• Journal of Technologic Dentistry
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• v.29 no.1
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• pp.121-131
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• 2007

A preparation process's conditions of aqueous sol which contains anatase-type nano titania particles with photocatalyic properties was established by using Yoldas process, so called, DCS(Destabilization of Colloidal Solution) process in this study. And crystal size change and phase transformation of titania particles in aqueous titania sol depending on reaction conditions was investigated by a light scattering method and XRD analysis of frozen dried powders, respectively. This sol with photo catalytic nano titania particles was used to the following hydrophilic hybrid coating film's fabrication and its properties was evaluated. Subsequently, for coating film using the above mentioned aqueous titania sol, non-aqueous titania sol was prepared without any chemical additives and its time stability according to aging time was investigate. By using the above mentioned aqueous titania sol and non-aqueous sol, a complex oxide coating sol for metal and ceramic substrate and a organic-inorganic hybrid coating sol for polymer substrate was prepared and it's hydrophilicity depending on UV irradiation conditions was evaluated. As a conclusions, the following results were obtained. (1)Aqueous titania sol The average particle size of titania in formed aqueous titania sol was distributed between 20$\sim$90nm range depending on reaction conditions. And the crystal phase of titania powders obtained by frozen drying method was changed from amorphous state to anatase and subsequently transformed to rutile crystal phase and it is attributed to concentration gradient in aqueous sol. (2)Non-aqueous titania sol Non-aqueous titania sol was prepared using methanol as a solvent and a little distilled water for hydrolysis and nitric acid as a catalyst were used. The obtained non-aqueous titania sol was stable at room temperature for 20 days. Additionally, non-aqueous titania sol with addition of chealating reagent such as acethylaceton and ethylene glycol prolonged the stability of sol by six months. (3)Complex sol and hybrid sol with super hydrophilicity The above mentioned aqueous titania sol as a main photocataylic component and non-aqueous titania sol as a binder for coating process was used to prepare a complex sol used for metal, ceramic and wood material substrate and also to prepare the organic-inorganic hybrid sol for polymer substrate such as polycarbonate and polyethylene, in which process APMS(3-Aminopropyltrimethoxysilane), GPTS(3-Glycidoxypropyl-trimethoxysilane) as a hydrophilic silane compound and HEMA(2-Hydroxyethyl methacrylate) as a forming network in hybrid coating film were used. The hybrid coating film such as prepared through this process showed a superhydrophilicity below 1$10^{\circ}$ depending on processing conditions and a pencil's hardness over 6 H.

• The Korean Journal of Food And Nutrition
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• v.25 no.3
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• pp.521-528
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• 2012

This study was performed to develop a therapeutic diet against aging and obesity, using Yangha(Zingiber mioga R.). Before development of a therapeutic diet, we performed cell viability assay, analysis of general composition, macrominerals and antioxidantive activities of Yangha. Based on the findings from analyzing the results, mook using Yangha powder(0~20%) was processed, and tested for quality characteristics such as color values, sensory evaluation and mechanical properties. The result of cell viability assay of myoga, using liver cells, revealed that within the concentration range from 500 ${\mu}g/m{\ell}$ to 10,000 ${\mu}g/m{\ell}$, cell survivability increased in line with the concentration rate. Therefore, it will not be harmful to consume it as food. Regarding the normal substance of myoga, the water substance of myoga was 94%, which exceeds that of ginger and tumeric with 89% and 83%, respectively. As for crude protein, fat, carbon hydrates and ash, myoga contained less than the other two, which I think is due to the high water substance. Regarding the minerals, potassium had the highest contents among macrominerals of 234.74 mg%. As for the antioxidant test, hydroxy radical scavenging activity and superoxide radical scavenging activity were shown. As for the production of Yangha mook(Yangha powder levels were 0~20%) for quality characteristics, the more of the powder, the less the L, but the greater the a and b values. Also, for the material property, an increased amount of the powder, resulted in chewiness and springiness, but less gumminess in a correlated manner. However, there were no significant differences in the springiness and cohesiveness in relation to the powder. For the sensory test, jelly type ZM5 with 5% powder showed highest overall preference. According to the sensory test, based on the powder substance, the jelly with 5% powder showed the highest overall score, including preference.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.6
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• pp.319-326
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• 2017

