• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.392-398
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• 2014

$Al_2O_3$-SiC composites reinforced with SiC whisker ($SiC_w$) were fabricated using three different methods. In the first, $Al_2O_3-SiC_w$ starting materials were used. In the second, $Al_2O_3-SiC_w$-SiC particles ($SiC_p$) were used, which was intended to enhance the mechanical properties by $SiC_p$ reinforcement. In the third method, reaction-sintering was used with mullite-Al-C-$SiC_w$ starting materials. After hot-pressing at $1750^{\circ}C$ and 30 MPa for 1 h, the composites fabricated using $Al_2O_3-SiC_w$ and $Al_2O_3-SiC_w-SiC_p$ showed strong mechanical properties, by which the effects of reinforcement by $SiC_w$ and $SiC_p$ were confirmed. On the other hand, the mechanical properties of the composite fabricated by reaction-sintering were found to be inferior to those of the other $Al_2O_3$-SiC composites owing to its relatively lower density and the presence of ${\gamma}-Al_2O_3$ and ${\gamma}-Al_{2.67}O_4$. The greatest hardness and $K_{1C}$ were 20.37 GPa for the composite fabricated using $Al_2O_3-SiC_w$, and $4.9MPa{\cdot}m^{1/2}$ using $Al_2O_3-SiC_w-SiC_p$, respectively, which were much improved over those from the monolithic $Al_2O_3$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.6
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• pp.258-263
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• 2008

The fine aggregates of below 2 mm size was fabricated using by the vertical furnace in which the aggregates could be sintered at floating state and its physical properties were analyzed. The liquid formed at the surface of specimens sintered at $1200{\sim}l300^{\circ}C$ induced a gas in core to expand so the denser shell and porous core could be produced. The C series specimen fabricated by crushing an extruded body had an irregular shape and sharp edges but those became spheroidized by bloating due to gas expansion inside. The fine aggregates fabricated in this study was as light as floating in the water and had an apparent density of $0.68{\sim}1.08$. The absorption rate was proportioned to a porosity showing that the pores in core was not closed completely. The properties of fine aggregates fabricated in vertical furnace were similar with those of in an electric muffle furnace but the sticking-together phenomenon by surface fusion was not occurred in the vertical furnace. The aggregates fabricated in this study had a little lower impact resistance than that of natural aggregate but satisfied the unit volume weight standard specified in KS.

• Fashion & Textile Research Journal
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• v.22 no.3
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• pp.386-398
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• 2020

This study compared dip-coating and in situ polymerization methods for the development of nanofiber-based E-textile using polypyrrole. Nanofiber webs were fabricated by electrospinning an aqueous poly (vinyl alcohol) (PVA) solution. Subsequently, the PVA nanofiber web underwent thermal treatment to improve water resistance. Dip-coating and in situ polymerization methods were used to deposit polypyrrole on the surfaces of the nanofiber web. An FE-SEM analysis was also conducted to examine specimen surface characteristics along with EDS and FT-IR that analyzed the chemical bonding between polypyrrole and specimens. The line resistance and sheet resistance of the treated specimens were measured. Finally, an electrocardiogram (ECG) was measured with textile sensors made of the polypyrrole-deposited PVA nanofiber webs. The polypyrrole-deposited PVA nanofiber webs fabricated by dip-coating dissolved in the dip-coating solution and indicated damage to the nanofibers. However, in the case of in situ polymerization, polypyrrole nanoparticles were deposited on the surface and inter-web structure of the PVA nanofiber web. The resistance measurements indicated that polypyrrole-deposited PVA nanofiber webs fabricated by in situ polymerization with an average sheet resistance of 5.3 k(Ω/□). Polypyrrole-deposited PVA nanofiber webs fabricated by dip-coating showed an average sheet resistance of 57.3 k(Ω/□). Polypyrrole-deposited PVA nanofibers fabricated by in situ polymerization showed a lower line and sheet resistance; in addition, they detected the electrical activity of the heart during ECG measurements. The electrodes made from polypyrrole-deposited PVA nanofiber webs by in situ polymerization showed the best performance for sensing ECG signals among the evaluated specimens.

