• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.1
• /
• pp.130-135
• /
• 2010

In this study, the performance improvement of epoxy resin system had been tried by the improvement of particle size distribution and globularization of filler using polymerization method. From the results of particle size distribution measurement, the polydispersity value of reformed filler was 1.04 and that of silica flour before reformation was 2.6, it could be confirmed that the particle size uniformity of reformed filler had been improved greatly and the shape of particle was globular. Compatibility between monomer and silica was improved remarkably with the silanization pretreatment of silica flour. From the results of degree of crosslinking test, it could be confirmed that the binding structure of reformed filler was 3-dimensional net structure. And it could be also confirmed that the fluidness was improved at the casting of epoxy resin with reformed filler. From the above results, it could be concluded that the reformation of filler with the improvement of particle size distribution and globularization was very successful method to improve the performance of cast epoxy resin system.

• The Korean Journal of Rheology
• /
• v.7 no.3
• /
• pp.225-236
• /
• 1995

세가지 가교제 즉 황, tetramethyltyiuram disulfide (TMTD) 및 dicumyl peroxide(DCP)로 각각 가교시킨 카본블랙 충진 고분자 망상 시료들에 대해 일축연신 실험 을 통해 얻은 Mooney plot를 분석, 가교 탄성율 Gc와 엉킴 탄성율 Ge를 각각 구하였다. 각 가교계에 대하여 Gc를 통해서는 가교 사슬간의 평균분자량, 망상사슬과 카본블랙간 결합체 의 밀도 및 평균 면적 등을 Gc를 통해서는 카본블랙 첨가에 따른 관경비를 각각평가하였다. 황 가교제의 경우 Gc가 가장 높았으며 망상 사슬과 카본블랙간의 결합이 가장 잘 이루어졌 다. TMTD와 DCP가교제의 경우는 황의경우보다 카보블랙 입자와의 결합력은 낮았으나 결 합체들의 분포는 더욱 조밀하게 나타났다. 또한 Ge평가로부터는 TMTD 가교계가 카본블랙 충진에 의해 관경이 가장크게 증가함을 알수 있었다.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.2
• /
• pp.224-230
• /
• 1999

Agglomeration of colloidal alumina particles in a suspension is simulated. Particles in a suspension have potential energies between them and move to decrease the summation of all the potential energies between particles. The effects of various types of potential curves on particle agglomeration were checked. Strong short range attractive energy without repulsive energy barrier makes small strong clusters with disordered network structure but weak short-range force with big repulsive energy barrier makes big agglomerates with a close packing structure. As particles are agglomerated the potential energy with strong repulsive energy barrier between agglomerates gradually decreases the importance of the repulsive energy barrier and induces a different type of agglomeration behavior.

• Korean Journal of Materials Research
• /
• v.5 no.7
• /
• pp.829-834
• /
• 1995

Homogeneously dispersed zirconia suspension was prepared by addition of 500ppm polyvinyl alcohol (PVA). The powder compact by centrifugal casting from this suspension shows more uniform packing, higher packing density, and smaller pore size than that of suspension without PVA. On using this powder compacts, sintered monocllnic zirconia with the relative density of 98% could be obtained at low temperature of 125$0^{\circ}C$.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2000.11a
• /
• pp.121-122
• /
• 2000

현재, 반도체 등의 정밀 공업제품의 제조 기술의 발전에 따라서, 공기중의 미세 입자 제거 기술의 고도화가 요구되어 지고 있다. 이러한 미세 입자 제거에 사용되는 물질중 섬유층 필터는 구조가 단순하고, 여러 가지의 집진 조건에 비교적 용이하게 사용이 가능하여, 오늘날 폭넓은 분야에서 사용되어 왔다. 이러한 고성능의 포집 효율을 위한 노력으로, 섬유경을 작게하에 제작된 HEPA필터등이 이제까지의 청정공기의 생성에 널리 이용되어 왔지만, 장치를 대형화하지 않고서는 고포집효율, 저압력손실로 대량의 공기를 처리하는 것에는 한계가 있으며, 섬유경이 작게 되면, 압력손실이 증가되고, 압력손실의 증가는 동력 비용을 높이는 결과와 함께, 섬유 충진율의 분균일성등의 문제점이 발생한다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2000.11a
• /
• pp.28-28
• /
• 2000

