• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.84-84
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• 2003

Purpose： To assess clinical proton MR spectroscopy (MRS) as a noninvasive method for evaluating tumor malignancy at 3T high field system. Materials and methods： Using 3T MRI/MRS system, localized water-suppressed single-voxel technique in patients with brain tumors was employed to evaluate spectra with peaks of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine/phosphocreatine (Cr) and lactate. On the basis of Cr, these peak areas were quantificated as a relative ratio.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.761-767
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• 2007

In centralized control system, complicated control systems including sensors, power supply and dampers should be required to satisfy the target response of large-scale structures. The practical applications of the centralized control system, however, is very difficult due to high order finite element model of structures, uncertainty of models, and limitations of the excitation system. In this study, the decentralized response-dependent MR damper of which magnetic field is automatically modulated according to the displacement or velocity transferred to the damper without any sensing and computing systems. this decentralized response-dependent MR damper are investigated according to the ranges of relative magnitude between the control force of MR damper and the story shear force of structures by nonlinear time history analysis. Finally, its performance is compared with centralized LQR algorithm which is used in general centralized control theory for a three story building structure.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.12a
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• pp.48-48
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• 2020

Fire blight, caused by Erwinia amylovora(Burrill), is a destructive disease of apple that damages blossoms, shoots, and woody plant organs. The fire blight disease is a worldwide problem for pome fruit growers because all popular apple cultivars are susceptible to the disease. Recently, fire blight of apple rootstocks has become a serious economic problem in high-density orchard systems in korea. The most commonly used dwarfing root stocks, M.9 and M.26, are highly susceptible to E. amylovora. The objective of the apple rootstock-breeding program has been to develop pomologically excellent rootstocks with resistance to abiotic and biotic stresses, including fire blight. Budagovsky 9 (B.9) apple rootstock is reported to be highly susceptible when inoculated with E. amylovora, although results from multiple trials showed that B.9 is resistant to rootstock blight infection in field plantings. So we tried to collect the apple rootstocks traits of fire blight resistance. The apple genotype Malus Robusta 5 (MR5) represents an ideal donor for fire blight resistance because it was described as resistant to all currently known European strains of the pathogen. The PCR for detecting the MR5 gene using the primers Md_MR5_FL_F/Md_MR5_FL_R. The results of these experiments confirmed some apple rootstocks traits of fire blight resistance showed the MR5. Furthermore, this gene is confirmed to be the resistance determinant of Mr5 as the transformed lines undergo the same gene-for-gene interaction in the host-pathogen relationship MR5-E. amylovora.

• Progress in Superconductivity and Cryogenics
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• v.23 no.4
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• pp.30-34
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• 2021

Superconducting magnets have paved the way for opening new horizons in designing an electromagnet of a high field magnetic resonance imaging (MRI) device. In the first phase of the superconducting MRI magnet era, low-temperature superconductor (LTS) has played a key role in constructing the main magnet of an MRI device. The highest magnetic resonance (MR) field of 11.7 T was indeed reached using LTS, which is generated by the well-known Iseult project. However, as the limit of current carrying capacity and mechanical robustness under a high field environment is revealed, it is widely believed that commercial LTS wires would be challenging to manufacture a high field (>10 T) MRI magnet. As a result, high-temperature superconductor together with the conducting cooling approach has been spotlighted as a promising alternative to the conventional LTS. In 2020, the Korean government launched a national project to develop an HTS magnet for a high field MRI magnet as an extent of this interest. We have performed a design study of a 7 T 320 mm winding bore HTS MRI magnet, which may be the ultimate goal of this project. Thus, in this paper, design study results are provided. Electromagnetic design and analysis were performed considering the requirements of central magnetic field and spatial field uniformity.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.235-237
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• 1998

Gradient coil offers the spatial informations of sample or patient in Nuclear Magnetic Resonance Imaging(NMRI) and its gradient field linearity over the field of view(FOV) has many influence on the MR imaging. Accurate and good quality MR imaging can be acquired by the high gradient field linearity over the FOV. So it is an important part to design of gradient coil with good linearity in the wide imaging range. Usually, Z-directional gradient field is generated by using the Helmholtz type coil which is consisted of one-pair loop with anti-current path. It gets less about 40% linearity of the diameter spherical volume(DSV). In this study, we calculated optimized geometrical parameters of two-pair loop system to cancel odd terms up to $B_7$ included effectively. we also analyzed and compared the gradient field distribution and linearity of the common Helmholtz coil with them of the two-pair loop system.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.66-67
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• 2003

