• Journal of Power System Engineering
• /
• v.17 no.1
• /
• pp.91-96
• /
• 2013

The present paper focuses on the fabrication of materials with higher thermal conductivity. Nanofluid is a novel transfer prepared by dispersing nanometer-sized solid particles in traditional heat transfer fluid to increase thermal conductivity and heat transfer performance. The purpose of this study is making the nano-size particle. The experiment of MWCNT and $Al_2O_3$ was carried out using a planetary ball mill at several rotation speeds: 200 ~ 400 rpm. The results were examined using scanning electron microscope(SEM). In the case of the MWCNT, it could be more grinding into the small particle in the dry condition and it confirm in the case of the $Al_2O_3$ to be more grinding into the small particle contrary to the MWCNT in the wet condition. In the mixture grinding result of MWCNT and $Al_2O_3$, the dry condition showed the good result in low rotation speed than the wet condition.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.6
• /
• pp.69-74
• /
• 2006

The effects of mechanical grinding(MG) treatment on the hydrogen storage of $Mg_2Ni$ alloy and $Mg_2Ni$ composite alloy($Mg_2Ni+graphite$) were investigated by pressure-composition-temperature(PCT) measurement, the micro-electrode technique of electrochemistry and etc, in which PCT was measured at high temperature(around $300[^{\circ}C]$) of gas phase and a carbon-filament micro-electrode for electrochemical evaluation was manipulated to make electrical contact with the particle in 1M KOH aqueous solution. It was found that the hydrogenation properties of $Mg_2Ni$ and graphite composite particle were greatly improved by the mechanical grinding treatment by which the $Mg_2Ni$ and graphite composite alloys could be changed into microstructure and nano-level particles. namely; the hydrogen dissociation pressure of PCT measurement was decreased from 0.55[MPa] to 0.42[MPa] and hydrogenation peaks by micro-electrode were also observed more clearly on the same sample.

• Journal of the Korean Ceramic Society
• /
• v.40 no.7
• /
• pp.696-701
• /
• 2003

The grinding efficiencies of silica powder in a small scale stirred ball mill were investigated by energy consumption estimate. Comparing with a non-treated silica powder and a heating treated silica powder, it was found that a silica powder cooled in room temperature after heating treatment at 600∼900$^{\circ}C$ consumed lower grinding energy than non-treated silica powder, and a silica powder quenched after heating treatment consumed lower grinding energies about 52∼62%, in case of dry grinding. Additionally, if heating treated silica powder grind in wet method, energy consumption will be decreased about 40% than in dry grinding, and the dependency of the particle size to the grinding efficiency, quenching significantly improved it.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.7
• /
• pp.1005-1010
• /
• 2010

This study was carried out to investigate the steaming and wet grinding conditions to save effective compositions and to utilize whole roots of ginseng. The sweetness at the 3 different steaming conditions of non steaming group (A), $95^{\circ}C$/3 hr group (B) and $121^{\circ}C$/15 min group (C) resulted in 7.7, 10.7 and $11.2^{\circ}Brix$, and the browning intensity of 0.37, 1.97 and 1.50, respectively. The contents of crude saponin at the different steam heat treatments were 7.19 (A), 6.99 (B) and 8.83 mg/g (C). When sensory evaluation was conducted, the ginseng products processed at C condition showed the highest scores in the evaluation categories of bitter taste reduction, sweetness and overall acceptance. These results suggest that sensory characteristics of ginseng could be enhanced by the steam heat treatments. When the wet grinding with water addition volume to the steamed ginseng treated at $121^{\circ}C$ for 15 min was also investigated, the smallest particle size resulted from the water addition volume of 300%. The grinding efficiency of ginseng was found to be high at 30 min of grinding time and 3 times of grinding frequency with the mean particle size of $67.66\;{\mu}m$. The content of effective component did not show significant differences by grinding time and grinding frequency. Based on the results, the steam heat treatments ($121^{\circ}C$/15 min) and wet grinding procedures were found to be effective in utilizing whole roots and saving the effective compositions of ginseng.

