폴리카보네이트 필름 표면 처리가 증착 SiOx 베리어층 접착에 미치는 영향

김관훈(Gwan Hoon Kim),황희남(Hee Nam Hwang),김양국(Yang Kook Kim),강호종(Ho Jong Kang) 한국고분자학회 2013 폴리머 Vol.37 No.3

폴리카보네이트(PC) 필름을 유연기판으로 사용하기 위해서는 SiOx 증착에 의한 베리어 특성 개선이 필요하며 이때 베리어 층과 PC 계면 접착력이 매우 중요하다. 본 연구에서는 언더 코팅, UV/O3 및 저온 플라즈마와 같은 다양한 표면 처리 방법에 의하여 PC 필름 표면을 개질하여 표면의 물리적 화학적 변화가 증착된 베리어 층 계면 접착력에 미치는 영향을 살펴보았다. 표면 처리 전의 PC 필름은 표면 거칠기 및 표면 에너지가 매우 낮아 SiOx 베 리어 층과의 접착력이 현저히 떨어짐을 알 수 있었다. PC 필름을 저온 플라즈마로 표면 처리한 결과, 표면의 거칠 기 증가와 극성 관능기 생성에 의하여 극성 표면 에너지가 향상되는 반면 UV/O3 처리의 경우, 표면 거칠기 변화 없이 표면에 생성된 극성 관능기에 의해 극성 표면 에너지가 증가됨을 알 수 있었다. 이러한 표면의 변화는 베리어 층과 PC 기판의 계면 접착력 증가에 기여함을 알 수 있었다. 표면 처리 방법으로 언더 코팅을 사용하는 경우 표면 에 에너지를 가하지 않아도 코팅제의 아크릴산과 SiOx의 접착력 향상에 의하여 PC 필름과의 계면 접착력이 증가되며 유무기 하이브리드 다층 구조에 의한 베리어 특성 개선이 함께 일어남을 알 수 있었다. The interfacial adhesion strength is very important in SiOx deposited PC film for the barrier enhanced polycarbonate (PC) flexible substrate. In this study, PC films were treated by undercoating, UV/O3 and low temperature plasma and then the effect of physical and chemical surface modifications on the interfacial adhesion strength between PC film and SiOx barrier layer were studied. It was found that untreated PC film shows significantly low interfacial adhesion strength due to the smooth surface and low surface free energy of PC. Low temperature plasma treatments resulted in the increase of both surface roughness and surface free energy due to etching and the appearance of polar molecules on the PC surface. However, UV/O3 treatment only shows the increase of surface free energy by developed polar molecules on the surface. These surface modifications caused the enhancement of surface interfacial strength between PC film and SiOx barrier. In the case of undercoating, it was found that the increase of surface interfacial strength was achieved by adhesion between various acrylic acid on acrylate coated surface and SiOx without increase of polar surface energy. In addition, the barrier property is also improved by organic-inorganic hybrid multilayer structure.

Transparent and Flexible Surface-Enhanced Raman Scattering (SERS) Sensors Based on Gold Nanostar Arrays Embedded in Silicon Rubber Film

Park, Seungyoung,Lee, Jiwon,Ko, Hyunhyub American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.50

<P>Integration of surface-enhanced Raman scattering (SERS) sensors onto transparent and flexible substrates enables lightweight and deformable SERS sensors which can be wrapped or swabbed on various nonplanar surfaces for the efficient collection and detection of analytes on various surfaces. However, the development of transparent and flexible SERS substrates with high sensitivity is still challenging. Here, we demonstrate a transparent and flexible SERS substrate with high sensitivity based on a polydimethylsiloxane (PDMS) film embedded with gold nanostar (GNS) assemblies. The flexible SERS substrates enable conformal coverage on arbitrary surfaces, and the optical transparency allows light interaction with the underlying contact surface, thereby providing highly sensitive detection of analytes adsorbed on arbitrary metallic and dielectric surfaces which otherwise do not provide any noticeable Raman signals of analytes. In particular, when the flexible SERS substrates are covered onto metallic surfaces, the SERS enhancement is greatly improved because of the additional plasmon couplings between GNS and metal film. We achieve the detection capability of a trace amount of benzenethiol (10(-8) M) and enormous SERS enhancement factor (similar to 1.9 X 10(8)) for flexible SERS substrates on Ag film. In addition, because of the embedded structure of GNS monolayers within the PDMS film, SERS sensors maintain the high sensitivity even after mechanical deformations of stretching, bending, and torsion for 100 cycles. The transparent and flexible SERS substrates introduced in this study are applicable to various SERS sensing applications on nonplanar surfaces, which are not achievable for hard SERS substrates.</P>

