• Journal of Powder Materials
• /
• v.24 no.6
• /
• pp.464-471
• /
• 2017

A metal mesh TCE film is fabricated using a series of processes such as UV imprinting of a transparent trench pattern (with a width of $2-5{\mu}m$) onto a PET film, filling it with silver paste, wiping of the surface, and heat-curing the silver paste. In this work nanosized (40-50 nm) silver particles are synthesized and mixed with submicron (250-300 nm)-sized silver particles to prepare silver paste for the fabrication of metal mesh-type TCE films. The filling of these silver pastes into the patterned trench layer is examined using a specially designed filling machine and the rheological testing of the silver pastes. The wiping of the trench layer surface to remove any residual silver paste or particles is tested with various mixture solvents, and ethyl cellosolve acetate (ECA):DI water = 90:10 wt% is found to give the best result. The silver paste with 40-50 nm Ag:250-300 nm Ag in a 10:90 wt% mixture gives the highest electrical conductance. The metal mesh TCE film obtained with this silver paste in an optimized process exhibits a light transmittance of 90.4% and haze at 1.2%, which is suitable for TSP application.

• Computers and Concrete
• /
• v.8 no.3
• /
• pp.279-292
• /
• 2011

The main purpose of this study includes investigation of the rheological properties of fresh self consolidating cement paste containing chemical and mineral additives using Artificial Neural Network (ANN) model. In order to develop the model, 200 different mixes are cast in the laboratory as a part of an extensive experimental research program. The data used in the ANN model are arranged in a format of fourteen input parameters covering water-binder ratio, four different mineral additives (calcium carbonate, metakaolin, silica fume, and limestone), five different superplasticizers based on the poly carboxylate and naphthalene and four different Viscosity Modified Admixtures (VMAs). Two common output parameters including the mini slump value and flow cone time are chosen for measuring the rheological properties of fresh self consolidating cement paste. Having validated the model, the influence of effective parameters on the rheological properties of fresh self consolidating cement paste is investigated based on the ANN model outputs. The output results of the model are then compared with the results of previous studies performed by other researchers. Ultimately, the analysis of the model outputs determines the optimal percentage of additives which has a strong influence on the rheological properties of fresh self consolidating cement paste. The proposed ANN model shows that metakaolin and silica fume affect the rheological properties in the same manner. In addition, for providing the suitable rheological properties, the ANN model introduces the optimal percentage of metakaolin, silica fume, calcium carbonate and limestone as 15, 15, 20 and 20% by cement weight, respectively.

• Journal of Powder Materials
• /
• v.23 no.6
• /
• pp.437-441
• /
• 2016

Recently, the grain boundary diffusion process (GBDP), involving heavy rare-earth elements such as Dy and Tb, has been widely used to enhance the coercivity of Nd-Fe-B permanent magnets. For example, a Dy compound is coated onto the surface of Nd-Fe-B sintered magnets, and then the magnets are heat treated. Subsequently, Dy diffuses into the grain boundaries of Nd-Fe-B magnets, forming Dy-Fe-B or Nd-Dy-Fe-B. The dip-coating process is also used widely instead of the GBDP. However, it is quite hard to control the thickness uniformity using dip coating. In this study, first, a $DyF_3$ paste is fabricated using $DyF_3$ powder. Subsequently, the fabricated $DyF_3$ paste is homogeneously coated onto the surface of a Nd-Fe-B sintered magnet. The magnet is then subjected to GBDP to enhance its coercivity. The weight ratio of binder and $DyF_3$ powder is controlled, and we find that the coercivity enhances with decreasing binder content. In addition, the maximum coercivity is obtained with the paste containing 70 wt% of $DyF_3$ powder.

• Journal of Electrochemical Science and Technology
• /
• v.13 no.4
• /
• pp.453-461
• /
• 2022

A chemically sintered and binder-free paste of TiO₂ nanoparticles (NPs) was prepared using a binary-liquid mixture of 1-octanol and CCl₄. The 1:1 (v/v) complex of CCl₄ and 1-octanol easily interacted chemically with the TiO₂ NPs and induced the formation of a highly viscous paste. The as-prepared binary-liquid paste (P_BL)-based TiO₂ film exhibited the complete removal of the binary-liquid and residuals with the subsequent low-temperature sintering (~150℃) and UV-O₃ treatment. This facilitated the fabrication of TiO₂ photoanodes for flexible dye-sensitized solar cells (f-DSSCs). For comparison purposes, pure 1-octanol-based TiO₂ paste (P_O) with moderate viscosity was prepared. The P_BL-based TiO₂ film exhibited strong adhesion and high mechanical stability with the conducting oxide coated glass and plastic substrates compared to the P_O-based film. The corresponding low-temperature sintered P_BL-based f-DSSC showed a power conversion efficiency (PCE) of 3.5%, while it was 2.0% for P_O-based f-DSSC. The P_BL-based low- and high-temperature (500℃) sintered glass-based rigid DSSCs exhibited the PCE of 6.0 and 6.3%, respectively, while this value was 7.1% for a 500℃ sintered rigid DSSC based on a commercial (or conventional) paste.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.10
• /
• pp.1720-1724
• /
• 2007