HTPB/AP/AI 추진제는 none-reinforcing filler가 다량 함유되어 있어 기계적 특성은 바인더와 고체 충진제의 계면 접착력에 따라 크게 영향을 받으며 이를 향상시키기 위해 결합제의 연구가 다수 진행되었고 추진제의 인장 변형율을 증가시키기 위해 HTPB의 관능기수에 따른 가교밀도, 경화제와 경화촉매, 가소제등 최적의 바인더조성을 위해 가능한 원료 및 함량 연구에 많은 노력을 기울여 왔다. 또한 추진제의 주원료로서 AP는 추진제의 성능 및 내탄도 관점에서 입자크기에 따른 연소특성 및 고성능을 위한 충전 분율에 대해 주로 연구되었으며 특히 Oberth와 Farris는 고체추진제 분야에서 많은 업적을 이루었다.(중략)

• Proceedings of the Korean Fiber Society Conference
• /
• 1992.06b
• /
• pp.67-67
• /
• 1992

• Solar Energy
• /
• v.13 no.2_3
• /
• pp.91-106
• /
• 1993

The purpose of this study was to investigate the enhancement of heat transfer coefficient in double pipe fluidized bed heat exchangers. The inner tube used a smooth tube and a finned tube equipped with longitudinal fins. The heat transfer coefficients between the heated tube and fluidized bed of alumina beads were calculated as a function of fluidized velocity in various particle sizes($d_p$=0.41, 0.54, 0.65, 0.77mm) and static bed heights($H_o$=50, 100, 150, 200, 250mm). The coefficient for finned tube is higher than for smooth tube. And the maximum increasing rate is 7.8 times in smooth tube and 12.9 times in finned tube.

• Clean Technology
• /
• v.27 no.1
• /
• pp.24-32
• /
• 2021

Unburned carbon (UC) was successfully separated from fly ash by up to 85.8% in weight via froth flotation using soybean oil as a collector. An 18 wt% yield of microceramics (CM) could be achieved by employing a hydro cyclone separator located immediately after the flotation equipment. UC and CM were tested as alternatives to weight-adding material and polymer (especially polypropylene in this study) filler, respectively. Large particles of UC were broken down into smaller ones via ball milling to have an average particle diameter of 10.2 ㎛. When crushed UC was used as an alternative to clay as a rubber weight-adding material, a somewhat lower tensile strength and elongation rate than the allowed values were unfortunately obtained. In order to satisfy the standard limits, further treatment of UC is required to enhance surface energy for more intimate bonding with rubber. CM was observed in spherical forms with an average diameter of 5 ㎛. The surface of the CM particles was modified with phenol, polyol, stearic acid, and oleic acid so that the surface modified CM could be used as a polypropylene-filling agent. The flowability was good, but due to the lack of coupling forces with polypropylene, successful impact strength and flexural strength could not be obtained. However, when mixing the surface-modified CM with 1% silane by weight, a drastic increase in both the impact strength and flexural strength were obtained.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.04a
• /
• pp.21-24
• /
• 2003

SiO$_2$ 입자는 촉매, 촉매의 담체, 크로마토그래피를 위한 충진제등 여러 산업에 응용되고 있다.$^{1)}$ 본 연구 에서는 기능성을 가지는 입자를 제조하기 위해 SiO$_2$로써 기본적인 입자를 제조하고, 그 속에 소취특성을 가지는 TiO$_2$와 날염을 위한 EVA-microsphere를 포함시켜서 소취제로서, 그리고 날염 분체로서의 기능을 가진 입자들을 제조하고자 하였다. 실리카(silica)는 일반적으로 규소산화물을 지칭하는 명칭으로서, SiO$_2$뿐 아니라 결정구조상 4-6개의 산소원자로 둘러싸인 모든 형태의 규소산화물을 지칭 하는 것이고$^{2)}$ 수용액상의 물유리는 실리카 졸의 값싼 상품으로 산업분야에 널리 알려져 있다. (중략)