• Journal of radiological science and technology
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• v.41 no.1
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• pp.25-31
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• 2018

This study aimed to evaluate the range of maximum TE that could measure T2 relaxation time accurately by setting diverse maximum TE with using contrast medium phantoms. Contrast medium phantoms ranging from low to high concentrations were made by using Gadoteridol. The relaxation time and relaxation rate were compared and evaluated by conducting T2 mapping by using reference data based on various TEs and data obtained from different maximum TEs. It was found that accurate T2 relaxation time could be expressed only when the maximum TE over a certain range was used in the section with long T2 relaxation time, such as the low concentration section of saline or gadolinium contrast medium. Therefore, the maximum TE shall be longer than the T2 relation time for accurately maturing the T2 relaxation of a certain tissue or a substance.

• Korean Journal of Materials Research
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• v.8 no.3
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• pp.245-251
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• 1998

Bi-doped n-type PbTe thermoeletric materials were fabricated by mechanical alloying and hot pressing. The intering characteristics and thermoelectric properties of the hot- pressed PbTe were characterized and compared with the properties of the specimens prepared by meltingigrinding method. The hot-pressed PbTe specimens fabricated by mechanical alloying exhibited more negative Seebeck coefficient, higher electrical resistivity and lower thermal conductivity. compared to ones prepared by meltingigrinding. The maximum figure-of-merit increased and the temperature for the maximum figure-of-merit shifted to lower temperature for the specimens fabricated by mechanical alloying. When hot pressed at $650^{\circ}C$, 0.3 wt% Bi-doped PbTe fabricated by mechanical alloying and meltingjgrinding exhibited maximum figure-of-merits of $1.33\times10^{-3}/K$ at $200^{\circ}C$ and $1.07\times10^{-3}/K$ at $400^{\circ}C$ respectively.

• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1364-1371
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• 2018

An extensive investigation of photon interaction properties has been made for $Zn_xTe_{100-x}$ alloys (where x = 5, 20, 30, 40, 50) to explore its possible use in sensing and shielding gamma radiations. The results show better and stable response of ZnTe alloys for various photon interaction properties over the wide energy range, with an additional benefit of ease in fabrication due to lower melting points of Zn and Te. Mass attenuation coefficient values show strong dependence on photon energy as well as composition. Effective atomic number has maximum value for $Zn_5Te_{95}$ and lowest for $Zn_{50}Te_{50}$ in the entire energy region. The alloy sample with maximum $Z_{eff}$ shows minimal value of $N_e$ and vice versa. Mean free path follows inverse trend as observed for mass attenuation coefficient. The exposure and energy absorption buildup factors depend upon photon energy, penetration thickness and composition (effective atomic number) of $Zn_xTe_{100-x}$ alloys. It finds its application for sensing and shielding from highly energetic and highly penetrating photons at sites where radioactive materials were used and visibility of material is not a big constraint. Further, energy down conversion property of ZnTe alloys with subsequent emission in green band suggests its potential use in sensing gamma photons.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.911-917
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• 2002

0.5 at% $Na_2$Te-doped ($Pb_{0.7}Sn_{0.3}$)Te and ($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ powders were fabricated by mechanical alloying process. 0.5 at% Na$_2$Te-doped ($Pb_{0.7}Sn_{0.3}$)Te powders were charged at one end of mold and ($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ powders were charged at the other end of a mold. Then these powders were hot-pressed to form p-type ($Pb_{0.7}Sn_{0.3}$)Te/($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ functional gradient materials with the segment ratios (the ratio of ($Pb_{0.7}Sn_{0.3}$)Te to ($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ ) of 1:2, 1:1, and 2:1. Power generation characteristics of the ($Pb_{0.7}Sn_{0.3}$)Te/($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ were measured. When the temperature difference ΔT at both ends of the specimen was larger than $300^{\circ}C$, the ($Pb_{0.7}Sn_{0.3}$)Te/($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ with the segment ratios of 1:2 and 1:1 exhibited larger output power than those of the ($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ and 0.5 at% $Na_2$ Te-doped ($Pb_{0.7}Sn_{0.3}$)Te alloys. The maximum output power of the ($Pb_{0.7}Sn_{0.3}$)Te/($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ predicted with the measured Seebeck coefficient and the estimated electrical resistivity was in good agreement with the measured maximum output power.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1055-1060
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• 1998

Thermoelectric properties of ($Pb_{1-x}Sn_x$)Te ($0\leq{x}\leq{0.4}$) alloys, fabricated by mechanical alloying and hot pressing, were investigated with variation of the SnTe content. For the hot-pressed PbTe and ($Pb_{0.9}Sn_{0.1}$)Te. transition from p-type to n-type occurred at $200^{\circ}C$ and $300^{\circ}C$, respectively. However, the specimens containing SnTe more than 0.2mole exhibited p-type conduction up to 450'C. In extrinsic conduction region, the Seebeck coefficient and electrical resistivity of the hot-pressed ($Pb_{1-x}Sn_x$)Te decreased with increasing the SnTe content. The temperature at which the hot-pressed (Pbl-,Sn,)Te exhibited a maximum figure-of-merit was shifted to higher temperature with increasing the SnTe content The hot-pressed (Pbo ,Sno dTe exhibited a maximum figure-of-merit of $0.68\times10_{-3}/K$ at $200^{\circ}C$.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.89-93
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• 2017

