• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.340-340
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• 2006

Applying force-distance curve measurement by atomic force microscopy to a theoretical mechanical model gives us elastic properties of polymer surfaces. Our group focuses on force-mapping method, in which force-distance curve is performed at each lattice point on a sample surface and subsequently a variety of properties derived from analytical results are combined to construct a 2-dimensional image. With this method we succeeded in deriving Young' s modulus distribution map method of rubbery/rubbery polymer blend surfaces with ${\sim}100\;nm$ lateral resolution. We also applied force-mapping method to another theory to divide distribution of hardness from that of adhesion. We will demonstrate recent progress.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.91-96
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• 1998

In recent years, the tribological behavior of coated ceramic material has been the topic of much interest. Particularly, the understanding of the tribological performance of thin film under light load is important for potential applications in MEMS. In this work under light load and low speed, the tribological behavior of coated silicon was investigated. The results show that both adhesive and abrasive wear occur depending on the sliding condition. Also the effect of humidity on friction was influenced by the apparent ares of contact between the two surfaces. Finally, undulations on the silicon wafer were found to be effective in trapping wear particles.

• IMMUNE NETWORK
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• v.12 no.3
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• pp.71-83
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• 2012

T cell activation and function require physical contact with antigen presenting cells at a specialized junctional structure known as the immunological synapse. Once formed, the immunological synapse leads to sustained T cell receptor-mediated signalling and stabilized adhesion. High resolution microscopy indeed had a great impact in understanding the function and dynamic structure of immunological synapse. Trends of recent research are now moving towards understanding the mechanical part of immune system, expanding our knowledge in mechanosensitivity, force generation, and biophysics of cell-cell interaction. Actin cytoskeleton plays inevitable role in adaptive immune system, allowing it to bear dynamic and precise characteristics at the same time. The regulation of mechanical engine seems very complicated and overlapping, but it enables cells to be very sensitive to external signals such as surface rigidity. In this review, we focus on actin regulators and how immune cells regulate dynamic actin rearrangement process to drive the formation of immunological synapse.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1733-1736
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• 2006

Nanosilver has intrinsic problem to adhesion on the surface of silica. To improve interfacial properties between nanosilver and silica substrate, a thin titanium film is introduced in this study. The titaniumcoated silica substrates are prepared by sputter technique. The commercial silver nanopaste with size around 3-7nm is used in this study. The results indicate thin layer of titanium can improve the bonding properties of nanosilver and expect to be used in fabrication of TFT display panel.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.818-821
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• 2003

Sn-doped $In_{2}O_{3}$ (ITO) thin film is one of the materials widely on research not only in the academic fields but also in industrial fields because of their transparency, high conductivity and good adhesion characteristics on substrate. ITO thin films are usually preferred oriented to one of the (222), (400), and (440) planes during crystallization process, which is dependent on processing variables. The preferred orientation affects electrical, optical and etching properties of the films. In this study, thin films of preferred oriented in different orientation were fabricated by controlling processing variables. The crystallization behavior, grain size, surface roughness, transparency and electrical properties of the thin films in different orientation were examined.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.791-794
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• 2003

DLC thin films were prepared by microwave plasma-enhanced chemical vapor deposition method on silicon substrates using methane ($CH_4$) and hydrogen ($H_2$) gas mixture. The negative DC bias ($-450V{\sim}-550V$) was applied to enhance the adhesion between the film and the substrate. The films were characterized by Raman spectrometer. The surface morphology was observed by an atomic force microscope (AFM). And also, the friction coefficients were investigated by AFM in friction force microscope (FFM) mode, which were compared with the pin-on-disc (POD) measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.842-845
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• 2003

DLC thin films were prepared by microwave plasma-enhanced chemical vapor deposition method on silicon substrates using methane ($CH_4$) and hydrogen ($H_2$) gas mixture. The negative DC bias ($-450V{\sim}-550V$) was applied to enhance the adhesion between the film and the substrate. The films were characterized by Raman spectrometer. The surface morphology was observed by an atomic force microscope (AFM). And also, the friction coefficients were investigated by AFM in friction force microscope (FFM) mode, which were compared with the pin-on-disc (POD) measurement.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.99-102
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• 2005

Plasma surface coating is applied to the wood powder to improve its bonding and dispersion with the polypropylene(PP). Some mechanical test results and visual inspection indicates the good compatibility between the wood powder and the PP, and relatively good interfacial adhesion between wood powder and PP matrix was seen. Also, this method is considered as a non-toxic process as compared to other direct chemical method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.329-336
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• 2009

A fretting wear test rig for cross contacting tube specimens, which employs a piezoelectric actuator, has been developed. Along with the simple loading scheme using dead weights, the rig is very simple to be used also. The accuracy was found acceptable. Inconel 690 tubes were tested in room temperature and ambient condition. Normal load and sliding amplitude range up to 35N and $100{\mu}m$, respectively. The sizes of wear scar and the wear volumes were measured, and wear coefficients have been calculated based on those. A study on the fretting wear mechanism of the tubes has been attempted via microscopic observation. Rugged wear surfaces are induced by the separation and adhesion of particles and formation and subsequent fracture of surface layers. Lapped specimens were also tested and abrasive wear seems to be playing a dominant role.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.388-392
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• 2003

As the machine tool industry progresses, the performance of cutting tools also needs to be of good quality and specialized. If the existing metal cutting tool tip is coated properly, its life would be longer and the machining of a difficult-to-cut material also could be possible. For the development of the high quality cutting tool, the applicabilities of TiAIN coating deposited by PVD on the cutting insert were experimentally investigated. The various measurements, such as, SEM micrograph, XRD pattern, AFM surface morphology, and hardness were performed to cross-check the possibility and availability of TiAIN coated tool in the field. The effects of it is successful and we hope to see good results in many fields.