In this study, a lightweight geopolymer was prepared using by slag discharged from IGCC (Integrated Gasification Combined Cycle) power plant and its physical properties, the density and compressive strength, were analyzed as a function of the concentration of alkali activators, W/S ratio and aging times. Also the possibility of applying it to lightweight materials by adding Si sludge as a foaming agent to the geopolymerg was investigated. In particular, a complex composition of alkali activator and a pre-curing process were applied to improve the strength properties of lightweight geopolymers. While the compressive strength of the lightweight geopolymer using a single activator was 9.5 MPa, the specimen made with a complex composition of alkali activator had compressive strength of 2~5 times higher. In addition, the lightweight geopolymer with pre-curing process showed a compressive strength value of 18~48 % higher than that of specimen made with no precuring process. In this study, by using a complex activator and a pre-curing process. the maximum compressive strength of lightweight geopolymer was obtained as 40 MPa (The specimen was aged for 3 days and had density of $1.83g/cm^3$), which is comparable to cement concrete. By analyzing the crystal phase and microstructure of geopolymers obtained in this study using by XRD and SEM, respectively, it was confirmed that the flower-bud-like zeolite crystal was homogeneously distributed on the surface of the C-S-H gel (sodium silicate hydrate gel) in the geopolymer.

• Advances in environmental research
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• v.6 no.3
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• pp.159-171
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• 2017

A successful oil well drilling depends largely on a good mud Program. During drilling, mud provides sufficient hydrostatic pressure, removes drill cuttings and cools drill bits. Mud additives are always required to provide sufficient hydrostatic pressure to ensure borehole stability. Barium Sulphate ($BaSO_4$) also known as barite is the prevalent weighting material but there is needed to develop local materials to augment the use of Barite. The present search is concerned on the early Carboniferous succession exposed in Um Bogma Formation, west central Sinai, Egypt as a new weighting agent in drilling fluids. The increases in the cost of drilling fluids and a shortage of using barite have introduced the locale dolomite as alternative weighting materials. The rheological properties of mud drilling samples weighted by local dolomite samples are being examined and investigated to know its potential to be used as a weighting material in drilling mud. Two mud samples were prepared which comprised of fresh water, caustic soda, bentonite and the weighting material. The weighting materials are added to achieve the required density. The first sample: Water-based mud with commercial barite of density between 10.00 lb/gm and 18.00 lb/gm. The second sample: Water-based mud with dolomite of density between 10.00 lb/gm and 18.00 lb/gm. These samples were analyzed and the density, rheological properties, aging of barite and dolomite and solid contents were investigated. At 10.00 lb/gm, the yield point of dolomite was $20.00lb/100ft^2$ and barite $22.00lb/100ft^2$ while the 10 second gel strength of dolomite was $30.00lb/100ft^2$ and $22.00lb/100ft^2$ for barite. Similarly, little difference was observed in plastic and apparent viscosities. At 10.00 lb/gm, the plastic and apparent viscosities of dolomite were 8.00 cp and 20.00 cp while barite was 8.00 cp and 24.00 cp. The result show that dolomite mud sample gave a little higher yield point and gel strength than barite mud sample. Therefore, dolomite has the potential to be used as weighting material in drilling mud in place of barite thereby enhancing the local content initiative of the government. When dolomite is sourced locally and used it will reduce overall mud and drilling costs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.6
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• pp.977-985
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• 2002

In order to improve the quality of traditional kochujang, submaterials like sea tangle and chitosan were added to kochujang and their effects on microbial characteristics, enzyme activities and physicochemical characteristics were investigated for 24 weeks of fermentation. The activities of $\alpha$,$\beta$-amylase in kochujmg were higher in sea tangle added at 2% level and chitosan added at 0.1% level. However, acidic protease activity decreased as the ratio of submaterials increased. Viable cells of yeasts in the kochujang increased rapidly for 4~8 weeks of fermentation, and bacterial counts decreased in submaterials added groups. Moisture contents of kochujang increased until 12 weeks of fermentation, but water activity decreased. As the ratio of sea tangle increased, water activity decreased. Consistency of kochujang increased after middle of fermentation, and they increased remarkably by addition of sea tangle. The degree of increase in total color difference ($\Delta$E) of sea tangle added group was lowest. The titratable acidity of kochujang decreased after 4 weeks, and they changed a little by addition of chitosan. Amino nitrogen contents of kochujang increased as mixing ratio of submaterials increased in the late period of aging. Ammonia nitrogen contents was lower in chitosan added kochujang at 24 week of fermentation. Reducing sugar contents of kochujang increased rapidly for 4~8 weeks of fermentation, and they increased as the ratio of chitosan increased. Ethanol contents of kochujang increased until 12~16 weeks of fermentation, with lower values in sea tangle added group. After 24 weeks of fermentation, the result of sensory evaluation showed that 0.1% chitosan added kochujang were more acceptable than sea tangle added kochujang in the taste, color and overall acceptability.all acceptability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.12
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• pp.1799-1805
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• 2015

