• Korean Journal of Materials Research
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• v.18 no.5
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• pp.283-288
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• 2008

The effect of sintering aids and glass-frit on the densification and resistivity of silver paste was investigated in an effort to enhance the sintered density and electrical conductivity of the silver electrode. To prepare Pb-free silver paste for use at low sintering temperatures, two commercial silver powders ($0.8\;{\mu}m$ and $1.6\;{\mu}m$ in size) and 5wt.% lab-synthesized nanoparticles (30-50 nm in size) as a sintering aids were mixed with 3 wt.% or 6 wt.% of glass frit ($Bi_2O_3$-based) using a solvent and three roll mills. Thick films from the silver paste were prepared by means of screen printing on an alumina substrate followed by sintering at $450^{\circ}C$ to $550^{\circ}C$ for 15 min. Silver thick films from the paste with bimodal particles showed a high packing density, high densification during sintering and low resistivity compared to films created using monomodal particles. Silver nanoparticles as a sintering aid enhanced the densification of commercial silver powder at a low sintering temperature and induced low resistivity in the silver thick film. The glass frit also enhanced the densification of the films through liquid phase sintering; however, the optimum content of glass frit is necessary to ensure that a dense microstructure and low resistivity are obtained, as excessive glass-frit can provoke low conductivity due to the interconnection of the glass phase with the high resistivity between the silver particles.

• Journal of Fashion Business
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• v.23 no.2
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• pp.1-17
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• 2019

The objective of this study was to investigate electrical conductivity of fabrics from polyester (PET) and Nylon (N) containing polyurethane (PU), with silver paste patterns screen-stenciled in three directions. The PET/PU and N/PU fabrics knitted or woven were uniaxially strain-recovered up to 22.5% in three times when each change in electrical resistance was simultaneously measured. This study established four variables that complexly affected electrical conductivity of these specimens; fabric structures, components, cover factors, and the percolation of silver particles. The woven or knitted fabric structures did not distinctively cause the changes in electrical resistance, however, the woven fabrics with the diagonal patterns showed their relatively high electrical resistance. The PET/PU fabrics with increasing the PET proportion generally presented the opposite propensity to its electrical conductivity. The changes in electric resistance of the PET/PU 85/15 2/1 twill and double plain fabrics instantaneously responded to the rate of elongation. The PET/PU group exhibited a reverse correlation between its cover factor and electrical resistivity. The highest electrical conductivity of the PET/PU 95/5 interlock fabric, with very few fluctuations, was attributed to the deep percolation of the silver particles that bridged the gaps between one loop and another. On the other hand, the occurrence of the silver cracks along with the elongated direction led to the immeasurably high change in electrical resistance as the strain increased.

• Journal of Powder Materials
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• v.23 no.5
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• pp.358-363
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• 2016

Noncontact direct-printed conductive silver patterns with an enhanced electrical resistivity are fabricated using a silver ink with a mixture of silver nanoparticles and nanoplates. The microstructure and electrical resistivity of the silver pattern are systematically investigated as a function of the mixing ratio of the nanoparticles and nanoplates. The pattern, which is fabricated using a mixture with a mixing ratio of 3(nanoparticles):7(nanoplates) and sintered at $200^{\circ}C$ shows a highly dense and well-sintered microstructure and has a resistivity of $7.60{\mu}{\Omega}{\cdot}cm$. This originates a mutual synergistic effect through a combination of the sinterability of the nanoparticles and the packing ability of the nanoplates. This is a conductive material that can be used to fabricate noncontact direct-printed conductive patterns with excellent electrical conductivity for various flexible electronics applications, including solar cells, displays, RFIDs, and sensors.

• Geophysics and Geophysical Exploration
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• v.22 no.3
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• pp.160-167
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• 2019

Resistivity inversion result may be distorted if the seepage line fluctuation within central core with the change of reservoir water level as well as the conductivity of the reservoir water is not taken into consideration because the reservoir dike is composed of three-dimensional (3D) resistivity structure. Consequently, to accurately analyze the resistivity changes inside the reservoir dike according to the change of reservoir water level, 3D electrical resistivity modeling for the 2D survey line considering topography and physical properties of dam components was carried out. In addition, 2D inversion was performed with the simulated 2D resistivity data for a given 3D model in order to compare it with the inversion result of real field data. For 283 reservoirs in Korea, 2D inversion results for the simulated 2D data and field 2D resistivity data were compared. Finally, the reservoirs with an inversion ratio of 50% or less were selected as reservoirs that require further precise investigation.

