• Journal of the Korean Magnetics Society
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• v.18 no.4
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• pp.136-141
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• 2008

In this study, the magnetic(static and high-frequency) and microwave absorbing properties have been investigated in Ru-Co substituted M-hexaferrites($BaFe_{12-2x}Ru_xCo_xO_{19}$). The powders and sintered specimens were prepared by conventional ceramic processing technique. With the calcined powders, the composite specimens were prepared using the silicone rubber as a matrix material. The substitution ratio of Ru-Co to obtain in-plane magnetic anisotropy, thus having the minimum coercivity, is much smaller (about x=0.3) than the previously reported Ti-Co substituted specimen. Owing to this low substitution, the specimen has a large value of saturation magnetization($M_s$=65 emu/g). Ferromagnetic resonance behavior and microwave absorbing frequency band is strongly influnced by the coercvity which can be controlled by Ru-Co substitution ratio. It is found that the M-hexaferrites with planar magnetic anisotropy by doping Ru-Co in both sintered and composite form have superior microwave absorbing properties in GHz frequency range.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.8
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• pp.919-928
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• 2017

The immuno-enhancing effects of alginate oligosaccharides from Sargassum coreanum were investigated. The alginate oligosaccharides were produced by an alginate-degrading enzyme from S. oneidensis PKA 1008. The degraded alginate oligosaccharides were visualized by thin-layer chromatography developed using a solvent system of 1-butanol/methanol/water, 4:1:2 (v/v/v). Alginate was degraded into dimmers at 60 h. As a result, the levels of Th1 cytokine [interferon $(IFN)-{\gamma}$ and interleukin (IL)-2] and Th2 cytokine (IL-6 and IL-10) increased with increasing incubation time compared to the control in vitro. Enzymatic extract treatment promoted proliferation of splenocytes at concentrations of 100 and 200 mg/kg at 24 h in vivo. Secretion of $IFN-{\gamma}$ and IL-2 significantly increased in a dose-dependent manner at 24 h as well as induced higher production of IgG2a in serum. Natural killer cell activity was measured and tended to increase. In addition, complete blood cell counts increased in a dose-dependent manner. These results indicate that alginate oligosaccharides produced by crude enzyme from S. oneidensis PKA 1008 may have significant immune activities.

• Investigative Magnetic Resonance Imaging
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• v.11 no.2
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• pp.103-109
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• 2007

To develop an advanced non-linear curve fitting (NLCF) algorithm for performing dynamic susceptibility contrast study of the brain. The first pass effects give rise to spuriously high estimates of $K^{trans}$ for the voxels that represent the large vascular components. An explicit threshold value was used to reject voxels. The blood perfusion and volume estimation were accurately evaluated in the $T2^*$-weighted dynamic contrast enhanced (DCE)-MR images. From each of the recalculated parameters, a perfusion weighted image was outlined by using the modified non-linear curve fitting algorithm. The present study demonstrated an improvement of an estimation of the kinetic parameters from the DCE $T2^*$-weighted magnetic resonance imaging data with using contrast agents.

• Journal of the Korean Magnetics Society
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• v.26 no.4
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• pp.115-118
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• 2016

We investigated the magnetocrystalline anisotropy of pure ${\alpha}^{{\prime}{\prime}}-Fe_{16}N_2$ by using full-potential linearized augmented plane wave method (FLAPW). A very high magnetic moment was obtained for Fe (4d) site due to the lattice expansion in the z-direction, while the magnetic moment of Fe (4e) and (8h) site were suppressed due to hybridization with neighboring N atom. The calculated spin magnetic moments for different Fe sites (4d, 4e and 8h) were in good agreement with previously reported values. Due to the tetragonal distortion, we found a very large uniaxial anisotropy constant of $0.58MJ/m^3$. Besides, a high value of magnetization of 1.76MA/m was obtained. In additon, the estimated coercive field and maximum energy product of 6.51 kOe and 71.7 MGOe were obtained for pure ${\alpha}^{{\prime}{\prime}}-Fe_{16}N_2$. This may suggest that the ${\alpha}^{{\prime}{\prime}}-Fe_{16}N_2$ can be utilized for potential rare-earth free permanent magnet material.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.18-23
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• 2010

Ferromagnetic resonance (FMR) measurement is an important experimental technique for the study of magnetic dynamics. We designed and set up the vector network analyzer ferromagnetic resonance (VNA-FMR) measurement system with home made coplanar waveguides (CPW). We examined 10-, 20-, 40-nm thick Py thin films to test the performance of the VNA-FMR measurement system. We measured S-parameter (transmission/reflection coefficient) of Py thin films on a CPW. Resonance frequency is investigated from 2.5 to 7 GHz for a field range from 0 to 490 Oe. The VNA-FMR data shows the resonance frequency increment when the external magnetic field increases. We also investigated Gilbert damping constant of Py thin film using resonance frequency (${\omega}_r$) and linewidth ($\Delta\omega$). After investigating dependence of thickness, we find that an decrease in S-parameter intensity as Py thin film thickness decreases. And the FMR results show that the effective saturation magnetization, $M_{eff}$, increase from 7.205($\pm$0.013) kOe to 7.840($\pm$0.014) kOe, while the film thickness varies from 10 to 40 nm.

