• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.52-55
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• 2003

Poly (ethylene 2, 6-naphthalate) (PEN) has been used for a high performance engineering plastics such as fiber, film, and packaging, because of excellent physical properties and outstanding gas barrier characteristics [1-2]. However, the application of PEN is limited because PEN exhibits a relatively high melt viscosity. Recently, many researches for organic/inorganic composites by applying nano-particles to the polymer matrix have been carried out [3], and the nano-particles exhibited greatly improved mechanical and rheological properties [4]. (omitted)

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 The Korea-Japan Joint Symposium
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• pp.65-66
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• 2003

Ternary blend fibers (TBFs) based on melt blends of PEN, PET, and TLCP were prepared by melt blending and spinning to achieve high performance fibers. The reinforcement effect and the TLCP fibrillar structure resulted in the improvement of mechanical properties for TBFs. Molecular orientation was an important factor in determining the tensile strength and modulus of TBFs. Another part of this research is silica nano-particle filled PEN composites were melt-blended to improve mechanical and physicalproperties, and processability. The tensile modulus and strength were improved adding silica nano-particles to the PEN. The decreased melt viscosity by the fumed silica resulted in the improvement of the processability. The fumed silica may act as a nucleating agent in the PEN matrix.

• 한국경영과학회지
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• 제13권1호
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• pp.51-64
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• 1988

A new approach to the logical design of 4NF database shceme, which can be easily automated, is proposed. The main features of the approach are : introduction of a single attribute right hand side, extension of the concept of independent relations, semantic analysis, and adaoption of dependency matrix. The underlying viewpoints of functional relationships of the approach are different from Fagin's in that we distinguish functional and multivalued dependency in terms of cardinality. An algorithm for automatic generation of fourth normal form is presented and implemented.

• Macromolecular Research
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• 제17권12호
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• pp.995-1002
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• 2009

Luminescent polynorbornene (PNB)/quantum dot (CdSe@ZnS; QD) composite nanorods and nanotubes were successfully prepared using anodic aluminum oxide (AAO) membranes of various pore sizes as templates. To protect QDs with high quantum yield from quenching during the phosphoric acid treatment used to remove the AAO templates, chemically stable and optically clear norbornene-maleic anhydride copolymers (P(NB-r-MA)) were employed as a capping agent for QDs. The amine-terminated QDs reacted with maleic anhydride moieties in P(NB-r-MA) to form PNB-grafted QDs. The chemical- and photo-stability of QDs encapsulated with PNB copolymers were investigated by photoluminescence (PL) spectroscopy. By varying the pore size of the AAO templates from 40 to 380 urn, PNB/QD composite nanorods or nanotubes were obtained with a good dispersion of QDs in the PNB matrix.

• Carbon letters
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• 제1권3_4호
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• pp.138-142
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• 2001

The effect of electrochemical surface treatments in KOH chemical solution on microstructures of carbon blacks was investigated in terms of surface functional values and XRD measurements. And their mechanical interfacial properties of the carbon blacks/rubber composites were studied by the composite tearing energy ($G_{IIIC}$). It was found that the development of basic-surface functional groups lead to the significant physical changes of carbon blacks, such as, decrease of the interlayer spacing ($d_{002}$), increase of the crystalline size along c-axis ($L_c$), and increase of degree of crystalline (${\chi}_c$). This treatment is possibly suitable for carbon blacks to be incorporated in a hydrocarbon rubber matrix, resulting in improving the hardness and tearing energy of the resulting composites.

• Carbon letters
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• 제4권2호
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• pp.69-73
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• 2003

In this work, the effect of a direct oxyfluorination on surface and mechanical interfacial properties of PAN-based carbon fibers is investigated. The changes of surface functional groups and chemical composition of the oxyfluorinated carbon fibers are determined by FT-IR and XPS measurements, respectively. ILSS of the composites is also studied in terms of oxyfluorination conditions. As a result, FT-IR exhibits that the carboxyl/ester groups (C=O) at 1632 $cm^{-1} and hydroxyl group (O-H) at 3450 $cm^{-1} are observed in the oxyfluorinated carbon fibers. Especially, the oxyfluorinated carbon fibers have a higher O-H peak intensity than that of the fluorinated ones. XPS result also shows that the surface functional groups, including C-O, C=O, HO-C=O, and C-$F_x$ after oxyfluorination are formed on the carbon fiber surfaces, which are more efficient and reactive to undergo an interfacial reaction to matrix materials. Moreover, the formation of C-$F_x$ physical bonding of the carbon fibers with fluorine increases the surface polarity of the fibers, resulting in increasing ILSS of the composites. This is probably due to the improvement of interfacial adhesion between fibers and matrix resins.