A thin film thermoelectric generator that consisted of 5 p/n pairs was fabricated with $1{\mu}m$-thick n-type $In_3Sb_1Te_2$ and p-type $Ge_2Sb_2Te_5$ deposited via radio frequency magnetron sputtering. First, $1{\mu}m$-thick GST and IST thin films were deposited at $250^{\circ}C$ and room temperature, respectively, via radio-frequency sputtering; these films were annealed from 250 to $450^{\circ}C$ via rapid thermal annealing. The optimal power factor was found at an annealing temperature of $400^{\circ}C$ for 10 min. To demonstrate thermoelectric generation, we measured the output voltage and estimated the maximum power of the n-IST/p-GST generator by imposing a temperature difference between the hot and cold junctions. The maximum output voltage and the estimated maximum power of the $1{\mu}m$-thick n-IST/p-GST TE generators are approximately 17.1 mV and 5.1 nW at ${\Delta}T=12K$, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.1
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• pp.15-19
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• 2013

The n-type $Bi_2(Te_{0.9}Se_{0.1})_3$ powders, which were fabricated by melting/grinding method and dispersed with 0.5 vol% $TiO_2$ nanopowders, were hot-pressed in order to investigate the effects of $TiO_2$ dispersion on the thermoelectric properties of the hot-pressed $Bi_2(Te_{0.9}Se_{0.1})_3$. Excellent thermoelectric properties such as a maximum figure-of-merit of $2.93{\times}10^{-3}/K$ and a maximum dimensionless figure-of-merit of 1.02 were obtained for the hot-pressed $Bi_2(Te_{0.9}Se_{0.1})_3$. With dispersion of 0.5 vol% $TiO_2$ nanopowders, the maximum figure-of-merit and the maximum dimensionless figure-of-merit decreased to $2.09{\times}10^{-3}/K$ and 0.68, respectively.

• Electrical & Electronic Materials
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• v.9 no.1
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• pp.67-75
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• 1996

This paper has presented the characteristics of thermoelectric devices and the plots of thermoelectric cooling and heating as a function of currents for different temperatures. The maximum cooling and heating(.DELTA.T) for (BiSb)$\_$2/Te$\_$3/ and Bi$\_$2/(TeSe)$\_$3/ as a function of currents is about 75.deg. C, A solderable ceramic insulated thermoelectric module. Each module contains 31 thermoelectric devices. Thermoelectric material is a quaternary alloy of bismuth, tellurium, selenium, and antimony with small amounts of suitable dopants, carefully processed to produce an oriented polycrystalline ingot with superior anisotropic thermoelectric properties. Metallized ceramic plates afford maximum electrical insulation and thermal conduction. Operating temperature range is from -156.deg. C to +104.deg. C. The amount of Peltier cooling is directly proportional to the current through the sample, and the temperature gradient at the thermoelectric materials junctions will depend on the system geometry.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.277-281
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• 2004

$Hg_{1-x}Cd_{x}Te$ (MCT) was grown by hot wall epitaxy. Prior to the MCT growth, the CdTe (111) buffer layer was grown on the GaAs substrate at the temperature of $590^{\circ}C$ for 15 min. When the thickness of the CdTe buffer layer was $5{\mu}m$ or thicker, the full width at half maximum values obtained from the x-ray rocking curves were found to significantly decrease. After a good quality CdTe buffer layer was grown, the MCT epilayers were grown on the CdTe (111)/GaAs substrate at various temperatures in situ. The crystal quality for those epilayers was investigated by means of the x-ray rocking curves and the photocurrent experiment. The photoconductor characterization for the epilayers was also measured. The energy band gap of MCT was determined from the photocurrent measurement and the x composition rates from the temperature dependence of the energy band gap were turned out.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.183-191
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• 2004

Single shortest path routing is known to perform poorly for Internet traffic engineering (TE) where the typical optimization objective is to minimize the maximum link load. Splitting traffic uniformly over equal cost multiple shortest paths in OSPF and IS-IS does not always minimize the maximum link load when multiple paths are not carefully selected for the global traffic demand matrix. However, among all the equal cost multiple shortest paths in the network, a set of TE-aware shortest paths, which reduces the maximum link load significantly, can be found and used by IP routers without any change of existing routing protocols and serious configuration overhead. While calculating TE-aware shortest paths. the destination-based forwarding constraint at a node should be satisfied, because an IP router will forward a packet to the next-hop toward the destination by looking up the destination prefix. In this paper, we present a problem formulation of finding a set of TE-aware shortest paths in ILP, and propose a simple heuristic for the problem. From the simulation results, it is shown that TE-aware shortest path routing performs better than default shortest path routing and ECMP in terms of the maximum link load with the marginal configuration overhead of changing the next-hops.