• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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• pp.59-67
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• 2006

Chemical Mechanical Polishing(CMP) in semiconductor production is characterized its output property by Removal Rate(RR) and Non-Uniformity(NU). Some previous works show that RR is determined by production of pressure and velocity and NU is also largely affected by velocity of flowfield during CMP. This study is about the direct measurement of velocity of slurry during CMP and whole flowfield upon the non-groove pad by Particle Image Velocimetry(PIV). Typical PIV system is modified adequately for inspecting CMP and slurry flowfield is measured by changing both pad rpm and carrier rpm. We performed measurement with giving some variation in the kinds of pad. The results show that the flowfield is majorly determined not by Carrier but by Pad in the case of non-groove pad.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.95-107
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• 2004

In this paper, the rheological characteristics of slurry used fur slurry-shield tunnels were studied with emphasis on penetration characteristics. The slurry penetration was modeled by soil-filter clogging theory. The coefficient of particle deposition was suggested as an indicator of sin clogging during tunnel construction and calculated through model tests. The measured slurry weight, clogged in the base soil, was compared with the value obtained from clogging theory. Based on the testing results, a stability analysis of a tunnel face was performed to pinpoint the most influential factor affecting stability of slurry-shield tunnels. It was found that the stability of tunnel face is dependent on the ratio of infiltration velocity to the coefficient of particle deposition, and the penetration distance of slurry increases with the ratio of infiltration velocity to the coefficient of particle deposition. Since the stability of tunnel face decreases with the slurry penetration distance, it was necessary to add some additives in order to reduce the slurry penetration distance. It was found that the ground condition needs additives when the soil has the effective particle diameter$(D_{10})$ larger than 0.75mm. It was also found that the tunnel face stability due to slurry penetration is significantly affected by the tunnel advance rate.

• Journal of Energy Engineering
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• v.9 no.3
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• pp.178-183
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• 2000

본 연구에서는 유동과 냉각수를 이용하는 아이슬러리 제조관정을 관찰하고, 이 시스템의 가장 큰 문제점인 관내동결 특성을 파악하였다. 시험수로는 수도수(city water)를 이용하였다. 시스템을 순환하는 시험수가 제빙관내에서 $0^{\circ}C$ 이하의 과냉각 조건이 형성되어 제빙관을 빠져 나오면서 축냉조에 설치된 충격판상에서 과냉각 해소가 일어났다. 이때 유동과냉각수는 내부에너지를 방출하면서 그 일부가 얼음 입자로 상변화되었고, 나머지는 실험장치를 계속순환하였다. 제빙관에서 시험수와 브라인의 열교환 방식을 대향류와 평행류 두 조건에서 시험수의 과냉각도는 Reynolds 수가 증가함에 따라 감소하는 경향을 보였고, 이들 결과 값으로부터 각각의 관계식을 유도하였다. 또한 브라인의 냉각속도가 0.29~0.53[$^{\circ}C$/min] 범위에서 시험수의 과냉각도는 브라인 냉각속도에 종속되지 않았다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.213-219
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• 2001

In this paper, particle velocity of slurry flow, a kind of solid-particle two phase flow, was measured by using a particle tracking velocimetry. Particles are modeled by sphere-shaped glass whose diameters are 3mm, 5mm, and 7mm At first, a particle which is falling in the water is captured and analyzed to give their free falling velocity. The falling velocity was very high up to about 4m/sec in the air, which needs special algorithm for the accurate measurement. For the upwelling slurry flow in the straight duct, there are some noises caused by cavity. However, the effect was so small that it does not affect the measurement of large particles. From the preliminary study of applying the PTV to measurement of particle movement in slurry flow, we could find out the optimum value of parameters: threshold value., searching area radius and correlation area size.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.89-96
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• 1999

Manufacturing conditions of the porous alumina mold were established to overcome various limits of the gypsum mold. For the preparations of the porous alumina mold, an activated charcoal was added to the Al2O3 with the wt% variation and then mixed. The binary slurry was study dispersed based on the examination of the ESA and rheological behaviro. The cylinder type alumina mold was cast in the gyspum mold and characterized by the shrinkage rate at the variable sintering temperature and the resistance against wear. It was proper to make a sintering of the Al2O3 by the surface diffusion which was non-shrinkage sintering mechansim, and intergranular neck growed stronger while sintering was being made. We studied a sintering by three categories; 1) thermodynamic method below 1,000$^{\circ}C$, 2) kinetic method above 1,000$^{\circ}C$ and 3) combined method. In the results of the respective works, combined method was superiro to the others. The prepared Al2O3 mold had relatively high strength, low drying rate, the resistance against the acid or base and good casting behavior.