• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.94-99
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• 1995

Naphthalene sulfonated condensatd(NSF) has been widely using for the superplasticizing of ement and concrete. But NSF has a very large mobility loss with elapsed tiom. To retain mobility of NSF during a certain time, maleic anhydride and acrylic acid copolymer(MA) was polymerized and mixed with NSF in order to perpare admixture holding mobility-retention property of cement. By applying this admixture for ement paste, we examined the fluidity and mobility retention property as a function to elapsed time and measured the compressive strength of mortar with curing time. As a result, NSF containing 20wt% of MA showed very excellent fluidity and mobility-retention property. These properties were affected by the added amount of admixture and the ratio of water to cement.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.463-469
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• 2016

In this paper, the use of a dual composite right/left-handed coplanar waveguide (CPW) transmission line is proposed for the design of a band rejection filter. The notch property of the filter is achieved by combining the convex signal line with the shorted concave meander line, and the equivalent circuit model is extracted from the geometry of the unit cell for organizing the band rejection property. Then the equivalent parameters of the unit cell are analyzed to identify those behaviors. And the dispersion characteristics and energy distributions are simulated. In the end, the band rejection filter is manufactured by cascading two proposed unit cells. We show that the measurement result for the resonant frequency demonstrates good agreement with the simulation result and the band rejection filter provides a rejection performance of 17.5 dB at the stopband frequency ranging from 869 MHz to 894 MHz.

• 한국분말재료학회지
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• 제10권2호
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• pp.123-128
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• 2003

$TiO_2$ nanopowder was synthesized by chemical vapor condensation (CVC) process and its photocatalytic property depending on microstructure was considered in terns of decomposition rate of organic compound. In order to control microstructure of $TiO_2$ nanopowder such as particle size and degree of agglomeration, precursor flow rate representing number concentration was changed as a process variable. In TEM observation, spherical $TiO_2$ nanoparticles with average size of 20 nm showed gradual increases in particle size and degree of agglomeration with increase of precursor flow rate. Also decomposition rate of organic compound increased with decreasing precursor flow rate. Thus, it was concluded that photocatalytic property was enhanced by targe surface area of disperse $TiO_2$ nanoparticles synthesized at lower precursor flow rate condition in CVC process.

• 한국전기전자재료학회논문지
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• 제21권3호
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• pp.236-241
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• 2008

The effect of organic solvent mixture ratio on the rheology property of slurry and thickness control of ceramic green sheet was investigated. For selecting a suitable dispersant multiple light scattering method was used to evaluate the particle migration velocity and variation of clarification layer thickness. Using the selected dispersant the dispersion property of solution according to solvent mixture ratio was investigated. Binder and plasticizers were added to formulate slurries and their viscosity was evaluated according to solvent mixture ratio. Ceramic green sheets with average thickness of 30, 50 urn were fabricated via tape casting and their thickness tolerances measured. As a result according to solvent mixture ratio the solution and slurry properties varied and for the mixture ratio of ethanol/toluene of 80/20 the ceramic green sheet with the lowest thickness tolerance was obtained.

• Elastomers and Composites
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• 제39권4호
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• pp.263-273
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• 2004

The effects of zinc surfactant (ZB) on the bis(triethoxysilylpropyl)disulfide (TESPD)-silica mixture in natural rubber (NR) and solution butadiene-co-styrene rubber(S-SBR) were compared with respect to their rheological property, processability, physical properties, and silica dispersion. In the NR compound, addition of the ZB increased the reversion resistance time (T-2), the tensile modulus, and the BO time; however, lowered the viscosity, the HBU, and tans values. In the S-SBR copound, addition of the ZB increased the $tan{\delta}$ values while lowered the T-2, the tensile modulus the BO time, the viscosity, and the HBU of the compound. In the NR compounds, addition of the ZB significantly increased the processability and mechanical property. However, in the S-SBR compounds, it improved the processability the mechanical property was not improved.

• 펄프종이기술
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• 제38권4호
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• pp.47-52
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• 2006

This study is about the effect from properties of coated paper and ink dispersion to the printed mottle. Ink receptivity would be expected that it is mainly effected by roughness of coated paper Because the transfer of ink can not be uniform with rough surface, it will cause the optical appearance such like printed mottle. And also it may be able to cause the printed mottle from uneven transfer of ink due to absorption property of based paper, depend on size degree, by using dampening in Off-set printing. Each different specific of surface and ink dispersion could cause printed mottle. Therefore this study was carried out by using densitometer and image analysis to show the interaction between properties of domestic coated paper and ink dispersion.

