• 한국주조공학회지
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• 제36권5호
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• pp.147-152
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• 2016

Aluminum has been used as an alternative material for copper, due to its good electrical and thermal conductivities. However, small quantities of transition elements such as Ti and V affect the conductivities of aluminum. Therefore, in this study, the influence of B addition to reduce the effects of Ti and V on the conductivities of aluminum was investigated. Both the electrical and thermal conductivities of aluminum were improved with addition of B up to 0.05 wt%, while the conductivities were gradually reduced with an excess amount of B. SEM-EDS and XRD results exhibited that B reacted with Ti and V element to form diborides, such as $TiB_2$ and $VB_2$ phase, and those diborides tended to settle down to the bottom of the crucible because their densities were higher than that of aluminum melt. As a result, B reduced the deleterious effects of Ti and V, and the electrical and thermal conductivities of aluminum were improved.

• 한국전기전자재료학회논문지
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• 제29권10호
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• pp.659-664
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• 2016

Thermal and electrical conductivities of the natural, artificial, and expandable graphites were analyzed after treatment in NaOH aqueous solution. In order to investigate the elimination of the oxidized groups and impurities on the graphite surfaces after NaOH treatment, the graphite samples were structurally characterized by using XRD, XPS, Raman, FE-SEM. The thermal and electrical conductivities of the graphite samples were significantly improved after NaOH treatment. These results were caused by the structural rehabiliation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.552-556
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• 2000

The crystallization behavior and dc Conductivities of CuO-Nb$_2$O$_{5}$ -V$_2$O$_{5}$ glasses prepared by quenching on the copper plate were investigated. The conductivities of the glasses were range from 10$^{-4}$ s.$cm^{-1}$ / at room temperature, but the conductivities of the glass-ceramics were 10$^{-3}$ s.$cm^{-1}$ / increased by 10$^1$ order. The linear relationship between In($\sigma$T) and T$^{-1}$ suggested that the electrical conduction in the present glass system would be due to a small polaron hopping mechanism. The value of activation energy of glass-ceramics heat-treated at 30$0^{\circ}C$ for 12hrs was found to be 0.leV

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.291-294
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• 2000

The crystallization behavior and dc Conductivities of CuO-P$_2$O$_{5}$ -Nb$_2$O$_{5}$ -V$_2$O$_{5}$ glasses prepared by quenching on the copper plate were investigated. The conductivities of the glasses were range from 10$^{-5}$ s.$cm^{-1}$ / at room temperature, but the conductivities of the glass-ceramics were 10$^{-3}$ s.$cm^{-1}$ / increased by 10$^2$order. The crystalline product in the glass-ceramics was CuV$_2$O$_{6}$ . The linear relationship between in($\sigma$T) and T$^{-1}$ suggested that the electrical conduction in the present glass-ceramics would be due to a small polaron hopping mechanism.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.81-84
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• 2002

An approach for predicting the effective thermal conductivities of fiber-reinforce composite has been developed based on a thermal-electrical analogy. The unit cell of the composite laminate is divided into regular volume elements and the material properties have been given to each element. By constructing the series-parallel thermal resistance network, the thermal conductivities of composite both in-plane and out-of-plane direction have been predicted. Graphite/Epoxy composite is used for a balanced plain-weave composite laminate. By comparing the predicted results and the previous works, good agreement has been found.

• Restorative Dentistry and Endodontics
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• 제37권3호
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• pp.149-154
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• 2012

Objectives: To evaluate the accuracy of the Root ZX in teeth with simulated root perforation in the presence of gel or liquid type endodontic irrigants, such as saline, 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine liquid, 2% chlorhexidine gel, and RC-Prep, and also to determine the electrical conductivities of these endodontic irrigants. Materials and Methods: A root perforation was simulated on twenty freshly extracted teeth by means of a small perforation made on the proximal surface of the root at 4 mm from the anatomic apex. Root ZX was used to locate root perforation and measure the electronic working lengths. The results obtained were compared with the actual working length (AWL) and the actual location of perforations (AP), allowing tolerances of 0.5 or 1.0 mm. Measurements within these limits were considered as acceptable. Chi-square test or the Fisher's exact test was used to evaluate significance. Electrical conductivities of each irrigant were also measured with an electrical conductivity tester. Results: The accuracies of the Root ZX in perforated teeth were significantly different between liquid types (saline, NaOCl) and gel types (chlorhexidine gel, RC-Prep). The accuracies of electronic working lengths in perforated teeth were higher in gel types than in liquid types. The accuracy in locating root perforation was higher in liquid types than gel types. 5.25% NaOCl had the highest electrical conductivity, whereas 2% chlorhexidine gel and RC-Prep gel had the lowest electrical conductivities among the five irrigants. Conclusions: Different canal irrigants with different electrical conductivities may affect the accuracy of the Root ZX in perforated teeth.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.31-34
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• 1995

