• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.130-131
• /
• 2008

Chalcogenide glass has been known for many photo induced phenomena and superial electron / optical specific by structure flexibility, unique electronic configuration. It is become known to the greatest specific as photonic material medium that possible to perfect controlling by continuity and photo inducing direction of amorphous chalcogenide. In our experiment, we choose the amorphous As-Ge-Se-S and coming glass as a substrate. And then we have evaporated in the ${\sim}2{\times}10^{-6}$ Torr using a E-beam evaporator, completed thin film sample that have 1um thickness of As-Ge-Se-S 600 $\AA$, 10~5 $\AA$/s. At first, we let the change the angle between laser and sample by holography litho method and then, expect that satisfied conclusion which 2-dimension diffraction lattice manufacture and specifics by investing a He-Ne laser for 2000 seconds.

• Carbon letters
• /
• v.14 no.3
• /
• pp.186-189
• /
• 2013

We report a highly sensitive $NO_2$ gas sensor based on multi-layer graphene (MLG) films synthesized by a chemical vapor deposition method on a microheater-embedded flexible substrate. The MLG could detect low-concentration $NO_2$ even at sub-ppm (<200 ppb) levels. It also exhibited a high resistance change of ~6% when it was exposed to 1 ppm $NO_2$ gas at room temperature for 1 min. The exceptionally high sensitivity could be attributed to the large number of $NO_2$ molecule adsorption sites on the MLG due to its a large surface area and various defect-sites, and to the high mobility of carriers transferred between the MLG films and the adsorbed gas molecules. Although desorption of the $NO_2$ molecules was slow, it could be enhanced by an additional annealing process using an embedded Au microheater. The outstanding mechanical flexibility of the graphene film ensures the stable sensing response of the device under extreme bending stress. Our large-scale and easily reproducible MLG films can provide a proof-of-concept for future flexible $NO_2$ gas sensor devices.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.7 no.3
• /
• pp.166-176
• /
• 2007

Radio frequency (RF) microelectromechanical systems (MEMS) have been pursued for more than a decade as a solution of high-performance on-chip fixed, tunable and reconfigurable circuits. This paper reviews our research work on RF MEMS switches and switching circuits in the past five years. The research work first concentrates on the development of lateral DC-contact switches and capacitive shunt switches. Low insertion loss, high isolation and wide frequency band have been achieved for the two types of switches; then the switches have been integrated with transmission lines to achieve different switching circuits, such as single-pole-multi-throw (SPMT) switching circuits, tunable band-pass filter, tunable band-stop filter and reconfigurable filter circuits. Substrate transfer process and surface planarization process are used to fabricate the above mentioned devices and circuits. The advantages of these two fabrication processes provide great flexibility in developing different types of RF MEMS switches and circuits. The ultimate target is to produce more powerful and sophisticated wireless appliances operating in handsets, base stations, and satellites with low power consumption and cost.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.31 no.1 s.160
• /
• pp.77-84
• /
• 2007

The purpose of this study was to investigate and to compare the performances of silicone laminated materials sold for swimming cap in market, to get the basic data for product development. We selected 4 specimens and tested their air permeability, waterproofness and breathability. We also tested the physical and mechanical properties of the specimens using KES system. Silicone-laminated material was not bursted on high hydraulic pressure since silicone membrane gave waterproofness while PU/Polyester substrate gave elasticity. It didn't have air permeability and breathability at all. Any toxic materials such as Formaldehyde, Deldrin, PCP, Amin, TDBPP were not detected in silicone-laminated material and other materials. Silicone-laminated material had higher stretchability with the low force but it had lower elastic recovery and shape stability comparing to PU laminated material. It had lower flexibility than PU laminated material. It had lower unrecoverable amount in shearing direction. Friction coefficient was higher in silicone-laminated material than PU laminated material due to its surface stickiness. It was compressed easily and its compression resiliency was higher with compared to PU laminated material.

