Korea Textile Development Institute

Daegu, South Korea

Korea Textile Development Institute

Daegu, South Korea
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Kim H.-J.,Kyungpook National University | Bagheri R.,Shiraz University of Medical Sciences | Kim Y.K.,Kyungpook National University | Son J.S.,Korea Textile Development Institute | Kwon T.-Y.,Kyungpook National University
Materials | Year: 2017

This study investigated the influence of curing mode (dual- or self-cure) on the surface energy and sorption/solubility of four self-adhesive resin cements (SARCs) and one conventional resin cement. The degree of conversion (DC) and surface energy parameters including degree of hydrophilicity (DH) were determined using Fourier transform infrared spectroscopy and contact angle measurements, respectively (n = 5). Sorption and solubility were assessed by mass gain or loss after storage in distilled water or lactic acid for 60 days (n = 5). A linear regression model was used to correlate between the results (%DC vs. DH and %DC/DH vs. sorption/solubility). For all materials, the dual-curing consistently produced significantly higher %DC values than the self-curing (p < 0.05). Significant negative linear regressions were established between the %DC and DH in both curing modes (p < 0.05). Overall, the SARCs showed higher sorption/solubility values, in particular when immersed in lactic acid, than the conventional resin cement. Linear regression revealed that %DC and DH were negatively and positively correlated with the sorption/solubility values, respectively. Dual-curing of SARCs seems to lower the sorption and/or solubility in comparison with self-curing by increased %DC and occasionally decreased hydrophilicity. © 2017 by the authors.


Son J.S.,Korea Textile Development Institute | Jang S.H.,Korea Textile Development Institute | Kwon T.-Y.,Kyungpook National University | Kim K.-H.,Kyungpook National University | And 2 more authors.
Materials Letters | Year: 2014

This paper studied the production and properties of bioceramics bone graft substitutes from duck beak bone, as a natural source. Duck beak bone particles were fabricated by de-fatting, followed by heat-treatment at 1000 C for 3 h in an air atmosphere. It was confirmed that heat-treated beak bone particles were highly porous in their structure, with a rough surface, and the Ca/P atomic ratio value was 1.65, similar to that of human bone. In addition, the heat-treatment process of beak bone particles resulted in single phase hydroxyapatite (HA) with high crystallinity. In vivo performance of beak bone particles using rat calvarial defects showed a significantly higher bone volume than that of bovine bone particles at 4 weeks post implantation. This study demonstrated that duck beak bones can be prepared as economical bone graft substitutes of natural, biological origin HA. © 2014 Elsevier B.V.


Lee M.-H.,Kyungpook National University | Son J.S.,Korea Textile Development Institute | Kim K.-H.,Kyungpook National University | Kwon T.-Y.,Kyungpook National University
Materials | Year: 2015

This in vitro study was conducted to evaluate the shear bond strength of "non-self-adhesive" resin to dental zirconia etched with hydrofluoric acid (HF) at room temperature and to compare it to that of air-abraded zirconia. Sintered zirconia plates were air-abraded (control) or etched with 10%, 20%, or 30% HF for either 5 or 30 min. After cleaning, the surfaces were characterized using various analytical techniques. Three resin cylinders (Duo-Link) were bonded to each treated plate. All bonded specimens were stored in water at 37 °C for 24 h, and then half of them were additionally thermocycled 5000 times prior to the shear bond-strength tests (n = 12). The formation of micro- and nano-porosities on the etched surfaces increased with increasing concentration and application time of the HF solution. The surface wettability of zirconia also increased with increasing surface roughness. Higher concentrations and longer application times of the HF solution produced higher bond-strength values. Infiltration of the resin into the micro- and nano-porosities was observed by scanning electron microscopy. This in vitro study suggests that HF slowly etches zirconia ceramic surfaces at room temperature, thereby improving the resin-zirconia bond strength by the formation of retentive sites. © 2015 by the authors; licensee MDPI, Basel, Switzerland.