Rice vinegar (RV) is primarily made from fermented rice or rice wine in Korea, China, and Japan. Ten commercially available naturally-fermented rice vinegars produced in Korea (KRV1~4), China (CRV1~2), and Japan (JRV1~4) were comparatively investigated for their physicochemical properties and antioxidant activities. KRV showed a significantly higher total acidity range (5.07~6.27) than both CRV (4.67~4.84) and JRV (4.64~4.84). These acidity ranges corresponded with respective standards of each country: Korea (Food Code), China (GB), and Japan (JAS). Six different organic acids were detected in RVs; acetic acid and succinic acid were the most prominent. Thirty different amino acids were detected in RVs, and main identified amino acids were alanine (KRV), phenylalanine and aspartic acid (CRV), and leucine and alanine (JRV). ${\gamma}-Aminobutyric$ acid was detected at high concentration in KRV1. KRV1 showed maximum total phenolic content, and DPPH and ABTS radical scavenging activities of samples were also determined with significantly increasing tendency. KRV1 (produced from brown rice with aging period of >1 year) exhibited the highest free amino acid content and antioxidant activity as compared to CRV and JRV.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.467-473
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• 2012

Coenzyme Q10 (CoQ10) is a natural lipid cofactor with antioxidant and anti-aging properties as cosmetic and food ingredients, involved in cellular energy metabolism. Here, nano-emulsions with CoQ10 were fabricated with lecithin, ethanol, oil, and sorbitan monostearate (Arlacel 60), as major components. Phase inversion emulsion method with ultrasonicator was utilized in producing CoQ10 solution, and stabilization effects from lecithin and ethanol and other diverse perturbation factors were evaluated over time. Physical properties of the emulsion were characterized such as its size, surface charges by zeta-potential, and the overall structures. Optimal concentrations of CoQ10 and Arlacel 60 were 0.8% and 3%, respectively, for producing the smallest sizes of nanoemersions in a 100 nm diameter with best morphology. No notable changes in the size were observed over 7 days from Ostwald ripening, when the concentration of Arlacel 60 was higher than 2%. Even after 270 days at room temperature, the size of nanoemulsions maintained as 115 nm in diameter, revealing only a 10% increase with high degrees of long termed stability and substantiality. In addition, changes in the surface potential occurred possible due to the flocculation effect on the nanoparticles.

• Restorative Dentistry and Endodontics
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• v.17 no.2
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• pp.307-330
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• 1992

The aim of this study was to investigate the physical properties of visible light curing Glass Ionomer cement for restorative esthetic filling. The control group was the autopolymerizing GC Fuji II Glass Ionomer cement (2.2: 1 P/L ratio) and the experimental groups were made by following procedure. To induce the polymerization by visible light, the powder of GC Fuji II GI cement and the liquid of Vitrabond for base & liner were mixed in an amalgam capsule with 2.5:1, 3.0:1, 3.5:1 P/L ratio (% wt/wt). After fabrication of specimens, compressive strength, fracture toughness ($K_{IC}$) Scanning Electron Microscope and X-ray Diffraction, water-leachable content, marginal leakage and surface roughness were studied. The results were as follows: 1. Only experimental No. 1 group (visible light curing) showed less compressive strength than control group 1 hour after curing. Strength was increased with aging in all groups, so the compressive strength of light curing groups was no less than that of autopolymerizing group after 3 weeks. 2. Experimental No.3 group (visible light curing) was inferior to No.2 group (visible light curing) in fracture resistance but light curing groups were more resistant to fracture than autopolymerizing group and showed ductile fracture pattern as compared with the brittle fracture pattern of autopolymerizing group. 3. From scanning electron microscopic image, various sized unreacted powder particles, surrounded by silica gel, were embedded in polysalt matrix. Light curing groups showed little crack and more dense unreacted particles than autopolymerizing group. 4. From X-ray diffraction analysis, GC Fuji II Glass Ionomer cement powder and all groups showed glassy appearance but light curing groups seemed to be more intensive in crystaline than autopolymerizing group. S. The most significant dissolution was shown in early setting period in all group. Light curing groups were dissolved less than autopolymerizing group. 6. Marginal leakage was not different significantly in case of cavity margin composed of same tooth structure (ex. only enamel margin, only dentin margin) but much more leakage was shown in dentin/cementum margin than enamel margin. In only case of only enamel margin, light curing groups were superior to autopolymerizing group. 7. All groups showed relatively smooth surface, which irregularity was less than $1{\mu}m$. Light curing groups were smoother than autopolymerizing group.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.505-518
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• 1997