• Elastomers and Composites
• /
• v.38 no.2
• /
• pp.128-138
• /
• 2003

It goes to be serious with environmental pollution because of great number of waste tires scrapped each you. That is why there are lots of studies for efficient recycle. We tried to reduce particle size of the waste tire powder using a new technology of self-designed grinding machine (SDGM) and ultrasonic treatment. The purpose of this study is to improve the physical properties of reduced waste tire powder. We investigated the fine powder by particle size distribution(PSD) analysis. And also we examined the physical and mechanical properties and cross-link density at various particle sire. Also we carried out morphological studies after making the products by SEM.

• Journal of Environmental Health Sciences
• /
• v.21 no.2
• /
• pp.1-6
• /
• 1995

Authors investigated the size distribution and mass fraction of dusts in work environment of Changwon industrial complex. Size distribution of suspended dusts in welding and grinding processes were evaluated using ambient cascade impactors. The mass median diameters of dusts were 0.25 to $0.60 \mu m$ at welding sites and 1.20 to $1.92 \mu m$ at grinding sites. Respirable mass fractions were 63.68 to 73.50% at welding sites and 43.24 to 51.47% at grinding sites. Respirable fractions were calculated from the size distribution data for the ACGIH criteria by the respirable particle mass. In case of dust removal system, electrostatic precipitator and bag filter were appropriate for welding process and grinding process, respectively.

• Journal of the Korean Applied Science and Technology
• /
• v.40 no.5
• /
• pp.945-954
• /
• 2023

In this study, Sparassis crispa(cauliflower mushroom), which is rich in beta-glucan, was pulverized using ultrafine grinding technology for its potential utilization as a diverse food ingredient. The physical and antioxidant properties of cauliflower mushroom powder were evaluated at various grinding times. The results showed that as the grinding time of cauliflower mushroom increased, the average particle size significantly decreased (p<0.05). Additionally, the water-holding capacity, swelling capacity, and water solubility index of cauliflower mushroom increased significantly(p<0.05). Based on the analysis mentioned above, cauliflower mushroom prepared as a superfine powder for 5 minutes exhibited superior physical and chemical properties as well as antioxidant characteristics and is expected to be widely used in various foods.

• Food Science and Preservation
• /
• v.21 no.2
• /
• pp.181-186
• /
• 2014

This study was conducted to that investigate the quality characteristics of wet-ground whole-grain buckwheat powder for the buckwheat husk. The particle size of buckwheat rice was 74.84 ${\mu}m$, which was approximately four to five times larger than wet-ground whole buckwheat by wet grinding. The particle size showed that there was no significant difference after 90 min on wet grinding. The total phenolics and total flavonoids contents of the whole buckwheat powder were higher than those of buckwheat rice, and they gradually increased wet grinding progressed. The rutin contents of the buckwheat increased after wet grinding and was 152.90 ppm at 90 min. There was no significant difference in the quercetin contents after wet grinding at different times. The mineral contents (Ca, K and Mg) of the whole buckwheat powder were greater than those of the buckwheat rice. Further, Zn and Mn were detected in the whole buckwheat powder. The total amino acid content of the whole buckwheat powder increased to 22.27 mg%, and the important glutamic acid increased from 14.58 to 30.45 mg%. These study results were based on 90 min wet-grinding time for whole-buckwheat-powder manufacture. Whole buckwheat powder manufactured through wet grinding can be used as an active ingredient of buckwheat husk.

