• YAKHAK HOEJI
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• v.41 no.3
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• pp.305-311
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• 1997

Sustained release-microspheres and immediate release-pellets were prepared to develop a controlled release multiparticulate system containing both water soluble and insoluble dr ug. Pseudoephedrin.HCl (EPD) and terfenadine (TRF) were used as model drugs, respectively. Sustained release-EPD microspheres were prepared by solvent evaporation method using Eudragit RL or RS as a matrix combined with pH-insensitive film coating. Smaller EPD microspheres were obtained when smaller amount of Eudragit as a matrix material or larger amount of magnesium stearate as a dispersing agent was used. However the obtained microspheres did not show syfficient sustained release characteristics. About 97% of EPD was released after 1 hr irrespective of matrix material used. Subsequent coating of the microspheres with pH-insensitive polymer such as Eudragit RS or ethylcelulose (EC) resulted good sustained in 37.5, 73.3 and 92.0% release of encapsulated EPD in distilled water after 1, 3 abd 7 hr, respectively. It corresponds to mean dissolution time (MDT) of 2.3 hr, which is much larger than that of un-coated EPD microspheres (0.0048 hr). Immediate release TRF pellets were prepared by spherically agglomerated crystallization using Eudragit E as an inert matrix and methylene chloride as a liquid binder. Using Eudragit E alone as a matrix resulted in satisfactory physical properties of the pellets such as sphericity, surface texture and flowability, but led to slower release of TRF from pellets than un-modified TRF powder (MDT of 1.70 vs 1.43 hr in pH 1.2 dissolution medium). Introducing propylene glycol or sodium lauryl sulfate as an emulsifier brought about faster release of TRF from pellets (MDT of 1.14 and 0.95 hr, respectively). In conclusion, microencapsulation by solvent evaporation combined with film coating and spherically agglomerated crystallization were successfully utilized to prepare controlled release multiparticulate system composed of sustained release EPD-microspheres and immediate release TRF pellets.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.777-783
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• 2003

The mechanical properties of B$_4$C/Al composites normally depend on the species and quantity of reaction products between B$_4$C and Al and then the control of reaction products is necessary to make desirable composites for lightweight advanced or armor materials. TiB$_2$ is chemically inert with aluminum and has a lower contact angle (85$^{\circ}$ at 100$0^{\circ}C$) to liquid aluminum than B$_4$C. Thus, TiB$_2$ coating on B$_4$C may lower infiltration temperature of aluminum when the B$_4$C/Al composites is fabricated by infiltration process. In this study, the effects of TiB$_2$ on the microstructure and mechanical properties of the B$_4$C/Al composites have been investigated. TiB$_2$ coated B$_4$C powder was prepared using the sol-gel technique. It was found that the B$_4$C surface is homogeneously covered with TiB$_2$ having a particles size of 20-50 nm. While the B$_4$C/Al composites prepared by infiltration after TiB$_2$ coating had 17 wt% of unreacted Al, on the other hand, the B$_4$C/Al composites without coating included 14 wt% of Al. As a result, the composites infiltrated after the coating showed higher fracture toughness and lower hardness. This strongly suggests that TiB$_2$ not only lowers the infiltration temperature, but also inhibits the reaction between B$_4$C and Al.

• Korean journal of applied entomology
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• v.9 no.2
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• pp.85-90
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• 1970

This study was conducted to find out the evidence of a sex attraction in the fall webworm moths, Hyphantria cunea D., in the fold conditions. The study dealt with the sex attraction between the sexes, selection of effective trap type, effect of moth age on the sex attractiveness, sex attractiveness after copulation, and the time of the sex attraction in the day, The trap was baited with a living moth in the cylindrical screened case 4cm. in long and 2.7cm in diameter. The traps were attached on the tree in a horizontal position at the height of about 3m. on the ground. A sex pheromone was evident in the female moth which attracted the male to the lure, and the modified sticky trap was most effective in this experiment. The trap consisted of a cylindrical powder milk can 11.5cm. in long and 10cm. in diameter with the entry hole 4.8cm, in diameter at both ends of the can, and the inside of can was lined with paper coated with acri-soil(sodium poliacrilate) to catch them. Males were mostly attracted to females during their first 2 days of life, and its attractiveness decreased with moth age, No males were attracted to females more than five days old, and no females lived for more than six days. After copulation, sexual attractiveness was decreased swiftly, Sexual attractiveness was found to be greatest between 4 and 6 A.M. Living females can be used as effective baits for luring the males to the fold trapt.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.69-79
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• 2003

