• Food Science of Animal Resources
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• v.39 no.5
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• pp.831-843
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• 2019

The purposes of this research were to form chitosan oligosaccharide (CSO)/A2 ${\beta}$-casein nano-delivery systems (NDSs) and to investigate the effects of production variables, such as CSO concentration levels (0.1%, 0.2%, and 0.3%, w/v) and manufacturing temperature ($5^{\circ}C$, $20^{\circ}C$, and $35^{\circ}C$), on the production and physicochemical characteristics of CSO/A2 ${\beta}$-casein NDSs to carry resveratrol. The morphological characteristics of CSO/A2 ${\beta}$-casein NDSs were assessed by the use of transmission electron microscopy (TEM) and particle size analyzer. High-performance liquid chromatography (HPLC) was applied to determine the entrapment efficiency (EE) of resveratrol. In the TEM images, globular-shaped particles with a diameter from 126 to 266 nm were examined implying that NDSs was successfully formed. As CSO concentration level was increased, the size and zeta-potential values of NDSs were significantly (p<0.05) increased. An increase in manufacturing temperature from $5^{\circ}C$ to $35^{\circ}C$ resulted in a significant (p<0.05) increase in the size and polydispersity index of NDSs. Over 85% of resveratrol was favorably entrapped in CSO/A2 ${\beta}$-casein NDSs. The entrapment efficiency (EE) of resveratrol was significantly (p<0.05) enhanced with an increase in manufacturing temperature while CSO concentration level did not significantly affect EE of resveratrol. There were no significant (p<0.05) changes observed in the size and polydispersity index of NDSs during heat treatments and storage in model milk and yogurt indicating that CSO/A2 ${\beta}$-casein NDSs exhibited excellent physical stability. In conclusion, the CSO concentration level and manufacturing temperature were the crucial determinants affecting the physicochemical characteristics of CSO/A2 ${\beta}$-casein NDSs containing resveratrol.

• Food Science of Animal Resources
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• v.38 no.6
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• pp.1294-1304
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• 2018

The aims of this research were to examine the effect of heating temperature (65, 75, and $85^{\circ}C$) and $CaCl_2$ concentration level (3, 4, and 5 mM) on the physicochemical properties of ${\beta}$-lactoglobulin (${\beta}$-lg) nanoemulsions (NEs) and to study how the droplet size of NEs affects the bioaccessibility (BA) of coenzyme $Q_{10}$ ($CoQ_{10}$). The droplet size of NEs and BA of $CoQ_{10}$ was assessed by particle size analyzer and UV-Vis spectrophotometer, respectively. An increase in heating temperature and $CaCl_2$ concentration level resulted in a significant (p<0.05) increase in the droplet size of NEs while there were no significant differences in polydispersity index and zeta-potential of NEs. When NEs containing $CoQ_{10}$ were incubated in simulated small intestinal phases, an increase in the droplet size and polydispersity index of NEs was observed. This indicated that NEs were not stable in small intestine and digestion of NEs occurred. As heating temperature and $CaCl_2$ concentration level were decreased, a significant (p<0.05) increase in BA of $CoQ_{10}$ was observed. There was a significant (p<0.05) increase in BA of $CoQ_{10}$ with a decrease in the droplet size of NEs. In conclusion, heating temperature and $CaCl_2$ concentration level were key-parameters affecting the initial droplet size of NEs and BA of $CoQ_{10}$ was negatively correlated with initial droplet size of NEs.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.1-4
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• 2003

The design and synthesis of new polymers is desirable to obtain materials with novel physical properties. Generally, these new polymers have their well-defined nature with the number of functional groups, molecular weight, polydispersity, and the presence or absence of branching being precisely controlledl. These polymers are mainly synthesized by living polymerizations to control of their structures. Among of various living polymerization Atom transfer radical polymerization (ATRP) has been a field of intensive research in recent years1. (omitted)

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1693-1698
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• 1991

An axial dispersion model is developed for the slim reactor employed in the LDPE autoclave process so that imperfect mixing caused by large L/D ratio (10-20) may be quantified by Peclet number. The model is then used to investigate the effect of mixing on the reactor performance represented by the monomer conversion, the reactor temperature, the molecular weight, and the polydispersity. In addition, the existence of steady state multiplicity is identified with the initiator feed concentration or the feed temperature as the bifurcation parameter. The effects of the initiator feed concentration and the feed temperature are also examined.

