• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.533-539
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• 2013

Recently, Ionic Polymer Metal Composite (IPMC) systems receive great attention in the fields of the medical and biomedical Engineering because of several merits in terms of new actuators and sensors and fuel cell materials. When the voltage is excited to IPMC system, it moves. Conversely, if there are any movement on the IPMC, the IPMC has charge voltage by the internal properties. Therefore the IPMC can be used as a motion sensor or force sensor. In this paper, we identify characteristics of the IPMC and control its movements from remote locations by the smart-phone system based on visual information for monitoring. Additionally, control of movements of the IPMC is realized by transmit motion commands using the smart-phone system with the blue-tooth communication. Unfortunately, there are some deficiencies to perfectly attain physical properties of the IPMC systems from our experiments in this paper. However, in its utilization point of view, we demonstrate that the IPMC has some potentials as new sensors, actuators, and fuel cells.

• Macromolecular Research
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• v.14 no.5
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• pp.573-578
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• 2006

Three different, polymer-platinum conjugates (hydrogels, microparticles, and nanoparticles) were synthesized by complexation of cis-dichlorodiammineplatinum(II) (cisplatin) with partially succinylated glycol chitbsan (PSGC). Succinic anhydride was used as a linker to introduce cisplatin to glycol chitosan (GC). Succinylation of GC was investigated systematically as a function of the molar ratio of succinic anhydride to glucosamine, the methanol content in the reaction media, and the reaction temperature. By controlling the reaction conditions, water-soluble, partially water-soluble, and hydrogel-forming PSGCs were synthesized, and then conjugated with cisplatin. The complexation of cisplatin with water-soluble PSGC via a ligand exchange reaction of platinum from chloride to the carboxylates induced the formation of nano-sized aggregates in aqueous media. The hydrodynamic diameters of PSGC/cisplatin complex nano-aggregates, as determined by light scattering, were 180-300 nm and the critical aggregation concentrations (CACs), as determined by a fluorescence technique using pyrene as a probe, were $20-30{\mu}g/mL$. The conjugation of cisplatin with partially water-soluble PSGC, i.e., borderline between water-soluble and water-insoluble PSGC, produced micro-sized particles $<500{\mu}m$. Cisplatin-complexed PSGC hydrogels were prepared from water-insoluble PSGCs. All of the cisplatin-incorporated, polymer matrices released platinum in a sustained manner without any significant initial burst, suggesting that they may all be useful as slow release systems for cisplatin. The release rate of platinum increased with the morphology changes from hydrogel through microparticle to nanoparticle systems.

• Polymer(Korea)
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• v.33 no.3
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• pp.248-253
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• 2009

Blend films based on the poly($\varepsilon$-caprolactone) (PCL) and amphiphilic biodegradable polymer, poly(ethylene glycol) grafted poly($\varepsilon$-caprolactone) (PCL-g- PEG), were prepared with different blend ratios in order to develop new biomedical material. PCL was the main component in the blend. The miscibility and characteristics of the blends were investigated. The crystallization temperature of the blend shifted to high temperatures with an increase of the graft copolymer contents when the homopolymer PCL was the main component of the blend. The PEG side chain in the blend affected the crystallization rate of the PCL crystals in the blend and alternating extinction bands were observed by optical microscopy. The protein adhesion behavior of the film was influenced by the water uptake of the film.

• Journal of Biomedical Engineering Research
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• v.25 no.1
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• pp.1-4
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• 2004

On the background of general idea and technique of bioscience, medicine and engineering, tissue engineering aim at maintenance, improvement and repair of human body function through manufacturing and transplantation of artificial tissue and organ exchangeable human body. Basic material used in the area is scaffold that aid tissue and organ formation. Making scaffold, solvent-casting and particulate leaching technique is widely used in manufacturing of porous polymer scaffold. There are many types of particle including salt and gelatin. Salt is a most commonly used particulate because it is easily available and very easy to handle and gelatin particle is another candidate for this method because it is known as a material, which enhances cell attachment and proliferation. But there is no comparative study of two kinds of materials. In this study we compared the biocompatibility of the two scaffolds made from salt(salt scaffold) and gelatin particle (gelatin scaffold). These results demonstrated that gelatin scaffold showed better attachment of cells at the initial stage and better proliferation of cells. The better performance of gelatin scaffold is contributed to the better connection of pores in the same porosity.

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.85-92
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• 1996

A monoleaflet polymer artificial heart valve which showed the remarkable improvement in pressure drop compared with other types of artificial valve was designed to minimize the deflection in vertical direction and the displacement of the valve tip in horizontal direction obtained by using finite element method as the location of the supporting members of the valve frame changed stress distribution change was also studied on each model generated by changing the distance between the frame and supporting members. It was found that by using the valve tip horizontal displacement the minimum valve thickness could be obtained in order to prevent the gap between the valve tip and the frame wall.

