• Journal of Korean Neurosurgical Society
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• v.46 no.3
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• pp.195-198
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• 2009

Objective : Medpor porous polyethylene was used to reconstruct small bone defects (gaps and burr holes) along a craniotomy bone flap. The feasibility and cosmetic results were evaluated. Methods : Medpor Craniotomy Gap Wedges, V and T, were designed. The V implant is a 10 cm-long wedge strip, the cross section of which is an isosceles triangle with a 4 mm-long base, making it suitable for gaps less than 4 mm after trimming. Meanwhile, the Medpor T wedge includes a 10 mm-wide thin plate on the top surface of the Medpor V Wedge, making it suitable for gaps wider than 4 mm and burr holes. Sixty-eight pterional craniotomies and 39 superciliary approaches were performed using the implants, and the operative results were evaluated with respect to the cosmetic results and pain or tenderness related to the cranial flap. Results : The small bone defects were eliminated with less than 10 minutes additional operative time. In a physical examination, there were no considerable cosmetic problems regarding to the cranial bone defects, such as a linear depression or dimple in the forehead, anterior temporal hollow, preauricular depression, and parietal burr hole defect. Plus, no patient suffered from any infectious complications. Conclusion : The Medpor Craniotomy Gap Wedge is technically easy to work with for reconstructing small bone defects, such as the bone gaps and burr holes created by a craniotomy, and produces excellent cosmetic results.

• Current Photovoltaic Research
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• v.10 no.2
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• pp.39-48
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• 2022

A Se-containing Cu/SnSe₂/ZnSe precursor was employed to introduce S to the precursor to form Cu₂ZnSn(S,Se)₄ (CZTSSe) film. The morphology of CZTSSe films strongly varied with two different pre-annealing environments: S and N₂. The CZTSSe film with S pre-annealing showed a dense morphology with a smooth surface, while that with N₂ pre-annealing showed a porous film with a plate-shaped grains on the surface. CuS and Cu₂Sn(S,Se)₃ phases formed during the S pre-annealing stage, while SnSe and Cu₂SnSe₃ phases formed during the N₂ pre-annealing stage. The SnSe phase formed during N₂ pre-annealing generated SnS₂ phase that had plate shape and severely aggravated the morphology of CZTSSe film. The power conversion efficiency of the CZTSSe solar cell with S pre-annealing was low (1.9%) due to existence of Zn(S.Se) layer between CZTSSe and Mo substrate. The results indicated that S pre-annealing of the precursor was a promising method to achieve a good morphology for large area application.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.187-192
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• 2006

The preparation and characterization of new polymer composite membranes containing polyphenylene oxide (PPO) thin films with hetropoly acid (HPA) are presented. PPO thin films with phosphotungstic acid (PWA) or phosphomolybdic acid (PMA) have been prepared by using the solvent mixture. The PWA and PPO can be blended using the solvent mixture, because PPO and PWA are not soluble in the same solvent. In this study, methanol was used as a solvent dissolving PWA and chloroform was used as a solvent dissolving PPO. PPO-PWA solutions were cast onto a glass plate with uniform thickness. The composite membranes were prepared by casting Nafion mixture on porous PPO-PWA films. The morphology and structure of these PPO-PWA films were observed with scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The composite membranes were characterized by measuring their ion conductivity and methanol permeability. The performance was evaluated with composite membranes as electrolytes in fuel cell conditions. The methanol cross-over of composite membranes containing PPO-PWA barrier films in the DMFC reduced by 66％.

• Korean Journal of Materials Research
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• v.23 no.4
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• pp.240-245
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• 2013

Electrochemical surface treatment is commonly used to form a thin, rough, and porous oxidation layer on the surface of titanium. The purpose of this study was to investigate the formation of nanotubular titanium oxide arrays during short anodization processing. The specimen used in this study was 99.9% pure cp-Ti (ASTM Grade II) in the form of a disc with diameter of 15 mm and a thickness of 1 mm. A DC power supplier was used with the anodizing apparatus, and the titanium specimen and the platinum plate ($3mm{\times}4mm{\times}0.1mm$) were connected to an anode and cathode, respectively. The progressive formation of $TiO_2$ nanotubes was observed with FE-SEM (Field Emission Scanning Electron Microscopy). Highly ordered $TiO_2$ nanotubes were formed at a potential of 20 V in a solution of 1M $H_3PO_4$ + 1.5 wt.% HF for 10 minutes, corresponding with steady state processing. The diameters and the closed ends of $TiO_2$ nanotubes measured at a value of 50 cumulative percent were 100 nm and 120 nm, respectively. The $TiO_2$ nanotubes had lengths of 500 nm. As the anodization processing reached 10 minutes, the frequency distribution for the diameters and the closed ends of the $TiO_2$ nanotubes was gradually reduced. Short anodization processing for $TiO_2$ nanotubes of within 10 minutes was established.