• 한국초전도ㆍ저온공학회논문지
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• 제23권4호
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• pp.30-34
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• 2021

Superconducting magnets have paved the way for opening new horizons in designing an electromagnet of a high field magnetic resonance imaging (MRI) device. In the first phase of the superconducting MRI magnet era, low-temperature superconductor (LTS) has played a key role in constructing the main magnet of an MRI device. The highest magnetic resonance (MR) field of 11.7 T was indeed reached using LTS, which is generated by the well-known Iseult project. However, as the limit of current carrying capacity and mechanical robustness under a high field environment is revealed, it is widely believed that commercial LTS wires would be challenging to manufacture a high field (>10 T) MRI magnet. As a result, high-temperature superconductor together with the conducting cooling approach has been spotlighted as a promising alternative to the conventional LTS. In 2020, the Korean government launched a national project to develop an HTS magnet for a high field MRI magnet as an extent of this interest. We have performed a design study of a 7 T 320 mm winding bore HTS MRI magnet, which may be the ultimate goal of this project. Thus, in this paper, design study results are provided. Electromagnetic design and analysis were performed considering the requirements of central magnetic field and spatial field uniformity.

• 한국초전도ㆍ저온공학회논문지
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• 제11권1호
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• pp.30-34
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• 2009

This paper deals with charging and persistent-current mode operating characteristics of BSCCO magnet load using high-temperature superconducting (HTS) power supply. The HTS power supply consists of two heater-triggered switches, an iron-core transformer with the primary copper winding and the secondary BSCCO solenoid, and a BSCCO magnet load. The magnet load was fabricated by double pancake winding and its inductance is about 21 mH. A hall sensor was installed at the middle of the magnet load to measure the current in the load. In order to investigate the efficient pumping characteristics, operating tests of heater-triggered switch with respect to dc heater current were carried out, and the electromagnet current was determined by considering saturation characteristics of its iron core. The saturation characteristics of charged current in the magnet load were observed with respect to various pumping periods: 12 s, 14 s, 24 s and 32 s. After charging the magnet load, the persistent current was measured. The operating characteristics of the persistent current mode were mainly determined by joint resistance and magnet load.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.119-125
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• 2016

본 논문에서는 기존 휠-레일 고속열차에 자기부상열차의 추진방법을 적용한 하이브리드 방식의 고속열차의 주행 동특성에 대해서 연구하였다. 초전도 선형동기전동기를 추진 동력으로 하는 휠-레일 방식의 고속열차는 강력한 추진력을 지니면서도 자기부상열차에 비해 기존 선로와의 호환성 및 경제성 측면에서 유리할 것으로 예상된다. 본 논문에서는 초전도 선형동기전동기를 기존의 휠-레일 고속철도에 적용하는 두 가지 방안에 대해서, 초전도 선형동기전동기 추진이 휠-레일 고속열차의 동특성에 미치는 영향을 살펴보기 위하여 초전도 선형동기전동기의 회전자와 고정자의 상호 작용을 검토하고 이를 포함한 차량의 동특성 모델을 구축하였다. 구축된 모델을 이용한 시뮬레이션을 통해 초전도 선형동기전동기의 회전자와 고정자의 상호 작용이 주행 중 고속 안정성, 승차감 및 가이드웨이 불규칙도에 미는 영향을 분석하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제6권1호
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• pp.43-48
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• 2004

This paper deals with design and fabrication of heater-triggered switching system for the high-Tc superconducting (HTS) power supply with series-connected double-pancake load. Amongst all components, heater triggering is the most important element for the performance of HTS power supply. To fabricate the optimal heater-triggered system, its characteristics have been analysed through the simulation and expriment. The thermal analysis of switching parts of the Bi-2223 solenoid according to the heater input was carried out. Based upon the analysis, 8A electromagnet current and 1.5A DC Heater current were optimally derived, and 8s and 20s for the pumping period were selected in this experiment. In the experiment. the maximum pumping current reached about 24A with Bi-2223 pancake load of 6mH.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.27-31
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• 2014

Magnetic fields (MF) generated both on board the vehicle and along the guideway provide levitation and propulsion forces. High speed maglev trains adopt electromagnet or superconducting magnet to realize levitation and propulsion functions. However, stray fields existing in passenger compartment and regions surrounding the vehicle and guideway have effect on passengers and environment. To investigate stray magnetic field effect, model of Transrapid and MLX are studied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.143-145
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• 1998

This paper presents the shape optimization algorithm of magnetic systems with, state variable constraints using the Finite Element Method. In the design' of electromagnetic systems, sometimes we have to consider the state variables when they seriously affect the performance of electromagnetic systems. So we should define that some design problems have the constraints of the state variables. We use the gradient of constraints and sensitivity analysis in order to consider the state variable constraints and obtain an optimal shape. The optimal shape must be satisfied constraints, so we take the gradient projection method as a kind of optimization methods. In this paper a numerical example with state variable constraints uses the superconducting electromagnet that has another constraint which the volume of the superconductor should be constant.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.444-444
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• 2011

Recently, patterned magnetic films and elements attract a wide interest due to their technological potentials in ultrahigh-density magnetic recording and spintronic devices. Among those patterned magnetic structures, magnetic anti-dot patterning induces a strong shape anisotropy in the film, which can control the magnetic properties such as coercivity, permeability, magnetization reversal process, and magneto-resistance. While majority of the previous works have been concentrated on anti-dot arrays with a single magnetic layer, there has been little work on multilayered anti-dot arrays. In this work, we report on study of the magnetic properties of bilayered anti-dot system consisting of upper perforated Co layer of 40 nm and lower continuous Ni layer of 5 nm thick, fabricated by photolithography and wet-etching processes. The magnetic hysteresis (M-H) loops were measured with a superconducting-quantum-interference-device (SQUID) magnetometer (Quantum Design: MPMS). For comparison, investigations on continuous Co thin film and single-layer Co anti-dot arrays were also performed. The magnetic-domain configuration has been measured by using a magnetic force microscope (PSIA: XE-100) equipped with magnetic tips (Nanosensors). An external electromagnet was employed while obtaining the MFM images. The MFM images revealed well-defined periodic domain networks which arise owing to the anisotropies such as magnetic uniaxial anisotropy, configurational anisotropy, etc. The inclusion of holes in a uniform magnetic film and the insertion of a uniform thin Ni layer, drastically affected the coercivity as compared with single Co anti-dot array, without severely affecting the saturation magnetization ($M_s$). The observed changes in the magnetic properties are closely related to the patterning that hinders the domain-wall motion as well as to the magneto-anisotropic bilayer structure.