• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.363.2-363.2
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• 2016

Stretchable strain sensors are becoming essential in diverse future applications, such as human motion detection, soft robotics, and various biomedical devices. One of the well-known approaches for fabricating stretchable strain sensors is to embed conductive nanomaterials such as metal nanowires/nanoparticles, graphene, conducting polymer and carbon nanotubes (CNTs) within an elastomeric substrate. Among various conducting nanomaterials, CNTs have been considered as important and promising candidate materials for stretchable strain sensors owing to their high electrical conductivity and excellent mechanical properties. In the past decades, CNT-based strain sensors with high stretchability or sensitivity have been developed. However, CNT-based strain sensors which show both high stretchability and sensitivity have not been reported. Herein, highly stretchable and sensitive strain sensors were fabricated by integrating single-walled carbon nanotubes (SWNTs) and nylon textiles via vacuum-assisted spray-layer-by-layer process. Our strain sensors had high sensitivity with 100 % tensile strain (gauge factor ~ 100). Cyclic tests confirmed that our strain sensors showed very robust and reliable characteristic. Moreover, our SWNTs-based strain sensors were easily and successfully integrated on human finger and knee to detect bending and walking motion. Our approach presented here might be route to preparing highly stretchable and sensitive strain sensors with providing new opportunity to realize practical wearable devices.

• Tribology and Lubricants
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• 제27권4호
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• pp.213-217
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• 2011

In this study, friction characteristics using elastomeric actuator with Magneto-rheological (MR) materials are identified. Typically, Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. MR fluid has been applied to various industry fields such as to brake, clutch, damper, engine mount and etc. However, MR fluid has been used under the sealed condition to prevent leaking issues. In order to overcome these problems, MR elastomer that has same property as MR fluid has been developed and studied. MR elastomer mainly consists of polymer material such as natural rubber or silicon rubber with particles that can be polarized with magnetic field. And it is called as a smart material since its stiffness and damping characteristics can be changed. In this study, MR elastomer is produced and pin-on-disc tests are carried out to identify the friction characteristics of the material. Several test conditions are applied to evaluate the feasibility to use as a smart actuator in the field of vibration control.

• Smart Structures and Systems
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• 제8권5호
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• pp.471-486
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• 2011

Various types of strain sensors have been developed and widely used in the field for monitoring the mechanical deformation of structures. However, conventional strain sensors are not suited for measuring large strains associated with impact damage and local crack propagation. In addition, strain sensors are resistive-type transducers, which mean that the sensors require an external electrical or power source. In this study, a gold nanoparticle (GNP)-based polymer composite is proposed for large strain sensing. Fabrication of the composites relies on a novel and simple in situ GNP reduction technique that is performed directly within the elastomeric poly(dimethyl siloxane) (PDMS) matrix. First, the reducing and stabilizing capacities of PDMS constituents and mixtures are evaluated via visual observation, ultraviolet-visible (UV-Vis) spectroscopy, and transmission electron microscopy. The large strain sensing capacity of the GNP-PDMS thin film is then validated by correlating changes in thin film optical properties (e.g., maximum UV-Vis light absorption) with applied tensile strains. Also, the composite's strain sensing performance (e.g., sensitivity and sensing range) is also characterized with respect to gold chloride concentrations within the PDMS mixture.

• Macromolecular Research
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• 제11권2호
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• pp.73-79
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• 2003

Generally, field performance of elastomeric track pad components has been poor, especially for the medium to heavy tonnage tracked vehicles, which are operated on the hilly cross-country course. The service life of these track pad, is affected not only by the terrain and environmental conditions but also by the speed, cornering, braking, weight of the vehicle, and the track tread design. In this research, modulus, tearing energy, and the rate of crack propagation of vulcanizates are evaluated by changing base materials to improve the service time of track pad. By increasing the contents of carbon black, modulus, tearing energy, and fatigue crack growth resistance of vulcanizates improved. Compared with the NR vulcanizate, the HNBR vulcanizate had a higher value of tearing energy. The rate of crack propagation of vulcanizates using smaller size carbon black was slower than that using larger size carbon black. When the HNBR was blended with the ZSC, the tearing energy of the vulcanizates was a little reduced because of the high modulus but the crack propagation rate was reduced significantly. In the relation between the crack propagation rate and the strain energy release rate, though up to 100% strain were applied to specimens, the slope on the log scale ($\beta$) varied between 1.72 and 2.3 with the kind of elastomer.

• Macromolecular Research
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• 제17권9호
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• pp.666-671
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• 2009

Water repellent elastomeric surfaces were fabricated successfully on SBS/MWNT nanocomposites films using the breath figure method and subsequent thermal treatment. The uniformly dispersed CNTs were found to play significant roles in tuning the size and ordering of the macroporous morphology at the nanocomposite surface as well as enhancing the mechanical properties of nanocomposites. In particular, the CNTs dispersed in a nanocomposite solution retarded the coarsening process of aqueous droplets during the breath figure process and decreased the pore size in the finally fabricated film. The water contact angle measurement showed that the double-scale structure comprised of self-organized macropores and surface the roughness induced by a thermal treatment produced a highly water-repellent nanocomposite surface.

