• Journal of the Korean Applied Science and Technology
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• v.26 no.2
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• pp.171-178
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• 2009

A comparative analysis of the hindered amine light stabilizers (HALS) and UV abosrber (UVA) and their respective photostabilizing effect on wood plastic composites (WPCs) are reported in this study. The influence of accelerated weathering on the mechanical properties of the composites and the microscopic morphology of a degraded layer on the cross section and the surface were studied. UV absorbers were more efficient at preventing composite lightening than was UV stabilizer. The amount of whitening decreased with the increase of photostabilizers. With the addition of a UV absorber (Tinuvin360), the tensile modulus and strength of the composites increased slightly. However, the addition of a light stabilizer (Tinuvin770) and a UV absorber decreased the tensile modulus and strength of the composites. After 250 and 500 hr exposure, tensile modulus and strength of the un stabilized and stabilized composites decreased. The tensile strength of UV absorber (Chimassorb81)-stabilized composites was significantly greater than that of control and light stabilizer (Tinuvin770)- and UV absorber (Tinuvin360)-stabilized composites. UV absorber-stabilized samples showed less whitening and photodegradation than control and light stabilizer-stabilized samples.

• Polymer(Korea)
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• v.33 no.5
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• pp.413-419
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• 2009

As the refractive index of the prism layer becomes higher, the optical performance of the prism sheet gets better and the efficiency of the LCD backlight unit is improved. In order to increase the refractive index of the prism layer, the ultraviolet curing type resins were prepared by mixing high refractive index materials containing aromatic groups and the multi-functional reactive diluents. By using 9,9-bis [4-(2-acryloyloxyethoxy)phenyl] fluorene, the refractive index of the prism layer was increased up to 1.58 and the brightness of the backlight unit was improved. Since the light source used in the backlight unit caused the yellowing in the prism sheet and deteriorated the brightness accordingly, the hindered amine light stabilizer was used to improve the yellowing resistance successfully.

• Journal of Pharmaceutical Investigation
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• v.22 no.4
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• pp.281-287
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• 1992

Omeprazole (OMZ) is very unstable in acidic solution, which selectively inhibit the release of the gastric juice in the gastric mucosa, In order to stabilize (OMZ) in oral solid dosage form, the enteric-coated microcapsules and compression-coated OMZ tablets containing lysine or arginine as stabilizer were prepared and their dissolution and stability test were performed. The haif life of OMZ microcapsules containing arginine was 194 days at $30^{\circ}C$ and OMZ was completely released in 60 min. The half-lives of enteric coated and non-coated compression-coated OMZ tablets with lysine were 292 and 95 days at $30^{\circ}C$, respectively. The half-lives of enteric coated and non-coated compression-coated tablets with arginine were 1752 and 293 days at $30^{\circ}C$, respectively, and OMZ were released completely in 20 min in the 2nd fluid of K.P.VI. Consequently, the enteric-coated compression-coated OMZ tablets with arginine as stabilizer provided a good formulation for oral solid dosage form.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2966-2970
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• 2012

Fullerene/polystyrene ($C_{60}$/PS) nano particle was prepared by using emulsion polymerization. Styrene and fullerene were emulsified in aqueous media in the presence of poly(N-vinyl pyridine) as an emulsion stabilizer, and polymerization was initiated by water soluble radical initiator, potassium persulfate. The obtained nano particles have an average diameter in the range of 400-500 nm. The fullerene contents in the nano particle can be controlled up to 15 wt % by varying the feed ratio, which was confirmed by themogravimetric analysis (TGA) and elemental analysis (EA). The structure and morphologies of the $C_{60}$/PS nano particles were examined by various analytical techniques such as dynamic light scattering (DLS), scanning electron microscope (SEM), transmission electron microscope (TEM), electron diffraction (ED) pattern, X-ray powder diffraction (XRD), and UV spectroscopy. Unlike conventional $C_{60}$/PS particles initiated by organic free radical initiators, in which the fullerene is copolymerized forming a covalent bond with styrene monomer, the prepared $C_{60}$/PS nano particles contain pristine fullerene as secondary particles homogeneously distributed in the polystyrene matrix.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.4
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• pp.165-174
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• 2000

This paper presents the application of H$\infty$ control synthesis using LMI optimization method to power system stabilizer(PSS) design. Since power system is usually operated under circumstance of unmeasurable uncertainties and external disturbances, the improvement of small signal stability becomes one of the most important issue for securing system stability and preventing low frequency oscillation phenomena. The LMI optimized H$\infty$ PSS provides robust performance and guarantees the internal stability under these operating conditions. The global optimal H$\infty$ norm is found using LMI convex optimization method which is more systematic than standard two Riccati solution method. The design results are simulated for a case study. We verified that the LMI method shows the best performance characteristic smong standard Riccati method and conventional lead/lag method.

• Korean Journal of Microbiology
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• v.36 no.3
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• pp.228-235
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• 2000

Until now, it was diIliculi to overproduce lignin peroxidase(LiP) fiom Pl~anemchaete ch~ysosporium since the lack of optimized growth conditions. In this paper, we optimized the LIP production conditions and monitored LIP isozyines of fl chqsospoi.ium PSBL-1. The optimized condition includes sponge matrix support, no addition of $MnSO_4$, excess addition of niixogen source(48 inM diarmnonium), and addition of stabilizer(2 mM verakyl alcohol). Finally we obtained Lip activity of 1,800 unitsll. HI isozyne was overproduced when inyceliuin was cultivated in media containing $Mn^{2+}$ (2.73 inM) and excess nitrogen(48 11d4 diannnonium). Three azo dyes(acid yellow 9, congo ued, orange IT; each concenimtion of50 $\mu$M) we1-e rapidly decolorized within 2 inins by 0.4 un~t or Lip.

• The Korean Journal of Mycology
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• v.16 no.2
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• pp.70-78
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• 1988

To obtain basic information for the genetic analysis and breeding of Flammulina velutipes, some factors affecting the release of protoplasts from the fungus were studied. Potato Dextrose peptone Agar medium was suitable for the growth of the mycelium and the protoplast formation of F. velutipes. The culture age for the high yields of protoplast was 5 days on PDPA. Few protoplasts were formed from the mycelium cultured on Mushroom minimum Media. The highest yield of protoplasts was obtained in enzyme solution containing Novozyme 234 plus cellulase CP at 10 mg $ml^{-1}$ concentration, while a half amount of protoplasts was obtained in enzyme solution containing Novozyme 234 only. The optimal reaction time of the mycelium in the Iytic enzyme mixtures was 3 hours. The best osmotic stabilizer for the protoplast formation of the mycelium was 0.6M sucrose without buffer at pH 6.2.

• Korean Journal of Agricultural Science
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• v.13 no.2
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• pp.185-192
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• 1986

Some factors affecting the protoplast release from mycelia of Ganoderma lucidum and regeneration of the protoplast were investigated and the results obtained are summarized as follows; Novozym 234 as a lytic enzyme was the most effective for the protoplast release from mycelia of Ganoderma lucidu m and its optimal concentration was 10mg per ml of osmotic stabilizer. The highest number of protoplasts were released after 3 hours incubation in the reciprocal shaking bath at 120 oscillations a minute. Among six osmotic stabilizers tested, 0.6M sucrose showed the best result. SCM medium showed good mycelial growth and high yields of protoplasts. The protoplasts released from the mycelium of G. lucidum were regenerated at 0.20 to 0.27 percent on MCM, MMM and SCM. Of the cultures obtained from protoplasts regenerated, 13 to 29 percent were monokaryon.