• 공업화학
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• 제21권1호
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• pp.34-39
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• 2010

${\gamma}-Methacryloxypropyl$이 가진 기능성 그룹으로 silica nanoparticle의 유기변형은 silica의 표면개질로 성공적으로 준비했다. 또한 ethanol 용매에서 AAm을 사용하는 radical 침전중합을 통해서 polyacrylamide를 MPSN nanosphere에 'raft from'방법으로 microsphere가 성공적으로 graft중합되었다. FTIR과 XPS는 ultra-fine silica particle의 표면에서 실리카개질이 공유결합하는 것을 보여주며 SEM분석은 ultra-fine particle과 유기변형된 입자는 각각 25, 30, 35 nm의 크기로 응집작용을 효과적으로 막아주고 나누어줌을 증명할 수 있다는 것을 보여준다.

• 한국재료학회지
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• 제14권11호
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• pp.790-794
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• 2004

Ultra-fine Copper particles for a conductive paste in electric-electronic field were prepared using wet-reduction process with hydrazine hydrate ($N_{2}H_4{\cdot}H_{2}O$) as a reductor. The effect of reaction conditions such as the amount of dispersion ($Na_{4}O_{7}P_2{\cdot}10H_{2}O$) and reductor ($N_{2}H_4{\cdot}H_{2}O$) on the particle size and shape for the prepared Cu powders was investigated. The quantity of dispersion and reductor varied from 0 to 0.0025 M and from 5 to 40 ml at a reaction temperature of $70^{\circ}C$, respectively. The particle size, shape, and structure for the obtained Cu particles were characterized by means of XRD, SEM, TEM, EDS and TGA. The aggregation of Cu particles was reduced with relatively increasing of the amount of dispersion at fixed other reaction conditions. The smaller Cu particle with size of approximately 300nm was obtained from 0.032 M $CuSO_4$ with adding of 0.0025 M $Na_{4}O7P_2{\cdot}10H_{2}O$ and 40ml $N_{2}H_4{\cdot}H_{2}O$ at a reaction temperature of $70^{\circ}C$.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.757-760
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• 2006

This study aims to manufacture ultra fine cement(UFC) with a multi air-classifier of the dry-type. The classifier employed and devised for materials refining was a cyclone type fitted with an air suction device. This study also investigates the basic physical properties and quality of UFC and evaluates its utilizable possibility as a construction material. The basic properties of the UFC containing granulated blast furnace slag were analyzed and examined through recovery ratio, particle size distribution, scanning electron microscopy and compressive strength. Results obtained from the analysis of ultra fine cement have shown that there are possibilities for manufacturing UFC, which could compensate the weak properties of ordinary Portland cement.

• 한국지역사회생활과학회지
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• 제27권3호
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• pp.343-350
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• 2016

The antioxidant activity was examined on ultra-fine powdered (UFP) Ulmus davidiana (U. davidiana) var. japonica. The average particle size of UFP or commercial powdered (CP) was $1-3{\mu}m$ or $100{\mu}m$. The extraction was performed using either ethanol (EtOH) or hot-water. Contents of phenolic compound of CP and UFP U. davidiana extracts in EtOH was 40.38 and 65.61 mg/g, respectively. In DPPH, EtOH extract of UFP U. davidiana showed a significantly greater activity than hot-water extract at 40 and $200{\mu}g/mL$. At $200{\mu}g/mL$, the activity was over 90% in all groups. The reducing power of UFP U. davidiana var. japonica in EtOH extraction was 74.3%, which was significantly greater than in other samples (p<0.05). In addition, reducing powder was significantly higher in UFP-EtOH than in other samples at all concentrations except for $0.32{\mu}g/mL$. The above results suggest that EtOH extraction of U. davidiana showed slightly higher DPPH radical scavenging activity, and ultra-fine powder of U. davidiana extracts may show higher antioxidative activities based on reducing power.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1205-1210
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• 2000

In this research we made the mean cement particle size 4 $\mu\textrm{m}$ which can penetrate even minor cracks based on the theory of J.K. Michel who reported particles can penetrate the crack of width up to 3 times of maximum particle size. The cement slurries were produced by adding super plasticizer. The slurries were tested with slurry characterization methods and its rheological properties were characterized. The early hydrated phenomena of ultra fine cement were observed by SEM, XRD and DSC during 24 hours. Mechanical properties of hardened slurry with JIS molds were also tested in 3, 7 and 28 days. The cracked specimens which were repaired with slurries produced various conditions were tested after 3, 7 and 28 days curing in the air and adhesion properties were characterized.

