• Polymer(Korea)
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• v.37 no.3
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• pp.269-275
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• 2013

Thiuram (DPTT, TMTD), thiazole (MBT, MBTS), sulfenamide (CBS, NOBS), and zinc containing thiuram (dithiocarbamate) (ZDBC) type accelerators were added into silica and carbon black filled natural rubber (NR) compounds. Their effects on vulcanization time and rate were compared. The vulcanization rate of thiuram type accelerator added compounds showed the fastest rate, followed by thiazole and sulfenamide types. Silica filled natural rubber (NR) compounds showed a slower vulcanization time ($t_{s2}$, $t_{10}$, $t_{90}$) and lower cure rate index (CRI) than carbon black filled ones upon each accelerator.

• Polymer(Korea)
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• v.36 no.5
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• pp.637-642
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• 2012

The effects of mixing geometry (intermeshing vs. tangential rotor) for the dispersion and distribution of silica agglomerates in SBR/BR compound were investigated. Silica dispersion and distribution were found to be better with the intermeshing rotor compared to the tangential rotor. It was concluded that the intermeshing rotor compared to the tangential rotor delivered a higher shear stress due to interlocked rotor geometry to silica agglomerates leading to better dispersity and distribution of silica in the agglomerates.

• Composites Research
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• v.35 no.4
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• pp.283-287
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• 2022

Stretchable strain sensors have been developed for potential future applications including wearable devices and health monitoring. For practical implementation of stretchable strain sensors, their stability and repeatability are one of the important aspects to be considered. In this work, we utilized 3D printed polymer structures having kirigami patterns to improve the stretchability and reduce the hysteresis. The polymer structures were coated with graphene/carbon nanofiber hybrids to make a robust electrical network. The stretchable strain sensors showed a high gauge of 36 at a strain of 32%. Because of the kirigami structures and the robust graphene/carbon nanofiber coating, the sensors also exhibited stable resistance responses at various strains ranging from 1% to 30%.

• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.87-103
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• 2019

Nonaqueous organic electrolyte solution in commercially available lithium-ion batteries, due to its flammability, corrosiveness, high volatility, and thermal instability, is demanding to be substituted by safer solid electrolyte with higher cycle stability, which will be utilized effectively in large-scale power sources such as electric vehicles and energy storage system. Of various types of solid electrolytes, composite solid electrolytes with polymer matrix and active inorganic fillers are now most promising in achieving higher ionic conductivity and excellent interface contact. In this review, some kinds and brief history of solid electrolyte are at first introduced and consequent explanations of polymer solid electrolytes and inorganic solid electrolytes (including active and inactive fillers) are comprehensively carried out. Composite solid electrolytes including these polymer and inorganic materials are also described with their electrochemical properties in terms of filler shapes, such as particle (0D), fiber (1D), plane (2D), and solid body (3D). In particular, in all-solid-state lithium batteries using lithium metal anode, the interface characteristics are discussed in terms of cathode-electrolyte interface, anode-electrolyte interface, and interparticle interface. Finally, current requisites and future perspectives for the composite solid electrolytes are suggested by help of some decent reviews recently reported.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.2
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• pp.71-77
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• 2023

Absorbable periodontal tissue regeneration barrier membranes (total 6; domestic 4; import 2) were comparatively analyzed. In the case of the xenograft barrier membrane, the collagen product had excellent tensile strength but low strain, and the porcine pericardial membrane had good mechanical properties, but its thickness was too thick to control. The synthetic PLLA membrane manufactured by the electrospinning had a relatively low water absorption capacity. However, the hybrid barrier membrane was able to control mechanical properties and biocompatibility through proper mixing of synthetic polymer and natural polymer. DA02 (PLLA/gelatin), a newly developed hybrid absorbable periodontal tissue regeneration membrane that is entirely dependent on imports, can be applied to an absorbable periodontal tissue regeneration barrier membrane due to suitable mechanical properties and biocompatibility.

• Composites Research
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• v.37 no.3
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• pp.155-161
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• 2024

Boron nitride nanotubes and carbon nanotubes are the most representative one-dimensional nanostructures, and have received great attention as reinforcement for multifunctional composites for their excellent physical properties. The two nanotubes have similar excellent mechanical stiffness, strength, and heat conduction properties. Therefore, the reinforcing effect of these two nanotubes is greatly influenced by the properties of their interface with the polymer matrix. In this paper, recent comparative studies on the reinforcing effect of boron nitride nanotubes and carbon nanotubes through experimental pull-out test and in-silico simulation are summarized. In addition, the conflicting aspect of the two different nanotubes with structural defects in their side wall is discussed on the viscoelastic damping performance of nanocomposites.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.262-266
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• 2013