Lee M.-H.,Kyungpook National University | Min B.K.,Yeungnam University | Son J.S.,Korea Textile Development Institute | Kwon T.-Y.,Kyungpook National University
Materials | Year: 2016

This in vitro study investigated whether different storage conditions of plasma-treated zirconia specimens affect the shear bond strength of veneering porcelain. Zirconia plates were treated with a non-thermal atmospheric argon plasma (200 W, 600 s). Porcelain veneering (2.38 mm in diameter) was performed immediately (P-I) or after 24 h storage in water (P-W) or air (P-A) on the treated surfaces (n = 10). Untreated plates were used as the control. Each group was further divided into two subgroups according to the application of a ceramic liner. All veneered specimens underwent a shear bond strength (SBS) test. In the X-ray photoelectron spectroscopy (XPS) analysis, the oxygen/carbon ratios of the plasma-treated groups increased in comparison with those of the control group. When a liner was not used, the three plasma-treated groups showed significantly higher SBS values than the control group (p < 0.001), although group P-A exhibited a significantly lower value than the other two groups (p < 0.05). The liner application negatively affected bonding in groups P-I and P-W (p < 0.05). When the veneering step was delayed after plasma treatment of zirconia, storage of the specimens in water was effective in maintaining the cleaned surfaces for optimal bonding with the veneering porcelain. © 2015 by the authors.


PubMed | Chonnam National University, Korea Textile Development Institute, Chungbuk National University and Seoul National University
Type: | Journal: BioMed research international | Year: 2015

The aim of this study was to evaluate the bone regeneration of hydroxyapatite (HA)/alumina bilayered scaffold with a 3mm passage-like medullary canal in a beagle tibia model. A porous HA/alumina scaffold was fabricated using a polymeric template-coating technique. HA/alumina scaffold dimensions were 10mm in outer diameter, 20mm in length, and with either a 3mm passage or no passage. A 20mm segmental defect was induced using an oscillating saw through the diaphysis of the beagle tibia. The defects of six beagles were filled with HA/alumina bilayered scaffolds with a 3mm passage or without. The segmental defect was fixated using one bone plate and six screws. Bone regeneration within the HA/alumina scaffolds was observed at eight weeks after implantation. The evaluation of bone regeneration within the scaffolds after implantation in a beagle tibia was performed using radiography, computerized tomography (CT), micro-CT, and fluorescence microscopy. New bone successfully formed in the tibia defects treated with 3mm passage HA/alumina scaffolds compared to without-passage HA/alumina scaffolds. It was concluded that the HA/alumina bilayered scaffold with 3mm passage-like medullary canal was instrumental in inducing host-scaffold engraftment of the defect as well as distributing the newly formed bone throughout the scaffold at 8 weeks after implantation.


Pant H.R.,Chonbuk National University | Pant H.R.,Tribhuvan University | Nam K.-T.,Chonbuk National University | Oh H.-J.,Chonbuk National University | And 4 more authors.
Journal of Colloid and Interface Science | Year: 2011

In this work, different fractions of solvent-induced polymer degraded solution were mixed with freshly prepared solution of same polymer, and its effect on fiber morphology of electrospun mats was investigated. Nylon-6 solution in formic acid was allowed to degrade for 3. weeks and different fractions of it were mixed with freshly prepared nylon-6 solution to get the electrospun mats. FE-SEM images of the mats indicated that the a large amount of sub-nanofibers (<50. nm in diameter) in the form of spider-net like structures were achieved by tailoring the amount of solvent degraded polymer solution in the freshly prepared nylon-6 solution. Large quantity of these ultrafine sub-nanofibers present in electrospun nylon-6 mats could increase its hydrophilicity and mechanical strength. The decreased average pore diameter and increased BET surface area of the mat, caused by spider-net like structure, can make it as a potential candidate for air/water filtration. © 2011 Elsevier Inc.


