• Proceedings of the KIEE Conference
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.144-145
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• 2007

SMES의 운전 상태는 충전, 운전, 방전의 3가지 모드로 나눌 수 있으며, 충 방전 구간에서 와전류 손실이 발생한다. SMES의 에너지 방전 시 마그넷에서의 전류 감소로 인한 와전류 손실은 비록 짧은 시간동안 발생하지만 그 크기가 냉동기의 정격 열 부하 용량에 비해 상대적으로 크기 때문에, SMES 시스템 설계 시 이에 대한 영향을 고려해야 한다. 본 논문은 고온초전도 선재를 이용하여 개발 중인 600 kJ SMES의 방전 시, 마그넷을 냉각시키기 위한 권선 보빈형 열전도판의 분할과 슬릿의 위치에 따른 와전류 손실 변화를 3차원 유한요소법을 이용해 해석하고 그 결과를 제시하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.292-292
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• 2010

양성자기반공학기술개발단에서는 100MeV와 20MeV의 가속기를 개발하고 있으며 빔 이용을 위하여 각 에너지에 5개의 빔라인을 구축 할 계획이다. 빔라인에는 각 마그넷과 빔 계측, 진공 등의 부품이 포함되어 있다. 본 연구에서는 빔라인의 기초 구성품인 진공 부품의 설계를 위한 압력의 계산을 수행하였다. 각 빔라인 재질에 따른 gas load는 표면의 아웃게싱이 주요하게 고려되었으며 고진공용 Cu gasket의 진공 leak는 거의 없다고 가정하였다. 재질은 스테인레스스틸과 알루미늄의 두 가지 경우를 사용하였으며 주 배기 펌프는 이온펌프로 펌핑 스피드 125L/s의 diode 타입이다. 빔튜브의 사이즈는 CF6"의 규격 플랜지를 기본으로 빔 사이즈가 고려된 여러 플랜지의 조합으로 내부 부피를 구할 수 있었다. 빔라인 뿐만 아니라 타겟룸에 위치되어지는 튜브를 합한 경우와 펌프의 개수를 다르게 하였을 때에도 길이에 따른 압력의 프로파일을 계산하였다. 빔을 분배해 주는 AC 마그넷 이전에 이온펌프 한 개를 위치하였을 때 스테인레스스틸 빔 튜브의 경우에 최대값은 1.3E-6 torr, 최소값은 1.7E-6 torr 으로 계산 되었다. 이 결과는 가속기의 아래쪽 3개의 빔라인을 동시에 배기하고 빔 조사가 가능하도록 운영되는 조건이며 운영 마진 2배를 고려한다고 하여도 최소 진공도는 3.4E-6 torr 이다. 이온펌프는 일반적으로 9.0E-6 torr 이하에서 사용이 가능하므로 이온펌프 1개의 진공도로도 운영에 무리가 없으며 이온펌프의 수가 증가됨에 따라서 최대 도달 압력이 낮아짐을 알 수 있다.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 한국초전도저온공학회 2000년도 KIASC Conference 2000 / 2000년도 학술대회 논문집
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• pp.143-146
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• 2000

Generally, two methods can be used to correct the undesirable magnetic field of MRI. One is active shimming method and the other is passive shimming. Passive shimming method uses many magnetized shims to correct the field. And it involves hardwared for supporting shim trays and a software to calculate a field map and optimaze the locations of the shims[1]. The software is the most important part of the passive shimming system. We made a prototype of the software and tested it in a virtual situation.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제34권1호
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• pp.27-33
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• 2010

This paper focuses on the design of microspeakers with minimum flux leakage, for use in radiotelegraphy. The response surface methodology (RSM) is applied as the optimization technique for obtaining a large magnetic force and a small flux leakage on diaphragm. The object functions of this optimization are the magnetic force and the flux leakage along three factors; pole piece thickness, magnet grade and yoke thickness, which are determined by the design of the experiment. The magnetic force and the flux leakage are calculated for each condition and optimized by results evaluated with RSM. For a pole piece thickness of 0.9 mm, a magnet grade of N42H and a yoke thickness of 0.75 mm, the magnetic force is satisfied as initial model and flux leakage is decreased to 11.8% than initial model.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제35권6호
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• pp.599-607
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• 2011

