• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.200-206
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• 1998

The effect of surface tension and viscosity of polymer solution on the thickness of water casting membranes was studied. Spreading of polymer solutions on water surface was governed by the surface tension and viscosity of the polymer solution. The thickness of water casting membrane was affected by these two factors. The properties, mentioned above, were proportional to the polymer concentration. The order of magnitude in surface tension was PVC>PS>CA and that of viscosity was CA>PS>PVC. The difference of surface tension between water and polymer solution acts as driving force for spreading of polymer solution, but the viscosity as resistance. The thickness of polymeric membrane prepared by water casting was PS>CA>PVC. The order of membrane thickness was not as same as that of surface tension. This phenomena were due to the viscosity which acts as more effective spreading resistance than the surface tension.

• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.155-161
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• 2007

A new and simple method of 3-dimensional circuit modeling and analysis is proposed and verified experimentally for the first time by determining 3-dimensional current flow and 2-dimensional light distribution in blue InGaN/GaN multi-quantum well (MQW) light emitting diode (LED) devices. Circuit parameters of the LED consist of the resistance of the metallic film and epitaxial layer, and the intrinsic diode which represents the active region emitting the light. The circuit parameters are extracted from the transmission line model (TLM) and current-voltage relation. We applied the >> proposed method and extracted circuit parameters to obtain the light emission pattern in a top-surface emitting-type LED. The current spreading effect is analyzed theoretically and quantitatively with a variation of the resistance of metallic and epitaxial layers. The emitting-light distribution of the fabricated blue LED showed a good agreement with the analyzed result, which shows the dark emission intensity at the corner of the p-electrode.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.1
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• pp.96-100
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• 2001

Three commercial strains bred in the US (Hubbard), Holland (Lohman), and Canada (Shaver) and Balady breed of chickens were orally infected with $10^6$ cfu of Salmonella gallinarum per chick. Chicks were compared for weight gain, feed intake, feed conversion ratio, mortality rate and contamination of the liver, spleen and intestine with Salmonella gallinarum on the day of slaughter. The Balady chicks had significantly the lowest mortality rate (p<0.01) and weight gain (p<0.001) and poorest feed conversion ratio (p<0.001). Salmonella gallinarum could be shed from the liver, spleen and intestine with alternative rates in all strains. Lohman was the most resistance over the other two commercial strains, while Hubbard had the highest susceptibility. The Balady chicks were the most resistance. However, they may serve as a possible reservoir of Salmonella gallinarum and it may play a role of spreading the infection to the commercial farms in Jordan.

• Korean Journal of Materials Research
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• v.19 no.8
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• pp.443-446
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• 2009

This study develops a highly transparent ohmic contact scheme using indium oxide doped ZnO (IZO) as a current spreading layer for p-GaN in order to increase the optical output power of nitride-based lightemitting diodes (LEDs). IZO based contact layers of IZO, Ni/IZO, and NiO/IZO were prepared by e-beam evaporation, followed by a post-deposition annealing. The transmittances of the IZO based contact layers were in excess of 80% throughout the visible region of the spectrum. Specific contact resistances of $3.4\times10^{-4}$, $1.2\times10^{-4}$, $9.2\times0^{-5}$, and $3.6\times10^{-5}{\Omega}{\cdot}cm^2$ for IZO, Ni/Au, Ni/IZO, and NiO/IZO, respectively were obtained. The forward voltage and the optical output power of GaN LED with a NiO/IZO ohmic contact was 0.15 V lower and was increased by 38.9%, respectively, at a forward current of 20 mA compared to that of a standard GaN LED with an Ni/Au ohmic contact due to its high transparency, low contact resistance, and uniform current spreading.

• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.163-167
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• 2013

A modified two-point impedance spectroscopy technique exploits the geometric constriction between an electrolyte and a cathode with an emphasis on semispherical-shaped electrolytes. The spatial limitation in the electrolyte/electrode interface leads to local amplification of the electrochemical reaction occurring in the corresponding electrolyte/electrode region. The modified impedance spectroscopy was applied to electrical monitoring of a YSZ ($Y_2O_3$-stabilized $ZrO_2$)/SSC ($Sm_{0.5}Sr_{0.5}CoO_3$) system. The resolved bulk and interfacial component was numerically analyzed in combination with an equivalent circuit model. The effectiveness of the "spreading resistance" concept is validated by analysis of the electrode polarization in the cathode materials of solid oxide fuel cells.

