• Journal of dental hygiene science
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• v.5 no.3
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• pp.97-103
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• 2005

Irritation fibroma (IF) is the most common tumor-like oral lesion that is evolved by proliferation of collagen in response to chronic irritation. Oral leukoplakia (OL) is considered as precancerous lesion characterized by proliferation of epithelial cells due to chronic irritation, smoking and drinking. TGF-${\beta}1$ and EGFR are important factors that play an essential role in extracellular matrix remodeling during normal wound healing process. The epithelial reaction by chronic irritation may be connected with pathogenesis of IF and OL. In the present study, we examined the expression of TGF-${\beta}1$ and EGFR in the IF and OL using immunohistochemistry. We used 88 cases of IF, 44 cases of OL and 9 cases of normal oral mucosa as normal control. TGF-${\beta}1$ was decreased in the epithelium of IF and OL. As for EGFR, the epithelial cells revealed the increased positive expression in IF and OL. In case of OL, the Spearman correlation coefficient of TGF-${\beta}1$ and EGFR was -0.10 (p< 0.05), which showed weak correlation. In the fibrous tissue, TGF-${\beta}1$ was increased only in IF. The expression difference of TGF-${\beta}1$ and EGFR may be involved in the pathogenesis of IF and OL.

• Composites Research
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• v.26 no.1
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• pp.14-20
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• 2013

The electrospun PVDF containing CNT was made for fabricating materials of the actuator. The electrochemical and their actuating movement were evaluated for the actuator performance in the electrochemical environment. The actuator (which was fabricated by electrospinning) had some advantages, i.e., good dispersion and flexible properties. In the electrospinning process, the final product would have different forms based on different essential factors. In this work, electrospun nanofibers were aligned by using the drum-type collector, and the morphology was identified via the field emission-scanning electron microscope (FE-SEM). The uniform dispersion of CNT in PVDF nanofiber was observed by electron probe X-ray micro-analysis (EPMA) test. The results of tensile strength and electrical resistivity provided the aligned state. The electrospun CNT/PVDF nanofiber sheet on the aligned direction showed better mechanical and electrical properties than the case of the vertically-aligned direction. The efficiency and electrical capacities of electrospun CNT/PVDF nanofiber sheets were compared with the cast PVDF sheet for actuator application. Electrospun CNT/PVDF nanofiber sheet exhibited much better the case of actuator performance than cast neat PVDF actuator, due to the excellent electrical connecting areas.

• Fire Science and Engineering
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• v.28 no.5
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• pp.71-79
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• 2014

This study was performed to test the combustive properties of Medium Density Fibreboards (MDFs) treated with chemicals of the bis-(dimethylaminomethyl) phosphinic acid (DMDAP), N,N-dimethylethylenediaminomethyl-bis-phosphonic acid (DMDEDAP), piperazinomethyl-bis-phosphonic acid (PIPEABP), and methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP). MDFs were painted in three times with 15 wt% solution of the bis-(dimethylaminomethyl) phosphinic acid and alkylenediaminoalkyl-bis-phosphonic acids at the room temperature, respectively. After drying MDF treated with chemicals, combustive properties and volatile organic compounds (VOCs) contents were examined by the cone calorimeter (ISO 5660-1), test for flame retardant (NEMA Notice No. 2012034), and gas chromatography (KS M ISO 11890-2), respectively. It was indicated that the MDFs treated with chemicals showed the longer time to combustion time (CT) = (442~492) s than that of virgin plate by reducing the burning rate except for CT treated with DMDAP. In adition, the MDFs treated with chemicals showed both of the higher char area (44.33~61.33) kg/kg and char length (10.33~11.67) cm than those of virgin plate. Especially, the MDFs treated with chemicals showed the higher mean volatile organic compounds (VOCs) (0.188~0.333) g/L than that of virgin plate within the prescribed limits. Thus, It is supposed that the combustion- retardation properties were improved by the partial due to the treated chemicals in the virgin MDF.

• Polymer(Korea)
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• v.38 no.1
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• pp.74-79
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• 2014

Microfibrillated cellulose (MFC) was chemically modified with two different silane coupling agents (3-aminopropyltriethoxysilane and 3-mercaptopropyltriethoxysilane) and lauroyl chloride. The surface modification of MFC was confirmed by infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), and contact angle measurements. Composite paper was successfully prepared with surface modified MFC and polyamide (PA) fiber. The surface modification of MFC not only prevented aggregation of MFC but also improved adhesive property between PA fiber and surface modified MFC. It was impossible to prepare papers of only PA fiber because there is no binder to connect PA fibers. That is, surface modified MFC as a binder in PA fiber played a crucial role in making composite paper. Composite paper with silane modified MFC showed higher tensile strength and modulus than composite paper with lauroyl moiety modified MFC. The structure, morphology, and mechanical properties of composite paper were analyzed by scanning electron microscope (SEM) and universal testing machine (UTM).

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.437-446
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• 1993

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04a
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• pp.35-40
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• 1999

• Journal of the Korean Home Economics Association
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• v.3 no.1
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• pp.419-427
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• 1962

• Environmental engineer
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• v.21 s.211
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• pp.82-92
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• 2004

• 대한치주과학회:학술대회논문집
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• 1994.12a
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• pp.97-97
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• 1994

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2005.05a
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• pp.202-206
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• 2005