• BMB Reports
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• v.41 no.6
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• pp.461-465
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• 2008

IL-18 production may enhance immune system defense against KG-1 cells ; NB4 cells, which are associated with good prognosis, do not produce IL-18. In this study, we treated KG-1 cells with IL-18 and used microarray technology to assess subsequent effects on gene expression. In UniGene-array of 7488 human genes, expression of 57 genes, including stress related genes, increased at least 2-fold, whereas expression of 48 genes decreased at least 2-fold. Following exogenous exposure of KG-1 cells to IL-18, expression of CRYGC, $NF{\kappa}BIA$ and NACA gene were monitored. The latter is a transcriptional coactivator potentiating c-Jun-mediated transcription.$NF{\kappa}BIA$ is an inhibitor of $NF{\kappa}B$, and affects growth regulation, apoptosis and hypoxic stress. Studies, such as this one, are beginning to clarify the differences between cells associated with good and bad cancer prognoses, which may ultimately assist in medical treatment for acute myeloid leukemia.

• Electrical & Electronic Materials
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• v.4 no.3
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• pp.211-219
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• 1991

본 논문은 고주파에서의 Ni-Zn페라이트의 첨가물에 따른 소결특성에 관하여 연구한 것이다. 연구에서 사용한 시편은 20mol% NiO, 30mol% ZnO 및 50mol% Fe$_{2}$ $O_{3}$이 조성으로된 페라이트를 모재로 하고 첨가물로서 각각 0.0025mol%, 0.005mol% 및 0.001mol%의 비율로 Nb$_{2}$ $O_{5}$, Bi$_{2}$ $O_{3}$ 및 V$_{2}$ $O_{5}$를 첨가하였다. 그리고 소결을 1100.deg.C에서 이루어졌다. 초투자율은 V$_{2}$ $O_{2}$가 첨가된 시편의 100KHz-1000KHz주파수대에서 4*$10^{2}$~8*$10^{2}$의 높은 값을 얻었다. 손실계수는 100KHz~500KHz주파수대에서 1*10~3*$10^{-2}$이었다. 1/(.mu.*Q)값은 0.005mo;% Bi$_{2}$ $O_{3}$가 첨가된 시편에서 가장 높은 값을 나타내었다. 자기저항은 초유자율과 반비례의 관계를 나타내었다. 실험의 결과 첨가물에 의한 소결특성은 액상형성에 의하여 고른 입자성장을 확인할 수 있었다. 따라서 0.01mol% V$_{2}$ $O_{5}$를 첨가한 시편이 가장 우수한 자기특성을 나타내고 있음을 확인하였다.

• Journal of Powder Materials
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• v.17 no.5
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• pp.404-408
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• 2010

The effects of high energy ball-milling (HEBM) on the sintering behavior and piezoelectric properties of 0.1 wt% $Li_2CO_3$ doped 0.8Pb($Mg_{1/3}Nb_{2/3}$)$O_3$-0.2Pb($Zr_{0.475}Ti_{0.525}$)$O_3$ (PMN-PZT) ceramics were investigated. It was found that HEBM treatment was quite effective to reduce the average particle size down to 300 nm, leading to increased density as well as enhanced piezoelectric properties of a sintered specimen even though prolonged HEBM resulted in unwanted secondary phases that caused a degradation of piezoelectric properties. The dielectric constant ($\varepsilon_r$), piezoelectric coupling factor ($k_p$) and piezoelectric constant $d_{33}$ of 0.1 wt% $Li_2CO_3$ doped PMN-PZT ceramics prepared via HEBM for 10 h reached 2040, 0.68 and 554 pC/N, respectively.

• Progress in Superconductivity
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• v.12 no.1
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• pp.12-16
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• 2010

We have measured the trapped field of YBCO bulk with different configuration by applying the magnetic field of $Nb_3Sn$ superconducting magnet. Initially the circular type of YBCO bulk superconductor was prepared and then hole, parallel to the c-axis and located at the center of bulk was mechanically drilled. The YBCO bulk with hole was filled with resin. Typical size of hole in YBCO bulk was 10 mm in diameter. Trapped field characteristics were compared with different specimen conditions. Our preliminary result indicates the increment rate of trapped field, 0.232 kG, measured on the YBCO without hole was much higher than that, 0.011 kG, measured on YBCO with hole.

