• Computers and Concrete
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• v.30 no.5
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• pp.323-337
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• 2022

This paper proposes a numerical model to simulate the rotational behavior of steel fiber in fresh cement-based materials in the presence of a magnetic field. The results indicate that as the aspect ratio of fiber increases, the required minimum magnetic field intensity to make fiber rotate in viscous fluid increases. The optimal magnetic field intensity is 0.03 T for aligning steel fiber in fresh cement-based materials to ensure that the applying time of the magnetic field can be conducted concurrently with the vibrating process to increase the aligning efficiency. The orientation factor of steel fiber in cement mortar can exceed 0.85 after aligning by 0.03 T of the uniform magnetic field. When the initial angle of the fiber to the magnetic field direction is less than 10°, the magnetic field less than 0.03 T cannot make the fiber overcome the yield stress of fluid to rotate. The coarse aggregate in steel fiber-reinforced concrete is detrimental to the rotation and alignment of the steel fiber. But the orientation factor of ASFRC under the 0.03T of the magnetic field can also exceed 0.8, while the orientation factor of SFRC without magnetic field application is around 0.6.

• Journal of the Korean Chemical Society
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• v.21 no.5
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• pp.320-329
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• 1977

p-Phenylenediamine dihydroperchlorate, $C_6H_4N_2H_4{\cdot}2HC1O_4$, crystallizes in space group $P\={1}$ with $a=4.79{\pm}0.02,\;b=9.03{\pm}0.02,\;c=7.12{\pm}0.03{\AA},\;{\alpha}=109.4{\pm}0.2,\;{\beta}=79.6{\pm}0.2,\;r=104.6{\pm}0.2^{\circ},\;Z=1$. The structure has been solved by the Patterson and Fourier methods. The refinement by block-diagonal least-squares cycles gives R = 0.13 for 387 observed reflexions collected on equi-inclination Weissenberg photographs with CuK${\alpha}$ radiation. There are two different types of five hydrogen bonds. The first type consists of one trifurcated N${\cdot}{\cdot}{\cdot}$O hydrogen bond and the second of two normal N${\cdot}{\cdot}{\cdot}$O hydrogen bonds, both of which exist between the amino group and the perchlorate, groups. A p-phenylenediamine group is approximately planar within an experimental error and bonded to twelve perchlorates: ten perchlorates forming hydrogen bonds and two being contacted with the van der Waals forces. A perchlorate group is surrounded by six p-phenylenediamines and four perchlorates; among the six p-phenylenediamines, five of them are hydrogen-bonded, and the rest contacted with the van der Waals force.ce anaysis of our samples and investigated the variarions in the values of parameters obtained through fitting the theoretical impedance to the experimental impedance. The characters of the dielectric constant and the impedance showed abnormal variations for the 0.2 at K-doped NSBN ceramics, which we were able to interpret in terms of the variations in the number A-site vacancies with the K doping ratio. From these results, A-site vacancies are thought to be space charges that influence the ferroelectric properties of NSBN ceramics.

• Journal of the Korean Chemical Society
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• v.9 no.3
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• pp.128-133
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• 1965

Hydrazonium diphosphate crystallizes with the space-group symmetry $P2_1/C.$ There are two formular units of $N_2H_6H_4(PO_4)_2$ in the unit cell, for which $a = 4.52{\pm}0.02, b = 8.06{\pm}0.03, c = 10.74{\pm}0.03{\AA}\;and\; {\beta} = 100{\pm}0.5^{\circ}.$ The determination of the crystal structure was carried out by means of Patterson, Fourier and difference syntheses. The phosphate group has configuration of nearly regular tetrahedron with the mean P-O distance of $1.55{\AA}.$ The N-N distance found is $1.40{\AA},$ which corresponds to previously reported values for the $N_2H_6^{++} \;ion \;in\; N_2H_6SO_4.$ A molecule has a transform with a center of symmetry in it. Each nitrogen atom forms three hydrogen bonds with the N…O distances 2.62, 2.79 and $2.89{\AA}.$ And a O…O hydrogen bond between different phosphate groups is found with the distance $2.63{\AA}.$ The structure is held together by three-dimensional network of the strong hydrogen bonds.

