• Archives of Plastic Surgery
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• v.33 no.6
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• pp.723-731
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• 2006

Purpose: Collagen is the principal structural biomolecule in cartilage extracellular matrix, which makes it a logical target for cartilage engineering. In this study, porous type I collagen scaffolds were cross-linked using dehydrothermal(DHT) treatment and/or 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide(EDC), in the presence and absence of chondroitin-6-sulfate(CS) for cartilage regeneration. Methods: Cartilage defects were created in the proximal part of the ear of New Zealand rabbits. Four types of scaffolds(n=4) were inserted. The types included DHT cross-linked(Group 1), DHT and EDC cross- linked(Group 2), CS added DHT cross-linked(Group 3), and CS added DHT and EDC cross-linked(Group 4). Histomorphometric analysis and cartilage-specific gene expression of the reconstructed tissues were evaluated respectively 4, 8, and 12 weeks after implantation. Results: The largest quantity of regenerated cartilage was found in DHT cross-linked groups 1 and 3 in the 8th week and then decreased in the 12th week, while calcification increased. Calcification was observed from the 8th week and the area increased in the 12th week. Group 4 was treated with EDC cross-linking and CS, and the matrix did not degrade in the 12th week. Cartilage-specific type II collagen mRNA expression increased with time in all groups. Conclusion: CS did not increase chondrogenesis in all groups. EDC cross-linking may prevent chondrocyte infiltration from the perichondrium into the collagen scaffold.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.372-378
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• 1998

Two types of formaldehyde-treated soy protein isolate (SPI) films, formaldehyde-incorporated and formaldehyde-adsorbed films, and control SPI films were prepared. Cross-linking effect of formaldehyde on selected film properties such as color, tensile strength (TS), elongation at break (E), water vapor permeability (WVP), and water solubility (WS) were determined. Physical properties of formaldehyde-incorporated films were not geneally different from those of control films, while almost all of those among formaldehyde-adsorbed films were significantly different. Through cross-linking development within formaldehyde-adsorbed films, WS decreased significantly (P<0.05) from 26.1% to 16.6%, and TS increased two times while E decreased two times compared with control films. This was caused by insolubilization and hardening of protein by cross-linking most likely attributed to the significant changes in properties of protein films reacted with formaldehyde.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.278-283
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• 1999

Formaldehyde has widely been used for the cross-linking of polyvinyl alcohol polyvinyl alcohol polymer. The effects of formaldehyde on the water resistance of MDF cement composites were investigated as a function of types of catalyst, base or acid, and the amount of formaldehyde. The acetalization, reaction of OH group of PVA with aldehyde, was ended incompletely under base atmosphere. However, by addition of citric acid, the cross-linking of PVA polymer could be acheved through acetalization of PVA and formaldehyde. The effects of these different patterne according to the types of catalyst on the water resistance of MDF cement were studied by the preparation of PVA films and MDF composites. Thanks to the cross-linking reaction of PVA polymer chains by formaldehyde, the modified PVA films and MDF composites showed a good water-resistant propety. The modified MDF cement composite to which 3 wt% formaldehyde and 1 wt% cirtic acid were added showed 80% of initial flexural strength and good interfacial state between cement grain and polymer matrix. However, 4 wt% formaldehyde deteriorted the processing conditions, microstructures and eventually the flexural strength, causing sharp increase in the viscosity of sample dough during the mixing process. To study the relatins of flexural strength and interface of cement grain and polymer matrix, SEM and MIP measurement were performed.

• Transactions on Electrical and Electronic Materials
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• v.11 no.2
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• pp.69-72
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• 2010

This study investigates the thermal and mechanical properties of insulation elements through the mixing of epoxy based micro and nano particles. Regarding their thermal properties, differential scanning calorimeter and dynamic mechanical analyser were used to calculate the cross-linking densities for various types of insulation elements. The mechanical properties of the bending strength, the shape and scale parameters, were obtained using the Weibull plot. This study obtained the best results in the scale parameters, at 0.5 phr, for the bending strength of the epoxy nano-and-micro mixture composites.

• English Language & Literature Teaching
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• v.10 no.1
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• pp.153-178
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• 2004

The purpose of the present study is to develop several types of English teaching/learning models in view of cross-curricular approach in Korean elementary school. Brewster(1992)' model is suitable for younger children as well as the 1st or 2nd graders. For 3rd or 4th graders, Halliwel1(1997)' model seems more proper type in Korean EFL situation. There has been studying for cross-curricular approach in elementary English education. Many studies has recently focused the characteristics of elementary students by cognitive and psychological perspectives. Among them, Park(1996)'s research talks about the elementary school students. Han(1996)'s research based on the notion of applied to other subjects. Kim(1999)'s also emphasized the importance of linking other subjects. Kim(2003) argued the need of integrating English with other subjects. The elementary education as the National Common Basic Curriculum(NCBC) has the essence of cross-curricular approach, so the English education will be linked with other subject matters more and more, not just as for Communicative function based English education but as both content and function based subject matter.

