• Korean Journal of Materials Research
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• v.29 no.11
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• pp.664-669
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• 2019

In this paper, a water-based green polymer mud is synthesized by simple compounding method. Effects of different kinds of tackifiers, their molecular weight on the viscosity of polymer mud and the effects of different fluid loss additives on mud fluid loss are studied. The results show that when polystyrene and anionic polyacrylamide with molecular weight of 8 ~ 10 million are used as the main thickening ingredient, polymer mud with high viscosity and high stability can be obtained. When the prepared polymer mud is formulated as NPAM: PEO: Hydroxypropyl cellulose(HPC) : Water = 42:10:10:100000 (unit: kg), the viscosity can reach 20.6 s, the filtration loss in 7.5 min is 24 mL, and the sand content is only 0.1 %. Compared with traditional bentonite mud, the green environment-friendly polymer mud has the advantages of small amount of waste, low environmental pollution, and low pulping cost, and can meet the construction needs for most topography and geomorphology drilling engineering.

• Elastomers and Composites
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• v.34 no.2
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• pp.177-182
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• 1999

SBS thermoplastic elastomers offer an inexpensive alternative to vulcanised rubbers for many undemanding applications. They are, however, particularly susceptible to attack from atmospheric ozone leading to cracking as soon as any strain is applied. In most rubber applications some strain is unavoidable. In this paper a compounding approach to protecting SBS thermoplastic rubbers against ozone is described. An explanation is offered for why a protective effect Is observed only when certain combinations of additive are used. SBS elastomers are the most affordable class of thermoplastic rubbers. To achieve finished products resistant to ozone and without compromising the light colours often demanded, recourse must be made to blending with other saturated elastomers or replacement by hydrogenated (SEBS) types. The latter is a significantly more expensive alternative. Under laboratory conditions where the rate of ozone attack is increased by several decades, unprotected SBS begins to crack within a few hours. Several different protective agents are examined here, the best of which, a cyclic enol ether, $Vulkazon^{(R)}$ AFD, can extend the resistance to any cracking to several weeks by the use of a few percent by weight of additive. The systems reported neither discolour the polymer nor stain other materials with which it may be in contact. Use of the protective systems described here could enable SBS elastomers to compete in many applications with the more expensive SEBS polymers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.203-213
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• 2023

Owing to carbon materials' diverse functionalization and versatility, the design and synthesis of carbon-based three-dimensional porous structures have become important foundational research topics across various fields. Among the various methods for producing porous carbon structures, laser-induced graphene (LIG) has garnered attention because of its large surface area, controllable structure, excellent electrical conductivity, scalability, and eco-friendly synthesis process. In addition, recent research results have reported more novel functionalities by advancing further from the unique characteristics of LIG through functionalization or compounding of LIG, making it an attractive material for various applications in electronic devices, sensing, catalysis, and energy storage. This review aims to update the research trends in LIG and its functionalization, providing insights to inspire more interesting studies on functional LIG to expand its potential applications ultimately. Starting with the synthesis method and material characteristics of LIG, we introduce the functionalization of LIG, which is classified into surface modification, heteroatom doping, and hybridization based on the interaction mechanism. Finally, we summarize and discuss the prospects of LIG and its functionalization.

• Elastomers and Composites
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• v.37 no.4
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• pp.234-243
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• 2002

A general scheme of a rubber structure is proposed. Using the thermomechanical method(TMA), some changes in the molecular and topological structures for uncured and cured, and unfilled and filled rubbers during processing are shown. In our investigations as region it is understood a complex structure, which is expressed at the thermomechanical curve(TMC) as a zone differed from others in thermal expansion properties. This zone is between the noticed temperatures of relaxation transitions, usually on the level like those determined by DMTA at 1Hz. These regions, which shares, are not stable, and differ in molecular-weight distribution(MWD) of chain fragments between the junctions. Differences in dynamics of the formation of the molecular and topological structures of a vulcanizate are dependent on the rubber formulation, mixing technology and curing time. Some of characteristics of these regions correlate with mechanical properties of vulcanizates what is shown for NR rubbers containing ENR or CPE as a polymeric additive. It is well known that the state of order influences diffusivity of low-molecular substances into the polymer matrix. Because of this, the two topological amorphous regions should influence the distribution of the ingredients and resulting in rubber compounds' heterogeneity, and related properties of cured rubber. Investigation of this problem is expected to be, in the future, one of the essential factors in determining further improvement of polymeric materials properties by compounding with additives and in reprocessing of rubber scrap.

• Elastomers and Composites
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• v.58 no.3
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• pp.136-141
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• 2023

Polyacrylic rubber (ACM) is well known for its excellent heat resistance and chemical stability. Additionally, its performance can be readily manipulated by modifying its functional groups, rendering it highly attractive to various industries. However, extreme climate changes have necessitated an expansion of the operating temperature range and lifespan of ACM products. This requires the optimization of both the compounding process and functional-group design. Hence, we investigated the relationship between the cross-linking system and mechanical properties of an ACM with a carboxylic cure site. The crosslink density is determined by chemical kinetics according to the structure of additives, such as diamine crosslinkers and guanidine accelerators. This interaction enables the manipulation of the scotch time and mechanical properties of the compound. This fundamental study on the correlation analysis between cross-linking systems, physical properties, and storage stability can provide a foundation for material research aimed at satisfying the increasingly demanding service conditions of rubber products.

