Papers by Author: Do Hoon Shin

Abstract: The thin films of indium tin oxide (ITO) are used for a variety of electronic devices such as solar cells, touch panels, liquid crystal displays (LCDs). However, these electronic devices are not strong enough against heavy impact since their ITO thin films are deposited on glass substrates. Therefore, ITO thin films were prepared by the inclination opposite target type DC magnetron sputtering equipment onto the Polyethylene Terephthalate (PET) substrate at room temperature using oxidized ITO with In2O3 and SnO2 in a weight ratio of 9:1. In this study, the transmittance, resistivity and electromagnetic wave shielding effectiveness of the ITO thin films prepared at various sputtering time (20~80min namely film thickness; 130~500nm) are measured. The results show that transmittance of the ITO thin films could show about 70% in the range of a visible ray by the variation of film thickness. It also can be seen that a minimum exists in the resistivity of ITO thin films for the variation of film thickness. Electromagnetic wave shielding effectiveness was increased as film thickness increased.

Abstract: To prove the suitability the honeycomb composites structure with VARTM, the mechanical properties of the skin materials and honeycomb composites structure were evaluated with the static strength tests. The mechanical properties of honeycomb composites structure made by VARTM were satisfied with the real using conditions instead of the composites structure made by autoclave process. Accordingly, the honeycomb sandwich composites made by VARTM is available for manufacturing various composites parts. VARTM was very effective method to manufacture the honeycomb sandwich composites. It was possible that the manufacturing process was changed from autoclave process to VARTM to solve the problems on the autoclave process.

Abstract: Diamond film was deposited on the pure titanium substrate by CH4-H2 gas mixture using MPCVD method. In order to carboxylate the surface of the diamond film, it was chemically treated in H2SO4:HNO3 (9:1, case 1) stirred at room temperature or in H2SO4:HNO3 (3:1, case 2) stirred at reflux. The oxidized diamond film was successively treated with 0.1M NaOH for 2hours and 0.1M HCl at 363K for 2hours, and then washed by distilled water. The surface of diamond film was observed by scanning electron microscopy (SEM). The diamond film was characterized using Raman spectroscopy and X-ray diffraction (XRD). Carboxylated diamond film was evaluated by Fourier transform infrared spectrometer (FT-IR), Mini secondary ion mass spectrometer (Mini SIMS) and X-ray photoelectron spectroscopy (XPS). In the FT-IR spectrum, the peak at 1640cm -1 was assigned with C=O stretching vibration of carboxylic acid. In the Mini SIMS profile, the peak intensities of mass number 16 (-O-) and 17 (-OH) were increased after the chemical treatment. The XPS results indicated COO- group and C=O group on the surface of diamond film.