• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.199-200
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• 2002

Three-body abrasive wear resistance of mild steel, low alloy steel (Bisalloy) and 27%Cr white cast iron was investigated using a ball-cratering test. Glass beads, silica sand, quartz and alumina abrasive particles with sizes larger than $100{\mu}m$ were used to make slurries. It was found that the wear rates of all three materials tested increased with time when angular abrasive particles were used and were rather constant when round particles were used. This increase in wear rates was mainly due to the gradual increase in ball surface roughness with testing time. Abrasive particles with higher angularity caused higher ball surface roughness. Mild steel and Bisalloy were more affected by this ball surface roughness changes than the hard white cast iron. Generally, three-body rolling wear dominated. The contribution of two-body grooving wear increased when the ball roughness was significant. More grooves were found when round particles were used or the size of the particles was decreased.

• 한국광물학회지
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• 제23권2호
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• pp.141-150
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• 2010

제주도 우도 응회구의 현무암질 화산재는 대부분 미약하게 변질되었으나, 지표부근에서는 연황색으로 변질되었다. 육상 환경에서 화산재의 표성 변질 및 고화과정을 조사하기 위하여 표성 변질 우도 화산재에 대하여 X선회절, 주사 및 투과전자현미경, 전자현미분석을 실시하였다. 분석결과, 화산재 입자는 현무암질 유리 기질과 사장석, 감람석, 휘석 결정으로 구성되어 있었다. 입자 가장자리로부터 유리가 선택적으로 변질되어 교질상 변질테가 형성되었으며, 큰 입자 중심에는 변질되지 않은 유리가 잔존한다. 변질테와 유리 경계에는 매우 얇은 용탈 유리층이 존재하며, 변질테는 Fe와 Ti이 풍부한 극미립 비정질 규산염과 스멕타이트로 구성되어 있다. 변질 유리에서 방출된 용존물은 공극에 벌집모양 스멕타이트 집합체로 다량 침전되었으며, 화산재의 고화작용에 기여하였다.

• The Korean Journal of Ceramics
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• 제6권1호
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• pp.15-20
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• 2000

Thick inorganic-organic hybrid films were prepared on ITO-coated glass substrates by the electrophoretic sol-gel deposition of polyphenylsilsesquioxane particles. The morphology of the deposited films changed from the aggregate of the spherical particles to monolith by heat treatment at temperatures higher than $200^{\circ}C$. Transparency of the films was significantly improved accompanied by the morphological change of the particles. The degree of the morphological change was governed by two factors; maximum heat treatment temperature and heating rate. Transparent thick films of ca. 3$\mu\textrm{m}$ in thickness were obtained only by heat treatment at $400^{\circ}C$ for 2h with rapid heating from room temperature to $400^{\circ}C$. These films obtained were strongly adhered to the ITO-coated glass substrates and has a very smooth surface.

• 한국정밀공학회지
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• 제28권12호
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• pp.1419-1424
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• 2011

Nanoimprint lithography is a next generation lithography technology, which enables to fabricate nano to micron-scale patterns through simple and low cost process. Nanoimprint lithography has been applied in various industry fields such as light emitting diodes, solar cells and display. Functional patterns, including anti-reflection moth-eye pattern, photonic crystal pattern, fabricated by nanoimprint lithography are used to improve overall efficiency of devices in that fields. For these reasons, in this study, sub-micron-scaled functional patterns were directly fabricated on Si and glass substrates by thermal imprinting process using ZnO nano-particles dispersion resin. Through the thermal imprinting process, arrays of sub-micron-scaled pillar and hole patterns were successfully fabricated on the Si and glass substrates. And then, the topography, components and optical property of the imprinted ZnO nano-particles/resin patterns are characterized by Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy and UV-vis spectrometer, respectively.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.95-98
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• 2006

Filtration by fibrous filter is one of the Principle methods used for removing pollutant particles in the liquid. Because of the increasing need to protect both human health and valuable devices from exposure to fine particles, filtration has become more important. Filters have been developed with modified surface charge characteristics to capture and adsorb particles by electrokinetic interaction between the filter surface and particles contained in water. The main purposes of this study are to develop and evaluate the performance evaluation of the apparatus for making a positively charged porous filter media and to analyze the surface characteristics of the filter media for capturing negavitely charged contaminants mainly bacteria and virus from water. The experimental apparatus consists of a mixing tank, a vacuum pumping system, a injection nozzle, a roller press and a controller. The filter media is composed of glass fiber(50-750 nm), cellulose($10-20{\mu}m$) and colloidal charge modifier. The characteristics of filter media is analyzed by SEM(Scanning Electron Microscopy), AFM(Atomic Force Microscopy) and quantified by measuring the zeta potential values.