• Geophysics and Geophysical Exploration
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• v.12 no.4
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• pp.328-337
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• 2009

To investigate the relation between pore fluid conductivity and bulk resistivity of a rock sample it is assumed that electrolyte solution perfectly substitute the pore fluid that occupied the pore space within the sample in general. In this study, it is investigated that how much can the electrolyte solution substitute the pore fluid by repeating the same saturation process. Four kinds of NaCl solutions of 8, 160, 3200, 64000 ${\mu}S$/cm are used. The saturation process has repeated four times for each electrolyte in increasing conductivity order first then four times each in decreasing order. The more the saturation process repeated with the same electrolyte, the more electrolyte solution substitute the pore fluid. Geometric mean of bulk resistivity in increasing and decreasing orders with the same electrolyte solution is assumed to be mostly close to the bulk resistivity with perfect substitution. Bulk resistivity measurements for both increasing and decreasing order differs within 10% to the geometric mean when repeating the saturation process 4 times while maximum 40% difference is observed when single saturation process for each electrolyte solution with increasing order. The modified parallel resistant model can generally represent the relations between pore fluid resistivity and bulk resistivity in the experiment, but more experimental data with various rock samples with different porosity is needed to generalize the model.

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.92-95
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• 1997

Because of the novel characteristics such as chemical stability, hardness, electrical resistivity and thermal conductivity, diamond-like carbon (DLC) film is a suitable material for the passivation layers. For this purpose, using the PECVD, DLC films were synthesized at room temperature. The adhesion and the hardness of the DLC films deposited on Si an SiO2 substrate were measured. The resistivity of 5.3$\times$$10^8$$\Omega$.cm was measured by automatic spreading resistance probe analysis method. The thermal conductivities of different DLC films were measured and compared with that of phospho silicate glass (PSG) film which is commonly used as passivation layers. The thermal conductivity of DLC film was improved by increasing hydrogen flow rate up to 90 sccm and was better than that of PSG film. The patterning techniques of the DLC film developed using the RIE and the lift-off method to form 5$\mu\textrm{m}$ line. Finally, the thermal characteristics of the power transistor with the DLC film as passiviation layer was analyzed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.8
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• pp.618-621
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• 2001

Plate-type $\beta$-FeSi$_2$single crystals were grown using FeSi$_2$, Fe, and Si as starting materials by the chemical transport reaction method. The $\beta$-FeSi$_2$single crystal was an orthorhombic structure. The direct optical energy gap was found to be 0.87eV at 300K. Hall effect shows a n-type conductivity in the $\beta$-FeSi$_2$ single crystal. The electrical resistivity values was 1.608Ωcm and electron mobility was 3x10$^{-1}$ $\textrm{cm}^2$/V.sec at room temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.215-222
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• 2001

Polyaniline-Camphorsulfonic Acid Emeraldine Salt(PANI-CSA ES) was prepared by doping Polyaniline Ermeralidine Base(PANI EB) with DL-10-Camphorsulfonic Acid(CSA). PANI-CSA ES was solved in an organic solvent by ultrasonification for different periods of time and its surface resistivity was measured. Several PANI-CSA ES solutions solved in different organic solvents were prepared and their surface resistivities were measured. Thermal stability of film casted with PANI-CAS ES solution in m-cresol was estimated by measuring its surface conductivity and the content of this moisture and organic solvents. PANI-CSA ES was blended with different polymeric binders to improve its physical properties and the surface resistivities of several kinds of PANI-CSA ES blends were measured as a function of the content of PANI-CSA ES. PANI-CSA ES polymerized by 1-step oxidative polymerization was prepared and its surface resistivity was measured.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.353-360
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• 2007

We practiced fresh water injection test to identify its applibility as a method of seawater intrusion mitigation technique, and monitored the change of borehole fluid conductivity and the behavior of injected fresh water using borehole multichannel electrical conductivity monitoring and well-logging, and DC resistivity and SP monitoring at the surface. Well-logging and multichannel EC monitoring showed the decrease of fluid conductivity due to fresh water injection. We note that such an injection effect lasts more than several month which means the applibility of fresh water injection as a seawater intrusion control technique. Although SP monitoring did not show meaningful results because of weather condition during monitoring and the defects of electrodes due to long operation time, DC resistivity monitoring showed its effectiveness and applicability as a monitoring and assessment techniques of injection test by means of imaging the behavior and the front of fresh water body in terms of the increase of resistivity with reasonable resolution. In conclusion, we note that geophysical techniques can be an effective method of monitoring and evaluation of fresh water injection test, and expect that fresh water injection may be an practical method for the mitigation of seawater intrusion when applied with optimal design of injection well distribution and injection rate based on geophysical evaluation.

• Korean Journal of Materials Research
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• v.19 no.12
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• pp.644-648
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• 2009

Temperature dependency of resistivity of the carbon black-polyethylene composites below and above percolation threshold is studied based on the electrical conduction mechanism. Temperature coefficient of resistance of the composites below percolation threshold changed from minus to plus, increasing volume fraction of carbon black; this trend decreased with increasing volume fraction of carbon black. The temperature dependence of resistivity of the composites below percolation threshold can be explained with a tunneling conduction model by incorporating the effect of thermal expansion of the composites into a tunneling gap. Temperature coefficient of resistance of the composites above percolation threshold was positive and its absolute value increased with increasing volume fraction of carbon black. By assuming that the electrical conduction through percolating paths is a thermally activated process and by incorporating the effect of thermal expansion into the volume fraction of carbon black, the temperature dependency of the resistivity above percolation threshold has been well explained without violating the universal law of conductivity. The apparent activation energy is estimated to be 0.14 eV.