• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.411-412
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• 2015

형태 변형이 가능한 스마트 디바이스 관련 기술이 급성장하고 있다. 스마트폰과 스마트패드의 등장이 사용자들의 콘텐츠 활용방식에 큰 영향을 끼쳤던 것과 같이 스마트 디바이스의 형태 변형은 사용자들의 콘텐츠 활용 경험에 많은 영향을 미칠 것이다. 이에 이 연구에서는 미래 디바이스의 형태변화 유형을 Bendable, Foldable, Stretchable, Squishable로 정의하고 형태 변형을 인터랙션 관점에 따라 Input과 Output의 영역으로 분류하며, 분류된 유형별 특성을 기존 연구를 기반으로 콘텐츠 경험의 관점에서 분석하여 향후 각 유형별로 형태 변화가 콘텐츠 조작 및 소비에 미치는 영향을 정립 및 예측하였다.

• Journal of Welding and Joining
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• v.32 no.3
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• pp.34-42
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• 2014

Flexible devices have been developed from their rigid, heavy origins to become bendable, stretchable and portable. Such a paper displays, e-skin, textile electronics are emerging research areas and became a mainstream of overall industry. Thin film transistors, diodes and sensors built on plastic sheets, textile and other unconventional substrates have a potential applications in wearable displays, biomedical devices and electronic system. In this review, we describe current trends in technologies for flexible/wearable electronics.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.3.2-3.2
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• 2010

There have been many efforts to utilize the outstanding properties of graphene for macroscopic applications such as transparent conducting films useful for flexible/stretchable electronics. However, the lack of efficient synthesis, transfer, and doping methods limited the scale and the quality needed for the practical production of graphene films. In this presentation, we introduce ultra-large scale (~30 inch) synthesis, roll-to-roll transfer, and chemical doping of graphene films showing excellent electrical and physical properties suitable for practical applications. Considering the outstanding scalability/processibility of roll-to-roll and CVD methods and the extraordinary flexibility/conductivity of graphene films, we expect the commercial production and application electrodes replacing the use of ITO can be realized in near future.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.263-263
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• 2010

실제 옷처럼 입는 컴퓨터를 구현하거나 복잡하고 움직임이 많은 사람의 장기 등 생체에 이식 가능한 정보 전자 소자를 개발하려는 시도가 많이 이루어지고 있다. 현재는 기존의 반도체 공정과 실리콘 소재를 기반으로 연구 결과가 보고되고 있는데, 이는 소자 제작에 있어서 높은 공정 온도 등으로 인해 응용성이 제한되는 상황이다. 우리는 metal oxide 나노선과 단일벽 탄소나노튜브 (SWCNT)를 성장하여 각각 슬라이딩 전이법과 thermal tape 전이법을 이용하여 원하는 기판에 전이하고 소자를 제작하였다. metal oxide 나노선은 슬라이딩 전이를 통해 정렬된 상태로 패턴을 제작하였으며, SWCNT는 density 제어와 채널 크기 조정을 통해 반도체성 채널을 유도하여 소자 특성을 확보하였다. 또한 각 나노선의 전계효과소자와 SWCNT로 구성된 PMOS inverter를 유연한 고분자 필름기판위에 구현하고, 이를 스트레칭이 가능한 스테이지를 이용해 strain 대비 전기특성 변화를 분석하였다. 유연성이 좋은 나노선/나노튜브로 제작된 해당 소자는 전체 소자가 스트레칭이 가능할 수 있게 연결구조를 디자인하여 수십% 의 stain에도 각각의 전기특성이 유지되었다. 이처럼 스트레칭이 가능한 1차원 나노소재 소자는 그 유연성을 바탕으로 입는 옷처럼 구겨지거나 늘여지게 되는 다양한 스트레칭 상황에도 특성이 보장되어 미래 정보전자소자로 많은 응용이 가능할 것으로 예상된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.3-3
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• 2011