• 한국태양에너지학회 논문집
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• 제32권3호
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• pp.170-177
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• 2012

To apply the nanofluids into the general vapor compression cycle, basically have to know the thermal properties including thermal conductivity and dynamic viscosity. And needs to show the dispersion characteristics for various nanofluids and concentrations. So, firstly this study showed experimentally the thermal properties for various concentration (0.1%~0.7%, as mass balance) and temperature($20^{\circ}C{\sim}40^{\circ}C$) on $Al_2O_3$, $TiO_2$, and CuO nanofluids using base fluid as POE oil that has used in the scroll compressor for various refrigeration system. From the results, the dynamic viscosity of nanofluids was considerably changed from the base POE oil. And, the dispersion characteristics of various nanofluids using the simple methods like as analyzing the RGB value or measuring the sinking height of nanofluids were showed experimentally. Through the results, the dispersion characteristics of $Al_2O_3$ nanofluid was better than those of $TiO_2$, and CuO nanofluids not considering the real refrigeration cycle rurming conditions.

• 한국염색가공학회지
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• 제24권1호
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• pp.69-78
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• 2012

This paper surveys the physical properties of the MWNT dispersion solution dispersed with the three types of solvents and of the polyurethane composite film for improvement of mechanical properties and electrical characteristics of PU/MWNT composite film. For this purpose, the MWNT dispersed solution was mixed with three types of solvent such as IPA, MEK and Toluene and then mixed with polyurethane (100part) with variation of loading content (0, 10, 20, 30, 40, 50 part) of MWNT dispersed solution in the ultrasonic wave dispersion apparatus. And eighteen PU/MWNT composite films were prepared as specimens. The various physical properties of these PU/MWNT films were measured and discussed with the loading content of three types of MWNT dispersed solutions. The highest absorbancy among the three types of dispersed solutions was shown in the IPA/MWNT solution. But the absorbancy of PU/MWNT films was not same as the solution. The low electrical surface and volume resistivity of PU/MWNT film were shown at the condition of 20 and 10 parts loading of IPA/MWNT dispersed solution, respectively. The low triboelectricity of PU/MWNT film was shown at the condition of above 30part loading of IPA/MWNT dispersed solution. The breaking strength and strain of PU/MWNT film prepared with IPA/MWNT dispersed solution were decreased with increasing loading content of IPA/MWNT from 10 to 40 parts. The maximum breaking strength and breaking strain according to the dispersion solution were shown on the IPA/MWNT dispersed solution. The uniform dispersion of PU/MWNT film according to the loading content of MWNT solution was shown by surface image analysis on the films dispersed with IPA.

• 청정기술
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• 제14권1호
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• pp.21-28
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• 2008

본 연구에서는 LCD 컬러필터에 사용되는 밀베이스를 제조하기 위해 Red, Green, Blue 안료 분산에 대한 특성을 연구하였다. 또한 기존의 포토리소그라피 방법을 대체할 수 있는 스크린 인쇄 방식에 적용할 수 있도록 물성 및 점도를 맞추었다. 분산제는 BYK-2000, 모노머는 EB-140이 가장 우수한 분산 특성을 나타내었다. Torus mill을 사용하여 millbase를 500 rpm으로 30 min 동안 pre-mixing한 뒤, 4000 rpm으로 $5{\sim}6$시간 분산시켜서 Red $100{\sim}110\;nm$, Green $50{\sim}70\;nm$, Blue $60{\sim}80\;nm$의 분산 결과를 얻을 수 있었다. 저점도 type 포물레이션에서 millbase의 점도가 $200{\sim}300\;cps$ 일 때 비드의 충격력이 충분히 발휘되었으며, 레오로지 거동 및 색특성을 통하여 분산성이 확보되었음을 확인하였다.

• Composites Research
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• 제28권4호
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• pp.232-238
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• 2015

본 연구에서는 탄소 나노복합재료 수지의 분산도를 평가하기 위해 전기저항 측정방법을 활용한 평가 예측 연구를 시도하였다. 탄소 나노복합재료 수지을 탄소섬유 토우에 떨어뜨려 탄소섬유의 배열 변화에 따른 전기저항 변화도를 이용하여 분산도를 평가하였다. 분산도가 균일한 탄소 나노복합재료 수지의 상태는 섬유 토우의 배열을 변화시키더라도, 섬유들 사이에 CNT의 영향으로 전기적 접촉면을 생성시켜 비교적 낮은 전기저항 변화도를 나타낸다. 그러나 불균일한 나노입자 분산상태의 수지는 탄소섬유 토우의 필터링 현상에 나노입자와 에폭시가 분리되었다. 탄소섬유의 전기저항 변화도는 크게 변화되며, 이러한 전기저항 변화도의 크기차이를 이용하여 분산도를 분석할 수 있었다. 나노복합재료 수지 적용 섬유강화 복합재료의 ILSS 측정 결과와 전기저항 측정법을 이용한 분산도 평가 결과간의 상관관계를 비교하였다. 균일한 분산도 상태의 나노복합수지를 이용한 경우가 섬유강화 복합재료화 하였을 경우 우수한 계면 특성을 확인하였다.