• The Journal of Advanced Prosthodontics
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• v.12 no.3
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• pp.124-130
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• 2020

PURPOSE. The aim of this in vitro study was to evaluate the effect of sintering procedures on marginal discrepancies of fixed partial metal frameworks fabricated using different sintering-based computer-aided design and computer/aided manufacturing (CAD/CAM) techniques. MATERIALS AND METHODS. Forty resin die models of prepared premolar and molar abutment teeth were fabricated using a three-dimensional (3D) printer and divided into four groups (n = 10) according to the fabrication method of metal frameworks used: HM (via hard milling), SM (via soft metal milling), L25 (via direct metal laser melting [DMLM] with a 25 ㎛ layer thickness), and L50 (via direct DMLM with a 50 ㎛ layer thickness). After the metal frameworks were fabricated and cemented, five vertical marginal discrepancy measurements were recorded in each site (i.e., buccal, facing the pontic, lingual, and facing away from the pontic) of both abutment teeth under a stereomicroscope (×40). Data were statistically analyzed at a significance level of 0.05. RESULTS. No statistically significant differences (P>.05) were found among the four axial sites of metal frameworks fabricated by sintering-based CAD/CAM techniques. The HM and L25 groups showed significantly (P<.001) lower marginal discrepancy values than the SM and L50 groups. CONCLUSION. Marginal discrepancy in the sites facing the pontic was not influenced by the type of sintering procedure. All fabrication methods exhibited clinically acceptable results in terms of marginal discrepancies.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.300-305
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• 2007

In this study, we have studied the fabrication and the performance evaluation of digital radiation detector of the based on selenium (a-Se) prototype which is widely researched about recently. The detector was fabricated using amorphous selenium in the specification of active area size $7{\times}8.5"$, pixel pitch $139{\mu}m$, and 12 bit ADC. In order for the performance evaluation of the fabricated detector, we used radiation quality RQA 5 that is suggested by the International Electrotechnical Commission (IEC), and evaluated modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). Concerning MTF measurement, we used slit camera (Nuclear Associates, Model : 07-624-2222), and evaluated in the slit method. Also so as to compare the performance evaluation on the detector fabricated in this study, we used Hologic Direct-Ray (DR-1000) and GE Revolution XQ/I system, and evaluated and compared in the same method MTF, NPS, and DQE which are image quality factors. And as a result, the MTF of each detector In Nyquist frequency were evaluated to be 58% (at 3.5 lp/mm) in the case of DR-1000 and 65% (at 2.5 lp/mm) in the case of XQ/I, and that for the detector fabricated in this study was evaluated to be 36% (at 3.51 lp/mm). Also in the case of DQE(0), the detector fabricated in this study, DR-1000 of Hologic company, and XQ/I system of GE company respectively were evaluated as 36%, 32%, and 50%.

• Korean Journal of Materials Research
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• v.13 no.1
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• pp.18-23
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• 2003

Properties of Ag thick films fabricated by using low temperature curable silver pastes were investigated. Ag pastes were consisted of polymer resins and silver powders. Ag pastes were used for conductive or fixing materials between board and various electrical and electronic devices. Low temperature curable Ag pastes have some advantages over high temperature curable types. In cases of chip mounting, soldering properties were required for screen printed Ag thick films. In this study, four types of Ag pastes were fabricated with different compositions. Screen printed Ag thick films on alumina substrates were fabricated at various curing temperatures and times. Thickness, resistivity, adhesive strength and solderability of fabricated Ag thick films were characterized. Finally, Ag thick films produced using Ag pastes, sample A and B, cured at $150^{\circ}C$ for longer than 6 h and $180^{\circ}C$ for longer than 2 h, and $150^{\circ}C$ for longer than 1 h and $180^{\circ}C$ for 1 h, respectively, showed low resistivities of $10^{-4}$ $∼10^{-5}$ Ωcm and good adhesive strength of 1∼5 Mpa. Soldering properties of those Ag thick films with curing temperatures at solder of 62Sn/36Pb/3Ag were also investigated.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.518-526
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• 2006

Nanoporous alumina film was fabricated by anodization of an aluminum sheet. Highly ordered nanowellstructured and nanonets-tructured metal films were fabricated by vacuum evaporation of several metals(Al, Sn, and Co) using the anodic nanoporous alumina film as a template. In this experiment, an anodic porous alumina film with the cell size of 100 nm and the pore diameter of 60 nm was used. The resistance heating method was adopted for evaporating a desired metal, and vapor deposition was carried out under the base pressure of torr. It was founded that whether the structure fabricated by vacuum evaporation is nanowell or nanonet is dependent on the amount of deposited material. When an anodic porous alumina film with the cell size of 100 nm and the pore diameter of 60 nm was used, a nanowell-structured film was fabricated when a sufficient amount of metal was suppled to cover the surface pores. On the other hand, nanonet-structured film was fabricated bellow a half the amount of metal required for nanowell-structured film.

