• Fire Science and Engineering
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• v.32 no.1
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• pp.81-88
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• 2018

Air and ultra lightweight aerogels were used to lighten the weight of the firefighters' protective clothing. In order to lighten the firefighters' protective clothing composed of 3 layers (outer shell, mid-layer, lining), it was most effective to replace the lining which occupied the largest weight in the total weight with the new materials. Thermal protective performance tests were carried out on flame (ASTM D 4108), radiant heat (KS K ISO 6942) and mixing heat (KS K ISO 17492) of flame and radiation. When the lining felt was replaced with an air layer, the air layer must be at least 3 mm to meet the KFI and ISO standards for the thermal protective performance. However, even if the thickness of the air layer increased to 10 mm, the thermal protective performance was lower than that of the existing products. When the felt was replaced with aerogels, the TPP rating (ASTM D 4108) satisfied the KFI standard at the 2 mm thickness of the aerogels. When the thickness of the aerogels was 3 mm, the TPP rating was improved about 140% compared to the existing products. It was confirmed that not only weight reduction but also thermal protective performance was improved by use of aerogels. However, due to the fragile nature of aerogels, a method of fixing them to a constant thickness between layers constituting a firefighters' protective clothing should be considered in the future.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.478-485
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• 2014

This study is to form the self assembly of cubic crystalline phase to penetrate into the skin epidermis. The various performance synthesized diglyceryl phytylacetate (DGPA) having hydroxyl group (-OH) and 4 methyl chains with phytyl group was carried out as an amphoteric lipid such as emulsifying power, self assembly. Emulsifying activity of DGPA was very stabilized on only 1% of small content, it could make a W/O emulsion containing high internal phase incorporated with water. Cubic liquid crystal structure with DGPA on three-phase diagram was formed, when mixed DGPA, dimethicone (2CS), and water. Through three-phase diagram forming the cubic liquid crystal area, hexagonal structure zone, and mixing water phase and hexagonal structure area, reversed micelle area were respectively certified. Its structure was proved by the SAXS (small angled x-ray scattering) analysis. As an application, formation of cubosome containing 10% of magnesium ascorbylphosphate and 5% of pyridoxine tris-hexyldecanoate was encapsulated. Occlusive effect of cubosome had above 1.7 times better than reversed micelle. From using poloxamer of dispersing agent, phase structure recovered from W/O emulsion to cubic liquid crystal phase when storage in $33^{\circ}C$ incubator. Therefore, our this study is expected to be as epidermal-dermal skin absorbers in skin care cosmetics and pharmaceuticals industries as raw materials to form a cubic crystal phase through a more in-depth research to DGPA having amphoteric lipid property.

• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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• pp.5-16
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• 2022

In recent years due to the development of urban and underground space, the number of ground disasters is increasing, and it is also leading to social problems. To solve the problem, a grouting method is generally used. However, the grouting method has material (grout) limitations in permeability, gelation properties and tensile resistance. Therefore, research on grout materials mixed with fibers is actively carried out to improve the problems. However, in the actual ground injection process, many difficulties have been faced causing the blockage of the inlet port and the injection tube. In this study, 'CNT-mixed grout material' was developed using CNT powder that can reinforce the tensile strength of soils. The uniaxial compressive and tensile strength tests were performed to obtain the optimal content and mechanical properties of the CNT Powder-mixed grout. It was found that the optimal CNT powder content is 0.5% that gives the average maximum strength. A one-dimensional injection test and the bulb formation test were carried out, and it was identified that the injection rate and bulb form could be controlled by pressure and mixing ratio. Field application of the CNT-Mixed grout is simulated using numerical analysis of slopes, foundations, and tunnels reinforced in several types. The positive effect of reducing plastic ranges and settlements was confirmed.

• Journal of the Korean Geotechnical Society
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• v.25 no.6
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• pp.31-45
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• 2009

The aim of this study is to evaluate the applicability of Granulated Blast Furnace Slag to the development of the Powdered Ready-mixed Shotcrete. First of all, after accomplishing SEM analysis and Leaching Test, the laboratory and field experiments for evaluating the utility of Granulated Blast Furnace Slag were performed. As a result of SEM and Leaching test, the environmental stability was confirmed. That is, non-detection of harmful lists and dense shotcrete structure result from mixing Granulated Blast Furnace Slag. As a result of lab. and field test, Blast Furnace Slag is superior to Plain Batch in improving strength and durability. And it will be able to improve to some extent the problem caused by the delayed reaction of existing Granulated Blast Furnace Slag with alkali activated material. Also the proper amount of Granulated Blast Furnace Slag is estimated to be under 30%. Finally, it is possible that Granulated Blast Furnace Slag can apply to economical recycling and development of the Ready-mixed Shotcrete for its price is only about 5% of Silica-finne's price.

