• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.357-363
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• 2015

The development of the environment-friendly tire that meets the standard requirements according to tire labeling system can be improved through using highly homogeneous silica immobilized zinc oxide nanoparticles. In this study, a considerable amount of nanoporous silica was essentially added into nano zinc oxide to improve the physiochemical properties of the formed composite. The introduction of nanoporous silica materials in the composite facilitates the improvement of the wear-resistance and increases the elasticity of the tread. Therefore, the introduction of nanoporous silica can replace carbon black as filler in the formation of composites with desirable properties for conventional green tire. Herein, mesoporous silica immobilized zinc oxide nanoparticle with desirable properties for rubber compounds was investigated. Composites with homogeneous dispersion were obtained in the absence of dispersants. The dispersion stability was controlled through varying the molar ratio, ageing time and mixing order of the reactants. A superior dispersion was achieved in the sample obtained using 0.03 mol of zinc precursor as it had the smallest grain size (50.5 nm) and then immobilized in silica aged for 10 days. Moreover, the specific surface area of this sample was the highest ($649m^2/g$).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.1
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• pp.21-26
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• 2005

In order to simulate the powder compaction process and to assess the effects of packing randomness and particle arrangement 2-dimensional model of rod array compaction using quasi-random multiparticle array is introduced. The elastic modulus of porous ceramics is computed by the homogenization method. With 3 Al₂O₃ and 3 Al particles the compaction processes associated with the porosities are simulated by the explicit finite element method, based on the elastic modulus found by the homogenization method. The simulation results are compared with both previous analytical ones and experimental measurements. Finally, in order to find the relationship between the friction coefficient of powder particles and the relative density, the sensitivity analysis is performed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.4
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• pp.162-167
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• 2005

As the properties of porous materials during the drying process relate to the atomistic defects of heterogeneous materials such as dislocation, grain, grain boundary, pore, etc., the knowledge of nano-scale analysis is needed in order to accurately analyze the drying process for porous materials. In this study, the atomic behavior of porous materials Is statically predicted by using the molecular dynamics simulation and the nano-scale material properties are computed. The elastic modulus, thermal expansion coefficient, and volumetric heat capacity numerically found from the molecular dynamics simulation are compared with those of experiment and theory and proved the accuracy.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.4
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• pp.505-513
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• 2022

Minor orthodontic treatment using a thin wire with high elasticity can shorten the treatment period and reduce the load on the anchorage by the application of light force. Since it can be applied immediately without a dental laboratory procedure and does not require the patient's cooperation, it can be clinically useful. The cases reported here have led to positive results in short periods of treatment, using only a segmented straight 0.012 inch NiTi wire and flowable resin to address various locations within the oral cavity, such as the anterior teeth, premolars, and molars.

• Korean Journal of Food Science and Technology
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• v.49 no.2
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• pp.151-157
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• 2017

The physicochemical properties of rice flours and quality characteristics of rice cupcake were investigated using the domestic rice varieties Goami, Hanareum, Hanmaeum, Deuraechan, Seolgaeng, and Haiami. Protein and amylose contents were highest in. The final and setback viscosities of Haiami, Hanmaeum, Deuraechan, and Hanareum were higher than those of Goami and Seolgaeng. The specific volume of rice cupcakes was lower with Goami and Haiami than with the others. Seolgaeng cupcake had a dented surface and irregular air pockets, while the Hanareum cupcake was well shaped and had uniform air pockets. The hardness, springiness, and chewiness of Goami and Haiami cupcakes were higher than those of the others, while adhesiveness was observed only in Seolgaeng cupcake. The overall preferences scores of rice cupcakes prepared from Hanareum, Hanmaeum and Deuraechan were higher than for the other cupcakes (p<0.05). These results suggested that amylose content, and final and setback viscosities of rice flour are very important factors in rice cupcakes.

