• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.729-734
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• 2000

This paper proposes virtual-magnetic system by a force-reflecting interface to drive a ultrasonic motors(USMs) To approach virtual magnet in graphic the 6 dDOF force-reflecting interfaces provides force feedback to users as if I is magnetic-force, So users can feel real magnet Effectively to display the magnetic-force we need the interface with specific characteristics such as low inertia almost zero friction and very high stiffness As an actuator for the interface the USMs have many good advantage satisfied these conditions over conventional servo motors. To estimate capability of this virtual-magnetic system we did an experiment of magnetism based on coulomb's law when Coulmb's low apply this experiment it is vey conformable to real magnet

• Journal of Magnetics
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• 제19권4호
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• pp.393-398
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• 2014

This paper proposes new types of models that have coaxial magnetic gear (CMG) configurations to increase torque transmission capability. They have flux concentrating structures at the outer low speed rotor, and permanent magnets (PMs) are embedded in the space between stationary pole pieces. The torque performances of the proposed models are compared with those of a basic CMG model. The harmonic torque components due to air gap field harmonics are also analyzed to investigate the torque contribution of each harmonic by using finite element analysis (FEA) and the Maxwell stress tensor. The proposed CMG model is optimized to have high torque density with low torque ripples by response surface methodology (RSM). Compared to the basic CMG model, the proposed model has a huge increase in transmitted torque density, and is very advantageous in term of PM use.

• International Journal of Aeronautical and Space Sciences
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• 제8권2호
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• pp.17-27
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• 2007

Minimum-time attitude maneuvers of three-axis stabilized spacecraft are presented to study the feasibility of using three magnetic torquers perform large angle maneuvers. Previous applications of magnetic torquers have been limited to spin-stabilized satellites or supplemental actuators of three axis stabilized satellites because of the capability of magnetic torquers to produce torques about a specific axes. The minimum-time attitude maneuver problem is solved by applying a parameter optimization method for orbital cases to verify that the magnetic torque system can perform as required. Direct collocation and a nonlinear programming method with a constraining method by Simpson's rule are used to convert the minimum-time maneuver problems into parameter optimization problems. An appropriate number of nodes is presented to find a bang-bang type solution to the minimum-time problem. Some modifications in the boundary conditions of final attitude are made to solve the problem more robustly and efficiently. The numerical studies illustrate that the presented method can provide a capable and robust attitude reorientation by using only magnetic torquers. However, the required maneuver times are relatively longer than when thrusters or wheels are used. Performance of the system in the presence of errors in the magnetometer as well as the geomagnetic field model still good.

• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1077-1085
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• 2007

Typically, three types of levitation technologies are applied to magnetic levitation systems: electromagnetic suspension, electrodynamic suspension, and hybrid electromagnetic suspension. A Halbach array is a special arrangement of permanent magnets which augments the magnetic field on one side of the device while cancelling the field to near zero on the other side. The application of this Halbach array magnet to the electrodynamic suspension has been recently studied in order to increase the levitation capability. This paper is focused on an analytical method of the magnetic levitation system using Halbach array magnet. The suitability of the proposed method is verified with comparing to the finite element method. In addition, dynamic stability of the magnetic levitation system is discussed. From this study, it is confirmed that the proposed method provides a reasonable solution with less computation time compared to the finite element method and the magnetic levitation system using Halbach array magnet is stable dynamically.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1285-1293
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• 2018

This paper proposes a new type of consequent-pole permanent-magnet (CPPM) machine with stator axial magnetic ring that increases torque capability over a wide speed range and enhances efficiency for the built-in rare-earth permanent magnet synchronous machine used in new energy vehicles. The excitation winding of the CPPM hybrid excitation synchronous machine in the stator is replaced by ferrite magnetic ring to simplify the structure and manufacturing process of the machine. The basic structure and magnetic regulation principle of the proposed machine are introduced and compared with the traditional interior rare-earth permanent magnet synchronous machine and CPPM hybrid excitation synchronous machine. Finally, experimental results of a new type of CPPM synchronous motor prototype with axial magnetic ring are introduced in the paper.

• 한국통신학회논문지
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• 제40권2호
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• pp.349-354
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• 2015

본 논문은 차량감지를 위해 자기센서를 이용하여 자기신호를 측정하고 형상을 분석한 결과에 관한 것이다. 자기센서는 하니웰사의 MR센서를 이용하였고, 센서의 성능을 알아보기 위해 3축의 길이가 1.2 m인 자기장 발생장치를 제작하여 자기장 감지능력을 측정하였다. 차량감지는 주행차로와 비 주행차로에 센서를 설치한 후 감지여부와 차체의 크기가 다른 7개 차량에 대해서 자기장을 측정하였다. 또한 SUV와 소형 차량의 주차구역과 비 주차구역에 센서를 설치하고 자기장 형상을 분석하였다. 마지막으로 차량의 각 부분별 자기장 형상을 측정하였다. 측정 결과 주행차로에 자기장 형상은 비 주행차로의 경우보다 자기장 첨두치가 크며 복잡한 형상을 보여 센서의 설치 위치로 주행차로와 주행차의 방향을 구분할 수 있었으며, 차체가 클수록 자기장의 변화가 커서 차량 종류를 식별할 수 있었다. 또한 차량의 각 부분별 자기장의 변화를 측정하여 형상을 분석하였다.