• Carbon letters
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• 제27권
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• pp.72-80
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• 2018

In the present work, a comparative study of the mechanical behavior of two series of elastomeric composites, based on carboxylated styrene butadiene rubber (X-SBR) and reinforced with rice bran carbon (RBC) and graphite, is reported. Hybrid composites of X-SBR filled with RBC-graphite were also investigated in terms of the cure characteristics, hardness, tensile properties, abrasion resistance, and swelling. It was observed that the cure times decreased with the incorporation of a carbon filler whereas the torque difference, tensile strength, tensile modulus, hardness, and swelling resistance increased compared to the neat X-SBR revealing a favorable characteristic of crosslinking. Dynamic rheological analysis showed that the G' values of the composites, upon the addition of RBC-graphite, were changed to some extent. This demonstrates that the presence of a strongly developed network of fillers will ensure a reinforcing characteristic in a polymer matrix.

• 품질경영학회지
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• 제12권1호
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• pp.35-44
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• 1984

스판덱스 섬유는 신축성 섬유로서 착용감이 좋기때문에 스포츠웨어나 편물에 많이 이용되고 있으며 화학적으로 폴리아미드 조성과 비슷하나 주 사슬속에 산소원자를 포함하고 있어서 유연하며 융점이 낮다. 스판덱스 섬유에 대한 연구동향은 구조에 관한것, 물성에 관한것, 편성에 관한것, 염색가공에 관한것, 등으로 대별할 수 있으나 가공조건에 따른 물성변화를 검토한 것은 별무하다. 따라서 스판덱스 섬유의 가공시와 유사한 조건을 부여하고, 영향을 미칠 것으로 예상되는 인자 즉 강도, 신도, 수축율, 피로도에 대한 통계적 검정을 통하여 영향력을 확인했고, 반응 방정식을 유도했다. 이 보문은 본 학회지 Vol.9,No1 에 게재한 "스판덱스 섬유의 염색조건이 섬유품질에 미치는 영향" 을 정리 영문 번역한 것이다.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.387-392
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• 2018

Various technical approaches and concepts have been proposed to develop conductive super-hydrophobic (SH) surfaces. However, most of these approaches are not usable in practical applications because of insufficient adhesion and cost issues. Additionally, durability and uniformity issues are still in need of improvement. The goal of this research is to produce a large-area conductive SH surface with improved adhesion performance and uniformity. To this end, carbon nanotubes (CNT) with a high aspect ratio and elastomeric polymer were utilized as a conductive filler and matrix, respectively, to form a coating layer. Additionally, nanoscale silica particles were utilized for stable implementation of the conductive SH surface. To improve the adhesion properties between the SH coating layer and substrate, pretreatment of the substrate was conducted by utilizing both wet and dry etching processes to create specific organic functional groups on the substrate. Following pretreatment of the surface, a zirco-aluminate coupling agent was utilized to enhance adhesion properties between the substrate and the SH coating layer. Raman spectroscopy revealed that adhesion was greatly improved by the formation of a chemical bond between the substrate and the SH coating layer at an optimal coupling agent concentration. The developed conductive SH coating attained a high electromagnetic interference (EMI) shielding effectiveness, which is advantageous in self-cleaning EMI shielding applications.

• 한국가스학회지
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• 제10권3호
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• pp.34-40
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• 2006

본 논문은 LPG 충전노즐의 밀봉성능에 밀접한 관련을 맺고 있는 구형 그루브와 도브테일 그루브에 장착된 O-링의 최적화 설계를 위해 수행된 연구이다. O-링 그루브에 대한 최적설계 해석결과를 얻기 위해 비선형 유한요소해석 프로그램 MARC와 다구찌 설계법을 이용하였다. O-링을 최적의 조건으로 설치할 수 있도록 설계하기 위해 4개의 그루브 모델과 3개의 소재를 고려하였다. 그루브의 설계 파라미터로 폴리머 소재, 그루브의 깊이와 폭, O-링의 직경을 선정하였다. FEM 해석결과에 의하면, 최적설계에 가장 큰 영향을 미치는 기여도는 O-링의 직경과 소재특성으로 그루브의 폭, 깊이, 압축률에 비하여 높다는 사실을 알 수 있다. 가스 공급압력 1.764MPa에 적합한 O-링을 안전하게 설치되어야 할구형 그루브는 모델 3이, 그리고 도브테일 그루브는 모델 4가 가장 우수한 것으로 해석되었다.

• Elastomers and Composites
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• 제36권3호
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• pp.188-194
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• 2001

고무상으로 천연고무(NR)와 trans-octylene rubber(TOR)를 플라스틱상으로는 isotactic 폴리프로필렌(iPP)을 고무:플라스틱이 70:30(wt/wt)이 되도록 내부혼합기에서 용융혼합하고, 동적가황시킴으로써 열가소성탄성체를 제조하였으며, 고무상의 TOR 함량에 따른 기계적물성, 동적점탄성물성 및 열적특성의 변화에 관하여 UTM, DMA, TGA등을 이용하여 조사하였다. 고무상에 TOR이 첨가됨으로써 모듈러스, 인장강도 및 신율등의 인장물성의 증가, 영구압축줄음률의 감소, 경도의 증가를 가져왔으며, 또한, 동적특성 및 열적안정성도 함께 향상시킬 수 있음을 알았다. 이와같은 물성의 증가는 TOR이 천연고무에 첨가됨으로써 고무상의 가교밀도를 증가시키고, 고무상의 용융점도를 낮춤으로써 고무와 iPP와의 혼화성을 증대시키기 때문이라고 판단되었다.