distribution in a HTS tape has not been properly considered when the critical current has been estimated. This paper shows the calculation of critical current of a HTS magnet consisting of pancake windings. Non-uniform distribution of current in the HTS tape is considered during the calculation of the critical current. Results of calculation show the current concentrated in the middle part of the HTS tape which is used for one pancake winding.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.55-57
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• 2009

This paper deals with an improved core loss calculation under the load conditions, namely, no-load, AC-load and DC-load of multi-pole PM generator from curve fitting method using modified Steinmetz equation considered anomalous loss. For an accurate calculation, magnetic field analyses in stator core considering the time harmonics are performed. And using the nonlinear finite element analysis (FEA), we applied separated rotating and alternating magnetic field to core loss calculation. In order to verify the core loss results by proposed method, the experimental system for no-load core loss measurement has been implemented with DC motor, power analyzer and manufactured PM generator. And, the analysis results with rotational speed agree extremely well with those obtained by measurement.

• Journal of Power Electronics
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• v.19 no.3
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• pp.794-802
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• 2019

Magnetic geared motors are driven using the same operating principle as conventional synchronous motors in which a magnetic gear is embedded. The magnetic geared motor is structurally similar to a magnetic gear. However, by applying currents to the stator coil, the high-speed rotor is rotated by a magnetic field and the low-speed rotor is rotated according to the gear ratio. In this paper, the operational principle of a magnetic geared motor and the magnetic flux density in its inner and outer air gaps are described. Then the magnetic flux density in the two air gaps is used to express a method for calculating the electrical and mechanical output. Results obtained with the analytical calculation method are compared with those of the finite element analysis. Finally, a prototype is used to verify the results of the analytical calculation and FEA.

• The KIPS Transactions:PartB
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• v.12B no.1 s.97
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• pp.57-68
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• 2005

It is important to segment a text, which is independent upon any text-embedded auxiliary information. This paper presents a technique for dividing the text into field-coherent passages. The presented method is based upon extracting field-associated terms from the text measuring how the topics grow, shrink and shift from sentence to sentence. We propose measures of topic continuity and of topic transition and suggest how those could be used to find the boundaries among passages. After collecting 12,500 documents, we obtain $88{\%}$ for average precision and $78{\%}$ for recall in Korean training set.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.28-32
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• 2015

Nowadays the magnetic field mapping is widely used in the design and analysis of the NMR/MRI magnet system, and the accuracy of mapping result has become more and more important. There are several factors affecting the accuracy of the mapping such as the mapping method, the precision of the sensor, the position of the measurement points, the calculation accuracy, and so on. In this paper the error due to the misalignment of the measurement points was discussed. The magnetic field in the central volume was mapped using an indirect method in an MRI magnet system and the magnetic field was fitted to a polynomial. Considering the misalignment between the original measurement points and the practical measurement points, there must be some errors in the mapping calculation and we called it positioning error. Several comparisons of the positioning error have been presented through the theoretical estimates and the exact magnetic field values. Finally, the allowable positioning errors were suggested to guarantee the accuracy of the magnetic field mapping within a certain degree for an example case.

• Progress in Superconductivity and Cryogenics
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• v.11 no.4
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• pp.33-36
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• 2009

An air gap between the pancake windings was provided in this paper to increase the central magnetic field of a high temperature superconducting (HTS) magnet consisting of pancake windings. Unlike the LTS magnet, providing an air gap between the pancake windings increases the central magnetic field of a HTS magnet. Furthermore, the uniformity of the magnetic field near the center of the magnet increased because the pancake windings spread out in wider area. Effects of the air gap on the central magnetic field of an HTS magnet was described in this paper, Calculation of the critical current was carried out by using E-J relation of the HTS wire and the optimization technique was adopted to obtain the appropriate critical current which could maximize the central magnetic field. Pancake windings with BSCCO-2223 HTS wire were wound on glass epoxy bobbin. 6 double pancake windings with 200 turns were used to construct a HTS magnet. Characteristics of the HTS magnet including the central magnetic field and the uniformity of the magnetic field were measured and compared with the results of calculation.

• 전기의세계
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• v.30 no.9
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• pp.589-593
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• 1981

Anumerical method for the calculation of electric fields with two-dielectric media is described. The basis of the method is the use of fictitious charges as a particular solution of Laplace's (and Poisson's) equations. Simple examples were chosen for the explanation of the method and the close agreement between calculated and analytical values was obtained. It has been shown that the charge simulation method is better in calculation time and accuracy.

• Korean Journal of Computational Design and Engineering
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• v.13 no.4
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• pp.296-304
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• 2008

Recently, various attempts are being done to apply off-line programming system to field of paint robot. But most commercial simulation softwares have problems that are slow simulation speed and not support various painting paramenters on simulation. This paper proposes enhanced paint simulation method for off-line programming system. For these, this method used the mathematical model of flux field from a previous research. The flux field has the flux distribution function, which reflects on the feature of paint spray. A previous research derived this flux distribution function for an integral function and calculated paint thickness function for an integral function. But if flux distribution function is defined as an integral function, it is inadequate to use for real-time simulation because a number of calculation is needed for estimation of paint thickness distribution. Therefore, we defined the flux distribution function by numerical method for reducing a mount of calculation for estimation of paint thickness. We derived the equation of paint thickness function analytically for reducing a mount of calculation from the paint distribution function defined by numerical method. In order to prove proposed paint simulation method this paper compares the simulated and measured thickness. From this comparison this paper show that paint thickness distribution is predicted precisely by proposed spray paint simulation process.