• Current Applied Physics
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• 제18권11호
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• pp.1422-1425
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• 2018

$NaTa_{1-x}Fe_xO_3$ ($0{\leq}x{\leq}0.40$) nanocubes were synthesized by a relatively low temperature hydrothermal method, using $Ta_2O_5$, $FeCl_3$ and NaOH as the precursors. The UV-vis diffuse reflectance spectra showed that $NaTa_{1-x}Fe_xO_3$ had significant visible-light-absorbing capability, and the absorption edge of $NaTaO_3$ shifted to longer wavelength with the increase of Fe dopants. Moreover, $NaTa_{1-x}Fe_xO_3$ exhibited room-temperature ferromagnetism when $Fe^{3+}$ occupied $Ta^{5+}$ sites in $NaTaO_3$ crystal lattice. The ferromagnetism is mainly attributed to the superexchange interactions between doped $Fe^{3+}$, rather than the contribution of oxygen vacancies caused by Fe doping. Therefore, Fe doping can simultaneously regulate the optical and magnetic properties of $NaTaO_3$ semiconductor, which will enable its potential applications in multifunctional optical-electronics and opticalspintronics devices.

• 한국초전도ㆍ저온공학회논문지
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• 제6권2호
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• pp.11-14
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• 2004

YBCO thin films have good characteristics for current limiting materials due to compact size and high current carrying capability. But the irregularities and the extreme thin thickness of YBCO films cause some difficulties in simultaneous quench and thermal shock protection. In order to solve these problems, vertical magnetic field generated from solenoid coil was applied to the YBCO element. And also to minimize the inductance caused by the serial connection of magnetic field source with superconducting elements, magnetic field source was separated from the power lines adapting protective current transformer. In this study, electric field-current (E-I) and quench characteristics of YBCO films were analyzed both by electrical measuring method and observations of bubble propagation. From the experiment results, it was revealed that the magnetic fields generated by surrounding coil could induce the uniform quench distribution for all stripes of current limiting units and finally simultaneous quenches were realized in all serial connection of YBCO elements. In addition, the separation of magnetic field source form electrical network could be good solution for simultaneous quench of YBCO films without any unnecessary effect caused by serial connection.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권10호
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• pp.509-516
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• 2001

Isolated phase bus(IPS) has a special structure for carrying large current generated by a generator to a main transformer. In the analysis of IPB, the understanding of the magnetic field distribution generated by large current is important. Especially, while the bus conductor current is flowing, almost same amount of current as bus conductor current is induced in the enclosures under the influence of time varying magnetic field, and therefore the large electric loss and the deterioration of insulating capability might occur due to Joule heating effect. Hence for the optimal design of IPB satisfying the condition to minimize the loss, the accurate analysis of magnetic field distribution and the eddy current characteristics of three phase isolated phase bus have been investigated. In the analysis of time varying magnetic field, instead of finite difference method(FDM) which is generally used, finite element method with phasor concept is investigated under the assumption that the bus current is purely sinusoidal. The characteristics is studied along the phase angle by comparing the effect of eddy current on the magnetic field distribution with the case that eddy current is not considered, and also the effect of material, thickness and radius of enclosure on the eddy current distribution is discussed.

• Journal of Magnetics
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• 제18권3호
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• pp.370-374
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• 2013

This paper introduces an innovative hybrid array consisting of both permanent and electro magnets. It will enable us to develop an active control mechanism for underdamped electro-dynamic suspension (EDS) Maglev systems. The proposed scheme is based on the Halbach array configuration which takes the major technical advantage from the original Halbach characteristics: a strongly concentrated magnetic field on one side of the array and a cancelled field on the opposite side. In addition, the unique feature of the proposed concept only differs from the Halbach array with permanent magnets. The total magnetic field of the array can be actively controlled through the current of the electro-magnet's coils. As a result, the magnetic force produced by the proposed hybrid array can also be controlled actively. This study focuses on the magnetic characteristics and capability of the proposed array as compared to the basic Halbach concept. The results show that the proposed array is capable of producing not only an equivalent suspension force of the basic Halbach permanent magnet array but also a controlled mode. Consequently, the effectiveness of the proposed array confirms that this study can be used as a technical framework to develop an active control mechanism for an EDS Maglev system.