• Polymer(Korea)
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• v.25 no.1
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• pp.63-70
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• 2001

The objective of this study was to investigate the effect of cure type on the processing and physical properties under conditions of similar stress-strain properties. On the carbon black filled natural rubber(NR) based compound, the induction time decreased, but the cure rate became fast with increasing loading of sulfur donor agent. Tensile strength was little affected on the curing type. However, elongation generally decreased with increasing accelerator. Effect of cure type on the blow-out properties was followings: CV

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.185-185
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• 2001

The CD95 (Fas, APO-1) is known to play a key role as a transmembrane cell surface receptor that mediates apoptosis of many cell types through binding with Fas ligand or cross-linking to agonistic anti-Fas antibody. Activation of CD95 provokes a potent and rapid responses in a variety of cell types by unknown mechanism.(omitted)

• Archives of Plastic Surgery
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• v.34 no.4
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• pp.413-419
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• 2007

Purpose: In this study, porous type I collagen scaffolds were cross-linked using dehydrothermal(DHT) treatment and/or 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide(EDC), in the presence and absence of chondroitin-6-sulfate(CS) and cultured autologous chondrocytes(Chondro) for cartilage regeneration. Methods: Cartilage defects were created in the proximal part of the ear of New Zealand rabbits. Four prepared types of scaffolds(n=4) were inserted. The groups included Chondro-Collagen-DHT(Group 1), Chondro- Collagen-DHT-EDC(Group 2), Chondro-CS-Collagen- DHT(Group 3), and Chondro-CS-Collagen-DHT-EDC (Group 4). Histomorphometric analysis and cartilage-specific gene expression of the reconstructed tissues were evaluated 4, 8, and 12 weeks after implantation. Results: EDC cross-linked groups 2 and 4 regenerated more cartilage than other groups. However, calcification was observed in the 4th week after implantation. CS did not increase chondrogenesis in all groups. Cartilage-specific type II collagen mRNA expression increased in the course of time in all groups.Conclusion: EDC cross-linking methods maintain the scaffold and promote extracellular matrix production of chondrocytes.

• Journal of Periodontal and Implant Science
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• v.45 no.6
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• pp.229-237
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• 2015

Purpose: The aim of this study was to determine the clinical feasibility of using dehydrothermally cross-linked collagen membrane (DCM) for bone regeneration around peri-implant dehiscence defects, and compare it with non-cross-linked native collagen membrane (NCM). Methods: Dehiscence defects were investigated in twenty-eight patients. Defect width and height were measured by periodontal probe immediately following implant placement (baseline) and 16 weeks afterward. Membrane manipulation and maintenance were clinically assessed by means of the visual analogue scale score at baseline. Changes in horizontal thickness at 1 mm, 2 mm, and 3 mm below the top of the implant platform and the average bone density were assessed by cone-beam computed tomography at 16 weeks. Degradation of membrane was histologically observed in the soft tissue around the implant prior to re-entry surgery. Results: Five defect sites (two sites in the NCM group and three sites in the DCM group) showed soft-tissue dehiscence defects and membrane exposure during the early healing period, but there were no symptoms or signs of severe complications during the experimental postoperative period. Significant clinical and radiological improvements were found in all parameters with both types of collagen membrane. Partially resorbed membrane leaflets were only observed histologically in the DCM group. Conclusions: These findings suggest that, compared with NCM, DCM has a similar clinical expediency and possesses more stable maintenance properties. Therefore, it could be used effectively in guided bone regeneration around dehiscence-type defects.

• Korean Journal of English Language and Linguistics
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• v.1 no.1
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• pp.101-117
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• 2001

In English, whether or not wh-movement creates weak crossover effects depends upon the type of wh-phrases that cross over. A bare interrogative like who shows a typical weak crossover effect whereas which N type (e.g. which girl) and partitive type (e.g. which of these girls) wh-phrases would show mere weaker and weakest crossover effects, respectively. Previous approaches to English crossover phenomena that resort to a binary notion of specificity or D-linking cannot account for the three-way contrast the three different types of wh-phrases show. To overcome this problem, I argue in this paper that specificity should be a non-binary set-theoretic notion and propose the following subset principle and optimal binding relation: Between two lexical nominal expressions A and B, A is regarded as more specific than B iff the denotation of A comes from a more narrowly defined non-singleton set than B. Between two lexical nominal expressions A and B, if A locally binds B, then the non-singleton set from which the denotation of A comes should be a subset of the set from which the denotation of B comes (i.e. B cannot be more specific than A). The smaller the subset (i.e. the wider the specificity gap between binder and binder), the more optimal the local binding relation is. A locally binds B iff A is coindexed with B, and A c-commands B, and there is no such C that does not bind A but binds B. Finally, I show that partitivity functions to carve out a smaller subset and thus make partitive wh-phrases more specific than simple which N type wh-phrases.