• Korean Journal of Materials Research
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• v.14 no.3
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• pp.181-185
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• 2004

The mechanical properties of a bulk amorphous alloy ($Zr_{41.2}$ $Ti_{13.8}$ /$Cu_{10}$ $Ni_{10}$ $Be_{22.5}$ /at.%) before and after an annealing treatment were investigated. For the bulk amorphous alloy, the compressive strength was about 2.0 GPa, irrespective of the strain rates in the range of $10^{-4}$ to $10^3$$ sec^{-1}$ . Fine-sized nanocrystalline particles (10～100 nm) were precipitated homogeneously in the bulk amorphous matrix after the annealing treatments. Compared to the bulk amorphous materials, these composite materials, composed of the nanocrystalline phases and a bulk amorphous matrix had much different mechanical properties. The strength and strain of coposite materials measured by a compressive test showed a peak-maximum values at 7 vol.% of the nanocrystalline phases. The values in higher volume fraction of the crystalline phases in the amorphous matrix were decreased, as measured by both quasi-static and high strain rate. The decrease in fracture strength is due to presence of the dispersed large-crystalline phases in the amorphous matrix.

• Electrical & Electronic Materials
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• v.8 no.5
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• pp.594-600
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• 1995

Dielectric properties at microwave frequencies of ($Zr_{0.65}$, $Sn_{0.35}$) $Ti_{1.04}$ $O_{4.04}$ ceramics with additives, NiO as an agent to improve dielectric properties and $B_{2}$ $O_{3}$ as a firing agent were investigated. When 0.5 - 1.5 wt% of NiO is add, the grain growth is inhibited and the shape of the grain is uniformed, Dielectric constant(Fr) and bulk density are increased with raising amount of NiO at sintering temperature of 1330 - 1360.deg. C, but the temperature coefficient of resonant frquency(.epsilon.$_{r}$) decreased gradually as the NiO content increased. The value of Qx $f_{o}$ was increased as the amount of NiO was increased in the range of 0.5 to 1.0 wt% and the Qx $f_{o}$, was decreased slightly with raising sintering temperature. With NiO of 1.0 wt% and at sintering temperature of 1360.deg. C, this ceramics was found to have excellent microwave properties of .epsilon.$_{r}$=37.8, Qx $f_{o}$ = 48.600 and .tau.$_{f}$ = 7 ppm/.deg. C.C.. C.. C.C.. C.. C.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.330-338
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• 2016

The U-Zr or U-TRU-Zr cylindrical metallic fuel slug used in fast reactors is known to swell significantly and to grow during irradiation. In neutronics simulations of metallic-fueled fast reactors, it is assumed that the slug has swollen and contacted cladding, and the bonding sodium has been removed from the fuel region. In this research, a realistic burnup-dependent fuel-swelling simulation was performed using Monte Carlo code McCARD for a single-batch compact sodium-cooled breed-and-burn reactor by considering the fuel-swelling behavior reported from the irradiation test results in EBR-II. The impacts of the realistic burnup-dependent fuel swelling are identified in terms of the reactor neutronics performance, such as core lifetime, conversion ratio, axial power distribution, and local burnup distributions. It was found that axial fuel growth significantly deteriorated the neutron economy of a breed-and-burn reactor and consequently impaired its neutronics performance. The bonding sodium also impaired neutron economy, because it stayed longer in the blanket region until the fuel slug reached 2% burnup.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1001-1002
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• 2004

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.455-459
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• 2001

In this paper, the dielectric and pizoelectric properties of 0.05Pb(M $n_{04}$ $W_{0.2}$N $b_{0.4}$) $O_3$-0.95(PbZ $r_{x}$ $Ti_{1-x}$ ) $O_3$+yN $b_2$ $O_{5}$ , are investigated as a function of the mole ratio of Zr and the amount of N $b_2$ $O_{5}$ . Also, the phase is analyzed by XRD. When the mole ratio of Zr is 0.51, the electromechanical coupling coefficient( $k_{p}$ ), relative dielectric constant ($\varepsilon$$^{T}$ $_{33}$ /$\varepsilon$$_{0}$ ), piezoelectric stain constrain ( $d_{33}$ and dielectric loss tangent show maximum, while the mechanical quality factor shows minimum value ; $k_{p}$ =56.5%, $d_{33}$ =258pC/N, $\varepsilon$$^{T}$ $_{33}$ /$\varepsilon$$_{0}$ =1170, $Q_{m}$ =1150, tan$\delta$=0.51%. At that composition, MPB which rhombohedral and tetragonal phase coexist in this ternary system is shown by the results of XRD analysis. Also, when the amount of N $b_2$ $O_{5}$ is 0.3wt%, the mechanical quality factor is increased to about 2000. The phase transition temperature of the ternary piezoelectric ceramic system showed about 35$0^{\circ}C$.TEX>.>.>.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.434-439
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• 1997

