• Journal of the Korean Magnetics Society
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• v.26 no.2
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• pp.45-49
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• 2016

Ground state energy levels of $Gd^{3+}$ ion (effective spin S = 7/2) in $PbWO_4$ single crystal doped with $Gd^{3+}$ paramagnetic impurity at tetragonal symmetry are calculated with spectroscopic splitting parameters and zero field splitting parameters using by effective spin Hamiltonian. It turns out that the zero field splitting energies of $Gd^{3+}$ ion were the same regardless of the directions of $PbWO_4$ : Gd single crystal. The calculated energy differences for ${\mid{\pm}7/2}$ > ${\leftrightarrow}{\mid{\pm}5/2}$ >, ${\mid{\pm}5/2}$ > ${\leftrightarrow}{\mid{\pm}3/2}$ >, and ${\mid{\pm}3/2}$ > ${\leftrightarrow}{\mid{\pm}1/2}$ > transitions were 6.9574 GHz, 6.9219 GHz, and 15.8704 GHz, respectively when the applied magnetic field is zero. The calculated energy level diagrams were different for different directions of applied magnetic field. For B // a- and c-axis, the energy level diagrams are calculated and discussed.

• Journal of the Korean Magnetics Society
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• v.19 no.3
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• pp.106-112
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• 2009

$Ni_{1-x}Mg_xFe_2O_4$ ferrite system was studied by using X-ray diffraction and $M{\ddot{o}}ssbauer$ spectroscopy. The samples were prepared by ceramic sintering method with Mg content x. The X-ray diffraction patterns of samples show phase of cubic spinel structure. There are no remarkable changes of lattice constants in $Ni_{1-x}Mg_xFe_2O_4$ ferrite system. The $M{\ddot{o}}ssbauer$ spectra were consisted of two sets of six lines, respectively, corresponding to $Fe^{3+}$ at tetrahedral and octahedral sites. The magnetic hyperfine field of samples was decreased as increasing Mg contents x in both sites and it was shown Yafet-Kittel magnetic structure. $NiFe_2O_4$ was shown complete inverse spinel, but $NiFe_2O_4$ was shown partial inverse spinel which absorption area ratio (oct/tet) was 1.449 in $M{\ddot{o}}ssbauer$ spectrum.

• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.117-126
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• 2009

Purpose : A numerical method of designing a multiple quantum filter (MQF) is presented for the optimum detection of myo-inositol (mI), an important brain metabolite, by using in vivo proton nuclear magnetic resonance spectroscopy ($^1$-HMRS). Materials and Methods : Starting from the characterization of the metabolite, the filter design includes the optimization of the sequence parameters such as the two echo times (TEs), the mixing time (TM), and the flip angle and offset frequency of the 3rd $90^{\circ}$ pulse which converts multiple quantum coherences (MQCs) back into single quantum coherences (SQCs). The optimized filter was then tested both in phantom and in human brains. Results : The results demonstrate that the proposed MQF can improve the signal-to-background ratio of the target metabolite by a factor of more than three by effectively suppressing the signal from the background metabolites. Conclusion : By incorporating a numerical method into the design of MQFs in $^1$-HMRS the spectral integrity of a target metabolite, in particular, with a complicated spin system can be substantially enhanced.

• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.10-13
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• 2007

Single crystalline, $LuFe_2O_4$, was grown by the floating zone method. The crystal structure was a two-dimensional layered-type rhombohedral($R\={3}mh$) structure, with an $a_0=3.440(2)\;{\AA}\;and\;a\;c_0=25.263(2)\;{\AA}$. The magnetic $N\'{e}el$ temperature($T_N$) was determined to be 250 K. The $M\"{o}ssbauer$ spectrum at 12 K was fitted with four sextet sets which was resulted from the crystal structure. The spectrm at room temperature consisted of three singlets and a doublet with the electric quadrupole splitting. The isomer shift($\delta$) value of the singlet was $0.20{\pm}0.01mm/s$ relative to the Fe metal indicating the $Fe^{3+}$ valence state, and the value of the doublet was $0.70{\pm}0.01mm/s$ indicating $Fe^{2+}$. The $M\"{o}ssbauer$ absorption area ratio between $Fe^{3+}$ and $Fe^{2+}$ at room temperature was 1:1. The doublet phase of spectra gradually disappears by up to 360 K. At 360 K, the spectrum shows the singlet phase. We suggested that the spontaneous polarization effect of $LuFe_2O_4$ was caused by the change of iron behavior.

• Journal of radiological science and technology
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• v.31 no.4
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• pp.355-365
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• 2008

Purpose : This study isto determine the grade of brain tumor and compare the characteristics in each grade using in MRS (MR Spectroscopy). Method : STEAM (Stimulated Echo Acquisition Method) and protocol of PRESS (Point Resolved Spectroscopy) were used in the levels of tumor grade. We classified the pattern of tumor and analysis of the spectrum signals quantitatively from voxel in the brain tumor grade. In accordance with the result, we calculated the accuracy of biochemical. Result : In high-grade tumor, the NAA/Cr showed the signal reduction of 29.4% and 53.9%. However Cho/Cr increased 570% and 711%. However, in low-grade tumor, NAA/Cr downed to 42.6% and 58.1%. Cho/Cr increased to 188% and 195%. Conclusion : The study suggests that the comparative analysis of signals from MR spectroscopy could be useful to evaluate the grade of tumor and find out the characteristics of it. By extension, MR spectroscopy can be used for research with other organs in the human.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.589-595
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• 2017

