• Polymer(Korea)
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• v.36 no.4
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• pp.413-419
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• 2012

Multi-functional urethane acrylate monomers as the curing agent of poly(phenylene ether) (PPE) were synthesized and then the urethane bond formation was checked by FTIR spectrometry and NMR analysis. The synthesized monomers were mixed with PPE and fabricated to dielectric substrates. After forming PPE/monomer composite sheets by a film coater, several sheets were laminated to a test substrate in a vacuum laminator and then its properties depending on the type and the amount of monomers, such as dielectric constant, dielectric loss, and peel strength, were measured. Between the two different hydroxyl acrylates, when the monomer synthesized with 2-hydroxy-3-phenoxypropyl acrylate containing a phenyl group was used as a curing agent, a smaller dielectric loss was obtained and the dielectric constant and loss decreased with a decrease in the amount of the monomer. The peel strength values of the test substrates, however, did not show any specific difference between the cases of two synthesized monomers. As a result, it was obtained the polymer substrate for high frequency application having peel strength of about 10 N, low dielectric constant of 2.54, and low dielectric loss of 0.0027 at 1 GHz.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.212-218
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• 2019

To investigate the effect of the oxyfluorination of carbon nanotubes (OF-CNTs) on electroless Ni deposition and electromagnetic interference shielding efficiency (EMI SE), CNTs were treated with a mixture of oxygen and fluorine gases and sequentially deposited with nickel. These samples were then manufactured into thin films on a polyimide film to evaluate their EMI SE. The surface chemical property of OF-CNTs was investigated by X-ray photoelectron spectroscopy. From the results of thermogravimetric and scanning electron microscopic analyses, it was found that both the amount of deposited Ni and the surface morphology changed depending on oxyfluorination. Moreover, the Ni-deposited CNTs pretreated with $O_2:F_2=1:9vol%$ exhibited the maximum EMI SE as approximately 19.4 dB at 1 GHz. These results were attributed to the formation of oxygen and fluorine functional groups on the surface of CNTs due to the oxyfluorination, and the functional groups enabled to deposit a suitable amount of Ni and improve the dispersion in the deposited solution.

• Polymer(Korea)
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• v.39 no.3
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• pp.394-402
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• 2015

Modification of polyacrylonitrile (PAN) films by using hydroxylamine (HA) and hydrazine to produce hydroxyl and amine groups, respectively, and to introduce cross-linking of PAN polymers was studied. Modified PAN films obtained by HA and/or hydrazine treatment including a successive or a simultaneous process were analyzed by the degree of conversion, water and N,N'-dimethylformamide (DMF) swelling ratio, FTIR spectra, atom content, and thermal analysis data. PAN films reacted with HA showed increased hydrophilicity and low dimensional stability in water. Hydrazine treatment gave PAN films high dimensional stability of low DMF swelling. Although the DMF swelling ratio of the modified PAN films was dramatically decreased by the successive treatment of hydrazine and HA, the introduction of the hydrophilic functional groups was limited due to the cross-linking. Simultaneous treatment of HA and hydrazine was the most effective method to increase hydrophilicity of PAN films with a high dimensional stability.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.879-884
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• 2015

Printed electronics is a technology that produces electronic devices and circuits by printing functional ink on a web, which is a film-like flexible material. This technology is suitable for large-scale and high-speed mass production, and is a next-generation process technology that can fabricate electronic devices from flexible materials. As precise measurement of the positions of the web is required in order to commercialize such a printed electronics process, a measurement system with an optical encoder with a precision of micrometers had been proposed in the preceding research of this study. However, the lateral positions of the web could not be measured in the preceding research as the phenomenon of the entire web being moved in the lateral direction could not be detected. In this study, a measurement system that utilizes the differences in the amount of light reflected from the alignment patterns depending on the web positions in the lateral direction was proposed for measuring the lateral positions of the web. In addition, its reliability was verified and then the effect when measuring printed alignment patterns was analyzed by experiments.

• Polymer(Korea)
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• v.36 no.6
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• pp.816-821
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• 2012

In this study, silane-crosslinked proton exchange membranes were prepared by step-wise radiation grafting of styrene and 3-(trimethoxysilyl)propyl methacrylate (TMSPM) onto an poly(ethylene-co-tetrafluoroethylene) (ETFE) film and followed by sol-gel processing and sulfonation. The sequentially grafted films with styrene to provide the proton conductivity and TMSPM to form the crosslinked structure were prepared by different grafting order. The structural changes and thermal properties of the prepared films were investigated by FTIR and TGA, respectively. After the introduction of sulfonic acid functional groups, the distributions of sulfonic acid group and silicon atoms at the inside of the sulfonated membranes were analyzed by SEM-EDX.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.10
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• pp.986-992
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• 2007