• Journal of the Korean Magnetics Society
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• v.24 no.2
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• pp.60-65
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• 2014

We obtained resonance field ($H_{res}$) and linewidth (${\Delta}H_{PP}$) from measured ferromagnetic resonance signal in the functions of polar angle (${\Theta}_H$) in Ni thin film of 240 nm thickness fabricated by electrodeposition method. The angular dependence of $H_{res}$ was well fitted with the calculated ones. We confirmed that the g-factor and effective demagnetization field were 2.18 and 445 emu/cc by the theoretical analysis of the resonance field, respectively. The angular dependence of ${\Delta}H_{PP}$ showed very large values at in-plane direction (${\Theta}_H=90^{\circ}$), which could not explained by the homogenous linewidth due to the Gilbert damping and inhomogeneous linewidth due to the angular variations and magnetization variations by the surface layer. Therefore, we considered the spin wave scattering (two magnon scattering) process in order to analyze the measured inhomogeneous linewidth, which was appeared in thicker film than the critical thickness of 50 nm. The defect medicated spin wave scattering played a key role in the electrodoposited Ni thin film of 240 nm thickness.

• Journal of Korean Society of Forest Science
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• v.90 no.6
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• pp.717-724
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• 2001

This study was conducted in an attempt to quantify some traits that may be involved in the reproductive process of Pinus thunbergii. During the past 6 years (1995-2000), we surveyed flowering patterns of 60 P. thunbergii clones in a seed orchard which was established in Anmyon-do, 1979. From this survey, we estimated clonal contributions of male and female flowers and sexual asymmetry. Among 60 clones, 18 clones (30%) accounted for 0.37 (1999)~0.46 (1995) of clonal contribution in female flowers and 0.44 (1999)~0.57 (1995) of clonal contribution in male flowers. As compared with the previous reports in other pine species, more clones made contributions to reproductive process in P. thunbergii seed orchard. The relative effective population numbers for females (v♀) varied from 0.59 (1995) to 0.91 (1999) and those for males ( v♂) were between 0.56 (1995) and 0.83 (1998) at gamete level. This showed that the female gametes effectively contribute to the reproductive process more than did the male gametes. The relative effective population numbers at clonal level ($v_b$) were in the range of 0.72 (1995) and 0.93 (1999). More than 73% of the total clones showed values of 0.4~0.6 ($0.5{\pm}0.1$) in maleness index. The values averaged over all the clones were temporally variable with the range of 73% in 1996 and 100% in 2000. The degree of sexual asymmetry ($A_s$) ranged from 0.09 to 0.26. These values were relatively low when compared with those of other trees, suggesting that P. thunbergii seed orchard remains a high level of homogeneity in the number of male and female. All of the various types of effective population numbers were positively correlated with each other while they were negatively correlated with the degree of sexual asymmetry.

• Applied Biological Chemistry
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• v.50 no.2
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• pp.111-115
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• 2007

To modify the physical properties of alginate film, the gamma ray irradiation was performed, and alginate film properties such as elongation strength (ES), elongation rate (ER), water vapor permeability(WVP), and water solubility (WS) were measured. The film made from 1.75% alginate solution (w/w) with the addition of 2% CaCl$_2$ solution suggested a good application for a film preparation in that elongation strength(ES) increased 5 fold by CaCl$_2$ treatment and water vapor permeability was decreased by 17${\sim}$22%. A solid form of alginates were irradiated with Co$^{60}$ gamma rays in the dose range of 2 to 10 kGy to make a low molecular weight alginate film, and then the intrinsic viscosity and the molecular weight of alginates were measured. Increasing the dose range of 2 to 10 kGy produced lower intrinsic viscosity and lower molecular weight, causing the decrease in the ES and WS. However, ER increased four times compared to that of without gamma ray dose, which is an indication of the different properties of algiante film. WVP of the films did not show any significant change at different doses.

• Journal of Sericultural and Entomological Science
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• v.52 no.2
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• pp.159-164
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• 2014

In this study, functionality of products of silkworm hemolymph fermented by Bacillus species was studied such as cell viability, antioxidant effect, and inhibitory effect on tyrosinase activities. A matured silkworm hemolymph was degraded by fermentation with Bacillus subtilis 10854 and Bacillus amyloliquefaciens M27. Especially, proteins of matured silkworm hemolymph were degraded to 3,000 Da by fermentation with B. amyloliquefaciens M27. Cell viability for MTT assay was higher than PBS in hemolymph and fermented hemolymph. A DPPH free radical scavenging activity of fermented hemolymph was as higher as Vitamin C and dependent on sample concentrations. Thus, these results suggest that degraded hemolymph fermented by B. amyloliquefaciens M27 may have antioxidant properties as a material for cosmetics.

• Korean Journal of Food Science and Technology
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• v.40 no.5
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• pp.545-550
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• 2008

The anticancer and immunomodulatory activities of low molecular weight (Mw 11 kDa) fucoidan isolated from Hizikia fusiforme (H. fusiforme) via the ultrasonification extraction process were assessed in this study. Low molecular weight fucoidan improved the growth of human B and T cells, up to approximately 40% as compared to the controls (untreated) and 30% for commercially available fucoidan (Mw 150 kDa). IL-6 and TNF-$\alpha$ were secreted from human B cells at levels of $7.8\times10^{-4}$ pg/mL and $7.2\times10^{-4}$ pg/mL, respectively, and these levels were higher than the levels measured in the controls and with other high molecular weight fucoidan. It was also determined that the cytokine from human B and T cells cultivated with added fucoidan enhanced the growth of human NK cells. The fucoidan isolated from H. fusiforme showed low cytotoxicity, approximately 19%, after the addition of 1.0 mg/mL, the highest tested concentration. The growth of human lung cancer cells (A549) and human breast cancer cells (MCF-7) were inhibited by 69.8% and 83.3%, respectively. These results demonstrated that the low molecular weight fucoidan isolated from H. fusiforme has potential as a new functional food component that evidences immunomodulatory activities and anticancer activity. One of the primary positive features of this fucoidan is that low molecular weight polysaccharides can be readily handled during processing.