It this paper, the piezoelectric and electro-induced strain properties of (P $b_{1-}$2x/3/B $i_{x}$ )[N $i_{1}$3/N $b_{2}$3/)$_{0.4}$( $Ti_{0.6}$Z $r_{0.4}$)$_{0.6}$] $O_3$ceramics (x=0, 0.005, 0.02) were investigated with the substitution of B $i^{3+}$, and the feasibility of the application for bimorph actuator was evaluated by measuring the dynamic properties of the piezoelectric bimorph fabricated with above ceramics. Dielectric constant was enhanced with the increase of B $i^{3+}$ substitution, and appeared the maximum value of 5032 at x=0.01 composition. Increasing the substitution of B $i^{3+}$, the electromechanical coefficient( $k_{p}$ , $k_{31}$ ) was increased up to the substitution of 0.5 mol% B $i^{3+}$, showed the value of 0.656, 0.439, respectively. The piezoelectric constant( $d_{33}$ $d_{31}$ ) had the highest value of 344, 825 with the substitution of 0.5 mol% B $i^{3+}$. The strain, generated by 60 Hz AC electric field, had the largest value of 1200($\times$10$^{-6}$ $\Delta$1/1) in the composition with the substitution of 0.5 mol% B $i^{3+}$. The dynamic properties of the bimorph actuator, fabricated with the composition substitution of 0.5 mol% B $i^{3+}$, showed the largest value of 325 $\mu$m at $\pm$150 V square pulse. square pulse.are pulse..

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.201-202
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• 2017

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.473-479
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• 2000

The nanocrystalline Fe$_{84}$Zr$_{7}$B$_{6}$Cu$_{1}$ $Al_{2}$ alloy was annealed at 450 $^{\circ}C$ and 550 $^{\circ}C$ for l hour to achieve the ultra-soft magnetic properties such as large magnetoimpedence ratio(MIR), the incremental permeability ratio(PR), nearly zero coercivity, zero magnetostriction, etc. The PR and MIR of the sample were measured from 100 kHz to 10 MHz at a cryogenic chamber where the temperature can be varie from 10 K to 300 K. The increment of MIR value is proportional to increasing temperature. The maximum PR values measured at high frequency above 1 MHz remain almost same despite of the temperature variation from 10 K to 300 K except the sharpness in PR curves. However, the maximum PR values measured below 1 MHz show drastic increment at above 150K due to thermal activation of magnetic domains.s.s.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.841-845
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• 1995

The effect of small addition of Nb on the electrical resistivity and Hall coeffcient of the amorphous $Fe_{83}Zr_{7}B_{10}$ alloy and annealed ones ones below the crystallization temperature were investigated, which has been considered to be suitable for high frequency core material. At room temperature, their resistivities $\rho$ and the spontaneous Hall coeffcients $R_{s}$ are $~1.6\;{\mu}{\Omega}m$ and $~3{\times}10^{-8}m^{3}/As$, respectively. $R_{s}$ and $\rho$ are decreased with increasing temperature from 100 K to room temperature. Side-jump effect was adopted to analyze the effect of the small variation of conentration and annealing. The quantity of $R_{s}/{\rho}^{2}$ at room temperature, which is directly related to the electronic structure of the mother alloy, remained almost a constant except as quenched one as it can be predicted from the side-jump effect. The unexpected temperature dependence of $R_{s}/{\rho}^{2}$ measured at low fields much below Tc is left as a question.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.772-777
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• 1995

The effect of small addition of Nb on the electrical resistivity and Hall coefficient of the amorphous $Fe_{83}Zr_{7}B_{10}$ alloy and annealed ones below the crystallization temperature were investigated, which has been considered to be suitable for high frequency core material. At room temperature, their resistivities $\rho$ and the spontaneous Hall coefficients $R_{s}$ are $~1.6\;{\mu}{\Omega}m$ and $~3{\times}10^{-8}m^{3}/As$, respectively. $R_{s}$ and $\rho$ are decreased with increasing temperature from 100 K to room temperature. Side-jump effect was adopted to analyze the effect of the small variation of concentration and annealing. The quantity of $R_{s}/{\rho}^{2}$ at room temperature, which is directly related to the electronic structure of the mother alloy, remained almost a constant except as quenched one as it can be predicted from the side-jump effect. We suggested the temperature dependence of $R_{s}/{\rho}^{2}$ can be compared to Ms{T}.