• Food Science and Preservation
• /
• v.21 no.1
• /
• pp.75-81
• /
• 2014

In this study, the biological activity of water and ethanol extracts from Saururus chinensis by ultra-fine grinding for functional food source are examined. It is more effective to use ethanol than water when extracting phenolic compounds. Approximately 2.5 times higher extraction yield were shown when it was ultra-fine grinded because the particle size decreases, thereby increasing the extraction yield. Normal grinded sample extracts showed 69.8% of DPPH inhibition effect, while fine grinded and ultra-fine grinded sample extracts showed 70.7% and 83.8% each, respectively. Normal extract, as well as fine grinded and ultra-fine grinded extracts, showed over 97% of ABTS inhibition effect, thereby indicating only a slight difference in the anti-oxidative activity with the grinding method. Higher PF was determined with fine grinded and ultra-fine grinded extracts than the normal grinded extract, while ultra-fine grinded 50% ethanol extracts showed the highest anti-oxidative activity value of 1.8 PF. The fine grinded and ultra-fine grinded particle sizes are smaller than the normal grinded particle size, thus increasing the inhibition rate of the TBARS. Furthermore, the ethanol extract was revealed to have a higher effect than the water extracts. The xanthin oxidase inhibition, on the other hand, was identified as ultra-fine grinded that led to the increase in the enzyme inhibition effect. In the angiotensin-converting enzyme, water extracts with normal grinding did not show inhibition activity, while 50% ethanol extracts showed 24% inhibition activity. Moreover, the ethanol extracts showed higher inhibition effect compared to the water extracts. Ultra-fine grinded 50% ethanol extracts showed a slight antibacterial effect on the Staphylococcus aureus and Escherichia coli, while the other extracts showed none. The result suggests that Saururus chinensis extracts by ultra-fine grinding may be more useful than normal grinding as potential sources due to anti-oxidation, angiotensin converting enzyme and xanthine oxidase inhibition.

• Korean Chemical Engineering Research
• /
• v.58 no.1
• /
• pp.84-91
• /
• 2020

The efficiency of the synthetic magnesium silicate used in basic polyols and edible oil purification is evaluated by its purification ability and filtration rate and is affected by the particle size and surface area of magnesium silicate. In this study, it was investigated the change on the particle size of magnesium silicate was influenced by the reaction temperature, injection rate, injection order (Si, Mg) and Mg/Si reaction mole ratio. The synthesized magnesium silicate was compared and analyzed for the synthesis, grinding, and refining processes. In the synthesis process, the reaction temperature and feed rate did not affect the average particle size change of magnesium silicate, while the reaction molar ratio of Mg / Si and the order of injection acted as main factors for the change of average particle size. The average particle size of magnesium silicate increased by 8.7 ㎛ from 54.4 ㎛ to 63.1 ㎛ at Mg injection when Mg molar ratio increased from 0.125 to 0.500, and increased by about 4.8 ㎛ from 47.3 ㎛ to 52.1 ㎛ at Si injection. The average particle size according to the order of injection was 59.1 ㎛ for Mg injection and 48.4 ㎛ for Si injection and the difference was shown 10.7 ㎛, therefore the filtration rate was about 2 times faster under the condition of Mg injection. That is, as the particle size increases, the filtration time is shortened and washing filtration rate can be increased to improve the productivity of magnesium silicate. The cake form of separated magnesium silicate after filtration becomes a solid through drying process and is used as powdery adsorbent through the grinding process. As the physical strength of the dried magnesium silicate increased, the average particle size of the powder increased and it was confirmed that this strength was affected by the reaction molar ratio. As the reaction molar ratio of Mg / Si increased, the physical strength of magnesium silicate decreased and the average particle size after grinding decreased by about 40% compared to the average particle size after synthesis. This reduction of strength resulted in an improvement of the refining ability due to the decrease of the average particle size and the increase of the amount of fine particle after the pulverization, but it resulted in the decrease of the purification filtration rate. While the molar ratio of Mg/Si was increased from 0.125 to 0.5 at Mg injection, the refining ability increased about 1.3 times, but the purification filtration rate decreased about 1.5 times. Therefore, in order to improve the productivity of magnesium silicate, the reaction molar ratio of Mg / Si should be increased, but in order to increase the purification filtration rate of the polyol, the reaction molar ratio should be decreased. In the synthesis parameters of magnesium silicate, the order of injection and the reaction molar ratio of Mg / Si are important factors affecting the changes in average particle size after synthesis and the changes of particle size after grinding due to the changes of compressive strength, therefore the synthetic parameter is an important thing that determines productivity and refining capacity.