Graphene has been attracting much attention owing to its fascinating physical properties such as quantum electronic transport, a tunable band gap, extremely high mobility, elasticity, thermal conductivity, mechanical strength and so on. There have been many efforts to utilize these outstanding properties of graphene for macroscopic applications such as transparent conducting films useful for flexible/stretchable electronics. However, the scale and the quality graphene need to be further enhanced for practical applications by developing more efficient synthesis, transfer, and doping methods. In this tutorial, the recent advances in graphene synthesis and applications will be reviewed, and discuss the future directions of graphene research.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.69.3-69.3
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• 2012

A high-performance low-voltage graphene field-effect transistor (FED array was fabricated on a flexible polymer substrate using solution-processable, high-capacitance ion gel gate dielectrics. The high capacitance of the ion gel, which originated from the formation of an electric double layer under the application of a gate voltage, yielded a high on-current and low voltage operation below 3 V. The graphene FETs fabricated on the plastic substrates showed a hole and electron mobility of 203 and 91 $cm^2/Vs$, respectively, at a drain bias of - I V. Moreover, ion gel gated graphene FETs on the plastic substrates exhibited remarkably good mechanical flexibility. This method represents a significant step in the application of graphene to flexible and stretchable electronics.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1645-1653
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• 2017

This investigation explores the thermally stratified stretchable flow of an Oldroyd-B material bounded by a linear stretched surface. Heat transfer characteristics are addressed through thermal stratification and heat generation/absorption. Formulation is arranged for mixed convection. Application of suitable transformations provides ordinary differential systems through partial differential systems. The homotopy concept is adopted for the solution of nonlinear differential systems. The influence of several arising variables on velocity and temperature is addressed. Besides this, the rate of heat transfer is calculated and presented in tabular form. It is noticed that velocity and Nusselt number increase when the thermal buoyancy parameter is enhanced. Moreover, temperature is found to decrease for larger values of Prandtl number and heat absorption parameter. Comparative analysis for limiting study is performed and excellent agreement is found.

• Journal of the Korean Electrochemical Society
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• v.17 no.4
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• pp.237-244
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• 2014

We report novel and simple structure of supercapacitors fabricated by using flexible glass fibre separators as templates. This method does not require separate electrodes, binders and high pressure/temperature to build the supercapacitor unit cells as required by the conventional technology. The supercapacitors were fabricated by drop-casting solution mixtures of carbonaceous active materials/gel electrolytes onto two sides of glass fibre separators. Two carbonaceous materials (nanoscaled activated carbons, multi-walled carbon nanotubes) were investigated as electrode materials. The electrochemical measurements reveal that the separatorbased supercapacitors using ACs successfully demonstrated significant mass specific capacitance ($22.3F\;g^{-1}$) and energy density ($9.7Wh\;kg^{-1}$), indicating this method can be useful in fabricating flexible, wearable and stretchable energy storage devices in more straightforward and cost-effective way than current technology.

• Transactions of the Society of Information Storage Systems
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• v.11 no.2
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• pp.36-40
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• 2015

The demand for flexible devices including solar cells, memories and batteries has increased rapidly over the past decades. In most flexible devices, polymer-based materials are used to enable the mechanical deformations such as bending or folding. Shape Memory Polymers (SMPs) is a high molecular compound polymer with flexibility and shape recovery characteristics. In this work, flexible shape memory device was fabricated by simply coating the conducting material, carbon nano-tube (CNT), on a shape memory polymer. Furthermore, durability of the device under various type of mechanical deformations was assessed. It is believed that the result of this work will aid in realization of a stretchable and wearable electronic device for practical applications.

• Elastomers and Composites
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• v.56 no.3
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• pp.117-123
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• 2021

Electronic skin (or E-skin) is an artificial smart skin composed of one or more than two sensors. E-skins detect external stimuli and convert them into electrical signals. Various types of E-skin sensors exist, including mechanical, physical, and chemical, depending on the detection signals involved. For wearable E-skins with superior sensitivity and reliability, developing conductors that possess both good elasticity and sensitivity is essential. Typical electrical conductors used in these sensors show very high sensitivity, but they have drawbacks such as non-linearity, irreversibility, and a narrow sensing range. To address these issues, stretchable and lightweight ionic conductors have been actively used in E-skin applications. This study summarizes the recent progress on various types of ionic conductors and ionic-conductor-based E-skin sensors.