• Applied Chemistry for Engineering
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• v.32 no.5
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• pp.509-515
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• 2021

In this study, poly lactic-co-glycolic acid (PLGA) nanoparticles (PNP) were prepared through double (w/o/w) emlusion and emulsifying solvent-evaporation technique using PLGA, which has biocompatibility and biodegradability. To maximize stability and bioavailability of the particles, chitosan-coated PLGA nanoparticles (CPNP) were prepared by charge interaction between PNP and chitosan. We demonstrated that CPNP can be utilized as a drug carrier of oral administration. The chemical structure of CPNP was analyzed by ¹H-NMR and FT-IR, and all characteristic peaks appeared, confirming that it was successfully prepared. In addition, particle size and zeta potential of CPNP were analyzed using dynamic light scattering (DLS) while morphological images were obtained using transmission electron microscope (TEM). Thermal decomposition behavior of CPNP was observed through thermogravimetric analysis (TGA). In addition, the cytotoxicity of CPNP was confirmed by MTT assay at HEK293 and L929 cell lines, and it was proved that there is no toxicity confirmed by the cell viability of above 70% at all concentrations. These results suggest that the CPNP developed in this study may be used as an oral drug delivery carrier.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3B
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• pp.231-239
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• 2011

This paper reviews the recent theoretical and empirical studies on the European countries that the bill and keep settlement between mobile operators is superior to the financial settlement like CPNP from the perspectives of social welfare and fare competition in market. Besides these the recent studies, considering the change of mobile wholesale market in Korea, the necessity to introduce the bill and keep settlement as an alternative for the current CPNP as well as policy implication is examined.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.527-534
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• 1999

This study was carried out to investigate the effects of pine needle extracts on lipid oxidation and free radical reaction in iron sources reacted with active oxygen species. The results were summarized as follow; the catalytic effects of active oxygen on lipid oxidation in oil emulsion tended to be showed $OH,\;H_2O_2\;and\;KO_2$ in order. At the same time, pine needle extracts itself were tended to be showed a little catalytic effects. Active oxygen scavenging ability of pine needle extracts didn't show, but pine needle extracts played role as a strong chelating agents to bind iron ion if $Fe^{2+}$ ion exist in oil emulsion. The content of $Fe^{2+}$ ion and total iron in CPNP were higher than those of HPNP and FPN. The content of ascorbic acid of FPN showed the highest (87.77 ppm) among several pine needle extracts. Electron donating ability of HPNP and CPNP were 81% and 78%, respectively, which were showed higher content than those of FPN. The SOD-like activity of HPNP showed 44.30%, compared to other pine needle extracts which means the most strong antioxidant reaction. The nitrite scavenging effects were tended to be different, depending on pH value as pH value was increased. Especially, they didn't show the nitrite scavenging effect in pH6.0.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.542-547
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• 1998

In order to study bread properties utilizing extracts of pine needle, various mixing percentage were applied to select appropriate ratio between water and extracts. Dough pH, dough pH after first fermentation, dough volume, bread volume and baking loss rate were tested to investigate bread properties after adding extracts of pine needle to bread. The results were summarized as follows; The effects of extracts percentage on pH value of dough according to preparation method were the lowest in the method of hot air drying of pine needle powder. After first fermentation, dough pH was tended to have a the same tendency as above. Dough volume and bread volume were tended to be increased as extracts percentage of pine needle were increased. The percentage of baking loss tended to be a little increased as addition level of extracts was increased. Strength of hardness were increased as storage time passed away. In conclusion, the taste and texture of bread were tended to be decreased as storage time goes, but the strength of pine needle flavour were tended to be increased as addition level of extracts were increased, irrespective of preparation method.