• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.39-42
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• 2011

The composite electroplating is accomplished by adding inert materials during the electroplating. Permalloy is the term for Ni-Fe alloy and it is used for industrial applications due to its high magnetic permeability, surface wear resistance, corrosion protection. Microhardness for microdevices is enhanced after composite coating and it increases the life cycle. However, the hydroxyl group on the silica makes their surface susceptible to moisture and it causes the silica nanoparticles to be agglomerated in the aqueous solution. The agglomeration problem causes poor dispersion which eventually interrupts uniform deposition of silica nanoparticles. In this study, the dispersion of silica nanoparticles in the permalloy electroplated layer is reported with variation of additives and current densities. The optimum current density was 20 $mA/cm^2$ and the silica content was 9 at% at $50^{\circ}C$. The amount of silica nanopowder codeposition and surface morphologies were influenced with variation of additives. In the bath, smooth surface morphology and relatively high contents of silica nanopowder codeposition were obtained with addition of sodium lauryl sulfate.

• Clean Technology
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• v.26 no.1
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• pp.30-38
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• 2020

The kinetic and thermodynamic parameters of Acid Red 66, adsorbed by granular activated carbon, were investigated on areas of initial concentration, contact time, and temperature. The adsorption equilibrium data were applied to Langmuir, Freundlich, Temkin, Redlich-Peterson, and Temkin isotherms. The agreement was found to be the highest in the Freundlich model. From the determined Freundlich separation factor (1/n = 0.125 ~ 0.232), the adsorption of Acid Red 66 by granular activated carbon could be employed as an effective treatment method. Temkin's constant related to adsorption heat (B_T = 2.147 ~ 2.562 J mol^-1) showed that this process was physical adsorption. From kinetic experiments, the adsorption process followed the pseudo-second order model with good agreement. The results of the intraparticle diffusion equation showed that the inclination of the second straight line representing the intraparticle diffusion was smaller than that of the first straight line representing the boundary layer diffusion. Therefore, it was confirmed that intraparticle diffusion was the rate-controlling step. From thermodynamic experiments, the activation energy was determined as 35.23 kJ mol^-1, indicating that the adsorption of Acid Red 66 was physical adsorption. The negative Gibbs free energy change (ΔG = -0.548 ~ -7.802 kJ mol^-1) and the positive enthalpy change (ΔH = +109.112 kJ mol^-1) indicated the spontaneous and endothermic nature of the adsorption process, respectively. The isosteric heat of adsorption increased with the increase of surface loading, indicating lateral interactions between the adsorbed dye molecules.

• Korean Journal of Crystallography
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• v.12 no.2
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• pp.70-75
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• 2001

The purpose of this study is to investigate the effect of V₂O/sub 5/ addition on physical and magnetic properties of NiCuZn ferrite for multi-layer chip inductors. NiCuZn ferrite pastes doped with 0, 0.1, 0.3 and 0.5 wt% V₂O/sub 5/ were prepared and samples of ferrite sheets were prepared by the screen printing method. They were sintered at 870, 880, 890 and 900℃, and then their physical and magnetic properties were analyzed. After sintering at 870℃, the sintered density of the ferrite sheet doped with 0.5wt% V₂O/sub 5/ showed the highest value to 5.08g/cm³due to the best densification by the liquid phase sintering, while the microstructures of ferrite sheets doped with 0.1 and 0.3 wt% V₂O/sub 5/ showed and inhibited grain growth. Irrespective of the sintering temperature, the initial permeability of ferrite sheet doped with 0.5 wt% V₂O/sub 5/ was highest and after sintering beyond 880℃, the quality factor of 0.3 wt% V₂O/sub 5/-doped sample appeared to be highest.

• Journal of Life Science
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• v.19 no.9
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• pp.1251-1257
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• 2009