• Rubber Technology
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• v.9 no.1
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• pp.1-12
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• 2008

Effects of silane modifier, bis(triethoxysilylpropyl) tetrasulfide (TESPT(S4)) and bis(triethoxysilylpropyl) disulfide (TESPD(S2)), on silica filled compound were investigated upon processability, dynamic, mechanical, heat build-up, blowout properties, and silica dispersion in natural rubber (NR). The temperature of the S2 treated silica compound generated higher than that of the S4 treated compound during internal mixer compounding. The shear viscosity of the S2 compound exhibited lower than that of the S4 compound and the viscosity measured in dynamic mode was close to each other. The elongation modulus of the S2 compound exhibited lower than that of the S4; however, the tear resistance strength of the S2 compound exhibited higher than that of the S4 compound. The loss tan$\delta$ values of the S2 compound exhibited higher than those of the S4 at room temperature. The augmentation of the test temperature lowered the tan$\delta$ values of each compound, which results in close tan$\delta$ values to each other at $100^{\circ}C$. The S2 compound deformed less than the S4 compound, and the blowout time of each compound was close to each other. The S2 compound generated more heat build-up than the S4 compound. The abrasion loss of the S2 compound was less than that of the S4 compound. The size of the silica agglomerate reduced on both S4 and S2 compounds upon vulcanization. The addition of the bifunctional silanes (S2 and S4) on silica filled NR compound improved the processability of each compound and their effects were more significant on the S2 compound than the S4 compound. After vulcanization the silica agglomerate size of each compound reduced compared with before vulcanization.

• Journal of Digital Convergence
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• v.10 no.2
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• pp.141-146
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• 2012

U-healthcare, which grafted advanced IT technology onto medical technology, is in the limelight because it can provide medical services at anytime and anywhere. U-healthcare system applied RFID technology for Implantable Medical Device (IMD), but patient's biometric information can be easily exposed to third parties. In this article, RFID-based U-healthcare authentication protocol is proposed to prevent illegal usage for personal biometric information exposed to the third patty. The proposed protocol guarantees patients' biometric information integrity as compounding random numbers between administrators and hospital/clinic managers, and uses continuous number SEQ and time stamp T to synchronize IMD/administrators and administrators/hospital managers. Also, to protect user's privacy from the third party, patients' biometric information can be safely guarded by managing patients' security identifiers by administrators.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.2
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• pp.131-139
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• 2015

This study analyzed the differences in aerobic and anaerobic exercise ability and growth-related indicators, depending on the polymorphism of the ACE and the ACTN3 genes, to understand the genetic influence of exercise ability in the growth process of children. The subjects of the study consisted of elementary school students (n=856, age $10.32{\pm}0.07yr$). The anthropometric parameters, physical fitness and growth factors were compared among groups of the ACE I/D or the ACTN3 R577X polymorphisms. There were no significant differences between the anthropometric parameters, physical fitness and growth factors for the ACE gene ID or the ACTN3 gene R577X polymorphism. However, the DD type of ACE gene was highest in the side step test (p<0.05), and the DD type was significantly higher than the II+ID type (p<0.05) in the early bone age. The combined group of the ACE gene II+ID and the ACTN3 gene XX type significantly showed lower early bone age (p< 0.05). This study did not find any individual or compounding effects of the polymorphism in the ACE I/D or the ACTN3 R577X polymorphisms on the anthropometric parameters, physical fitness and growth factors of Korean children. However, the exercise experience and the DD type of the ACE gene may affect the early maturity of the bones.

• Journal of the Korean Society of Costume
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• v.58 no.8
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• pp.91-105
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• 2008

Spatial multiplication phenomenon, expressed through de-constructive trend since the late of 20C, have got changed existing fixed and dis-variable space to smooth, fluid, and changeable space. Ex-form and fluidity of new spatial paradigm have been focused through lots of scientific theories studied between digital thought and indeterminacy and rankless nature phenomena. In 21C fashion, indeterminate and irregular form and space have been crested continuously, which could not explain simply according as the fluidity theory Different from the space crested for multi-function and multipurpose, this is revealed the characteristics of chaosmos that communizes the order and the disorder, deconstruction and creation. Ex-formal space of fashion have shown the relationship of de-centerizing, de-territorial, and do-structural phenomenon among different fashion elements. This paper intends to understand the concept of ex-form, and study expressive manners of ex-formal space of 21C fashion, and conclusion as follows. 1) Overlap changes single space of fashion to multi-layered space through the repeat system of pleats, origami, and folding. 2) Ex-gravity expressed in deviation of the gravity acting vertical direction, for example, twisting, curve, winding, portion. 3) Morphing is shown the change process from single fixed form to different complex form. 4) Blurring is expressed in re-combination and re-arrangement among elements of fashion. 5) Blob shows hybrid fashion space through the liberal compounding and separation of a lot of different elements.

• Composites Research
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• v.33 no.5
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• pp.282-287
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• 2020

In the present study, a high-strength polyethylene terephthalate (PET) sheet was fabricated through a densification process of low melting PET fiber (LMF) combined PET sheet. During the thermal heat treatment process of the combined LMF, individual PET fiber was connected, which in turn leads to the improvement of the interfacial bonding force between the fibers. Also, the densification of the PET sheet leads to reduce macrospore density and in return could enhance the binding force between the overlapped PET networks. Consequently, the asprepared LMF-PET sheet showed about 410% improved tensile strength and the same elongation compared to before compression. Besides, the enhanced bonding force can prevent the shrinkage of the PET fiber network and exhibited excellent dimensional stability.