• Biomedical Science Letters
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• v.5 no.1
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• pp.17-26
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• 1999

To evaluate the spreading possibilities of the marRAB mutation of E. coli Mar mutant among gram-negative bacilli, chromosomal marRAB mutations of Mar mutants were transduced by $\lambda$placMu9 into pUC19 (Lac$^{+}$, Ap$^{r}$) cloning site in another strains of E. coli or onto the chrmosome of S. typhimurium and P. aeruginosa, selected for transduction by Mar phenotype, Lac$^{-}$, or Ap$^{r}$, and tested for their antimicrobial resistance with or without addition of salicylate (SAL). Compared with wild type strains of JM109, NM522, harboring pUC19 or not, respectively, all strains of JM109 or NM522 carrying pUC19::marRAB mutation showed higher levels of antimicrobial resistance and SAL induction of Mar phenotype than those of wild type. However, in contrast to the original Mar mutants, there were some tendencies of decreased antimicrobial resistance of JM109 or NM522 harboring pUC19::marRAB mutation with SAL induction against chlorarnphenicol (Cm) and tetracycline (Tc), or Tc and ciprofloxacin (Cp), respectively. Almost the same results, as shown as the cases of E. coli JM109 or NM522, were obtained from all transductants of S. typhimurium and P. aeruginosa, except Cp, against which increased antimicrobial resistance with SAL induction was shown. This study, employed the methods of transformation or transduction among intercellular gene transfer methods between gram-negative bacteria, shows the evidences that suggest indirectly the spreading possibilities of marRAB mutation among gram-negative bacilli.

• Journal of the Korean institute of surface engineering
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• v.48 no.6
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• pp.297-302
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• 2015

Nanocrystalline diamond(NCD) coated aluminium plates were prepared and applied as heat sinks for LED modules. NCD films were deposited on 1 mm thick Al plates for times of 2 - 10 h in a microwave plasma chemical vapor deposition reactor. Deposition parameters were the microwave power of 1.2 kW, the working pressure of 90 Torr, the $CH_4/Ar$ gas ratio of 2/200 sccm. In order to enhance diamond nucleation, DC bias voltage of -90 V was applied to the substrate during deposition without external heating. NCD film was identified by X-ray diffraction and Raman spectroscopy. The Al plates with about 300 nm thick NCD film were attached to LED modules and thermal analysis was carried out using Thermal Transient Tester (T3ster) in a still air box. Thermal resistance of the module with NCD/Al plate was 3.88 K/W while that with Al plate was 5.55 K/W. The smaller the thermal resistance, the better the heat emission. From structure function analysis, the differences between junction and ambient temperatures were $12.1^{\circ}C$ for NCD/Al plate and $15.5^{\circ}C$ for Al plate. The hot spot size of infrared images was larger on NCD/Al than Al plate for a given period of LED operation. In conclusion, NCD coated Al plate exhibited better thermal spreading performance than conventional Al heat sink.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.166-170
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• 1991

An advanced on-resistance model of VDMOS devices in the low voltage regime is proposed and verified by 2-D device simulations. The model considers the lateral gaussian doping profiles in the channel region and exact current spreading angles in the epitaxial layer for both linear and cellular geometries by employing the conformal mapping. It is found out that the on-resistance of low voltage VDMOS may be overestimated considerably if it is analyzed by the conventional method. The 2-D device simulation results show that the proposed model is valid for all ranges of cell spacings and breakdown voltages.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.133-134
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• 2014

As a previous research, improved durability of concrete by filling capillary pores with waste cooking oil was suggested as a method of controlling carbonation of the concrete replaced high volume of SCMs. on the other hand, the emulsified refined waste cooking oil for better mixing performance had a drawback of reducing air content related with decreasing freeze-thawing resistance. As a solution of this problem, surface applying method was suggested instead of adding in mixing process, and in this research, the performance regarding concrete durability are evaluated comparing emulsified refined cooking oil with water-repelling agent.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.3
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• pp.234-238
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• 2014

Multichip packaging was achieved the best solution to significantly reduce thermal resistance at the same time, to increase luminance intensity in LEDs packaging application. For the packaging, thermal spreading resistance is an important parameter to get influence the total thermal performance of LEDs. In this study, silicon-based multichip light emitting diodes (LEDs) packaged module has been examined for thermal characteristics in several parameters. Compared to the general conventional single LED packaged chip module, multichip LED packaged module has many advantages of low cost, low density, small size, and low thermal resistance. This analyzed module is comprised of multichip LED array, which consists of 32 LED packaged chips with supplement power of 0.2 W at every single chip. To realize the extent of thermal distribution, the computer-aided design model of 6.4 W Si-based multichip LED module was designed and was performed by the simulation basis of actual fabrication flow. The impact of thermal distribution is analyzed in alternative ways both optimizing numbers of fins and the thickness of that heatsink. In addition, a thermal resistance model was designed and derived from analytical theory. The optimum simulation results satisfies the expectations of the design goal and the measurement of IR camera results. tart after striking space key 2 times.