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Ohmyoung Kwon
Name
Ohmyoung Kwon | Professor
Tel
+82-2-3290-3371
Fax
+82-2-926-9290
E-mail
omkwon@korea.ac.kr
address
Department of Mechanical Engineering Korea University Anam-dong Sungbuk-gu Seoul 136-713 Korea
Education
1990. 2 B.S. Mechanical Engineering, Seoul National University, Korea
1992. 2 M.S. Mechanical Engineering, Seoul National University, Korea
2000. 12 Ph.D. Mecahnical Engineering, University of California, Berkeley
Lab.
MEMS & Nano Engineering lab.
Development of high-sensitive SThM probe for measurement of temperature and thermal properties in nanoscale
The scanning thermal microscope (SThM) that is a type of scanning probe microscope (SPM) maps out the topography, temperature and/or the thermal property of a sample surface by scanning a sharp SThM probe with a temperature sensor at the tip. We has develop the thermocouple SThM probe using fabrication process for micro-electro-mechanical systems (MEMS).
Dopant profiling on semiconductor with nanometer spatial resolution
The recent semiconductor device has been miniaturized a lot, therefore the gate length became less than 100nm. This miniaturization arouses a need of proper technique of dopant profiling in nanometer scale, however, a few methods existing are quantitative ones and there’s no method which can profile the dopant density quantitatively. We are developing the method which can map out the dopant density of silicon integrated circuit quantitatively. (Figure : p-type MOSFET with gate length of (a) 135nm, (b) 60nm, (c) 40nm.)
Thermal characterization of CNTs and CNFET using SThM
Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. CNTs have been constructed with length-to-diameter ratio of up to 28,000,000:1, which is significantly larger than any other material. CNTs are the strongest and stiffest materials yet discovered in terms of tensile strength and elastic modulus respectively. And they have very high chemical stability, electrical conductivity and thermal conductivity. Therefore, CNTs are interested in the application field widely, such as cooler, semiconductor device, composites and so on (Fig 2).
Microscale temperature gradient effects on stem cell
For the purpose of the treatment of various incurable diseases, a lot of researches which differentiating embryonic stem cells into the human body’s organs or tissues are in progress. However, physical microenvironments of proliferating and differentiating stem cells in vivo are not completely known. In case of existing chemical methods to differentiate stem cells, it is hard to control precisely the chemical substances, reagents, protein separation and purification, and the cost is also significant. In the other hand, adjusting the physical environment of cells is easy, and it has the cost-advantage because of reuse. The purpose of this study is induction of directed differentiation of embryonic stem cell by manipulating micro-thermal environment. To do this, we fabricate and develop a bio-compatible micro-chip that allows precise controls of micro-thermal environment. This micro-chip creates a micro temperature gradient through cell at a specific temperature range to induce differentiation.
Thickness and phase dependence of Ge2Sb2Te5 film thermal conductivity and thermal boundary resistance of Ge2Sb2Te5 and TiN
PRAM (Phase Change RAM) has simple structure, fast input/output speed, and low manufacturing cost compared to next-generation non-volatile memory. Phase change is performed by applying Joule-heating or cooling on electrode (TiN) connected to phase change material (Ge2Sb2Te5, GST). And phase (Amorphous, FCC, and HEX) of GST is determined by different heating time and temperature. Thermal properties of GST are very important for PRAM thermal design optimization. GST Film thermal capacitance is nearly same as Bulk property but film thermal conductivity isn’t because film thermal conductivity is sensitive to film structure, thickness, and interface. Therefore, exact understanding of GST film thermal conductivity is required for PRAM thermal design optimization.