• 마이크로전자및패키징학회지
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• 제19권4호
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• pp.33-37
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• 2012

Microstructure developments of $RuO_2$ based thick film resistors during firing as a function of glass viscosity were analytically quantified and its effect on the electrical property was investigated. The microstructure development was retarded as the viscosity of glass was increased. It was found that the viscosity range for each stage of microstructure development are as follows ; $7500-10^5Pa{\cdot}s$ for the glass sintering, $2000-7500Pa{\cdot}s$ for the glass island formation, $700-2000Pa{\cdot}s$ for the glass spreading, and $50-700Pa{\cdot}s$ for the infiltration. The sheet resistivity decreased as the viscosity of glass in the resistor film increased due to the higher chance of sintering for the conductive particles with the higher viscosity of the glass.

• 대한기계학회논문집A
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• 제38권6호
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• pp.629-636
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• 2014

비정질합금이 가지고 있는 우수한 기계적 성질과 화학적 특성을 부품소재에 표면개질을 목적으로 고속화염 용사법으로 대면적 코팅층을 형성하였고 내열성이 높은 자융성합금과 초경합금 성분들을 적절히 혼합하여 비정질기지 복합재료를 제조하여 코팅들의 미세조직 관찰과 나노인덴테이션을 이용한 미세표면의 기계적 거동을 분석하였다. 각 코팅층의 미세조직을 관찰한 결과, 단일상 비정질 코팅에는 미용융 입자와 lamellae 영역이 존재하고 자융성합금이 고용된 복합재에는 in-situ $Cr_2Ni_3$ 석출물, 자융성합금과 초경합금성분이 함께 혼합된 코팅층은 석출물과 ex-situ WC 강화입자가 공존하였다. 이들 미세표면의 기계적 거동은 제 2 상이 고용된 비정질 기지 복합재의 코팅층의 기계적 특성이 전체적으로 향상되었다.

• 한국재료학회지
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• 제26권1호
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• pp.54-60
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• 2016

We have investigated the crystallization mechanism of the lithium disilicate ($Li_2O-2SiO_2$, LSO) glass particles with different sizes by isothermal and non-isothermal processes. The LSO glass was fabricated by rapid quenching of melt. X-ray diffraction and differential scanning calorimetry measurements were performed. Different crystallization models of Johnson-Mehl-Avrami, modified Ozawa and Arrhenius were adopted to analyze the thermal measurements. The activation energy E and the Avrami exponent n, which describe a crystallization mechanism, were obtained for three different glass particle sizes. Values of E and n for the glass particle with size under $45{\mu}m$, $75{\sim}106{\mu}m$, and $125{\sim}150{\mu}m$, were 2.28 eV, 2.21 eV, 2.19 eV, and ~1.5 for the isothermal process, respectively. Those values for the non-isothermal process were 2.4 eV, 2.3 eV, 2.2 eV, and ~1.3, for the isothermal process, respectively. The obtained values of the crystallization parameters indicate that the crystallization occurs through the decreasing nucleation rate with a diffusion controlled growth, irrespective to the particle sizes. It is also concluded that the smaller glass particles require the higher heat absorption to be crystallized.

• 대한화학회지
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• 제47권6호
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• pp.619-624
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• 2003

졸겔법을 사용하여 $Gd_{1.9-x}Li_{0.1}Eu_xO_3$(x=0.02, 0.05, 0.08, 0.12) 형광체 분말을 합성하였다. 형광체 입자의 표면을 나노 크기의 $SiO_2$(입자크기${\thickapprox}30 nm$)로 코팅한 후 스핀-코팅법으로 유리 기판에 형광체 막을 제작하였다. 유리의 연화온도인 $700^{\circ}C$ 부근에서 융착 되는 $SiO_2$ 나노 입자들에 의해 $Gd_{1.9-x}Li_{0.1}Eu_xO_3$ 입자들은 유리 기판 표면 위에 강하게 융착 되었다(>9H, 연필 경도계). 본 연구에서 채택한, 형광체 막을 제조하는 간단하고 비용이 저렴한 이 방법은 디스플레이장치의 응용 분야에 적용될 수 있을 것으로 생각한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.903-908
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• 2002

The production of waste glasses has been increased with the development of industry. The utilization of waste glass for concrete can cause the concrete to be cracked and to be weakened due to an expansion by alkali-silica reaction(ASR). When used the fibers with waste glass, there is an effect on reduction of expansion and strength loss due to ASR between the alkali in the cement paste and the silica in the waste glass. In this study, we conducted basic experimental research to analyze the possibilities of recycling of amber waste glass as fine aggregates for steel fiber reinforced concrete. Test results of fresh concrete. slump is decreased because grain shape is angular and air content is increased due to involving small size particles so much in waste glasses. Also. tensile and flexural strengths increased as the content of steel fibers increased. In conclusion, the content of waste glass below 40% is reasonable and usage of pertinent admixture is necessary to obtain workability or air content.