• International Journal of Highway Engineering
• /
• v.15 no.5
• /
• pp.81-89
• /
• 2013

PURPOSES : This study is to evaluate ASR(alkali silica reactivity) resistance of ternary blended binder adding ultra fine mineral admixture. METHODS : This study analyzes ASR expansion using ASTM C 1260 and 1567. RESULTS : This study showed that the fineness of mineral admixture had no effect on ASR expansion. The expansion of ternary blended binder(UFFA 20%+FGGBS 10%) were below 0.1%, and this binder met the ASR standard. Also when adding the CSA expansion agent, ASR expansion slightly decreased. The expansion of latex modified mixture increased by 80% comparing plain mixture. CONCLUSIONS : Ternary blended binder met the ASR standard, and this binder is available in concrete bridge deck overlay.

• Journal of the Korea Concrete Institute
• /
• v.25 no.1
• /
• pp.3-9
• /
• 2013

In ultra high strength concrete, when electric arc furnace oxidizing slag is substituted for sea sand as fine aggregate, compressive strength was improved about 15 MPa. To figure out the cause of the improvement in compressive strength, this study considered the dissolution characteristics of Ca component in fine aggregate and examined the microstructure, porosity, microhardness, and Ca/Si mole ratio on the interface of fine aggregate and paste. And to examine the mechanism of strength improvement resulted from the shape of fine aggregate, this study measured the surface roughness of fine aggregate with AFM. According to the result of this experiment, the mechanisms of strength improvement in ultra high strength concrete resulted from the use of electric arc furnace oxidizing slag as fine aggregate can be divided into chemical and physical mechanisms. In the chemical mechanism, the soluble Ca component contained in electric arc furnace oxidizing slag is dissolved and forms a hydrate between fine aggregate and paste to improve the interlocking strength of fine aggregate-paste. Also, it makes the microstructure around the fine aggregate. And in the physical mechanism, electric arc furnace oxidizing slag has a twice greater surface roughness than sea sand, so the interlocking strength between fine aggregate and paste increases, which contributes to the development of compressive strength.

• Journal of Nutrition and Health
• /
• v.42 no.8
• /
• pp.740-749
• /
• 2009

The objectives of this study was to determine whether a new physically modified cornstarch by ultra-fine- or nanoscale pulverizer to reduce particle size offers better bioactive function than native cornstarch in weanling Sprague-Dawley rats. Male weaning Sprague-Dawley rats were fed diets containing native cornstarch (NAC), ultra fine pulverized cornstarch (UFC) or nano-scale pulverized cornstarch (NSC) for 4 weeks. In vitro rate of starch hydrolysis, growth performance, organ weight, intestine length intestinal proliferation and the fermentation by Bifidobacterium of rat cecum were evaluated. The diet with reduced particle size (UFC or NSC) significantly increased body weight gain and organ weight. Feed efficiency was increased in NSC fed rats and was not affected in UFC fed rats. Intestinal proliferation was decreased in NSC group. Reduction of particle size also increased cecal short chain fatty acid concentration and the growth and acidifying activity of Bifidobacterium. It is concluded that a reduction of particle size of starch granules by physically modification may increase growing performance and gut function.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.6
• /
• pp.10-16
• /
• 2013

Ultra-fine planing and micro punching are separately used for improving surface roughness and machining dot patterns, respectively, of metal molds. If these separate machining processes are applied for machining of identical molds, there could be an aligning mismatch between the machine tool and the mold. A hybrid machining system combining ultra-fine planing and micro punching was newly developed in this study in order to solve this mismatch; hybrid process technology was also developed for machining dot patterns on a mirror surface of a metal mold. The hybrid machining system has X, Y, and Z axes, and a cam axis for ultra-fine planing. The cam axis and attachable and removable solenoid actuators for micro punching can make large and small sizes of dot patterns, respectively. Ultra-fine planing was applied in the first place to improve the surface roughness of a metal mold; the measured surface roughness was about 20nm. Then, micro punching was applied to machine dot patterns on the same mold. It was possible to control the diameter of the dot patterns by changing the input voltage of the solenoid actuator. Before machining, severe inhomogeneous plastic deformation around the machined dot patterns was also removed by annealing heat treatment. Therefore, it was verified that metal molds with dots patterns for optical products can be machined using a hybrid machining system and the hybrid process technology developed in this study.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2006.10a
• /
• pp.179-212
• /
• 2006

1. $Welco^{(R)}$ Ultra fine solder powders are suitable for wafer bumping applications; mass production of ultra fine powders with high quality and high yield. - UFP based pastes for wafer bumping by stencil printing ($60-80{\mu}m$ pitch) are now available - Residue free solder flux was developed; meets voids specification of 20%. - F645 type 5 paste is suitable for components 01005

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.69-72
• /
• 1999

In this study, we blended 2 grades of ultra fine cement using the results of previous stud. And the cement slurry was produced by water each water/cement ratio. The slurries were observed hydration phenomena during 28 days with SEM, XRD and DSC. The specimen made by slurry were evaluated with the hardened properties such as compressive strength, flexural strength length change and water absorption. And were tested the adhesive strength of specimen made by injecting the slurry between mortar bars.

• Journal of the Korean Ceramic Society
• /
• v.22 no.1
• /
• pp.19-24
• /
• 1985

The synthetic method was studied on the $SrTiO_3$ powder of pure and homogeneous ultra fine particle of $SrTiO_3$. Pure and ultra fine particle was synthesized from $Sr(OH)_2$.$8H_2O$ and Ti(OH) at 3$0^{\circ}C$~9$0^{\circ}C$ in the $N_2$ gas atmosphere.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.301-306
• /
• 2001

This study was _ performed of rheological properities for slurry of ultra fine cement using admixtures. An experimental parameter is W/B and superplasticizier ratio and different water-soluble polymers. As a results, it's strongly appeared to rheological properties of slurry as particles ratio, it's know that rheological properities affected by admixtures.

• Journal of Industrial Technology
• /
• v.24 no.B
• /
• pp.65-71
• /
• 2004

The ultra fine gamma-alumina powder was prepared via ammonium aluminium carbonate hydroxide (AACH). The XRD, SEM, BET, thermal analysis were used to characterize the samples. The effects of various reaction parameters as concentration, of solution, anion on specific area, PH, aging time and thermal decomposition condition on the produced AACH and alumina were discussed.

• Journal of the Korean Ceramic Society
• /
• v.31 no.11
• /
• pp.1265-1270
• /
• 1994

Ultra-fine hydroxyapatite powder were synthesized by the hydrothermal reaction at 10 atm, 3 hrs of Ca(OH)2 suspension with (NH4)2HPO4 solution, and were characterized sintering behavior. Sintered bodies of hydroxyapatite powders which synthesized by hydrothermal reaction method has less weight loss, less sintering shrinkage and superior mechanical property, and was more dense than sintered bodies of hydroxyapatite powder which synthesized by wet method. Sintered bodies were hydroxyapatite single phase. When soack in Ringer's solution for 2 weeks, hydroxyapatite powders preserved hydroxyapatite and sintered body absorbed trace of Ca2+ ion with soaked time.