• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1237-1238
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• 2009

• Proceedings of the Korean Vacuum Society Conference
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• 2002.06a
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• pp.105-105
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• 2002

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.193-193
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• 2009

• Journal of the Korean Chemical Society
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• v.53 no.6
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• pp.824-827
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• 2009

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.887-890
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• 2009

Hydroxyapatite (HAp)-based materials have attracted considerable attention on account of their excellent stability and recrystallization. Nanoscale HAp powders with a mean particle size of 200 nm were used to regenerate the enamel layers of damaged teeth. An artificially scratched tooth was immersed in a nanoscale HAp powder suspension in d.i. water (HAp of 70 wt%) at 37 ${^{\circ}C}$ for a period of 1~3 months. SEM and AFM showed that the scratched surface was ultimately inlaid with HAp after three months and the roughness increased from 2.80 to 5.51. Moreover, the hardness of the neo-generated HAp layer on the crown was similar to that of the innate layer. $Ca^{2+}$ and ${PO_4}^{3-}$ ions from the HAp powders dissolved in d.i. water were precipitated on the tooth to produce cemented pasteson the enamel surface due to its high recrystallizing characteristics, resulting in a hard neo-regenerated HAp layer on the enamel layer. This nanoscale HAp powder solution might be used to heal decayed teeth as well as to develop tooth whitening appliances.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.06a
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• pp.5-6
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• 2004

• Journal of Magnetics
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• v.19 no.1
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• pp.68-71
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• 2014

Copper doped Zinc Oxide nanofilms were prepared using a simple and low cost wet chemical method. The microstructures, phase structure, Raman shift and optical absorption spectrum as well as magnetization were investigated for the nanofilms. Room temperature ferromagnetism has been observed for the nanofilms. Structural analyses indicated that the films possess wurtzite structure and there are no segregated clusters of impurity phase appreciating. The results show that the ferromagnetism in Copper doped Zinc Oxide nanofilms is driven either by a carrier or defect-mediated mechanism. The present work provides an evidence for the origin of ferromagnetism on Copper doped Zinc Oxide nanofilms.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.563-567
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• 2016

In this paper, the chaos-based secure scheme for power line communication is proposed for the first time. A digitalized chaotic generator based Lorenz system is utilized for generating nonlinear dynamic chaotic signal for masking the information signal instead of reported analog chaotic generators. A simple method of encryption and decryption is also given. In order to confirm the feasibility of the proposed scheme, the system is simulated using a simplified encryption/decryption method in Proteus. The gained results from simulation demonstrated that by using the chaos-based security method, the data can be encrypted and easily transmitted through the power line network efficiently.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.3950-3956
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• 2012

In order to improve the bioactivity and mechanical properties of hydroxyapatite (HAp), chitosan (Chi) was in situ combined into HAp to fabricate a composite scaffold by a sublimation-assisted compression method. A highly porous film with sufficient mechanical strength was prepared and the bioactivity was investigated by examining the apatite formed on the scaffolds incubated in simulated body fluid. In addition, the cytotoxicity of the HAp/Chi composite was studied by evaluating the viability of murine fibroblasts (L-929 cells) exposed to diluted extracts of the composite films. The apatite layer was assessed using scanning electronic microscopy, inductively coupled plasma-optical emission spectrometry and weight measurement. Composite analysis showed that a layer of micro-sized, needle-like crystals was formed on the surface of the composite film. Additionally, the WST-8 assay after L-929 cells were exposed to diluted extracts of the composite indicated that the HAp/Chi scaffold has good in vitro cytocompatibility. The results indicated that HAp/Chi composites with porous structure are promising scaffolding materials for bone-patch engineering because their porous morphology can provide an environment conductive to attachment and growth of osteoblasts and osteogenic cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.155-155
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• 2009