• International Journal of Precision Engineering and Manufacturing-Green Technology
• /
• v.5 no.5
• /
• pp.643-650
• /
• 2018

A self-powered electrochromic device was fabricated on an indium tin oxide-polyethylene naphthalate flexible substrate using a dye-sensitized solar cell (DSSC) as a self-harvesting source; the electrochromic device was naturally bleached and operated under outdoor light conditions. The color of the organic electrochromic polymer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, was shifted from pale blue to deep blue with an antimony tin oxide film as a charge-balanced material. Electrochromic performance was enhanced by secondary doping using dimethyl sulfoxide. As a result, the device showed stable switching behavior with a high transmittance change difference of 40% at its specific wavelength of 630 nm for 6 hrs. To improve the efficiency of the solar cell, 1.0 wt.% of Ag NWs in the photoanode was applied to the $TiO_2$ photoanode. It resulted in an efficiency of 3.3%, leading to an operating voltage of 0.7 V under xenon lamp conditions. As a result, we built a standalone self-harvesting electrochromic system with the performance of transmittance switching of 29% at 630 nm, by connecting with two solar cells in a device. Thus, a self-harvesting and flexible device was fabricated to operate automatically under the irradiated/dark conditions.

• Journal of Convergence for Information Technology
• /
• v.12 no.2
• /
• pp.127-133
• /
• 2022

Two types of charged particle-type electronic paper display panels with electrodes using ITO and CNT are fabricated to compare durability and electro-optical characteristics. The sheet resistance of the ITO electrode is 10 (ohm/sq.), and the sheet resistance of the CNT electrode is 300, 600, 1000 (ohm/sq.), and durability is carried out by impact and flexibility measurements. Variation in case of the ITO electrode begins at shocks of 40 times and curvature radius of 10 mm, and no change is observed in the CNT electrode. The driving voltage, electric field required for particle movement, reflectivity, and response time measurements show similar results for all ITO and CNT electrodes.

• Journal of the Korean Chemical Society
• /
• v.38 no.4
• /
• pp.295-301
• /
• 1994

The Ru(Ⅲ), Ni(Ⅱ), Cu(Ⅱ), and Pd(Ⅱ) complexes of N$_4$-polydentate ligands(meso-Me$_6$-[14]-ane, rac-Me$_6$-[14]-ane, and cyclam) have been prepared and their catalytic activity and selectivity in the oxidation of olefins in the presence of oxidant such as NaOCl, H$_2$O$_2$, t-BuOOH, and PhIO studied. The oxidations of cyclohexene, 1-hexene, cyclooctene, 1-octene, and styrene as substrates have been investigated gas chromatographically. The Ru(Ⅲ)-N$_4$ complexes showed high selectivity for epoxide in the catalyzed oxidation of olefins with NaOCl. The catalytic activities of Ru(Ⅲ)-N$_4$ complexes were discussed in terms of the flexibility of N$_4$-polydentate ligands, the Ru(Ⅲ)-Cl bond interaction and the steric effect of oxidants. The oxidation of 1-octene using PhIO as oxidant was carried out to verify. The Pd(Ⅱ) complex turned out to be more active catalyst than the Ni(Ⅱ) complexes.

• Membrane Journal
• /
• v.24 no.6
• /
• pp.463-471
• /
• 2014

While poly(styrene)-based anion exchange membranes have the advantage like easy and simple manufacturing process, they also possess the disadvantage of poor durability due to their brittleness. Acrylonitrile-butadiene rubber was used here as an additive to make the membranes have improved flexibility and durability. For the preparation of the anion exchange membranes, a PP mesh substrate was immersed into monomer solutions with vinylbenzyl chloride, styrene, divinylbenzene and benzoyl peroxide, then thermally polymerized & crosslinked. The prepared membranes were subsequently post-aminated using trimethylamine to result in $-N+(CH_3)_3$ group-containing composite membranes. Various contents of vinylbenzyl chloride and acrylonitrile-butadiene rubber were investigated to optimize the membrane properties and the prepared membranes were evaluated in terms of water content, ion exchange capacity and electric resistance. It was found that the optimized composite membranes showed higher IEC and lower electric resistance than a commercial anion exchange membrane(AMX) and have excellent flexibility and durability.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 2002.10a
• /
• pp.18-25
• /
• 2002