Electrochemical behaviors of bovine hemoglobin (Hb) at an acetylene black paste electrode based on the enhancement effect of sodium dodecyl sulfate (SDS) were investigated. In the optimal conditions, a very weak reduction peak was observed at an acetylene black paste electrode for hemoglobin in the absence of SDS. However, the reduction peak current increased remarkably after the addition of 4.0 × 10?4 mol L?1 SDS, suggesting that SDS exhibits obvious enhancement effect to the determination of hemoglobin. All the experimental parameters, such as pH value, concentration of SDS, accumulation time and accumulation potential were optimized for hemoglobin analysis. The proposed method possesses high sensitivity (detection limit is 3.0 × 10?9 mol L?1), wide linearity (6.0 × 10?9 to 6.0 × 10?7 mol L?1), rapid response and low cost. Finally, the method was successfully employed to determine hemoglobin in a spiked sample.

• Journal of the Korean Ceramic Society
• /
• v.44 no.9
• /
• pp.489-495
• /
• 2007

Effects of ultrafinely ground ash on the rheological properties of cement paste were investigated. Also compressive strength development and setting time of ultrafine ash blended cement mortar were investigated in the study. A sample with silica fume was included for comparison. According to the results of ultra fine ash blended cement paste in the lower W/B ratio, the fluidity were high, and the setting time was a little retarded. And the compressive strength of ultrafine ash blended mortar was increased in the long term. In the case of hardened cement paste at 28 days, $Ca(OH)_2$ contents was decreased in order of control, ultrafine ash, silica fume blended cement due to difference of the pozzolanic reaction.

• Journal of the Korean institute of surface engineering
• /
• v.32 no.3
• /
• pp.249-252
• /
• 1999

Boriding is one of the chemical method to increase surface hardness as well as carburizing, and nitriding. Gas boriding and boron paste boriding methods were investigated to replace salt bath boriding. Boron paste boriding method is selected due to safety, small waste and low cost. And then boriding is also carried out micro-pulsed PECVD in order to increase efficiency of boriding. Mechanical properties, microstructure, surface concentration, and depth profile of borided layer is investigated by micro-vickers hardness tester, SEM, XRD, and AES.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.876-879
• /
• 2003

The principal problems in development of dielectric paste materials for PDP(plasma display panel)are PbO free paste and low melting temperature. We prepared PbO free paste from glasses in the system $BaO-ZnO-B_2O_3-V_2O_5$. DTA, XRD and SEM were used to study and characterize $BaO-ZnO-B_2O_3-V_2O_5$ glasses. PbO free paste developed at this paper has thermal expansion of $74{\times}10^{-7}/^{\circ}C$, DTA transformation point of $460^{\circ}C$, and firing condition of $560^{\circ}C$, 10min.

• Journal of the Korea Institute of Building Construction
• /
• v.12 no.6
• /
• pp.607-614
• /
• 2012

In this study, the evolution of the electro-mechanical impedance (EMI) of a piezoelectric (PZT) patch embedded in fresh cement paste was investigated to discuss the possibility of monitoring the setting process of cement-based materials using an EMI sensing technique. A tailored thin square PZT patch was embedded in cement paste before casting, and EMI signatures of the embedded patch were continuously measured from casting up to 12 hours. A standard penetration resistance test was performed to compare and correlate the evolution of EMI during the setting process. The results showed that EMI responses differ according to the age of the cement paste, and that the behavior of the EMI resonance peak has a clear correlation with the penetration resistance of the cement paste. Based on the results, it is concluded that an EMI sensing technique using embedded PZT patch can be effectively applied to monitor the setting process of cement-based materials.

• Korean Journal of Microbiology
• /
• v.9 no.2
• /
• pp.47-54
• /
• 1971

This study is concerned to the microbial population and its effects in the fish paste products. Experimental results were summarized as following orders ; 1) The number of bacteria in accordance with raw materials and coocking site waas known to as ; Wheat flor - $7.0{\times}10^8$/gram , Brayed fish meat - $2.0{\times}10^7$/gram, Cooking table - $6.1{\times}10^6$/$1.54cm^2$Chopped fish meat -$4.1{\times}10^6$/gram, Wooden plate - $5.5{\times}10^5$/218.32cm, Sodium chloride - $8.8{\times}10^4$/gram, Wheat starch - $4.5{\times}10^4$/gram, Fish meat - $2.3{\times}10^4$/gram. However, there were a few bacterial numbers less than 300 per gram of raw materials, such as monosodium glutamate, tap water, sugar, saccharine and eggs. 2) Bacterial population in the raw materials might be changed according to the conditions of preservation. 3) When the heat tratment is used for the preservation, the thermal effects were rarely found at the interior part of fish paste products. Conduction of heat into the interior part dose not rise about $84^{\circ}C$ and the survival of bacteria could be possible under the condition. Therefore, cooking being used requires further studies. 4) Number of bacteria in the fish paste products sold in the market was higher on April and May than those on June. Especially on June, the number of bacteriz in the interior part were found higher than those in the exterior part of the products.