• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.273-276
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• 2008

Thermoplastic resin takes place stress relaxation and creep according to temperature and time. In room temperature, time dependent deformation (TDD) of polymer was carried out at previous study. In this study, it evaluates time dependent deformation to relate temperature. Nanoscale indents can be used as cells for molecular electronics and drug delivery, slots for integration into nanodevices, and defects for tailoring the structure and properties. Therefore, it is important to control pattern depth for change of indent depth by creep when using Nanoindenter. For evaluating TDD at high temperature, it is occurred thermal-nanoindentation test by changing hold time at maximum load. Temperature is putted at $90^{\circ}C$, hold time at maximum loads are putted at 1, 10, 50, 100, 200, 300 and 500s.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.62-70
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• 2005

The nanoindenter and AFM have been used for nanofabrication, such as nanolithography, nanowriting, and nanopatterning, as well as measurement of mechanical properties and surface topology. Nanoscale indents can be used as cells for molecular electronics and drug delivery, slots for integration into nanodevices, and defects for tailoring the structure and properties. Therefore, it is very important to make indents of desired morphology (shape, size and depth). Indents of different shapes can be obtained by using indenters of different geometries such as a cube comer and conical and spherical tips. The depth and size of indents can be controlled by making indentations at different indentation loads. However, in case of viscoplastic viscoelastic materials such as polymethylmethacrylate (PMMA) the time dependent deformation (TDD) should also be considered. In this study, the effect of process parameters such as loading rate and hold-time at peak load on the indent morphology (maximum penetration depth, elastic recovery, transient creep recovery, residual depth pile-up height) of PMMA were studied for hyperfine pattern fabrication.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.133-133
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• 2004

박막이나 초미세 구조체의 경도 및 탄성계수 측정을 위한 나노 압입실험에서는 Oliver ＆ Pharr가 제안한 하중-변위 측정 나노압입법이 널리 쓰이고 있다 위 실험법에서, 나노경도(nano-hardness; H$_{n}$)는 최대하중을 계산된 접촉면적 (A$_{c}$)으로 나누어 평가하고, 압입자 및 박막의 탄성성질을 포함하는 환산 탄성계수 (reduced modulus ; E$_{r}$)는 하중제거곡선의 초기 기울기인 접촉탄성강성 (S)를 이용하여 계산한다. 그러나, 하중-변위 측정 나노압입법에서는 탄성 및 소성변형만이 고려되고 시간 의존적 변형거동 (time dependent deformation; TDD)은 고려되지 않는다.(중략)