비정형 곡면 제작을 위한 가변스트레치 성형공정의 활용

박지우(J. W. Park),김정(J. Kim),강범수(B. S. Kang) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.5

Flexible stretch forming is appropriate process for flexible manufacturing, so it can use aerospace, shipbuilding and architecture industry. Flexible stretch forming process has some advantages including that it could be applied to various shape forming such as double curved one. In this study, a numerical simulation was carried out for saddle type surface using the flexible stretch forming process. In this simulation, it can confirm the decrease effect of elastic recovery of stretch process. The experiment was also carried out to confirm the formability of this forming process. By comparing the simulation and experiment results, the suitability of the flexible stretch forming process for double curved surface was verified. Consequently, it was confirmed that the flexible stretch forming process has the capability and feasibility to manufacture the curved surface.

Self-selective fine metal line coating using surface energy differences

Mun, Mu Kyeom,Kim, Doo San,Yeom, Geun Young,Kim, Dong Woo Elsevier 2018 MICROELECTRONIC ENGINEERING Vol.187 No.-

<P><B>Abstract</B></P> <P>Self-selective coating is a new coating process that utilizes surface energy differences for metal ink coating. Hydrophobic and hydrophilic areas are defined on carbon black coated Polyimide (PI) substrate surface using atmospheric plasmas. At this state, when Ag ink is sprayed on PI, metal line is self-formed on hydrophilic surface due to its surface energy differences. As a result, an Ag ink line width of less than 6μm could be formed on the PI surface after removing the carbon black. Due to the formation of the Ag line on the hydrophilic PI surface, the adhesion force of the Ag ink formed on the PI surface was ~64% higher than that of the Ag ink formed on the hydrophobic PI surface.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Metal line in flexible device was made using new direct patterning method. </LI> <LI> Surface energy differences were used for direct patterning. </LI> <LI> Line width narrower than 6um was acquired by coating Ag ink on hydrophilic surface. </LI> <LI> Adhesion forces between the substrate were enhanced by 64% compared to that of hydrophobic substrate. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Augmented Reality of Robust Tracking with Realistic Illumination

Young-Baek Kim,Hong-Chang Lee,Sang-Yong Rhee 한국지능시스템학회 2010 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.10 No.3

In this study we augmented a virtual object to an image of a flexible surface such as a paper, which is acquired from a web camera. To get more presence feeling, we consider realistic illumination on augmenting. To get the geometric relation between the camera and the flexible surface, we use markers that are printed on the surface. Using marker information in prior, three dimensional coordinates of the surface can be calculated. After the marker is removed from the input image, we attach a two dimensional texture and shadow to the flexible surface by considering realistic illumination.

Principles of Developing a Softness Evaluation Technology for Hygiene Paper

Young C. Ko,Jung Yoon Park,Jin Hee Lee,Hyoung Jin Kim 한국펄프·종이공학회 2017 펄프.종이技術 Vol.49 No.4

In developing objective tissue softness evaluation methods, reliable and reproducible subjective evaluation data are a prerequisite. A trade-off relationship generally exists between the relevance to a consumer’s in-use situations and the test variability. At present, sensory panel test (SPT) has been most widely used. It provides the least variable data, but it has the problem of being the least relevant to the real world. Recently we have developed a new sensory panel test which is referred to as new sensory panel test (NSPT). It performs like a HUT (home-user-test) for the relevance and like a physical test for the test variability. Since the pioneering work by Hollmark, it is now widely accepted that subjective tissue softness should primarily consist of the bulk softness component and the surface softness component. The bulk softness component can be determined by the tissue flexibility. The surface softness component can be determined by measuring the surface roughness and the surface friction. In the present study, the NSPT was performed on 7 commercial bathroom tissue products. For subjective softness evaluation, the Thurstone interval scale values have been determined for the 7 products. For the bulk softness component, the flexibilities of these samples were measured using a tensile tester (Criterion model-41, MTS, U.S.A.). For the surface softness component, the surface roughness and the surface friction were measured using the surface roughness/friction tester (KES-SESRU, Kato Tech., Japan). The result validates the hypothesis that the bulk flexibility and the surface roughness/friction should be sufficient for developing an objective tissue softness evaluation method.