Song Y.S.,Dankook University | Lee J.T.,Seoul National University | Ji D.S.,Dankook University | Kim M.W.,Seoul National University | And 2 more authors.
Composites Part B: Engineering | Year: 2012

This study examined the physical behavior of hemp/poly(lactic acid) (PLA) composites, particularly the thermal properties and viscoelastic behavior. Twill and plain woven hemp fabrics were used as reinforcements and hemp fabrics-reinforced PLA composites were produced using a film stacking method. The coefficient of thermal expansion of the composites decreased sharply with increasing the volume fraction of fiber. The twill structure was found to be suitable for reinforcing a PLA resin with higher impact strength and better mechanical properties than the plain woven. The viscoelastic properties of the composites including the storage modulus, loss modulus and loss tangent were also examined by dynamic mechanical analysis. In addition, morphological analysis was performed using scanning electron microscopy. © 2011 Elsevier Ltd. All rights reserved.


Ko Y.-I.,Shinshu University | Lee Y.,Korea Textile Development Institute | Devarayan K.,Chonbuk National University | Kim B.-S.,Chonbuk National University | And 2 more authors.
Materials Letters | Year: 2014

The annealing effects on thermodynamic properties and shape memory behaviors of the polycaprolactone (PCL) nanofiber filaments coated with silicone elastomer (Sylgard 184) were studied. The PCL nanofiber filaments were prepared from fiber mats having different thickness at different twist numbers via a twisting process. The thermodynamic and mechanical properties were remarkably enhanced by twist number as well as annealing process. Moreover, the Sylgard-coating has played a significant role to maintain the shape of each PCL nanofibers even above the melting point and to improve the toughness of the PCL nanofiber filaments. © 2014 Elsevier B.V.


Kim S.-J.,Yeungnam University | Shim S.-B.,Korea Textile Development Institute
Fibers and Polymers | Year: 2010

This paper is aiming to develop high shrinkable differential shrinkage and mixed fibre nylon composite yarns by applying the high shrinkable polyester manufacturing technology. The wet and dry thermal shrinkages and mechanical properties of developed nylon composite yarns are measured and discussed with processing factors in the spinning and texturing processes. And the effects of the processing factors on the physical properties of high shrinkable nylon composite yarns are investigated. For this purpose, twenty seven nylon 30d/12f SDY were prepared with variation of spinning temperature, 2nd godet roller temperature and draw ratio on the spinning machine. The optimum spinning condition which showed maximum wet thermal shrinkage and stress was determined and high shrinkable nylon 30d/12f SDY spun under this optimum condition used as a core and three kinds of regular nylon filaments used as sheath were processed on the texturing machine with variation of 1st and 2nd heater temperatures. The optimum texturing process condition was decided through analysis of dry thermal shrinkage of these core and sheath nylon filaments. Finally, high shrinkable differential shrinkage and mixed fibre nylon composite yarns were made under the optimum texturing condition on the texturing machine, its wet thermal shrinkage was 13. 8 %, which was much more higher than that of regular nylon composite yarns. The differential shrinkage effect of the developed nylon composite yarns was found in the yarn surface and cross section profiles by microscope and SEM. © 2009 The Korean Fiber Society and Springer Netherlands.


Lee S.H.,Korea Textile Development Institute | Song Y.S.,Dankook University
Journal of Composite Materials | Year: 2013

The morphological and physical properties of poly(lactic acid) composites reinforced by woven hemp fabrics pre-treated with enzyme and ammonia were investigated in this study. During the preparation procedure of the poly(lactic acid)/hemp composites, enzyme and ammonia treatments were applied to the surface of woven hemp fabrics in order to improve the interfacial adhesion between hemp fibers and poly(lactic acid) resin. The mechanical and morphological properties of poly(lactic acid)/hemp composites were examined via Instron measurement and scanning electron microscopic observation. Furthermore, the thermal shrinkage and flame-retardant properties of the composites were analyzed to understand the effect of the pre-treatment. © 2012 The Author(s).

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