The purpose of this present study was to develop a new way of self-curing acrylic resin, using commercially available polyphosphate, Calgon, which is known to be antimicrobial and safe. For the study, polyphosphate(polyP) was blended with acrylic powder and devided into four groups as follows: no polyP(control), 1% polyP, 2% polyP, and 3% polyP. For the experiment, Streptococcus mutans GS5, Streptococcus sobrinus 6715, Streptococcus gordonii G9B and Challis, Porphyromonas gingivalis 2561, and Candida albicans ATCC 90027 were used. Resin specimens in each group were tested in vitro for the purpose of investigating the effect of polyP on the microbial attachment, growth and hydrophobicity of the resin surface. The results were as follows. 1. PolyP added to the acrylic resin decreased attachment of S. mutans GS5, S. sobrinus 6715, S. gordonii G9B. The greater binding inhibition was found in acrylic resin polymerized with polyP at higher concentrations. 2. The addition of polyP to acrylic resin failed to significantly affect the growth of the tested microorganisms. 3. The addition of polyP to acrylic resin seemed to reduce hydrophobicity of the acrylic resin. PolyP in acrylic resin does not seem to exert a direct antibacterial activity, but rather inhibit attachment of oral bacteria, especially mutans streptococci to saliva-coated acrylic resin. The acrylic resin reduces attachment of streptococci may be due to the decreased hydrophobicity caused by polyP added to the resin. PolyP may be included to acrylic resin to inhibit dental caries which often occurs when removable acrylic resin appliance is placed.

• Journal of dental hygiene science
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• v.11 no.5
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• pp.405-410
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• 2011

The aim of this study was to evaluate antibacterial effect of Cl coated titanium. To coat the Cl on the titanium, first, the titanium was modified by blasting treatment with hydroxyapatite and alumina powder. Anodization process was completed using electrolyte solution of 0.04 M ${\beta}$-glycerol phosphate disodium salt n-hydrate, 0.4 M calcium acetate n-hydrate and 1 M NaCl on the condition of 250 voltages for 3 min. Surface morphology and elements' observation were performed with scanning electron microscopy and energy dispersive spectroscopy and surface profiler was used to analyze the surface roughness. Antibacterial effect was evaluated by film adhesion method. The anodized titanium after blasting showed dimpled surface contained the Cl. Surface average roughness of these surfaces had significantly higher compared to polished titanium. Result of antibacterial test showed that anodized titanium after blasting had an enhanced antibacterial effect compared to the polished titanium. Therefore, these results suggested that titanium contained Cl by anodization after blasting had a rough surface as well as antibacterial effect.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.1-7
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• 2012

In this article, I will introduce recent developments of environmental-friendly materials fabricated using atomic layer deposition (ALD). Advantages of ALD include fine control of the thin film thickness and formation of a homogeneous thin fim on complex-structured three-dimensional substrates. Such advantages of ALD can be exploited for fabricating environmental-friendly materials. Porous membranes such as anodic aluminum oxide (AAO) can be used as a substrate for $TiO_2$ coating with a thickness of about 10 nm, and the $TiO_2$-coated AAO can be used as filter of volatile organic compound such as toluene. The unique structural property of AAO in combination with a high adsorption capacity of amorphous $TiO_2$ can be exploited in this case. $TiO_2$ can be also deposited on nanodiamonds and Ni powder, which can be used as photocatalyst for degradation of toluene, and $CO_2$ reforming of methane catalyst, respectively. One can produce structures, in which the substrates are only partially covered by $TiO_2$ domains, and these structures turns out to be catalytically more active than bare substrates, or complete core-shell structures. We show that the ALD can be widely used not only in the semiconductor industry, but also environmental science.

• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.38-48
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• 1989

The purpose of this study was to investigate the proper consistency of root canal sealer needed in obtaining an efficient canal obturation in injection-thermoplasticized low-temperature ($70^{\circ}C$) gutta-percha method. The sealer was made by incorporating zinc oxide powder into $0.5m{\ell}$ of eugenol and then the $0.5m{\ell}$ of mixture slurry was placed between two flat glass plates. The consistency was determined by measuring the degree of spread of the slurry at loading the 120gm of weight from the top plate. The sealer was prepared according to P/L ratio corresponding to the acquired consistency of 65.45mm, 46.80mm, 28.95mm and 22.60mm. The distal roots were obtained by cutting off from 125 extracted human lower molars and the root canals were prepared by using step-back method. The prepared canals were coated with the sealers on their walls and obturated by using the injection-thermoplasticized low-temperature ($70^{\circ}C$) gutta-percha method. All specimens were immersed in 2% methylene blue dye solution for 48 hours at $37^{\circ}C$. Calipers was used to measured the dye penetration into the root canals from apical constrictions. The results were as follows : The canals obturated without sealer showed significantly more leakage than the canals obturated with sealer. Within the consistency from 65.45mm to 22.60mm, the sealer of 65.45mm appeared significantly better than that of 28.95mm and 22.60mm in the canals obturated by injection-thermoplasticized gutta-percha method, and better than that of 46.80mm without statistical significance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.7
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• pp.1064-1071
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• 2015

Viscous fermented red ginseng extracts were dried and coated using a fluidized bed coater to increase convenience and consumer acceptance. The methods for making spherical granules of fermented red ginseng extracts with increasing convenience were established by using indigestible dextrin. Spherical granules of fermented red ginseng extracts with increasing convenience were made by mixing indigestible dextrin at 40% (40% IDD), 50% (50% IDD), and 60% (60% IDD) versus the soluble solid content of fermented red ginseng extracts. Spherical granules of fermented red ginseng extracts showed less angle of repose than powder of fermented red ginseng extracts. This means that spherical granules of fermented red ginseng extracts had good fluency with increased convenience. The more indigestible dextrin showed higher yields. Although 50% IDD showed less yield than 60% IDD, 50% IDD was the best mixing ratio for making spherical granules of fermented red ginseng extracts, as fermented red ginseng extracts is known as a healthy food. The optimized operation conditions of the fluidized bed coater for making 50% IDD were feeding rate 0.54 mL/min, atomization air pressure 2.15 bar, and product temperature $83.03^{\circ}C$.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.160-165
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• 2006

A Pd-Cu-Ni alloyed hydrogen membrane has fabricated on porous nickel support formed by nickel powder. Porous nickel support made by sintering shows a strong resistance to hydrogen embrittlement and thermal fatigue. Plasma surface modification treatment is introduced as pre-treatment process instead of conventional HCl wet activation. Nickel was electroplated to a thickness of $2{\mu}m$ in order in to fill micropores at the nickel support surface. Palladium and copper were deposited at thicknesses of $4{\mu}m$ and $0.5{\mu}m$, respectively, on the nickel coated support by DC sputtering process. Subsequently, copper reflow at $700^{\circ}C$ was performed for an hour in $H_2$ ambient. And, as a result PdCu-Ni composite membrane has a pinhole-free and extremely dense microstructure, having a good adhesion to the porous nickel support and infinite hydrogen selectivity in $H_2/N_2$ mixtures.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.218-224
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• 2015

Recently, removing methods of red tide has been attempted by filtering the organisms using the ceramic porous bodies. However, the marine biofouling could be developed on the surfaces of porous ceramic body after use for more than one month, and it might decrease the function of the specimen. In this paper, a method of inhibiting marine biofouling by changing the physical properties or surface-modification of ceramic porous body was studied. After experiment with six different ceramic porous bodies, it was found that the specimen of lower porosity and water absorption showed the least amount of biofouling. In addition, by increasing the surface roughness with silica particles bonded to the surface of specimen, the amount of biofouling caused by large marine life such as barnacle and mussel could be decreased. On the other hand, when the surface of specimen was coated and fused by glass powder, the amount of biofouling was rather increased. This might be due to eluted inorganic ions from the glass which can promote the growth of the microorganism. In conclusion, the environmental-friendly methods to reduce the amount of marine biofouling, such as controlling the physical properties and the surface roughness of the porous ceramics, can be possible without the use of dangerous substances. So it is expected for the results obtained to be applicable to a marine structure.