• Advances in nano research
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• 제2권2호
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• pp.121-133
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• 2014

Polymer nanocomposites are advanced nanomaterials which exhibit dramatic improvements in various mechanical, thermal and barrier properties as compared with the neat polymer. Polystyrene/ alumina nanocomposites were prepared by an ultrasound-assisted solution casting method at filler loadings ranging from 0.2 to 2% and also at different ultrasonic frequencies, viz. 58 kHz, 192/58 kHz, 430 kHz, 470 kHz and 1 MHz. The composites were subjected to mechanical property tests (tensile and impact tests) and cavitation erosion tests to study the enhancement in functional properties. Filler dispersion in the polymer matrix was observed by SEM analysis. The effect of frequency on filler dispersion in the matrix was studied by SEM analysis and functional property enhancement of the composite material. The composites prepared at dual (high/ low) frequency (192/58 kHz) were found to show better property enhancement at low filler loadings as compared with neat polymer and also with composites prepared without ultrasound, thus reinforcing the finding that ultrasound-assisted synthesis is a promising method for the synthesis of nanocomposites.

• Journal of applied mathematics & informatics
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• 제30권5_6호
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• pp.699-717
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• 2012

In this paper, we deal with the robust mixed $H_2/H_{\infty}$ guaranteed-cost control problem involving uncertain neutral stochastic distributed delay systems. More precisely, the aim of this problem is to design a robust mixed $H_2/H_{\infty}$ guaranteed-cost controller such that the close-loop system is stochastic mean-square exponentially stable, and an $H_2$ performance measure upper bound is guaranteed, for a prescribed $H_{\infty}$ attenuation level ${\gamma}$. Therefore, the fast convergence can be fulfilled and the proposed controller is more appealing in engineering practice. Based on the Lyapunov-Krasovskii functional theory, new delay-dependent sufficient criteria are proposed to guarantee the existence of a desired robust mixed $H_2/H_{\infty}$ guaranteed cost controller, which are derived in terms of linear matrix inequalities(LMIs). Furthermore, the design problem of the optimal robust mixed $H_2/H_{\infty}$ guaranteed cost controller, which minimized an $H_2$ performance measure upper bound, is transformed into a convex optimization problem with LMIs constraints. Finally, two simulation examples illustrate the design procedure and verify the expected control performance.

• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1366-1370
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• 2004

Controlled pore glass bead was modified with bovine serum albumin (BSA), and glutathione (GSH) was immobilized through three kinds of linkers on top of BSA. Bis(3-sulfo-N-hydroxysuccinimide suberate) sodium salt $(BS^3)$, N-hydroxysuccinimide 3-(2-pyridyldithio)propionate (SPDP), or N-hydroxysuccinimide 4-maleimidobutyrate (GMBS) was introduced into the BSA-bound matrix. Subsequently, GSH was immobilized by addition of thiol side chain into the maleimido moiety, replacing a disulfide group, or formation of an amide group upon releasing 3-sulfo-N-hydroxysuccimide group. It was observed that conjugation methodology played a critical role for activity of the immobilized GSH. SDS-PAGE chromatogram showed that the matrix of glutathione immobilized on BSA through GMBS manifested high selectivity towards glutathione-S-transferase (GST) in cell lysate.

• 대한화장품학회지
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• 제46권2호
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• pp.147-157
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• 2020

서해안에 서식하는 해양생물인 전복은 항산화 및 항염증 효과가 있으며, 항생제 개발 및 화장품 원료 등 다양한 산업에 활용될 수 있는 잠재력을 가진 자원이다. 본 연구에서 우리는 서해안의 다양한 해양 생물 중에서 전복을 선택하였으며, 전복에서 분리한 항균펩타이드(AMP)를 이용하여 항균펩타이드 유도체인 Ab4-7를 규명하고 생리활성을 연구하였다. Ab4-7의 항염증 효능을 확인하기 위해 염증이 유도된 RAW 264.7에 Ab4-7을 처리한 결과, 염증성 사이토카인, TLR4, TNF-α, IL-1β, COX-2, iNOS 등을 억제하고 항산화와 관련된 유전인자인 HO-1의 mRNA 발현을 증가시켰다. Ab4-7의 강력한 항산화 및 항염증 효과를 바탕으로, 염증이 유도된 RAW 264.7 세포에서 Ab4-7이 extrocellular matrix metalloproteinase (ECM) 분해에 관여하여 다양한 염증성 피부질환을 유도하는 유전자인 matrix metalloproteinase (MMPs)를 조절하는 효과를 RT-PCR을 통해 확인하였다. Ab4-7은 강력한 항염증 및 항산화 효과를 가지고 있으며, 항염증 및 항산화 효과를 통한 MMPs 관련 유전인자 조절을 통해 다양한 염증성 피부질환 치료제의 기능성 재료로 활용될 수 있다고 사료된다.