We investigated the growth inhibitory effect of internal organs of Todarodes pacificus (TP) on proliferation in human cancer cell lines in vitro. The internal organs of TP were extracted with methanol (TPM), which was then further fractionated into four subfractions by using a solvent partition method, resulting in hexane (TPMH), methanol (TPMM), butanol (TPMB), and aqueous (TPMA) soluble fractions. We determined the cytotoxic effect of these four fractions in three kinds of cancer cell lines - HepG2, MCF-7 and HT-29 - by MTT assay. Among the four subfractions of TPM, TPMH showed the strongest cytotoxic effects at a concentration of $300{\mu}g$/ml, displaying 91.56% on the HepG2 cell line and 85.93% on the MCF-7 cell line. Morphological changes such as membrane shirinking and blebbing of cells were also observed during TPMH treatment of HepG2 cells. In addition, we also observed quinone reductase (QR) induced effect in the methanol (TPMM) layer of HepG2 cells. TPMM showed the highest induction activity of quinone reductase on HepG2 cells among the other partition layers. The QR induced effect of TPMM was determined to be 2.7 at a level of $360{\mu}g$/ml with a control value of 1.0. Although further studies are needed, the present work suggests that internal organs of Todarodes pacificus (TP) may be a chemopreventive agent for the treatment of human cells.

• Geotechnical Engineering
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• v.14 no.6
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• pp.113-125
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• 1998

At the end of 1997 about 3 million tons of coal ash was produced as byproducts from the coal fired electrical power plants in Korea. Only about 27% of that byproducts was utilized as the admixtures of cement and concrete industry. But the large quantity of coal fired fly-ash has been used as the soil improvement materials in other countries. So the aim of this study is the estimation of the applicability of the coal fired fly-ash as microfine grouting materials by admixing the superfine particles which were separated from the coal fired fly-ash for the higher values. The 6 types of specimens were manufactured in the laboratory for the purpose of estimating the chemical and physical properties of cement and grouts. These specimens consisted of 2 specific surfaces of 6, 000 and 8, 000$cm^2$/g in Elaine method. And these specimens are devide into 3 ratios (30%, 50%, 70%) of fly-ash by weight. From the estimated properties of the coal fired fly-ash microflne cements and grouts, 50% fly-ash is the most suitable ratio for grouting materials. However, further study of durability is necessary for using fly-ash grouts practically at the field projects. The higher content of the unburned carbon of fly-ash increases the thinner layer of carbon on the surface of solution of grouts, and requires more quantity of surface active agent. As a results of this study, it is found that the microfine fly-ash is very useful as a good grouting material if 50% of fly-ash is added with the microfine portland cement. So, in the near future, if the coal fired fly-ash is able to be used as grouting material in Korea, the demand of fly-ash will increase rapidly.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.125-136
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• 2006

Statement of problem. The success of the bonding between electroforming gold and resin is dependent on the surface-conditioning technique but its effective technique has net been studied widely. Purpose. The purpose of the study was to evaluate the bond strength between the electroforming gold and resin with varying the surface-conditioning technique. Materials and methods. Sixty rectangular shaped metal specimens were made and one side of each specimen were gold hard plated. The sand-blasted specimens were divided into four experimental groups with fifteen specimens in each group and were treated as follows. Group 1: Silicoating (Rocatec, 3M ESPE)+ Sinfony (3M ESPE), Group 2: SR Link+ SR Adoro (Ivoclar Vivadent), Group 3: Tin plating (Microtin, Danville Engineering)+ SR Link+ SR Adoro, Group 4: Tin plating (Micro tin, Danville Engineering)+ Silicoating (Rocatec)+ Sinfony. Shear bond strength at metal-resin interface were measured using universal testing machine. Energy Dispersive x-ray analysis was done and scanning electron microscope images were taken and observed. Results and Conclusion. The following conclusions were drawn. 1. The mean shear bond strength values in order were 11.69MPa (Group 2), 22.35MPa (Group 3), 22.40MPa (Group 1) and 27.71MPa (Group 4). There was no significant difference in Group 1, Group 3 and Group 4(P>0.05). 2. In the EDX line analysis, the Au was detected on the surface of all specimen. $SnO_2$ showed on the surface of Group 2 and $SiO_2$ was detected on the surface of Group 1. 3. Increasing of roughness by sandblasting(Group 2), formation of micro-irregularities and tin crystals by electrolytic tin plating(Group 3) and formation of surface irregularities and $SiO_2$ layer(Group 1,4) were observed in SEM photo. 4. Tin plating(Group 3) and Rocatec treatment(Group 1) showed clinically effective shear bond strength(>20MPa), but when the two surface conditioning method were used together higher bond strength were achieved.

• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.414-422
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• 2008

Adsorption experiments for $H_2$, $CH_4$, CO, $CO_2$ on activated carbon and zeolite 5A were performed by static volumetric method. A 4-bed pressure swing adsorption (PSA) process was to study separation of hydrogen from multi-component mixture gases ($H_2$ 72.2%, $CH_4$ 4.06%, CO 2.03%, $CO_2$ 21.6%). Dual-site langmuir (DSL) isotherm showed good or fair agreement with the experimental results. The optimum height of activated carbon layer was 55 cm with breakthrough results on the packing ratio of activated carbon to zeolite 5A. In PSA process, the effects of the process parameters such as total cycle time ($T_c$), ${\Delta}P$ at the provide purge step and adsorption pressure on the PSA performance were studied experimentally and theoretically.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.2
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• pp.209-222
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• 1997

Authors surveyed the ground water near the waste disposed from a fiberglass production factory to confirm the presence of glassfiber in the water and to determine the effect of sampling conditions and storage on the recovery of fibrous materials in the ground water. Sample was collected at every 4 hours for 48 hours consecutively. After finishing the 48 hours sample, water sampling was done from each tap after repeated turning on and off the water for 30 seconds at each time. Sample was collected in the two 1.5 liter polyethylene bottle after vigorously shaking the bottle with the same water several times with the flowing tap water. At each paired sample, one bottle was stored stand still at room temperature, and the other sample was filtered immediately after sampling. Water was filtered on the Mixed Cellulose Ester filter with negative pressure. Each sample was divided into upper and lower layer. The other bottle was stored at room temperature standstill for 7 days and filtered in the same fashion as the other pair of sample did. Each MCE filter was divided into 4 pieces and one piece was treated with acetone to make it transparent. Each prepared sample was observed by two researchers under the light and polarizing microscopy, scanning electron microscopy and energy dispersive X-ra microanalysis. Fibers were classified by the morphology and polarizing pattern under the polarizing microscope, and count was done. 1. There was a significant fluctuation in number of the fibers, but there was no specific demonstrable pattern. 2. Non-polarizing fibers frequently disappeared after 7 days's storage. But cluster of fibers were found at the wall of the same container by scratching technique. 3. Polarizing fibers were usually found in between the filter and the manicure pasted area. Possible explanations for this phenomenon will be that either these fibers are very light or have electronic polarity. Hence, these fibers are not able to be attached on the surface of slide glass. 4. Under the scanning electron microscopic examination, the fibers which are not refractive under the light microscopy were identified as glassfiber. Other fibers which is refractive under the polarizing microscopy were identified as magnesium silicate fibers. It is strongly suggested that development of standardized method of sample collection and measurement of fibrous material in the water is needed.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.107-115
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• 1999

Microstructural variation and strengthening effects with lamination methods of alumina fiber-reinforced ${\gamma}$-LiAlO2 matrixes for Molten Carbonate Fuel Cell(MCFC) were studied. The porosities of all matrix laminated by hot-pressing of two green sheets under 1 kg/$\textrm{cm}^2$ at 45$^{\circ}C$ for 1 min and by double-casting which the second layer cast on the first green sheet dried for 3.5h were more than 50%. The strength of the Al2O3 fiber-reinforced matrix prepared by lamination was enhanced by 70% in comparison with the non-laminated matrix (115 gf/$\textrm{mm}^2$) and the strength-directionality due to fiber-orientation also could be removed. The strength of matrixes laminated by triple-casting was higher than that of the double-cast matrix, but triple-cast matrix showed the directionality with the casting direction, and furthermore its porosity was less than 50%. Although the strength of matrixes laminated by double-casting (195 gf/$\textrm{mm}^2$) is slightly less than that of matrixes laminated by hot-pressing (212 gf/$\textrm{mm}^2$), the double-casting method was evaluated to be more efficient laminating process in MCFC matrix processing.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.2
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• pp.39-57
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• 2018

The purpose of this study was to construct an artificial intelligence model that learns and estimates the relationship between vehicle queue length and link travel time in urban areas. The vehicle queue length estimation model is modeled by three models. First of all, classify whether vehicle queue is a link overflow and estimate the vehicle queue length in the link overflow and non-overflow situations. Deep learning model is implemented as Tensorflow. All models are based DNN structure, and network structure which shows minimum error after learning and testing is selected by diversifying hidden layer and node number. The accuracy of the vehicle queue link overflow classification model was 98%, and the error of the vehicle queue estimation model in case of non-overflow and overflow situation was less than 15% and less than 5%, respectively. The average error per link was about 12%. Compared with the detecting data-based method, the error was reduced by about 39%.