• Food Science and Preservation
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• v.18 no.1
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• pp.39-45
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• 2011

We explored the quality characteristics of Sulgidduk prepared using different amounts of cheese powder (0%, 6%, 12%, 18%, 24%; all w/w); physico-chemical properties were determined. Proximate composition analysis showed that the moisture content of Sulgidduk decreased with a rise in the level of added cheese powder. Lightness and yellowness values were lowest in control Sulgidduk and highest in Sulgidduk with 24% added cheese powder. Texture profile analysis showed that all of hardness, cohesiveness, springiness, and brittleness increased with a rise in cheese powder level. Scanning election microscopy indicated that the number of air cells fell as the ratio of cheese powder to rice powder increased. Sensory evaluation tests indicated that color, cheese smell, and greasiness rose as the cheese powder level increased, whereas softness and moistness fell. Consumer acceptance testing showed no significant difference in overall acceptability scores among samples. In conclusion, we suggest that cheese powder may be incorporated into Sulgidduk without affecting sensory qualities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3794-3801
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• 2010

This study evaluated the linear dimensional changes with the factor of time and thickness using of three commercially available tissue conditioners (Coe-Comport, Visco-Gel, Soft-Liner). The thickness of materials were changed (1.5mm, 3.0mm) and the percentage changes in dimension were measured at 1h(baseline), 12h, 24h, 3 days and 7days after specimen preparation. The obtained data were analyzed by ANOVA with the SAS/PC statistical package. From the results, large differences appear between the various tissue conditioners. The results suggested that the period recommended for forming functional impression would be 36h to 3days after insertion in the mouth. Depending on the type of tissue conditioner over time, as there were significant differences in the elastic change(p<0.05). Tissue conditioner of the 1.5mm, 3.0mm thickness were significantly different by the dimensional stability(p<0.05). Elastic deformation of the ideal itself, and resilient when compared only the look, Visco-Gel 3.0mm group, stability was the most stable volume. In addition, it is important to select tissue conditioners suitable for functional impression because of the wide range of dimensional stability among the materials.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.224-235
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• 2013

A passively fitting prosthesis is an essential prerequisite to attain long-lasting success and maintenance of osseointegration. However, true "passive fit" can not be achieved with the present implant-supported prosthesis fabrication protocol. Many clinical situations are suitably treated with cantilevered implant-supported fixed restorations. The purpose of this study was to compare the stress distribution pattern and magnitude in supporting tissues around ITI implants with cantilevered, implant-supported, screw-retained fixed prosthesis according to the fitness of superstructures. Photoelastic model was made with PL-2 resin (Measurements, Raleigh, USA) and three ITI implants (${\phi}4.1{\times}10mm$) were placed in the mandibular posterior edentulous area distal to the canine. Anterior and posterior extended 4-unit cantilevered FPDs were made with different misfit in the superstructures. 4 types of prosthesis were made by placing a $100{\mu}m$ gap between the abutment and the crown on the second premolar and/or the first molar. Photoelastic stress analysis were carried out to measure the fringe order around the implant supporting structure under simulated loading conditions (30 lb).

• Food Engineering Progress
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• v.23 no.4
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• pp.283-289
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• 2019

This study was performed to determine the effect of psyllium husk addition on the physical properties of rice extrudates. Rice-based formulations mixed with psyllium husk (0, 7, 14 and 21%) were extruded at a die temperature of 140℃, screw speed of 200 rpm, and moisture content of 20%. As the content of psyllium husk increased, expansion ratio decreased, while piece density and specific length increased. Apparent elastic modulus, breaking strength, adhesiveness, and hardness augmented with an elevation in psyllium husk content. Lightness declined as psyllium husk content furthered, while redness, yellowness, and color difference intensified. Water soluble index and water absorption index increased with an increased amount of psyllium husk. In conclusion, the addition of psyllium affected the expansion of extruded rice snack possessing hard texture, small cells, and sticky texture due to higher water absorption during hydration.

• Korean Journal of Crystallography
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• v.5 no.2
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• pp.67-77
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• 1994

From the Y3-3xNd3xAl5O12single crystals grown by the Czochralski technique, various types of defects were detected and 1) the reason of opical in homogeneous phases, 2) the mechanism of formation of the iridum metal inclusions accompanying bubbles, and 3) the mechanism of formation of the core and facet were analysed After preparing the wafers of the <111> growth parallel, defscts were observed by the polarising microscope using a photoelasic effect and then some images of stress-birefringence were compared to their etch Pits patterns.