리니어 프로그래밍을 이용한 NMR 마그넷의 수동 자장보정 방법

다국어 초록 (Multilingual Abstract)

Shimming is an important technique in development of nuclear magnetic resonance (NMR) magnets where image resolution is highly dependent on magnetic field homogeneity. Classically, shimming may be categorized into two types: 1) active shimming that incorporates with extra coils and precise tuning of their currents; and 2)　passive shimming that incorporates with pieces of steel placed in a bore of a main magnet and their uniform magnetization under homogeneous external fields. Additional magnetic fields, produced by the coils and/or the steel sheets, compensate original magnetic field from the main magnet in such a way that the total field becomes more homogeneous. In this paper, we developed a passive shimming method based on linear programming optimization. Linear programming is well known to be highly efficient to find a global minimum in various linear problems. We firstly confirmed the linearity of magnetization of ferromagnetic pieces under a presence of external magnetic fields. Then, we adopted the linear programming to find optimized allocation of the steel pieces in the inner bore of a main magnet to improve field homogeneity.

목차 (Table of Contents)

• Abstract
• 1. 서론
• 2. 본론
• 3. 검증 및 자장보정 예
• 4. 결론
• 참고문헌
• 저자소개

참고문헌 (Reference)

1 "Resonance Research Inc"

2 A. Belov, "Passive Shimming of Superconducting Magnet for MRI" 5 (5): 679-681, 1995

3 W. H. Press, "Numerical Recipes(Book style)" Cambridge University Press 183-183, 1986

4 Hongbeom Jin, "A study on the design and fabrication of actively shielded superconducting MRI magnet(Book style)"