The aim of this study was to determine the total phenol, total flavonoids, and proanthocyanidin contents of fermented black rice and its fractions, as well as to assess the antioxidant activities. Antioxidative activities were assessed in various in vitro models using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), reducing power, ferric ion reducing antioxidant power (FRAP), and nitrite scavenging activity (Griess reagent assay). Our results show that the antioxidant activity was significantly higher in the low-molecular fraction of fermented black rice than in the other samples (p<0.05). Among the fermented black rice and its fractions, the low-molecular fraction had the highest total phenol ($109.2{\pm}2.9$ mg GAE, gallic acid equivalent/g), total flavonoids ($39.4{\pm}0.8$ mg RE, rutin equivalent/g), and proanthocyanidin ($32.9{\pm}1.4$ mg CE, catechin equivalent/g) contents, which correlated strongly with its antioxidative activity. Considering the high consumer demand due to the beneficial health effects, fermented black rice and its fractions can be utilized to develop functional food, as well as health-promoting and pharmaceutical agents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.182-183
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• 2008

본 연구에서는 유전 손실이 낮고, 고분자(LCP)의 유전율을 높이기 위하여 (100-x)LCP(polymer)-xNPO(ceramic) 복합체 (x= 0, 10, 20, 30, 40, 50)의 유전 특성 및 미세구조를 연구하였다. LCP와 ceramic filler(NPO)는 Brabender Mixer를 사용하여 $300^{\circ}C$에서 혼합한 후, Hot press 사용하여 $300^{\circ}C$, 7ton 성형 압력으로 pellet 형태 $(2.5cm\times2.5cm\times0.1cm)$로 제조 하였다. LCP-NPO 복합 소재를 SEM을 통해 미세구조를 관찰하였고, 복합체의 유전 특성을 조사하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.03a
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• pp.127-158
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• 1996

투과증발은 막분리 기술의 하나로 역삼투막, 한외여과막 등의 다른 막분리와 달리 혼합물 분리가 막소재 물질과 분리 대상 유기물 사이의 화학 친화도에 의해 이루어지기 때문에 혼합물중의 특정 성분에 대한 선택도가 높은 비다공성 고분자 복합막이 사용된다. 투과증발막 투과의 구동력은 투과 성분의 활동도(activity) 차로 이는 부분 증기압차로 구체화되며, 이 구동력을 높이기 위해서 feed side는 고온 유지를 위한 열교환기가 필요하며 permeate side는 진공하에서 감압에 의한 증기상으로의 전환을 이루게 하며 이를 다시 응축하여 연속 투과가 일어날 수 있게 한다. 따라서 투과증발의 핵심 기술은 분리하고자 하는 물질에 대하여 높은 투과선택도(permselectivity)를 갖는 투과증발막의 제조 기술이며, 제조된 막을 실공정에 적용하기 위한 모듈 설계, 제작 기술과 이를 시스템화하여 실규모로 Scale-up 할 수 있는 시스템 설계 기술도 실용화를 위해서 반드시 이루어져야 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.176.1-176.1
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• 2011

세계적으로 석유 기반 자원의 고갈에 따른 부족, 기후변화협약 및 환경규제 강화에 의해 세계적으로 바이오소재를 이용하고자 하는 연구와 더불어 유리강화복합재료의 대체물질로 적합한 천연섬유를 보강재로 사용하는 바이오복합재료의 연구 또한 활발하게 진행되고 있다. 최근 새로운 신재생에너지원으로 각광 받고 있는 바이오에너지 중 해조류는 가장 자연친화적이고 생산력이 뛰어난 바이오매스로 알려져 있다. 해조류는 바닷물 속에 녹아 있는 탄소를 흡수할 뿐만 아니라 광합성을 통해서도 탄소를 흡수하면서 성장하기 때문에 탄소흡수원의 역할을 하게 되며, 해조류 바이오에너지를 생산할 경우 화석연료를 대체하여 지구온난화의 주범인 온실가스를 감축하는 기능을 한다. 본 연구에서는 해조류를 이용한 바이오에너지 생산 공정에서 2차적으로 발생하는 부산물을 보강재로 사용한 바이오복합재료의 제조와 제조된 바이오복합재료의 열적 특성 및 동역학적 특성을 분석하였다. 해조류 부산물의 화학적 전처리에 따른 Thermogravimetric analysis(TGA) 분석 결과로 cellulose 함량이 가장 높고 불순물이 적은 황산 처리한 파래를 이용해 파래/Polypropylene(PP) 바이오복합재료를 다양한 보강비율 (20-50wt%)로 압축성형 하였다. 파래/PP 바이오복합재료의 저장탄성률은 파래 함량이 40wt%일 때 4.0 Gpa으로 최대값을 보였으며 이는 PP 매트릭스와 비교했을 때 약 8.1% 향상된 결과이다. 파래/PP 바이오보합재료의 열팽창 특성은 파래 함량이 증가함에 따라 열팽창계수가 낮아지는 경향으로 50wt%일 때 가장 낮은 값을 나타내었으며 이는 PP 매트릭스와 비교했을 때 약 56% 향상된 결과이다. 따라서 비생분해성 고분자에 새로운 신재생 바이오매스인 해조류를 보강재로 사용하여 열적 특성 및 동역학적 특성이 향상된 친환경적인 바이오복합재료의 제조 가능성을 확인하였다.