• Korean Journal of Materials Research
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• v.29 no.10
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• pp.623-630
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• 2019

Because of their excellent stability and highly specific surface area, carbon based materials have received attention as electrode materials of electrical double-layer capacitors(EDLCs). Biomass based carbon materials have been studied for electrode materials of EDLCs; these materials have low capacitance and high-rate performance. We fabricated tofu based porous activated carbon by polymer dissolution reaction and KOH activation. The activated porous carbon(APC-15), which has an optimum condition of 15 wt%, has a high specific surface area($1,296.1m^2\;g^{-1}$), an increased average pore diameter(2.3194 nm), and a high mesopore distribution(32.4 %), as well as increased surface functional groups. In addition, APC has a high specific capacitance($195F\;g^{-1}$) at low current density of $0.1A\;g^{-1}$ and excellent specific capacitance($164F\;g^{-1}$) at high current density of $2.0A\;g^{-1}$. Due to the increased specific surface area, volume ratio of mesopores, and surface functional groups, the specific capacitance and high-rate performance increased. Consequently, the tofu based activated porous carbon can be proposed as an electrode material for high-performance EDLCs.

• Polymer(Korea)
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• v.33 no.5
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• pp.469-476
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• 2009

In this study, biodegradable superporous hydrogels(SPHs) with fast swelling and superabsorbent properties were prepared using biodegradable crosslinkers and their physicochemical properties were characterized. A biodegradable crosslinker (PLA-PEG-PLA DA) was synthesized by a ring opening polymerization of D,L-lactide (LA) using hydrophilic poly(ethylene glycol) as a macroinitiator, followed by diacrylation of the end groups for the introduction of polymerizable vinyl groups. Various kinds of hydrogels with different chemical compositions were prepared and characterized in terms of swelling ratio, swelling kinetics, and biodegradation properties. The synthetic results were confirmed by $^1H$-NMR, FT-IR and GPC measurements, and the porous structures of the prepared SPHs and their porosities were identified by a scanning electron microscope and mercury porosimetry, respectively. The physicochemical properties of SPHs could be controlled by varying their chemical compositions and their cytotoxicity were found to be very low by MTT assay.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.321-322
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• 2003

Poly(vinyl alcohol) (PVA) is a polymeric biomaterial that obtained by the saponification of poly(vinyl acetate) (PVAc). It has a nontoxic and water-soluble synthetic polymer, and has excellent biodegradability, biocompatibility, ability of film forming, and hydrophilic property, which is widely used in biochemical and biomedical applications.$\^$1)/ Chitosan is one of a few natural cationic polysaccharides that can be obtaiend by alkaline deacetylation of chitin which is the second most abundant polymeric material in the earth.$\^$2)/ (omitted)

• Proceedings of the Korean Society of Toxicology Conference
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• 1997.05a
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• pp.20-27
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• 1997

Chinin is the second most plentiful natural polymer. Currently, chitin and chitosan are manufactured commercially in large scale from crab and shrimp shell as fish processing waste. They is being used in many commercial application because of their various functional properties. Chitosan, in particular, is being evaluated as biomedical materials in a number of food and pharmaceutical industries. Despite their potential abilities, the perfect safety had been demonstrated until now. However, the long-term feeding with chitin was not any negative effect the body weights and serum enzymatic activities in mice. And, in rats supplied with $5\%$ of chitosan diet for 450 days, there was no changes of Ca concentration in blood, bone and other organs except for in muscle. Consequently, there was no direct toxicity of chitin and chitosan against some animals such as rat and mouse by recently reports.

• Elastomers and Composites
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• v.52 no.4
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• pp.272-279
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• 2017

The heterocoagulation of latex is a simple and useful method to fabricate various polymer nanocomposites in which a precise control of the colloid stability is essential. In this work, a multi-layered graphenes (MLGs)/poly(styrene-co-butyl acrylate) (P(S-co-BA)) nanocomposite having an excellent dispersion of MLGs was prepared via the sudden heating heterocoagulation process. The P(S-co-BA) component was obtained by emulsion polymerization. This process can effectively shorten the process and particles growth steps. The colloid stability of these dispersions was controlled by factors such as ionic charge, temperature, and reaction times. The influence of these factors on heterocoagulation was evaluated and the properties of the nanocomposites were investigated. The conductivity of the MLGs/P(S-co-BA) nanocomposites increased from -11.53 to -5.70 S/cm for an increase in MLG content from 0.01 to 5 wt%. Moreover, percolation threshold was observed in the case of 0.01 wt% MLGs.