A Flexible Supercapacitor Prepared with Surface Modified Carbon Nanotube Film Electrode and Hydrogel Electrolyte

김혜주,송현준,Nilüfer Çakmakçı,강희수,박종현,신명규,정영진 한국섬유공학회 2021 Fibers and polymers Vol.22 No.10

As the demand for wearable devices increases, compatible energy storage systems have been explored. Energysystems integrated into wearable devices require mechanical robustness and stable electrochemical performance undermechanical deformations such as bending and folding. Herein, the flexible supercapacitor is fabricated with surface modifiedcarbon nanotube (CNT) film and a cross-linked acrylamide@N',N'-methylenebisacrylamide (AAM@MBA) hydrogel tomount on wearable devices. CNT film is a promising candidate for the electrode of flexible supercapacitors owing to its highelectrical conductivity, surface area, flexibility, and excellent mechanical properties. The high ionic conductivity, goodviscoelasticity, and shock absorption of hydrogel polymers make them suitable electrolyte materials for flexiblesupercapacitors. The heat treatment under air atmosphere is conducted on CNT film to enhance the interfacial adhesion withhydrogel electrolyte. The flexible supercapacitor delivers 8.15 F g-1 of specific capacitance and shows 93 % of goodcapacitance retention up to 400 cycles. Furthermore, it works normally when bending stress is applied. The flexiblesupercapacitor in this study is expected to be used in wearable devices, thanks to its good performance and high flexibility.

Development of flexible polymer sheet with high surface durability using discretely embedded micro-balls

Wang, Do-Young,Kim, Chang-Lae,Kim, Dae-Eun Elsevier 2017 CIRP annals ... manufacturing technology Vol.66 No.1

<P><B>Abstract</B></P> <P>A flexible PDMS sheet with high surface durability was developed using a novel coating concept. Instead of using a continuous hard coating to protect the polymeric sheet, the strategy was to use a discrete coating structure comprised of borosilicate glass micro-balls that were partly embedded into the surface. The hard micro-balls served to lower the contact area against the counter surface, thereby significantly lowering the friction and wear. Furthermore, by using the discrete coating structure the inherent flexibility as well as transparency of the PDMS sheet could be maintained. FEM analysis was used to understand the contact behavior of micro-balls.</P>

Shape error prediction and compensation of three-dimensional surface in flexibly-reconfigurable roll forming

Pan Liu,구태완,강범수 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

The Flexibly-reconfigurable roll forming (FRRF) scheme as one of the advanced continuous roll forming processes consists of upperand lower flexible rollers that can be controlled by each reconfigurable punch module. The shape error in the FRRF process often resultsin undesirable changes in the shape of the deformed surface and brings about a deviation in the precision of the deformed product. Thisstudy considers the changes in the shape error of a deformed configuration by controlling the non-uniform gap between both flexiblerollers in the transverse direction. A Non-uniform rational B-spline (NURBS) type control methodology is introduced based on the transversetarget curve and the thickness reduction ratio. The function for the transverse target curve is reconstructed by using a NURBS curve,and the function of the reduction ratios of the thickness is assumed to have linear increments. Finite element simulations are conductedfor the FRRF process with the AA5052-H32 sheet material by applying NURBS-type control methodology for both flexible rollers. Thetransverse shape error of the three-dimensional surface is predicted by using a numerical approach, and its results are experimentallyverified. A Reverse displacement compensation (RDC) method is adopted to compensate the transverse shape error of the deformedsurface. Consequently, the proposed RDC method is validated as a suitable approach to address the transverse shape error. This methodcontributes to further developing capabilities to modify the profiles of the upper and lower flexible rollers in the flexibly-reconfigurableroll forming process for various 3D surface parts.

Flexible Fine Die의 마이크로 엔드밀 가공에서 적정 오일미스트 조건 선정

김민욱(Min-Wook Kim),김태진(Tae-Jin Kim),강명창(Myung-Chang Kang),류기택(Ki-Teak Ryu) 한국기계가공학회 2008 한국기계가공학회 춘추계학술대회 논문집 Vol.2008 No.-

Flexible fine die is mainly used for cutting sheet of back light unit that component of LCD. Quality of cutting sheet determined fabrication and roughness of flexible-fine die. However, die in manufacturing process of high-speed machining using difficult-to-cut materials is difficult to maintain a constant state of fabrication. In order to improve productivity and quality of die, it is required to investigate cutting cusp of micro end-mill exactly. In this study, cutting experiments for flexible fine die were evaluated according to the variation of oil-mist conditions. Especially, an integrated evaluation system for high-speed micro end-milling, where the cutting force, tool wear and surface shape were simultaneously evaluated, was newly designed.