• Journal of the Korean Applied Science and Technology
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• v.21 no.1
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• pp.69-75
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• 2004

In this study, various model composite latexes were synthesized using n-butyl acrylate and methyl methacrylate as comonomers by seeded multi-staged emulsion polymerization. Monodispersed model composite latex particles with size of 190 nm and polydispersity index of 1.05, which have various morphology including random copolymer particle, soft-core/hard-shell particle, hard-core/soft shell particle, and gradient-type copolymer particle, homopolymers particles were prepared. The designed morphology of model composite particles were confirmed.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.332-332
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• 2006

Well difined sulfonated styrene and n-butyl acrylate (nBA) block copolymers were synthesized by CuBr catalyzed living radical polymerization followed by acification by thermolysis. Neopentyl styrene sulfonate (NSS) was polymerized with PnBA macroinitator precursor ($M_{n}=19,500,\;PDI\;<\;1.09$) and CuBr catalyst with N,N,N',N' -pentamethylethyleneamine (PMDETA) to give nBA-NSS block copolymer with narrow polydispersity ($M_{n}=29,900,\;PDI\;<\;1.15$). PNSS segments in the block copolymer were then acidified by thermolysis at $150^{\circ}C$ resulting in polystyrene segments with 100 % sulfonic acid groups.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.352-352
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• 2006

Corynebacterium glutamicum, which is well known as an amino acid fermentation bacterium, has been used as a producer of poly(3-hydroxybutyrate) [P(3HB)]. P(3HB) was synthesized in recombinant C. glutamicum harboring the expression plasmid vector with a strong promoter for cell surface protein gene derived from C. glutamicum and P(3HB) biosynthetic gene operon derived from Ralstonia eutropha. The expression of P(3HB) synthase gene was detected by enzyme activity assay. Intracellular P(3HB) was microscopically observed as inclusion granules and its content was calculated to be 22.5 % (w/w) with molecular weight of $2.1{\times}10^{5}$ and polydispersity of 1.63.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.766-771
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• 1993

A mathematical model is developed to represent the batch reactor for free radical polymerization of PMMA The model is validated by comparing the simulation result with the experimental data. A computational scheme is proposed to determine the trajectory of the reactor temperature that will produce polymer product having the desired molecular weight distribution. For this instantaneous number average chain length and polydispersity are introduced to calculate the reactor temperature. The former is assumed to be a second order polynomial of the sum of the living and dead polymer concentrations. Various reactor temperature, trajectories are observed depending on the reactor conditions and prescribed molecular weight distributions. Fuzzy and PID control algorithms are applied to trace the reactor temperature trajectory. While the PID control gives rise to an overshoot when the trajectory changes its direction, the fuzzy controller yields a more satisfactory performance because it secures information on the trajectory pattern.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2471-2476
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• 2007

A series of titanium complexes containing terdentate β-ketoiminate ligands were found to be efficient for the ring-opening polymerization of ε-caprolactone (ε-CL), producing poly(ε-caprolactone) (PCL) with bimodal distribution. Steric factors imposed by methyl substituents on the back bone of the alkoxy group affected significantly the polymerization rate and physical properties of the resulting PCL. Intra- and intermolecular transesterifications rather than disproportional rearrangements were responsible for the bimodal behavior and for the change in the molecular weight (Mw). Dilution with toluene reduced yield, and lowered polydispersity (PDI) and Mw of PCL, while the catalytic activities of the dimeric complex, [Ti(Oi-Pr)2(N-alkoxy-β- ketoiminate)]2 and Ti(Oi-Pr)4 were not sensitive to the added solvent. The dimeric complex showed living character, while other catalysts suffered from chain termination reactions.

• Fibers and Polymers
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• v.2 no.1
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• pp.131-134
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• 2001

Living cationic polymerization behaviors of isobutyl vinyl ehters (IBVE), initiated by iodomethyl methyl ether (IMME)/zinc iodide ($Znl_2$) have been investigated. The polymerization was carried out at 0, -15, and $-30^{\circ}C$ in toluene. It was found that the rate of polymerization increased as the IMME concentration increased and decreased as temperature decreased. 100% conversion was always achieved without exception. Furthermore, the number-average molecular weight ($M_{n}$) of polymers increased in direct proportion to monomer conversion. The molecular weights of polymers were in good agreement with the theoretical values, calculated on the basis that one polymer chain was formed by one IMME molecule and the values of polydispersity index are always less than 1.2, revealing the living nature. The living nature was also confirmed by synthesis of poly(IBVE-b-TBVE) by subsequent monomer addition of t-butyl vinyl ether (TBVE).