The NO$_2$ gas-deteotion characteristics were investigated using the functional organic Langmuir-Blodgett(LB) files of Dilithium phthalocyanines(Li$_2$Pc). The optimum conditions for a film deposition were obtained through a study of $\pi$-A isotherms, and the deposited film status was confirmed by the ellipsometry measurements. A propel number of layers for the gas-detection was proved to be 9 layers from a measurement of a measurement of change in the electrical conductivities when the films were exposed to the 200 ppm of the NO$_2$ gases. A response time, recovery time, and reproducibility were also studied. A proper temperature which was able to activate gas interaction between NO$_2$ gases and Li$_2$Pc LB films was around 150$^{\circ}C$ judging from the electrical conductivities in a temperature range of 20 to 200$^{\circ}C$. It was found that at 150\ulcorner there are increments of electrical conductivities by 65 tines, 30 seconds of response time and 60 seconds of recovery tine when the filmswere exposed to the gasses.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.934-937
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• 2003

Glasses in the system $CuO-P_2O_5-V_2O_5$ were prepared by a press-quenching method on the copper plate. The glass-ceramics from these glasses were obtained by post-heat treatment, and the crystallization behavior and DC conductivities were determined. The conductivities of the glasses were range from $10^{-6}s.Cm^{-1}$ at room temperature, but the conductivities of the glass-ceramics were $10^{-3}s.Cm^{-1}$ increased by $10^3$ order. The crystalline product in the glass-ceramics was $CuV_2O_6$. Heat-treatment conditions influenced the crystal growth of $CuV_2O_6$ and conductivity. The linear relationship between in (${\sigma}T$) and $T^{-1}$ suggested that the electrical conduction in the present glass-ceramics would be due to a small polaron hopping(SPH) mechanism.

• 한국세라믹학회지
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• 제42권9호
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• pp.602-606
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• 2005

[ $LiCoO_{2}$ ] is the most common cathode electrode materials in Lithium-ion batteries. $LiCo_{0.97}Mg_{0.03}O_2$ was synthesized by the solid-state reaction method. We investigated crystal structures, electrical conductivities and electrochemical properties. The crystal structure of $LiCo_{0.97}Mg_{0.03}O_2$ was analyzed by X-ray powder diffraction and Rietveld refinement. The material showed a single phase of a layered structure with the space group R-3m. The lattice parameter(a, c) of $LiCo_{0.97}Mg_{0.03}O_2$ was larger than that of $LiCoO_2$. The electrical conductivity of sintered samples was measured by the Van der Pauw method. The electrical conductivities of $LiCoO_2$ and $LiCo_{0.97}Mg_{0.03}O_2$ were $2.11{\times}10^{-4}\;S/cm$ and $2.41{\times}10^{-1}\;S/cm$ at room temperature, respectively. On the basis of the Hall effect analysis, the increase in electrical conductivities of $LiCo_{0.97}Mg_{0.03}O_2$ is believed due to the increased carrier concentrations, while the carrier mobility was almost invariant. The electrochemical performance was investigated by coin cell test. $LiCo_{0.97}Mg_{0.03}O_2$ showed improved cycling performance as compared with $LiCoO_2$.

• 한국세라믹학회지
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• 제35권12호
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• pp.1323-1328
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• 1998

The electrical conductivities of the yttria (8mol%) stabilizedzirconia-ceria solid solutions were measured as a function of oxygen partial between 80$0^{\circ}C$ and 100$0^{\circ}C$ using 4-probe d.c. method Under pure oxygen atmosphere the oxygen ionic conductivity of CeO2-ZrO2 decreased with the concentration of CeO2 Under reducing condition electronic conduction due to the redox equilibrium of Ce ion was observed. Total ionic and electronic conductivities fitted by a defect model enabled to determine the electronic transference number(tei) which increased with the concentration of CeO2 and with the degree of reduction.