This paper presents the fabrication and characterization of carbon films pyrolyzed with various photoresists for bioMEMS applications. To verify the usefulness of pyrolyzed carbon films as an electrode material in an electrochemical biosensor developed by the authors, interactions between avidin and biotin on the pyrolyzed carbon film were studied via electrochemical impedance spectroscopy based on electrostatic interactions between avidin and negatively-charged ferricyanide. The pyrolyzed carbon films were characterized using a surface profiler, a precision semiconductor parameter analyzer, a nanoindentor, scanning electron microscopy, and atomic force microscopy. Amine conjugated biotin was immobilized on the electrode using EDC/NHS as crosslinkers after $O_2$ plasma treatment to enhance functional groups on the carbon electrode pyrolyzed at $1000^{\circ}C$ with AZ9260. The detection of avidin binding with different concentrations in a range of 0.75 nM to $7.5\;{\mu}M$ to the pyrolyzed carbon electrode modified with biotin was carried out by measuring the electrochemical impedance change. The results show that avidin binds to the biotin on the electrode not by non-specific interaction but by specific interaction, and that EIS successfully detects this binding event. Pyrolyzed carbon films are a promising material for miniaturization, integration, and low-cost fabrication in electrochemical biosensors.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.4
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• pp.323-329
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• 2016

This paper describes an insole FFO(Functional Foot Orthosis) model for comfortable walking by considering weight distribution. There are many ways to make an insole FFO model such as using 3D computer graphics, or plaster manually. Thus, we proposed a standardized way to make an insole model, specifically called, robust and automatically personalized deformable insole model. Our proposed method showed 0.8cm average error compared between our proposed auto-deformable insole model and the other insole model manually deformed by experts. Therefore, our proposed method can be an efficient way to make a customized insole model with small error compared to the manually customized insole model.

• Radiation Oncology Journal
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• v.13 no.1
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• pp.87-94
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• 1995

Since March 1992, total 200 patients who visited our hospital as functional or organic lesions of central nervous system were treated by gamma knife stereotactic radiosurgery for 27 months. Thirty-nine patients of total cases was diagnosed as cerebral arteriovenous malformation. The rate of magnification on X-ray film was reduced by cutting fixation adaptor from 1.0 to below 1.45 times. In order to treat the deep- and lateral-seated cerebral arteriovenous malformation, we slightly modified the angiographic indicator, the commercial Leksell system, by cutting each inner sides about 5mm, We performed the more distinction of the scales by adapting 0.5mm or 1mm copper filter to angiographic indicator. The center point of indicator(X=100mm, Y=100mm, Z=100mm) is corrected by adjusting scales of X-, Y-, Z-axis to each inner 100 and outer 100 point within 1-2mm by repeated exposure of X-ray on films in trial-and-errors. We have developed the 'GKANGIO' programed as the Fortran-77 in Microvax - 3100, which can save treatment planning time and perform accurate pretreatment planning using the theoretical target metrix center. The theoretical description of the simplified method is presented for the reduction of experimental and numerical errors in treatment planning of radiosurgery.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.1
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• pp.14-20
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• 2018

Lead zinc niobate (PZN) added lead zirconate titanate (PZT) thick films with thickness of $5{\sim}10{\mu}m$ were fabricated on silicon and sapphire substrates using aerosol deposition method. The contents of PZN were varied from 0 %, 20 % and 40 %. The initial particles (PZT, 2PZN-8PZT, 4PZN-6PZT) had irregular shape and submicron sizes. The as-deposited film had fairly dense microstructure without any crack, and showed only a perovskite single phase formed with nano-sized grains. The as-deposited films on silicon were annealed at the temperatures of $700^{\circ}C$, and the films deposited on sapphire were annealed at $900^{\circ}C$ in the electrical furnace. The effects of PZN addition on the microstructural evolution were observed using by FE-SEM and HR-TEM.

• Journal of Periodontal and Implant Science
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• v.30 no.3
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• pp.527-538
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• 2000

Several extraction cases with advanced bone loss as a result of periodontal disease, root or labial bone fracture, extensive caries, and periapical lesions occur esthetic, functional problems and severe bone loss. Therefore, to treat these cases used several surgical methods and socket preservation among this therapies have been evaluated simple, effective and good prognosis in the implant placement. Socket preservation therapy have been used with barrier membranes or/and graft materials. Deproteinized bovine bone mineral have been evaluated ideal grafting materials. Recently, calcium-phosphate thin film coated bovine bone powders were developed in our country, but the study for these material wasn't reported. When two types of xenograft materials were implanted in extraction sockets of Beagle dogs, the effects of these were analyzed after 4 weeks and 8 weeks histological views. The results of this study were as follows. 1. In control groups, 4 weeks after implantation, the extraction sockets were filled with connective tissue which has dilated vessels and epithelial growth. And after 8 weeks, irregular connective bundles were observed. But new bone formation was not seen. 2. In Bio-Oss groups, epithelial growth was not seen and bone powder was covered with connective tissue fiber. New bone formation was found around the interproximal bone. There was no special change seen after 8 weeks, connective tissue fibers became more regular, and bone growth near bone powder was not made well. 3. In Ca-P BBP groups, epithelial cells didn't grow in the extraction sockets, there was a lot of new bone made around the bone powder after 8 weeks, new bone around bone powder was replaced with mature bone. It is thought that bone powder grafting into the extraction sockets is very useful for conservation of ridge, and Ca-P BBP is more effective in bone formation than Bio-Oss.