• Journal of the Korean Chemical Society
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• v.28 no.1
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• pp.47-53
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• 1984

The separation of the rare earth elements with diethylene triamine N, N, N', N', N"-pentaacetic acid (DTPA) as eluent was carried out at different pH and concentrations by using anion exchange resin column. The rare earth elements were absorbed on the upper of the resin column and the best condition of the separation behavior was 0.025M of DTPA at pH 8.35. The elution order of the rare earths was in the order of the atomic number of the rare earth elements except samarium. The resolution of adjacent rare earth elements that have been separated with 0.025M-DTPA as eluent, was from 3.03 to 1.25 at pH 8.35. Resolution of Ce-Pr was maximum value in 3.03 and Eu-Gd was minimum in 1.25 at condition mentioned above, respectively. The resolution of rare earth elements separated with 0.025M DTPA eluent was very good at pH range of 8.0~8.6.

• The Korean Journal of Mycology
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• v.47 no.4
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• pp.347-357
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• 2019

This study evaluated the raw materials for spawning Perenniporia fraxinea, to eliminate urushiol. The growth rates of spawns on grains of millet, brown rice, and wheat were 4.92±0.05, 2.20±0.03, and 1.93±0.03 mm/day, respectively, and the laccase activity was 0.86±0.02, 0.04±0.01, and 0.01±0.00 U/mL, respectively. These observations revealed millet as the most appropriate grain for spawn production in terms of growth rate and enzyme activity. Inoculation of lacquer tree (Rhus verniciflua Stokes) stem bark with millet spawns of P. fraxinea resulted in a reduction of its urushiol contents, up to 86.6% on the third day and up to 98.5% on the seventh day. The optimal period of cultivation to eliminate urushiol was three days with 68% of residual flavonoids and 42% of phenolic components. When compared to the product cultivated from liquid spawn, the millet spawn reduced the cultivation period from 10 days to 3 days for eliminating urushiol.

• Transactions on Electrical and Electronic Materials
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• v.12 no.2
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• pp.72-75
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• 2011

In this study, $(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3+0.9$ mol% $K_{5.4}Cu_{1.3}Ta_{10}O_{29}+x$ mol% $K_4CuNb_8O_{23}$ (x = 0, 0.2, 0.6, 0.8) ceramics were prepared by a conventional mixed oxide method. Their microstructure and electric properties were investigated. The secondary phase was made by virtue of $K_4CuNb_8O_{23}$ (KCN) addition in the $(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3$ system ceramics. However, the sinterability of the ceramics increased with increasing $K_4CuNb_8O_{23}$ content. At the 0.6 mol% $K_4CuNb_8O_{23}$ added composition ceramics sintered at $1,060^{\circ}C$, kp and $d_{33}$ showed the optimum values of 0.39 and 145 pC/N, respectively, suitable for piezoelectric actuator application.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.75-75
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• 2003

Since the establishment of embryonic stem cell, pluripotency of the cells was known to allow differentiation of the cells into various cell types consisting whole body. Several protocols have been developed to induce expression of specific genes.. However, no precise protocol that will generate a single type of the cells from stem cells has been reported. In order to produce cells suitable for transplantion into brain of PD animal model, which arouse due to a progressive degeneration of dopaminergic neurons in midbrain, human embryonic stem cell (hESC, MB03) was transfected with cDNAs cording for tyrosine hydroxylase (TH). Successful transfection was confirmed by western immunoblotting. Newly transfected cell line (TH#2/MB03) was induced to differentiate by the two neurogenic factors retinoic acid (RA) and b-FGF. Exp. I) Upon differentiation using RA/ascorbic acid (AA), embryoid bodies (EB, for 4days) derived from hES cells were exposed to RA (10$^{-6}$ M)/AA (50 mM) for 4 days, and were allowed to differentiate in N2 medium for 7, 14, 21, or 28 days. Exp. II) When bFGF was used, neuronal precursor cells were selected for 8 days in N2 medium after EB formation. After selection, cells were expanded at the presence of bFGF (20 ng/ml) for another 6 days followed by a final differentiation in N2 medium for 7, 14, 21 or 28 days. By indirect immunocytochemical studies, proportion of cells expressing NF200 increased rapidly from 20% at 7 days to 70 % at 28 days in RA/AA-treated group, while those cells expressing NF160 decreased from 80% at 7 days to 10% at 28 days upon differentiation in N2 medium. However, in differentiation by RA/AA treatment system, there was a significant increase in proportion of neuron maturity (73%) at day 14 after N2 medium. TH#2/MB03 cells expressing TH are >90% when matured at the absence of either bDNF or TGF-$\alpha$. These results suggested that TH#2/MB03 cells could be differentiated in vitro into mature neurons by RA/AA.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.603-607
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• 2010