This study evaluated the effect of gadolinium contrast agents on the spectrum of metabolites during $^1H-MRS$ of brain and to investigate whether the contrast agents injected before MR spectroscopy significantly affect the estimated peaks of MRS. From January to May 2017, brain MR spectroscopy was performed on 30 patients to compare the spectrum before and after contrast injection of the brain white matter tissue. As a result, the spectrum of metabolites decreased after the paramagnetic contrast agents injected. However, it was not statistically significant which indicated that the use of contrast agent did not meaningfully affect the spectrum of metabolites. In conclusion, the use of the paramagnetic contrast before the acquisition of the spectroscopy may aid voxel positioning especially when it is difficult to determine the exact location of the lesion or the contrast is low.

• Progress in Medical Physics
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• v.12 no.1
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• pp.31-39
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• 2001

NMR spectroscopy enables us to measure the molar concentration of the metabolites in the organisms, and this technique is the only method to measure the concentration non-invasively. The proton NMR spectroscopy has been used to study the biochemical changes in human as well as in animal brain. MRI uses the proton densities and its relaxation times for reconstructing images, but MRS gives the biochemical changes inside the body. NMR spectroscopy could provide the information which MRI and CT could not, and this makes NMR spectroscopy more useful in diagnosing diseases. This study was tried to develop the quantitation of the molar concentration of the metabolites in the brain using the proton MR spectroscopy. The spectra of each metabolites was obtained, and the proton MR spectra was obtained from the insula gray matter areas of the 16 volunteers. And this spectra was analyzed to estimated the molar concentrations of the metabolites in the region. The results showed the very similar to those of the others.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.517-527
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• 1997

Magnetic Resonance Spectroscopic Imaging is a methodology combining the imaging and spectroscopy. It can provide the spectrum of each areas of image so that one can easily compare the spectrum of one position to another position of the image. In this study, we developed pulse sequence or the spectroscopic imaging method, RF wave forms or the saturation of water signal, computer simulations to validate our method, and confirmed the methodology with phantom experiment. Then we applied the spectroscopic method to human subject and identified a few important metabolites in in vivo. To develope a water saturating RF waveform, we used Shinnar-Le-Roux algorithm and obtained maximum phase RF waveform. With this RF pulse, it could suppress the water signal to 1:1000. The magnet is shimmed to under 1.0ppm with auto-shimming technique. The saturation bandwidth is 80Hz(2ppm). The water and fat seperation is 3.3ppm(about 140Hz at 1 Tesla magnet), the bandwidth is enough to resolve the difference. But we are more concerned about the narrow window in between the two peaks, in which the small quantity of metabolites reside. We performed the computer simulation and phantom experiments in 8*8 matrix form and showed good agreement in the image and spectrum. Finally we applied spectroscopic imaging to the brain of human subject. Only the lipid signal was shown in the periphery region which agrees with the at distribution in human head surface area. The spectrum inside the brain shows the important metabolites such as NAA, Cr/PCr, Choline. We here have shown the spectroscopic imaging which is normally done above 1.5 Tesla machine can be performed in the 1 Tesla Magnetic Resonance Imaging Unit.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.518-525
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• 2000

The open-chain hexadentate N$_4$, O$_2$ ligands 1,13-bis(2-hydroxybenzyl)-2,5,9,12-tetraazatridecane-tetrahydrochloride (BSATD${\cdot}$4HCl) and 1,14-bis (2-hydroxybenzyl)-2,6,9,12-tetraazatetradecane-tetrahydrochloride (BSATED${\cdot}$ 4HCl) have been synthesized as their tetrahydrochloride salt and characterized by EA, IR, NMR and Mass. Their proton dissociation constants(log$K^{n}_{H}$) and stability constants(log$K_{ML}$) for Cu(II), Ni(II), Co(II), and Zn(II) ions were determined in aqueous solution by potentiometry and compared with those of analogous N$_4$, O$_2$ ligands contain ethylenic spacers or propylenic spacers, which make six-membered chelate rings between the aliphatic nitrogen atoms. Synthesis and characterization of [Cu(BSATD)]ClO$_4$ and [Cu(BSATED)](ClO$_4$)$_2$ complexes are described.

• Progress in Medical Physics
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• v.17 no.3
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• pp.153-158
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• 2006

The purpose of this study was to improve the technique so as to develop an advanced sensitive RF surface coil for investigating the sensitivities of the multi-spiral surface coils, and we eventually wanted to achieve high resolution of the microscopic MR images and MR spectra. The magnetic field inhomogeneity and shape of a surface coil were statistically estimated by simulation of the magnetic field distribution. On the basis of the experimental results with single, 3 and S-turned spiral RF surface coils, we found that the 3-turned coil had the highest sensitivity. The present study showed that the sensitivity of the RF surface coil was improved by increasing the number of spiral coil turns, and also the SNR of the RF surface coil was dependent upon the number of spiral coil turns. However, we found, rather strikingly, that the sensitivity of excessive turns of the coils was decreased due to the rise of the coil's Impedance. Thus, the present results demonstrated that the sensitivity was not proportional to the number of a spiral RF coil's turns, and the number of spiral coil turns should be optimized for obtaining the highest sensitivity and SNR.