The pikromycin biosynthetic system in Streptomyces venezuleae is unique for its ability to produce two groups of antibiotics that include the 12-membered ring macrolides methymycin and neomethymycin, and the 14-membered ring macrolides narbomycin and pikromycin. The metabolic pathway also contains two post polyketide-modification enzymes, a glycosyltransferase and P450 hydroxylase that have unusually broad substrate specificities. In order to explore further the substrate flexibility of these enzymes a series of hybrid polyketide synthases were constructed and their metabolic products characterized. The plasmid-based replacement of the multifunctional protein subunits of the pikromycin PKS in S. venezuelae by the corresponding subunits from heterologous modular PKSs resulted in recombinant strains that produce both 12- and 14-membered ring macrolactones with predicted structural alterations. In all cases, novel macrolactones were produced and further modified by the DesVII glycosyltransferase and PikC hydroxylase leading to biologically active macrolide structures. These results demonstrate that hybrid PKSs in S. venezuelae can produce a multiplicity of new macrolactones that are modified further by the highly flexible DesVII glycosyltransferase and PikC hydroxylase tailoring enzymes. This work demonstrates the unique capacity of the S. venezuelae pikromycin pathway to expand the toolbox of combinatorial biosynthesis and to accelerate the creation of novel biologically active natural products. The polyketide backbone of rifamycin B is assembled through successive condensation and ${\beta}$-carbonyl processing of the extender units by the modular rifamycin PKS. The eighth module, in the RifD protein, contains nonfunctional DH domain and functional KR domain, which specify the reduction of the ${\beta}$-carbonyl group resulting in the C-21 bydroxyl of rifamycin B. A four amino acid substitution and one amino acid deletion were introduced in the putative NADPH binding motif in the proposed KR domain encoded by rifD. This strategy of mutation was based on the amino acid sequences of the corresponding motif of the KR domain of module 3 in the RifA protein, which is believed dysfunctional, so as to introduce a minimum alteration and retain the reading frame intact, yet ensure loss of function. The resulting strain produces linear polyketides, from tetraketide to octaketide, which are also produced by a rifD disrupted mutant as a consequence of premature termination of polyketide assembly. Much of the structural diversity within the polyketide superfamily of natural products is due to the ability of PKSs to vary the reduction level of every other alternate carbon atom in the backbone. Thus, the ability to introduce heterologous reductive segments such as ketoreductase (KR), dehydratase (DH), and enoylreductase (ER) into modules that naturally lack these activities would increase the power of the combinatorial biosynthetic toolbox. The dehydratase domain of module 7 of the rifamycin PKS, which is predicted to be nonfunctional in view of the sequence of the apparent active site, was replaced with its functional homolog from module 7 of rapamycin-producing polyketide synthase. The resulting mutant strain behaved like a rifC disrupted mutant, i.e., it accumulated the heptaketide intermediate and its precursors. This result points out a major difficulty we have encountered with all the Amycolatopsis mediterranei strain containing hybrid polyketide synthases: all the engineered strains prepared so far accumulate a plethora of products derived from the polyketide chain assembly intermediates as major products instead of just analogs of rifamycin B or its ansamycin precursors.

• Tribology and Lubricants
• /
• v.32 no.3
• /
• pp.75-81
• /
• 2016

Future electronics such as electronic paper and foldable cellphone are required to be flexible and transparent and should have a high performance. In order to fabricate the flexible electronics using flexibility transfer process, techniques for transferring various devices from rigid substrate onto flexible substrate by elastomeric stamp, have been developed. Adhesion between the elastomeric stamp and various devices is crucial for successful transfer process. The adhesion can be controlled by the thickness of the stamp, separation velocity, contact load, and stamp surface treatment. In this study, we fabricated the bump shape stamp consisting of a UV-curable polymer and investigated the effects of curing condition, separation velocity, and contact load on the adhesion characteristics of bumps. The bumps with hemispherical shape were fabricated using a dispensing process, which is one of the ink-jet printing techniques. Curing conditions of the bumps were controlled by the amount of UV irradiation energy. The adhesion characteristics of bumps are evaluated by adhesion test. The results show that the pull-off forces of bumps were increased and decreased as UV irradiation energy increased. For UV irradiation energies of 300 and 500 mJ/cm², the pull-off forces were increased as the separation velocity increased. The pull-off forces also increased with the increase of contact load. In the case of UV irradiation energy above 600 mJ/cm², however, the pull-off forces were not changed. Therefore, we believe that the bump shape stamp can be applied to roll-based transfer process and selective transfer process as an elastomeric stamp.