• Composites Research
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• v.26 no.5
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• pp.295-302
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• 2013

In this study, Al5052/CFRP composites were fabricated for an automobile component by compression molding process inside a U-channel mold. Al5052 sheet were treated by sand blasting with two different particle sizes. Accordingly, surface roughness (Ra) values of $4.25{\mu}m$ and $1.85{\mu}m$ were obtained for the treated Al5052 sheets. The effect of surface roughness of Al5052 sheets on the adhesion and mechanical properties of Al5052/CFRP composites have been evaluated. Shear lap test and 3-point bending test were conducted. Results showed that the shear load for the composite fabricated by using the treated Al5052 sheets with Ra value of $1.85{\mu}m$ and $4.25{\mu}m$ were 3 and 5 times higher than Ra value of $0.73{\mu}m$ of the composite fabricated by using the untreated sheet. The bending stress of 200MPa was obtained for the composite fabricated with untreated Al5052 sheets. The bending stress increased to 400MPa when the composite fabricated from treated sheets. However, the bending stress was not influenced by treating condition through sand blasting.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.343-343
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• 2014

We reported on the electrical, optical, structural and morphological properties fabricated by co-sputtering for use as an anode for organic solar cells (OSCs). By adjusting RF and DC power of $MoO_3$ and IZO targets during co-sputtering, we fabricated the $MoO_3$-IZO electrode with graded content of the $MoO_3$ on the IZO films. At optimized $MoO_3$ thickness of 20 nm, the $MoO_3$ graded IZO electrode showed a higher mobility ($33cm^2/V-Sec$) than directly deposited $MoO_3$ on IZO film ($26cm^2/V-Sec$). At visible range (400nm~800nm), optical transmittance of the $MoO_3$ graded IZO electrode is higher than that of directly deposited $MoO_3$ on IZO film. High mobility of $MoO_3$ graded on IZO is attributed to less interface scattering between $MoO_3$ and IZO. To investigate the feasibility of $MoO_3$ graded IZO films, we fabricated conventional P3HT:PCBM based OSCs with $MoO_3$ graded IZO as a function of MoO3 thickness. The OSC fabricated on the $MoO_3$ graded IZO anode showed a fill factor of 66.53%, a short circuit current of $8.121mA/cm^2$, an open circuit voltage of 0.592 V, and a power conversion efficiency of 3.2% comparable to OSC fabricated on ITO anode and higher than directly deposited $MoO_3$ on IZO film. We suggested possible mechanism to explain the high performance of OSCs with a $MoO_3$ graded IZO.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.3
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• pp.161-165
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• 2007

In this paper, mesoporous Pt on micro pillars Pt electrode is newly designed, fabricated, and characterized on silicon substrate for non-enzymatic electrochemical sensor micro-chip integrated with CMOS readout circuitry. The fabricated micro/nano Pt electrode has cylindrical hexangular arrayed nano Pt pores with a diameter of 3.2 nm which is formed on top of the micro pillars Pt electrode with approximately $6{\mu}m$ in diameter, $6{\mu}m$ in space, and $50{\mu}m$ in height. The measured current responses of the fabricated plane Pt, mesoporous Pt, and mesoporous Pt on the micro pillar Pt electrodes are approximately $9.9nA/mm^2,\;6.72{\mu}A/mm^2,\;and\;7.67{\mu}A/mm^2$ in 10mM glucose solution with 0.1M phosphate buffered saline (PBS) solution, respectively. In addition, the measured current responses of the fabricated plane Pt, mesoporous Pt, and mesoporous Pt on the micro pillar Pt electrodes are approximately $0.15{\mu}A/mm^2,\;0.56{\mu}A/mm^2,\;and\;0.74{\mu}A/mm^2$ in 0.1mM ascorbic acid (AA) solution with 0.1M phosphate buffered saline (PBS) solution, respectively. This experimental results show that the proposed micro/nano Pt electrode is highly sensitive and promising for CMOS integrated non-enzymatic electrochemical sensor applications. Since the micro-pillar Pt electrode can also be utilized with a micro-fluidic mixer in the sensor chip, the sensor chip can be much smaller, cheaper, and easier to be fabricated.