Bismuth (Bi) has been an attractive materials for studying spin dependent transport properties because it shows very large magnetoresistance (MR) resulting from its highly anisotropic Fermi surface, low carrier concentrations, long carrier mean free path 1 and small effective carrier mass m*[1-3]. With all the intriguing properties, difficulty in fabrication of high quality Bi thin films may have prevented extensive application of Bi in magnetic field sensing and spin-injection devices. Previous works found that the surface roughness and small grain size in 100-200 nm of Bi thin film made by evaporation and sputtering are major causes of low MR. Although relatively higher MR in electrodeposited Bi followed by annealing was reported, it still suffers from rough sulfate roughness which is so severs that it is hardly able to make a field sensing and spin-injection device using conventional photolithography process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.2
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• pp.120-125
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• 2006

By employing a rapid solidification method and atmospheric annealing at $450^{\circ}C-1hr$, we were able to manufacture inexpensively granular CuCo alloy ribbons with thickness of $20{\mu}m$ showing giant magnetoresistance (GMR) ratio of more than 5% at a high magnetic field of 0.5T. To verify maximum MR effect, the MR ratio, saturation magnetization, and microstructure change were investigated with Co contents between 5 and 30 at%. It was possible to obtain GMR ratios of 5.2% at 1.2T, and 3% at 0.5T, which implies an appropriate MR for industrial purpose at a Co content of $8{\sim}l4%$. MR ratio was reduced rapidly at a Co content below 5% due to superparamagnetic effect and at a Co content above 20% due to agglomeration of Co clusters. Surface oxidation during rapid solidification and atmospheric annealing did not have much affect on MR ratio. Our result implies that our economic CuCo granular alloy ribbons may be appropriate for high magnetic field sensor applications with wide content range of $8{\sim}14$ at%Co.

• Journal of Biomedical Engineering Research
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• v.13 no.3
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• pp.217-224
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• 1992

A new three-channel surface gradient coil obtained by using numerical optimization and its application to MR computerized nomography are presented. The new surface gradient coil pro aided linear field gradient region more than twice wider compared with the t'irst surface gradi encl coil, removed torque and field offset, and reduced coupling between the surface gradient coil and combined surface rf coil. We realized the new surface gradient coil set with $30{\times}60{cm^2}$2 size, which generated more tharl 4G/cm with 100 amperes over a $4{\times}4{\times}4{cm^3}$ region with good linearity. The optimal geometries of the three-channel surface gradient coil and volun teer's high-resolution in wiuo spinal cord Images obtained by using the optimized surface gradi ent coil set are presented.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.456-460
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• 1995

Giant magnetoresistance(GMR) of $Cu_{85-x}Co_{15}Ni_{x}$ melt-spu ribbons is closely correlated with the microstructure produced by the spinodal decomposition. The solid solution range is extanded by the replacement of Cu by Ni in the as-quenched state. The wavelengths obtained by subsequent isothermal aging in Cu-Co-Ni ribbons are shorter than those in Cu-Co binary ribbons, resulting in the increase of the surface-to-volume ratio. The largest MR ratio of 8 % in high field has been achieved in the $Cu_{80}Co_{15}Ni_{5}$ aged ribbon. The field dependence of MR ratio in low fields becomes larger with the Ni content.

• Investigative Magnetic Resonance Imaging
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• v.20 no.3
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• pp.141-151
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• 2016

Purpose: Advances of magnetic resonance imaging (MRI), especially that of the Ultra-High Field (UHF) MRI will be reviewed. Materials and Methods: Diffusion MRI data was obtained from a healthy adult young male of age 30 using a 7.0T research MRI scanner (Magnetom, Siemens) with 40 mT/m maximum gradient field. The specific imaging parameters used for the data acquisition were a single shot DW echo planar imaging. Results: Three areas of the imaging experiments are focused on for the study, namely the anatomy, angiography, and tractography. Conclusion: It is envisioned that, in near future, there will be more 7.0T MRIs for brain research and explosive clinical application research will also be developed, for example in the area of connectomics in neuroscience and clinical neurology and neurosurgery.