Turquoise blue pigment of Vanadium-zircon blue (DCMA number 14-42-2), which was already commercialized, was stable to be reproduced but insufficient to give strong blue. However, it possible to obtain more intense blue by partially substituting cobalt ions into the willemite($Zn_2SiO_4$) lattice classified into DCMA number 7-10-2 for blue ceramic pigment. By the composition of willemite $Co_xZn_{2-x}SiO_4$(X=0.01, 0.03, 0.05, 0.07, 0.09 mole), this study used reagent grade zinc oxide, cobalt oxide and silicon dioxide as starting materials, carrying out the synthesis with solid reaction method by adding $H_3BO_3$ as a mineralizer. The firing temperature was between $1200^{\circ}C$ and $1400^{\circ}C$. The characteristics of synthesized pigment were analyzed by X-ray diffraction, Raman spectroscopy and SEM and the characteristics of color tones were analyzed by UV-Vis spectroscopy and CIE-$L^*a^*b^*$ measurement. As a result, the optimal composition was $Zn_{1.95}Co_{0.05}$ with 1wt% of $H_3BO_3$ as a mineralizer and firing condition was $1350^{\circ}C$/3 h. $L^*a^*b^*$ value was 29.25, 41.03, -59.93 for on glaze pigment and 37.03, 36.41, -60.03 for under glaze pigment.

• The Journal of Korean Physical Therapy
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• v.22 no.3
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• pp.61-69
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• 2010

Purpose: This study was designed to investigate correlations between physical fitness, antioxidant enzymes (SOD, CAT, GPX), lipid peroxidation levels (MDA), lipid profiles, lactate levels and cardiovascular variables in an exercising group and a control group. Methods: Twelve healthy young males (Exercise group: 6, Controls: 6). All subjects took physical fitness tests and blood samples were collected while subjects were resting. Results: In the exercise group, there were several significant correlations: between back strength and SOD enzyme levels (r=0.82, p=0.04), back strength and MDA (r=0.94, p=0.00), agility and GPX (r=0.81, p=0.04), and balance and GPX (r=0.81, p=0.04). In the control group, there were significant correlations between: dominant grip strength and MDA (r=-0.84, p=0.03), and agility and GPX (r= -0.82, p=0.04). In the exercise group, there were no significant correlations between physical fitness factors, TC, TG, HDL-C and lactate levels. In the control group, there were significant correlations between: back strength and TG (r=0.88, p=0.01), and agility and HDL-C (r= -0.84, p=0.03). In the exercise group, there were significant correlations between: non-dominant grip strength and SBP (r=0.94, p=0.00), dominant grip strength and SBP (r=0.85, p=0.03), and power and SBP (r=0.82, p=0.04). In controls, there were significant correlations between: dominant grip strength and DBP (r=-0.85, p=0.03), muscular endurance and ST level (r=-0.93, p=0.00), and muscular endurance and HR (r=-0.88, p=0.01). Conclusion: That cardiovascular patients and controls who participated in regular exercise maintained their antioxidant capacity suggests that long-term physical activity can counteract the negative dysfunction that characterizes sedentary lifestyle, probably by maintaining plasma antioxidant defenses and thereby preventing oxidative stress.

• Journal of the Korean Chemical Society
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• v.22 no.5
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• pp.311-316
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• 1978

The reaction between iron(III) and Xylenol Orange (XO or $H_6A$) has been investigated spectrophotometrically. It has been established that iron (III) and XO form two complexes with compositions iron(III) : XO = 2 : 1 and 1 : 1. The 2 : 1 complex is stable in acidic medium containing excess of iron, and 1 : 1 complex is stable in slightly acidic medium containing excess of XO. The absorption maxima are at 590 nm (2 : 1) and 500 nm (1 : 1), the molar absorptivities being $3.18{\pm}0.04{\times}10^4,\;1.32{\pm}0.03{\times}10^4$respectively. The stability constants of two complexes studied by varying pH are $loglog{\beta}_{21}=18.69{\pm}0.03,\;log{\beta}_{212}=42.08{\pm}0.09,\;log{\beta}_{11}=4.17{\pm}0.04,\;and\;log{\beta}_{113}=34.47{\pm}0.07.$