• Progress in Medical Physics
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• v.25 no.4
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• pp.248-254
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• 2014

The purpose of this study is to develope a control system for a small X-ray tube generator and investigate control methods for the X-ray generator. The small X-ray tube was developed for electronic brachytherapy, and thus, the new control method should be investigated, if the small X-ray tube is used for the imaging system. The Axxent S700 X-ray tube and the XF060NZZ485 high voltage generator were used to compose a X-ray imaging system and control board was developed by using AT90CAN128 MCU. The two control methods were investigated after tube voltage was set to 50 kV, one was filament current control method and the other was beam current control method. The former was subdivided into two methods according to the filament heating time, the 5 and the 10 seconds respectively. In the filament current method, the beam current did not rise up to the desired value, if the filament current had not been maintained for at least 10 seconds. The onset filament currents to generate beam current were varied from 1,300 to 1,350 mA and over 5 seconds were needed in order to reach the desired tube current value after beam current was generated. However, in the tube current control method, the beam current reached to the desired value without any time delay with the filament current of 1,500 mA. In this study, we found that the beam current control method was appropriate for the use of small X-ray tube developed for brachytherapy in the X-ray imaging system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.73-76
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• 1999

We have fabricated and tested a Bi-based high temperature superconducting current lead system. Ag sheathed Bi-2223 mono-filament tapes of $I_c=8.4$ A at 77 K under self-field condition were fabricated using powder-in-tube(P1T) method. Multi-layer current leads can be made by stacking of Ag sheathed Bi-2223 mono-filament wires. The critical current of this 10-layer current lead is about 68 A. The contact resistance across the copper-current lead interface has been studied using current-voltage characteristics. At temperature below critical temperature the resistive contribution of the interface to the total contact resistance dominates. We have measured AC transport losses in a current lead at 77 K, 60 Hz by a transport method.

• Electrical & Electronic Materials
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• v.9 no.6
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• pp.600-604
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• 1996

High-T$_{c}$, superconducting wire is very important element for the application of electrical power systems. But it is very difficult to develope the long high T, wire with excellent properties. BiSrCaCuO multi-layer tapes are fabricated by a rolling method and pressing method sintered for several step at 840.deg. C. The critical current densities of 637 filament multi-layer tapes sintering 100 hours fabricated by the rolling method and pressing method are 1.3*10$^{4}$ A/cm$^{2}$ and 5.5*10$^{3}$ A/cm$^{2}$. The critical cur-rent densites of multi-layer tapes made by rolling method are found to be better than those fabricated by the powder-in-tube method and pressing process. As result, the rolling method is the best way to fabricated the multi-layer filament.t.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3485-3492
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• 2023

One of the major topic of tokamak research is the determination of the magnetic profile due to magnetic coil fields and plasma current by mean of data from magnetic probes. The most practical approach is to use the current filament method, which models the plasma column with multiple current carrying filaments and the total current of these filaments is equal to the plasma current. Determining the plasma boundary in Alvand-U tokamak is the main purpose of this paper. In order to determine the magnetic field profile and plasma boundary, information concerning the magnetic coils, their position, and current is required in the computing code. Then, the plasma shape is determined and finally the plasma boundary is extracted by the code. In the conducted research, we discuss how to determine the plasma boundary and the performance of the computing code for extraction of the plasma boundary. The developed algorithm shows to be effective by running it in the regular pc machine with characteristics of Intel (R) core (TM) i3-10100 CPU @3.60 GHz and 8.00 GB of RAM. Finally, we present results of a test run for computing code using a typical experimental pulse.

• Korean Journal of Materials Research
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• v.34 no.3
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• pp.152-162
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• 2024

In this study, we introduce a novel TiN/Ag embedded TiO₂/FTO resistive random-access memory (RRAM) device. This distinctive device was fabricated using an environmentally sustainable, solution-based thin film manufacturing process. Utilizing the peroxo titanium complex (PTC) method, we successfully incorporated Ag precursors into the device architecture, markedly enhancing its performance. This innovative approach effectively mitigates the random filament formation typically observed in RRAM devices, and leverages the seed effect to guide filament growth. As a result, the device demonstrates switching behavior at substantially reduced voltage and current levels, heralding a new era of low-power RRAM operation. The changes occurring within the insulator depending on Ag contents were confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Additionally, we confirmed the correlation between Ag and oxygen vacancies (V_o). The current-voltage (I-V) curves obtained suggest that as the Ag content increases there is a change in the operating mechanism, from the space charge limited conduction (SCLC) model to ionic conduction mechanism. We propose a new filament model based on changes in filament configuration and the change in conduction mechanisms. Further, we propose a novel filament model that encapsulates this shift in conduction behavior. This model illustrates how introducing Ag alters the filament configuration within the device, leading to a more efficient and controlled resistive switching process.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.47-49
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• 2007

For the magnetron, two kinds of auxiliary power is required to generate proper heat and electromagnetic field. In this paper the development of filament power supply and magnet power supply for high power industrial magnetron is studied. The filament power supply which is generate proper heat, even it doesn't require high power like main power supplies, has many consideration such as high voltage insulation and power control coordinated with high voltage cathod current to maintain constant heat generation. The novel control method using constant resistance control is proposed for accurate control of filament power supply.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2703-2709
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• 1996

This paper proposes an exact numerical method for analyzing a dipole antenna attached on a dielectric slab. A Green's function for an infinitesimal current filament on a dielectric slab is derived and a field integral equation is formulated using a boundary condition. The moment Method is used to solve the field integral equation to otain current distribution on the antenna. Since an asymptotic function is used to compute the impedance matrix elements, the computataion time is significantly reduced. Using the computed current distributions, the input impedances, the resonance lengths and the resonant resistances of the antennas for various values of the thichnessandthe dielectric constant of the slab are obtained. It was found that the resonant length and the resonant resistance are decrease monotonically as the dielectric constant increases, however, those are changed up-and-down as the substrate thickness increases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.43-46
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• 1993

Superconducting cable (Ic: 60 A at 77K. 10 filaments) with Bi high-Tc superconducting system was developed by powder - in - tube method. Pressing and sintering process of the cables were repeated for growth of 2223 high-Tc superconducting phase. The cable can be fabricate by twist method that is nessary for high current density and cooled circulative system. This cab1e system can be used for commercial.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.488-491
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• 2000

Bi-2223/Ag superconducting wires have been mainly prepared by a powder-in-tube method. The drawing and the rolling are main processes to increase the core density and wire length. In the fabrication of long wire, especially, the drawing should be precisely controlled to assure the filament homogeneity. In this paper, the influences of drawing die angle, bearing length and reduction ratio on the sausaging and the critical current density of the wire are investigated. Single cored and multi-filamentary wires are fabricated by PIT method with different conditions. The core densities and sausaging in the wires are investigated and are discussed regarding their relationship to the I$_{c}$. It was made clear that the geometry of drawing die is sensitively dependent on the sausaging. The improvement of I$_{c}$ was achieved by reducing the die angle and high core density.ity.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1243-1244
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• 2006

Five kinds of double stacked 385 (55 x7) filamentary Bi2212/Ag round wires and 55 filamentary tapes with different Ag ratios (silver area/superconductor area) have been fabricated via PIT method, and the effects of Ag ratio and processing factors on critical current density were studied. The effects of the maximum temperature and average filament diameter on critical current density were also studied. The wire of 0.74 mm diameter having Ag ratio 3.7 showed critical current density of $2,218\;A/mm^2$ at 4.2 K, 0 T.