• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권2호
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• pp.54-58
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• 2004

This paper presents the iron core design method of a high temperature superconducting (HTS) transformer considering voltages per turn (V/T). In this research, solenoid type HTS coils were selected for low voltage (LV) winding and double pancake coils for high voltage (HV) winding, just as in conventional large power transformers. V/T is one of the most fundamental elements used in designing transformers, as it decides the core cross sectional area and the number of primary and secondary winding turns. By controlling the V/T, the core dimension and core loss can be changed diversely. The leakage flux is another serious consideration in core design. The magnetic field perpendicular to the HTS wire causes its critical current to fall rapidly as the magnitude of the field increases slowly. Therefore in the design of iron core as well as superconducting windings, contemplation of leakage flux should be preceded. In this paper, the relationship between the V/T and core loss was observed and also, through computational calculations, the leakage magnetic fields perpendicular to the windings were found and their critical current decrement effects were considered in relation to the core design. The ％ impedance was calculated by way of the numerical method. Finally, various models were suggested.

• 전기전자학회논문지
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• 제7권2호
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• pp.218-222
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• 2003

전자파 방사 및 측정 시험설비로 표준 시험장인 야외시험장을 사용하고 있으나 시험장 구축의 어려움으로 이를 대체할 수 있는 대용시험장을 사용하여 측정시험을 할 수 있도록 하고 있다. 본 논문에서는 최적화된 측정시스템을 구성하기 위한 대용시험시설인 GTEM CELL(Gigahertz Transverse Electro Magnetic Cell)의 구조분석 및 설계를 하기 위하여 내부도체(Septum)의 넓이 및 두께 변화에 따른 내부도체의 특성임피던스 변화를 살펴보았다.

• 한국군사과학기술학회지
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• 제11권6호
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• pp.74-80
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• 2008

Analysis of the electromagnetic environment on topside of a ship is needed for optimal arrangement of all kinds of antennas to be installed on the shipboard in order to minimize the probability of EMI of equipment and subsystems in real ship after construction phase. In this paper we analyze the characteristics of electric-fields such as radiation patterns and near E-fields of V/UHF antennas installed on a shipboard. We compare simulated results with measurements on the real ship for near E-fields to verify the reliability of the computed electromagnetic environment. Although there are various factors causing errors such as cable loss and impedance mismatching etc. when measuring near E-field, both data show similar trends in the range of the acceptable tolerance.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.69-70
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• 2005

In order to prevent the arc blow at the FCA welding system with multi-torches, the effects of arc length on the magnetic flux at the FCA weldment was evaluated using electro-magnetic filed analysis. Magnetic flux density around arc are slightly increased with an increase in the arc length. Based on the FEA results, the minimum distance of torches to control arc blow was established.

• 전기의세계
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• 제31권4호
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• pp.288-295
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• 1982

In this study, the characteristic equation of a double sided short stator linear induction motor, referred to as LIM excited by equivalent current sheet having linear current density was derived using Maxwell's electromagnetic field theory with its entry and exit, end effects taken into consideration. According to the treatment of several physical phenomena in the air-gap i.e. the magnetic flux density distributions, thrust-force, forward and backward travelling wave with decay, normal field, the fundamental data in this study are made reference to improve the characteristics of LIM, effectual electro-magnetic energy conversion devices.

• 한국재료학회지
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• 제11권11호
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• pp.972-977
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• 2001

It was investigated the effect of ultrasonic treatment on magnetic property of ultra fine magnetic Fe powders ($\alpha$-Fe) for magnetic tape. The properties were characterized with vibrating sample magnetometer (VSM), particle size analyzer (PSA) and scanning electron microscope (SEM). At 4hours ultrasonic treatment of 70 kHz, magnetic properties such as squareness ratio (S.Q. : 0.8868), orientation ratio (O.R. : 2.45) and switching field distribution (S.F. D. : 0.394) before taping were relatively enhanced. Cumulative particle size distribution of less than 5$\mu\textrm{m}$ fine powder was above 90% below 1 hour leaving time after ultrasonic treatment and it was supposed that ultrasonic treatment prevent aggregation. The magnetic values of S.Q. and S.F.D. of tape manufactured at 70 kHz and 4hour ultrasonic treatment were improved from 0.7747, 0.3818 to 0.8037, 0.3706, respectively. Electro-magnetic property used as in-output signal characteristic was improved, which showed that ultrasonic treatment developed the magnetic properties.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.186-188
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• 2001

Recently, the vacuum interrupters have been most widely used in medium voltage level. In the vacuum circuit breaker the most influential part is vacuum interrupter. By performing the precise electromagnetic analysis of the interrupter, we increase the capability of large current interruption. In this paper, diffuse arc and constricted arc are modeled to perform 3D electromagnetic analysis, and also flux distributions and electromagnetic force is calculated at the contacts' separation. It is expected these results will be used importantly in developing the new vacuum interrupters.

• Smart Structures and Systems
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• 제26권5호
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• pp.631-640
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• 2020

In this paper, nonlinear vibration behaviors of multi-phase Magneto-Electro-Elastic (MEE) doubly-curved nanoshells have been studied employing Jacobi elliptic function method. The doubly-curved nanoshell has been modeled by using nonlocal elasticity and classic shell theory. An exact estimation of nonlinear vibrational behavior of smart doubly-curved nanoshell has been obtained via Jacobi elliptic function method. This method can incorporate the influences of higher order harmonics leading to an exact estimation of nonlinear vibration frequency. It will be indicated that nonlinear vibrational frequency of doubly-curved nanoshell relies on nonlocal effect, material composition, curvature radius, center deflection and electro-magnetic field.

• Journal of Welding and Joining
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• 제19권5호
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• pp.526-533
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• 2001

Induction heating of float metal products has an increasing importance in many applications, because it generates the heat within workpiece itself and provides high power densities and productivity. In this study, the induction heating of a steel plate to simulate the line heating is investigated by means of the Finite Element Analysis of the magnetic field and temperature distribution. A numerical model is used to calculate temperature distribution within the steel plate during the induction heating with a specially designed inductor. The effects of materital properties depending on the temperature and magnetic field are taken into consideration in an iterative manner. The simulation results show good magnetic field with experimental data and provide good understanding of the process. Since the numerical model demonstrates to be suitable for analysis of induction heating process, the effects of air gap and frequency on magnetic-flux and power-density distribution are also investigated. It is revealed that these process parameters have an important roles on the electro-magnetic field and power-density distribution governing the temperature distribution of the plate.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.172-174
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• 2006