• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1748-1750
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• 2004

This paper deals with the detection method of the Quench phenomenon for superconducting magnet using the Acoustic Emission (AE) sensor. AE sensor is the elements, which is used to change the Acoustic signal to the voltage value. This signal may be used to detect whether the superconducting magnet has been at the Quench state or not. Recently, the development of the Quench detection technique, which is the using voltage and current signals, fiber-optic sensor, and so on, for the superconducting applications is widely studying. This method for the Quench detection of the superconducting magnet is also studying at some kinds of institute in Japan and the united state. Because of the large-scale superconducting magnet like International Thermonuclear Experimental Reactor(ITER) is charged a lot of energy, when the Quench phenomenon is being at the superconducting magnet it is happen to the problem of the protection for the applications. In this paper, we concluded that the Quench detection was possible when the mechanical stress by means of the local heat is generated at the part of inside superconducting magnets.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2171-2174
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• 2008

The design of thermal radiation shield cooled by a cryocooler is presented. This study is motivated mainly by our recent development of prototype superconducting magnet system for the Cyclotron K120. The superconducting magnet system is composed of the magnet cryostat, transfer line and supply cryostat. In order to minimize thermal radiation load, the superconducting coil form in the magnet cryostat is enclosed by the thermal radiation shield which is thermally connected to the first-stage cold head of a two-stage cryocooler in the supply cryostat. Since the supply cryostat is located far from the magnet cryostat large temperature gradient along the thermal shield is unavoidable. In this paper, the thermal radiation shield is optimized to minimize temperature gradient with taking into account the cryogenic load, system structure and electrical load. The effect of heat source from thermal conduction through mechanical supports on the temperature distribution of thermal radiation shield is also discussed.

• Progress in Medical Physics
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• v.5 no.1
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• pp.55-66
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• 1994

After proving home-made imaging pulse sequences including tailored RF pulse by phantom, susceptibility-contrast-enhanced MR venograms of cat brain were obtained using tailored RF gradient-echo(TRGE) method. Sagittal MR imaging of the cat brain obtained by TRGE technique shows several veins, for example, dorsal sagittal sinus, straight sinus, vein of corpus callosum and internal cerebral vein, etc., compared with cats anatomical figure. Tailored RF waveform was generated by PASCAL language in ASPECT 3000 computer(Switzland, Bruker). Rectangular-shaped slice profile with bi-linear ramp function as phase distribution in the slice, at which maximum value was 2$\pi$, was fourier transformed to make tailored RF pulse. Experimental MR imaging parameters were TR/TE=205/10 msec, slice thickness TH=7mm, maxtrix size=256$\times$256, in-plane resolution=0.62$\times$0.31mm$^2$, and field of view(FOV)=8cm for both conventional gradient-echo(GE) imaging and TRGE imaging techniques.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.3
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• pp.91-98
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• 2021

The installation and performance test of the ISOL (Isotope Separation On Line) system for the generation and separation of Rare Isotopes (RI) beams is in progress at the Rare Isotope Science Project (RISP), Institute for Basic Science (IBS). The various RI beams generated by the ISOL target/ion source go through the beam lines and separators, and only the RI beam desired by the user is selected and transmitted to the superconducting linear accelerator at the downstream of the ISOL. In the ISOL system, two separators are installed to separate a specific RI beam, and control is performed by the Experimental Physics and Industrial Control System (EPICS). In this study, an EPICS IOC (Input-Output Control) was developed to measure the magnetic field of a dipole magnet for mass separation of a multivalent (n+) RI beam in the A/Q separator, which is one of the ISOL RI beam separators. The operational stability of the A/Q separator was tested through a magnetic field measurement using a Hall probe.

• Progress in Superconductivity
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• v.7 no.2
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• pp.167-173
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• 2006

Coated conductors suitable for the fabrication of persistent mode high $T_c$ magnets are suggested and the fabrication method of persistent mode magnets using coated conductor are demonstrated. Persistent current was observed in a small piece of coated conductor. Closed loop of coated conductor with a diameter of around 1 em was successfully prepared and was cooled with a magnetic field of about 500 Gauss in order to induce supercurrent. Coated conductor with a $I_c$ of 100 A/cm-width was used for the preparation of closed loop of coated conductor. Persistent current was confirmed by measuring the magnetic field generated from closed loop of coated conductor by using Gauss meter. Magnetic field of 4.4 Gauss was detected from the supercurrent of closed loop of coated conductor. It shows that superconducting joint of coated conductor is not a prerequisite for the construction of persistent mode magnets. It is thought that this work opens the possibility to use coated conductor for the construction of persistent mode high $T_c$ magnets for MRI, NMR and magnetic separation applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.05a
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• pp.4-4
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• 2009

Paper factories use a large amount of water and same amount of wastewater is generated. It is important to recycle the wastewater because of water shortages and water pollution. The existing water treatment facilities like precipitation process need large-scale equipment and wide space to purify the wastewater of paper factory. High gradient magnetic separation (HGMS) system has the merits to purify rapidly because of large voids at filter and to occupy small space. In this paper, two types of superconducting magnets were used for HGMS systems. Cryo-cooled Bi-2223 superconducting magnet system with 70 mm room temperature bore and 200 mm of height was prepared. Cryo-cooled Nb-Ti superconducting magnet with 100 mm room temperature bore and 600 mm of height was used for magnetic separator. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets. The various magnetic seeding reactions were investigated to increase the reactivity of coagulation. The effects of magnetic separation of wastewater were investigated as variation of magnetic field strength and flow rate of wastewater.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.552-560
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• 1997

Analysis is performed to determine the optimal lengths or cross-sectional areas of refrigerator-cooled current leads that can be applied to the conduction-cooled superconducting systems. The binary current lead is composed of the series combination of a normal metal at the upper(warm) part and a high $T_c$ superconductor(HTS) at the lower(cold) part. The heat conduction toward the cold end of HTS part constitutes a major refrigeration load. In addition, the joint between the parts should be cooled by a refrigerator in order to reduce the load at the low end and maintain the HTS part in a superconducting state. The sum of the work inputs required for the two refrigeration loads needs to be minimized for an optimal operation. In this design, three simple models that depict the refrigeration performance as functions of cooling temperature are developed based on some of the existing refrigerators. By solving one-dimensional conduction equation that take into account the temperature-dependent properties of the materials, the refrigeration works are numerically calculated for various values of the joint temperature and the sizes of two parts. The results show that for given size of HTS, there exist the optimal values for the joint temperature and the size of the normal metal. It is also found that the refrigeration work decreases as the length of HTS increases and that the optimal size of normal metal is quite independent of the size of HTS. For a given length of HTS, there is an optimal cross-sectional area and it increases as the length increases. The dependence of the optimal sizes on the refrigerator models employed are presented for 1kA leads.