• Progress in Superconductivity and Cryogenics
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• v.12 no.2
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• pp.25-28
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• 2010

A cooldown time is one of the major factors in many cryocooler applications, especially for the design of conduction-cooled superconducting apparatus. The estimation of cooldown seeks the elapsed time to cool thermal object by a cryocooler during initial cooldown process. This procedure includes the dimension of cold mass, heat transfer analysis for cryogenic load and available refrigerating capacity of a cryocooler. This method is applied to the specific cooling system for a 3 Tesla superconducting magnet cooled by a two-stage GM cryocooler. The result is compared with that of experiment, showing that the results of proposed method have a good agreement with experiments during initial cooling of superconducting magnet.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.210-212
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• 1996

A nonlinear optimization method for the shape optimization of actively shielded superconducting MRI magnet is presented. The presented design method can optimize both main coil and shielding coil simultaneously by setting constraints on stray field intensity at a specified distance from the magnet center. A 1 Tesla actively shielded superconducting MRI magnet, with 30cm bore diameter, is designed using the presented method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.421-430
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• 2000

This paper describes an optimal design method which is applied a weighted least square (WLS) method for Magnetic Resonance Imaging (MRI) system. An optimal design approach is presented for a homogeneity superconducting magnet with the superconducting active shield especially for a magnetic resonance imaging system. The WLS is used to obtain the optimal configurations using the least amount and minimum volume of conductor, exhibiting the smallest level of field inhomogeneity and resulting in the least level of stray field. The proposed model is used to design a multiple-shield configuration for a 1.5 T MRI magnet. The field homogeneity is required less than 5 gauss stray field contour within 4m axially and 3m radially from origin. The designed magnet with the actively magnetic shielding coil out of main coils is analyzed by FEM and theoretical analysis method, investigated the field homogeneity.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.150-153
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• 2000

NMR researches are required high field and high homogeneous super-conducting magnet. Thus superconducting magnets for NMR applications are designed with minimization of coil winding volume satisfied constraints such as field strength, field homogeneity, etc. In this paper, we are discussed optimal design of high field super-conducting magnet for NMR applications. For a design example, we designed unshielded superconducting magnet for 600MHz NMR spectrometer with 100mm room temperature bore size and obtained 14.1011[T] field strength and 1.33 ppm field homogeneity.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.305-307
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• 1998

One of the merits of superconducting magnet system is that it has persistent current mode, in which the current can be constant without any external power supply. The problem is that when we energize the magnet we can not reach the target current with constant current source, in principle. It needs another energization methods, in which it can be energized with reasonable accuracy and time. This paper suggests two energization methods for a superconducting magnet with persistnet current mode and the comparisons of the two are made with respect to the accuracy and the time.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.9
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• pp.484-489
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• 1999

This paper deals with the design and fabrication of a heater-trigger type high-Tc superconducting power supply system, and characteristics have been analyzed through experiments. The high-Tc superconducting power supply consists of two heater trigger and electric magnet, and YBCO superconducting bulk. In this experiment, 0.6T class magnet and dc 2.3A heater current are used, and the current-pumping characteristics have been analyzed with computer aided sequence control system. Hall sensors are installed on the YBCO bulk and in the center of iron core in order to analyze the effect of the flux-pumping on the system with when magnet flux changes its value. In this experiment, maximum pumping-current has been achieved to about 6.6 amps.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.29.1-29.1
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• 2005

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.6-6
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• 2006

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.110-110
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• 2009

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.113-113
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• 2009