• Resources Recycling
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• v.3 no.2
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• pp.28-34
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• 1994

A part of used cables, such as electric and communication cables has already been recycled by using simple processing methods. However, it has been found that the main problems in recycling of the used cables are insufficient treatment of fine stranded wires and low recovery of copper by air separation process. It has been shown that copper can be effectively separated from the PE using a solvent treatment method. In the present study, the used communication wires having diameter of 0.4 mm are treated in the mixing solution of toluene and water at $86^{\circ}C$ for about 10 minutes. In the solvent treatment, the copper wires recovered have 10~15mm length, which are much longer than that of 1~2mm length copper wires recovered by air table concentration method used in current recycling plants. The process consisting of cutting, air separation and electrostatic separation would be recommendable for the treatment of mixed cables. In this investigation, fine copper powders can also efficiently be recovered from insulation materials using electrostatic separator at the conditions of 20~50RPM roller speed and 15~30KV high DC power.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.329-334
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• 2002

The $CaTio_3$powder with perovskite structure was synthesized by mixing anatase $TiO_2$and $Ca(OH)_2$powders as starting materials, and KOH or NaOH as mineralizer, followed by hydrothermal method. The change of crystal structure, particle shape and size of the synthesized $CaTiO_3$powder was investigated with kind and concentration of mineralizer. It was found that the spherical particles of 0.7 $\mu$m were obtained when using 1N KOH and the hexahedrons particles of 3$\mu$m were obtained for the case of using 10 N KOH. With increasing KOH concentration, the particle shape was changed from sphere to hexahedrons and its size also increased. When using 1 N NaOH, the powder was consisted of 0.5~1 $\mu$m particle in size, whereas hexahedrons of 1~4 $\mu$m and whiskers more than 10$\mu$m in size was obtained for the 10 N NaOH solution. With increasing NaOH concentration, the particle shape was varied from hexahedrons to whiskers, showing the similar result with the KOH case. It was confirmed from EDS analysis that Na element, which was detected in hexahedrones was not contained in the whiskers.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.743-749
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• 1996

This study was carried out to investigate the microencapsulatuion of ${\omega}-3$ fatty acid isolated from fish oil and to obtain fundamental information on the utilization of the ${\omega}-3$ fatty acid in the dairy foods field. To obtain the desirable microencapsulation efficiency, 1.5% agar and 0.5% gelatin were used as coating materials, and 0.5% SFAN 60 (HLB 4.5 value) was used to maintain the emulsion stability. The optimal mixing ratio of coating material to core material was 8:2 (w/w). The thermostability of microencapsulated product was not maintained above $60^{\circ}C$. Microencapsulation efficiency was kept at about 90% at $4^{\circ}C$ and $10^{\circ}C$ for 7 days storage at various temperatures. At $20^{\circ}C$ and $30^{\circ}C$, however, about 80% microencapsulatuion efficiency was obtained for 3 days storage. About 80.57% microcapsule was destroyed by 1%> pepsin solution at $37^{\circ}C$ for 10 min.

• Composites Research
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• v.23 no.3
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• pp.31-36
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• 2010

A new material, carbon-nanofiber/polypyrrole (CNF/PPy) composite films, with different CNF weight ratios were fabricated electrochemically. Compared to the fabrication process based on simple physical mixing, the flexibility of the new film has been improved much better than the previous similar material. Pure PPy films were also fabricated by the new electrochemical process for the comparison of difference. Several SEM images were taken at two locations (electrode-side and solution-side) and at the cross section of the samples. Electrical conductivity of the composite films was measured by the four-probe method. The conductivity of the pure PPy film 0.013cm thick was 79.33S/cm. The CNF/PPy composite film with 5% CNF showed a conductivity of 93S/cm. One with 10% CNF showed a conductivity of 126 S/cm. The conductivity of PPy improves, as the CNF weight ratio increases. The good conductivity of CNF/PPy composites makes them a candidate for a small bending actuator. A bending sensor consists of PPy and PVDF, which can be operated in the air, was designed and the bending deflection was calculated using FEM.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.2
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• pp.201-210
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• 2018

In this study, we formulated oil-in-water emulsion composition for skin care products containing jadeite powder which is well known as far-infrared radiating material. Jadeite powder could sustain stable dispersion in aqueous solvents over a month and this helped mixing it high content in oil-in-water emulsion formulation. To identify the effect of jadeite as a far-infrared radiator materials relating to the skin surface temperature change, we applied emulsion formulation containing 2 weight percent jadeite powder onto facial skin surface and blank formulation together and analyzed surface temperature with thermo-vision. Our results showed that the temperature difference between jadeite powder formulation applied region and blank formulation reached to 1.5 ~ 2.0 degree Celsius. We also performed same test with nephrite powder and titanium dioxide powder but only jadeite powder containing formulation showed significant skin temperature change. To elucidate main cause of heat energy transfer, we tested heat radiation, energy dispersive spectrometer analysis and measured far infrared radiance emissivity, diffuse reflectance spectra and water evaporation rate. We found out jadeite powder could retard water evaporation effectively from the skin surface and resist temperature drop down. This is because of the innate chemical composition and surface structure of jadeite, which can bind with water molecules to form hydrogen bonds. It is concluded that we can develop novel skin care products for moisturizing and thermos with jadeite powder.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.31-39
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• 2021

The aim of this paper is to improve durability of cement paste by imparting hydrophobicity to the surface and sphere of cement-based materials. A cement paste mixed with a silane/siloxane-based water repellent, and the initial hydration performance, flow performance, and age-specific compressive strength were measured. In addition, the water contact angle, SEM, and XRD before and after surface polishing were measured. When 0.5% of the silane/siloxane-based water repellent was mixed into the cement paste, the compressive strength increased, but the compressive strength decreased as the mixing amount increased by 1.5% and 3.0%. When a silane/siloxane water repellent was incorporated into the cement paste, the hydrophilicity was improved and the contact angle was increased due to hydrophobicity. In addition, the contact angle after surface polishing was found to be larger than the contact angle before surface polishing.