The objective of this investigation was to compare the effects of water storage on the aspect of hardness and diametral tensile strengths of four hybrid glass ionomer cements(two compomers and two resin-reinforced glass ionomers) with a resin composite material. One composite resin(Degufill Ultra), two compomers(Dyract, Compoglass Cavifil), and two resin-reinforced glass ionomers(Fuji Duet, Vitremer) were used in this study. Cylindrical specimens were prepared and stored at $36{\pm}1^{\circ}C$ in distilled water for 10 minutes after set, and then tested on an Instron testing machine(No.4467) at 1.0 mm/min displacement rate. Vicker's hardness and diametral tensile strengths as time elapsed were measured after aging in water for 10 minutes, 1 hour, 3 hours, 1 day, 3 days, 5 days and 7 days at $36{\pm}1^{\circ}C$. During the test of diametral tensile strength, stress-strain curves were obtained, from which the compressive modulus were calculated and compared. The structure of four set glass ionomer cement mass was observed on SEM(Hitachi, S-2300) after being etched with 9.6% hydrofluoric acid for 1 minute. The results were as follows; 1. The hardness of the experimental group(compomer and the resin reinforced glass ionomer cement) did not exceed the value of control group(Degufill Ultra). 2. Vicker's hardness of the Fuji Duet tended to increase succeedingly, Dyract was decreased after 3 hours in water, and Vitremer was the lowest. 3. The control group(Degufill Ultra) presented progressively on increased diametral tensile strength with time, Fuji Duet were decreased after 3 days, Compoglass Cavifil and Vitremer were decreased after 5 days in water storage. 4. Compressive modulus of the control group(Degufill Ultra) and Dyract were increased sharply timely, Fuji Duet and Vitremer were increased smoothly by lapse of time in water. Fuji Duet were stronger than Vitremer. On the other hand, Vitremer exhibited the lowest toughness. 5. The microstructure of compomer was similar with that of the composite resin(Degufill Ultra), and the fillers in resin-reinforced glass ionomer cements were noticed. It can be concluded that mechanical properties of hybrid glass ionomer cements is weaker than composite resin, and that the compomers or the resin-reinforced glass ionomers can not substitute the composite resins. A plenty of considerations should be done on the application of them to the area under the loading and high wear has a little adverse effect on the mechanical properties on the water storage for 7 days. The further research should be needed to confirm the advantage of the compomer.

• Korean Journal of Food Science and Technology
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• v.25 no.3
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• pp.252-257
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• 1993

Nine Korean native cattle were purchased from a beef cattle farm. Immediatly after slaughtering and skinning, each carcass was split into left and right sides and the one half was kept as a control, the other one was electrically stimulated by using 400v stimulator for 1 min. All samples were analyzed for shear force value, ATP and biochemical changes to investigate the effect of electrical stimulation during storage at $5^{\circ}C\;and\;15^{\circ}C$. The amount of lactate of electrically stimulated (E.S.) meat showed a rapid increment compared with that of control (p<0.01). E.S. treatment caused a rapid drop of pH value. Initial pH decreased from 6.85 to 6.38 in M. semitendinosus and from 7.0 to 6.58 in Triceps brachii by E.S. treatment (p<0.01). Electrically stimulated muscle showed decrease (34.67%) in ATP to $5.74{\mu}mole/g$ from $8.78{\mu}mole/g$ of unstimulated meat. ATP of the electrically stimulated muscle stored at $15^{\circ}C$ and $5^{\circ}C$ was degraded faster than that of control until 6 hours post-mortem (p<0.05). The tenderness of meat after aging was improved significantly by electrical stimulation with lower shear force value than that of untreated meat (p<0.01).