• 한국대기환경학회지
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• 제22권3호
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• pp.353-360
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• 2006

This study identified a particle size distribution (PSD) of fine particulate matter and emission characteristics of V and Ni by the comparison between anthropogenic sources of oil combustion (industrial boiler, oil power plant, etc.) and lab-scale combustion using a drop-tube furnace. In oil combustion source, the mass fraction of fine particles (less than 2.5 micrometers in diameter) was higher than that of coarse particles (larger than 2.5 micrometers in diameter) in $PM_{10}$ (less than 10 micrometers in diameter) as like in lab-scale oil combustion. In addition to this, it was identified that ultra-fine particles (less than 0.1 micrometers in diameter) had a large distribution in fine particles. Toxic metals like V and Ni had large mass fractions in fine particles, and most of all was distributed in ultra-fine particles. Most of ultra-fine particles containing toxic metals have been emitted into ambient by combustion source because it is hard to control by the existing air pollution control device. Hence, we must be careful on these pollutants because it is obvious that these are associated with adverse health and environmental effect.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2005년도 추계학술대회 논문집
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• pp.181-182
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• 2005

• 대한융합한의학회지
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• 제2권1호
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• pp.5-12
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• 2021

Objectives: The purpose of this study is to fabricate an ultra-fine ginsenoside particle atomizer that can provide a new treatment method by delivering ginsenoside components that have a therapeutic effect on respiratory diseases directly to the lungs. Methods: We fabricated the AAO vibrating mesh by using the micromachining process. The starting substrate of an AAO wafer has a 350nm pore diameter with 50㎛ thickness. A photomask having several 5㎛ opening holes with a 100㎛ pitch was used to separate each nanopore nozzle. The photoresist structure was optimized to pattern the nozzle area during the lift-off process precisely. The commercial vibrating mesh was removed from OMRON's NE-U100 product, and the fabricated AAO vibrating mesh was installed. A diluted sample of 20mL with 30% red ginseng concentrate was prepared to atomize from the device. Results: As a result of liquid chromatography analysis before spraying the ginsenoside solution, ginsenoside components such as 20S-Rg3, 20R-Rg3, and Rg5 were detected. After spraying through the AAO vibrating mesh, ginsenosides of the same component could be detected. Conclusion: A nutrient solution containing ginsenosides was successfully sprayed through the AAO vibrating mesh with 350 nm selective pores. In particular, during the atomizing experiment of ginsenoside drug solution having excellent efficacy in respiratory diseases, it was confirmed that atomizing through the AAO vibrating mesh while maintaining most of the active ingredients was carried out.

• 한국분말재료학회지
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• 제10권5호
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• pp.325-332
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• 2003

The effect of extrusion temperature on the microstructure and mechanical properties was studied in gas atomized TEX>$Al_{81}Si_{19}$ alloy powders and their extruded bars using SEM, tensile testing and wear testing. The Si particle size of He-gas atomized powder was about 200-800 nm. Each microstructure of the extruded bars with extrusion temperature (400, 450 and 50$0^{\circ}C$) showed a homogeneous distribution of primary Si and eutectic Si particles embedded in the Al matrix and the particle size varied from 0.1 to 5.5 ${\mu}m$. With increasing extrusion temperature from 40$0^{\circ}C$ to 50$0^{\circ}C$, the ultimate tensile strength (UTS) decreased from 282 to 236 ㎫ at 300 K and the specific wear increased at all sliding speeds due to the coarse microstructure. The fracture behavior of failure in tension testing and wear testing was also studied. The UTS of extrudate at 40$0^{\circ}C$ higher than that of 50$0^{\circ}C$ because more fine Si particles in Al matrix of extrudate at 40$0^{\circ}C$ prevented crack to propagate.