In this paper, a reaction-force compensation system for an XY linear motion stage, without an additional external isolation structure or extra motors, is developed. This system consists of a movable magnet track, a spring, a dummy weight, and a dedicated sensor module that measures the relative positions of the movable magnet track with respect to the motor coil. The reaction force compensation system is modeled, and simulations are carried out to optimize design parameters such as the moving distance of the magnet track, the transmission force, the dummy weight, and the allowed size of the mechanism. An XY linear motion stage is built, incorporating the reaction force compensation system, and the performance of the system is verified experimentally. For acceleration and deceleration values of 10 m/$s^2$, 85% of the reaction force is absorbed by the reaction force compensation system.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제56권9호
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• pp.1577-1583
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• 2007

The development of a magnet for very high magnetic field is usually envisioned with the use of an HTS insert coil. Pancake windings have been commonly used for the insert coil. All pancake windings have been connected in series and excited by a single power source. In that case, it is inevitable to operate some of the pancake windings well below their critical current densities. To increase the central magnetic field of the magnet, this paper proposed a new excitation method of the pancake windings by exciting the pancakes windings independently using multiple power sources. Results of the calculation show proposed method increases the central magnetic field of the magnet which consisted of 8 pancake windings by 17% comparing with excitation by using a single power source.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제57권3호
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• pp.384-389
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• 2008

The cental magnetic field of an HTS magnet consisting of pancake windings can be increased if the magnet is excited by multiple power sources. Multiple power sources enable all pancake windings to conduct their critical currents. The HTS magnet consisting of pancake windings was excited by separate power sources in this paper. Critical currents of each pancake winding were determined by using optimization technique. Fabrication of the BSCCO magnet consisting of 10 pancake windings is described and test results of the BSCCO magnet are given. Central magnetic field and perpendicular magnetic field of the magnet excited by multiple power sources were compared with those of the magnet excited by a single power source.

• Progress in Superconductivity and Cryogenics
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• 제6권1호
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• pp.18-21
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• 2004

This paper presents the optimization for shape design of a field coil used High Temperature Superconducting Motor (HTSM). In materials of HTSM, critical current Ic is more sensitive to magnetic fields directed along the axis or the unit cell ($B_{\bot}$). Thus, in the shape design of the HTS magnet. the maximum $B_{\bot}$ should be reduced to limit Ic. In order to reduce the maximum $B_{\bot}$, the shape optimization of the magnet, which is used for the field coil of HTSM, is necessary. It can be accomplished by using Response Surface Methodology (RSM). Finally, the result of RSM is verified by comparison with these experimental results.

• Proceedings of the KIEE Conference
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.888-889
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• 2011

As new one of superconducting power supplies, we proposed an HTS flux pump utilized a solar energy system. As an eternal electric energy can be converted by the solar system, the solar energy system is promisingly applied as an energy source in the power applications. A solar energy system is comprised of solar panel, photo-voltaic (PV) controller, converter and battery. The HTS flux pump consists of an electromagnet, two thermal heaters and a Bi-2223 magnet. In this paper, we describe the possibility the fusion technology between superconducting power supply and solar energy system. As a fundamental step, the fabrication, structure and experimental results are explained.

• Progress in Superconductivity and Cryogenics
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• 제13권1호
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• pp.36-40
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• 2011

This paper deals with the design on iron-core shape for superconducting hybrid electromagnet (SH-EM). A proto-type SH-EM was developed by Yonsei University. It is the first step study on the fundamental technology for advanced railroad system development. We proposed the method that reduce the number of cooling systems in order to improve operating efficiency of the SH-EM. The results was obtained by changing of iron-core shape were verified by the FEM analysis. This paper can be expected to suggest useful data for an advanced SH-EM.