Polysulfone 수지를 사용한 그래핀 복합조성물을 제조하고, 이것들의 멤브레인에 대한 잔류응력과 열전도 특성을 분석하였다. 그래핀을 포함하는 polysulfone 멤브레인의 잔류응력분석은 Si (100) 기판에 스핀코팅으로 10 μm 두께의 막을 도포하여 준비한 시료를 대상으로 하였으며, 잔류응력의 측정은 온도를 승온하고 냉각하는 완전한 1주기 동안 수행하였다. 그래핀을 포함하는 polysulfone 평막을 증류수를 사용한 상전이법으로 제조하여 두께방향과 면방향으로 열전도도를 구분하여 각각 측정하였으며 평막시료의 열전도 이방성을 분석하였다. 그래핀의 구조적 특징에 의해 이를 포함하는 polysulfone 막의 잔류응력은 그래핀 함량이 증가함에 따라 점차로 완화되는 경향을 나타내었고, 열전도특성은 평막형성의 구조적 특성과 그래핀의 고유특성에 의해 두께방향과 면방향의 차이를 확인할 수 있었다.

Natural and expandable graphites were chemically treated in acidic aqueous solutions such as acetic acid or mixtures of acetic acid and nitric acid. Structures and thermal conductivities of the as-treated graphites were characterized in detail. Both graphites were significantly oxidized in the mixed acidic solution of H2SO4 and HNO3, which condition was generally used for the oxidation of carbon nanotubes. This considerable oxidation of graphites caused a depression of their thermal conductivity. The structural characteristics, obtained by XRD and XPS, show that the graphites treated in the relatively weak acidic conditions (acetic acid or mixture of acetic acid and nitric acid) were quite similar to the untreated graphites. However, the thermal conductivities of both acidic-treated graphites were remarkably increased.

The spot weldability of dissimilar metal joints between stainless steels (AISI316) and interstitial free (IF) steels were investigated. This study was aimed to determine the spot welding parameters for a dissimilar metal joint and to evaluate the dissimilar metal joint's weldability, including its welding nugget shape, tensileshear strength, hardness, and microstructure. The fracture surface was investigated by using a Scanning Electron Microscopy (SEM). The experimental results showed that the shape of nugget was asymmetric, in which the fusion zone of the STS316 sheet was larger due to the higher bulk-resistance. The microstructure of the fusion zone was fully martensite. In order to evaluate the microstructure further, dilution of stainless steels were calculated and imposed onto the Schaeffler diagram. The predicted microstructure from the Schaeffler diagram was martensite. In order to confirm the predicted microstructure, XRD measurements were carried out. The results showed that that initial weld nugget was composed of austenite and martensite.