• Journal of Powder Materials
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• v.14 no.5
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• pp.303-308
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• 2007

The oxidation of $Fe_{73}Si_{16}B_7Nb_3Cu_1$ nanocrystalline powder has been conducted to investigate its influence on the electromagnetic wave absorption characteristics of the soft magnetic material. Oxidation occurred primarily on the surface of nanocrystals. Oxidation reduced the real part of complex permeability due to the reduction of the relative volume of the powder, which otherwise contributes to the permeability. Oxidation reduced the absorption efficiency of the sheet at frequencies over 1GHz, indicating that the relative contribution of skin depth increments to the absorption was not significant. The pulverization and milling process lowered the optimum crystallization temperature of the material by $40{\sim}50^{\circ}C$ because of the internal energy accumulated during the fragmentation and powder thinning processes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.286-293
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• 2000

In this paper we investigated the structural dielectric and piezoelectric properties of 0.03Pb(Sb$\_$1/2//Nb$\_$1/2/)-0.97Pb(Zr$\_$0.495//Ti$\_$0.505/)O$_3$+0.5 wt% excess PbO + wt% MnO(X=0, 0.1, 0.3, 0.5, 0.7) ceramics to develop the high-power piezoelectric transformer. The piezoelectric transformers with dimension of 27.5$\times$27.5$\times$2.5［mm$^3$］were fabricated and their electrical properties were measured. Maxima of piezoelectric properties such as electro-mechanical coupling factor of 0.534 and mechanical quality factor of 1487 were obtained for the PSN-PZT with 0.3wt% MnO. voltage step-up ratios of piezoelectric transformers at 500［Ω］and no load were 0.78, 12.82, respectively. The maximum efficiency of piezoelectric transformer was 98.6% at 800［Ω］. While the 14W fluorescent lamp were driven by the piezoelectric transformer for more than 20［min］, increment of temperature in the piezoelectric transformer was 7［$\^{C}$］.

• Korean Journal of Materials Research
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• v.28 no.5
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• pp.308-314
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• 2018

Among the fuel cell electrolyte candidates in the intermediate temperature range, glass materials show stable physical properties and are also expected to have higher ion conductivity than crystalline materials. In particular, phosphate glass has a high mobility of protons since such a structure maintains a hydrogen bond network that leads to high proton conductivity. Recently, defects like volatilization of phosphorus and destruction of the bonding structure have remarkably improved with introduction of cations, such as Zr4+ and Nb5+, into phosphate. In particular, niobium has proton conductivity on the surface because of higher surface acidity. It can also retain phosphorus content during heat treatment and improve chemical stability by bonding with phosphorus. In this study, we fabricate niobium phosphate glass thin films through sol-gel processing, and we report the chemical stability and electrical properties. The existence of the hydroxyl group in the phosphate is confirmed and found to be preserved at the intermediate temperature region of $150-450^{\circ}C$.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.304-306
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• 2003

The KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting magnet system which consists of 16 TF coils and 14 PF coils. The magnet system adopt a superconducting CICC (Cable-In-Conduit Conductor) type. The KSTAR TF CICC uses Nb$_3$Sn superconducting cable with Incoloy 908 conduit. To prepare for TF CICC jacket defect, repair welding of TF CICC is studied. And to confirm join method of TF CICC joint part, the welding method and the joint part design are also discussed.

• Journal of Magnetics
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• v.21 no.2
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• pp.235-238
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• 2016

Microstructure and magnetization behaviors of $MnBi/Fe_3B/Nd2_Fe_{14}B$ nanocomposite alloy have been investigated. It was found that the coercivity increased firstly and then decreased, and saturation magnetization decreased with the additon of MnBi alloy. The addition of 40 wt.% MnBi powder enhanced the coercivity from 192.8 kA/m to 311.2 kA/m. The ${\delta}M$ and D(H)-H plots suggested the occurrence of a stronger exchange-coupling occurring between the hard and soft magnetic phase for this sample. The dependence of coercivity with temperature was discussed in 40 wt.% $Mn_{55}Bi_{45}$/ 60 wt.% $Nd_{4.5}Fe_{76.5}Nb_{0.5}B_{18.5}$ alloy powder, and a positive temperature coefficient was founded from 298 K to 350 K.

• The Korean Journal of Zoology
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• v.39 no.2
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• pp.190-197
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• 1996

The optimal conditions and substrate specificity of whole body esterase (EST) activity, effects of inhibitors (Eserine, Paraoxon, p-HMB, DDVP, DFP) on the enzyme, and ontogenv of the isozymes were determined in Lucilio ilfustris Meisen. The optimal temperature was $45^{\circ}C$ regardless of kind of reacted substrate, $\alpha-naphthyl$ acetate $(\alpha-Nal,$ a.naphthvl butylate $(\alpha-N),$ and Pnaphthyl acetate $(\beta-Na),$ but the optimal pH showed some regioselectivitv to naphthvl group of the esters; PH 7.0 for Iform, pH 7.5 for a-form. The maximum reaction rate was recorded at about 2.5 $\times$ 10's M of PNa and etNa, but 1.0 $\times$ 10'S M of $\alpha-Nb.$ Among the five EST inhibitors tested, DDVP was the most powerful. However, distinction of the relative specificity of inhibitors between three body parts, head, thorax, and abdomen, was shouts, representing differences in the distribution and activity of isozvmes. Of 12 carboxyl-esterases (CE), 8 cholinesterases (ChE) and 2 arvlesterases (ArE) identified based on their inhibitor specificity throughout the development, two larval and prepupal stage specific ChEs, no pupal specific, and 2 CEs.2ChEs. and one ArE adult specific isozvmes were confirmed.