• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.821-826
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• 2006

This paper presents a novel type of hybrid dispensing head for IC fabrication and surface mount technology. The proposed mechanism consists of solenoid valve and piezoelectric stack as actuators, and provides positive-displacement and jet dispensing. The positive-displacement dispensing can produce desired adhesive amount without viscosity effect, while the jet dispensing can produce high precision adhesive amount. In order to determine the relationship between required voltage of the piezo actuator and needle displacement, both static and dynamic analysis are undertaken, In addition, finite element analysis is performed in order to find optimal design parameters. Dispensing flow rate and pressure in the chamber are evaluated through fluid dynamic model.

• 산업경영시스템학회지
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• 제29권1호
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• pp.151-154
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• 2006

The high degree of viscosity and the non-Newtonian fluid dynamics characterizes the process inside a glass furnace. Because the temperature is fluctuating in very short time-intervals, it is hard to determine that the status of its fluctuation is stable or unstable. Usually Shewhart-chart is used to determine the control status. However because of the characteristics of the temperature fluctuations in the glass furnace it does not directly serve the purpose here. Therefore we suggest using ARIMA to diagnose control status and confirm that the method using ARIMA can be a better tool than Shewhart-chart.

• 설비공학논문집
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• 제17권9호
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• pp.849-854
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• 2005

In this paper, the cooling performance of a microchannel heat sink with nano-particle-fluid suspensions ('nanofluids') is numerically investigated. By using theoretical models of thermal conductivity and viscosity of nanofluids that account for the fundamental role of Brownian motion respectively, we investigate the temperature contours and thermal resistance of a microchannel heat sink with nanofluids such as 6nm copper-in-water and 2nm diamond-in-water. The results show that a microchannel heat sink with nanofluids has high cooling performance compared with the cooling performance of that with water, the classical coolant. Nanofluids reduce both the thermal resistance and the temperature difference between the heated microchannel wall and the coolant.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.935-936
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• 2009

In this paper, we describe the basic operating mechanism of our novel reflective display, Fast Moving Ball Actuator (FMBA) mode[1], using micro-sized metal coated polymer ball in fluid medium. Metal surface of the ball can be charged up by contact electrode and their locations can be controlled by applied field to obtain optically on and off state. In the medium with high viscosity, the response speed of the moving ball might be reached into their terminal velocity and changed in proportion to the frequency of applied voltage on the electrodes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1885-1890
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• 2004

In this paper the numerical method with a zonal embedded grid system was applied to the spin-up flow within a semi-circular container. Flow visualization was also performed on a rotating table. The results show that at a low level of damping (i.e. low viscosity and high liquid depth) a cyclonic cell produced initially near the left-hand-side corner of the container moves along a wall and merged with the cell on the right-hand-side.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.191-197
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• 2001

Performance requirements for automatic transmission fluids have been changing to reflect the design changes of automatic transmission. The major purpose for these design changes is to improve fuel economy and drivability. The use of special base oils like API Group III and IV base oils has increased in order to formulate high performance ATF. In this study. the effect of base oils characteristics on ATF performance is investigated, mainly regarding differences in frictional characteristics with deterioration. Moreover, low-temperature fluidity. oxidation stability. and seal compatibility are also compared for four different ATFs. From the investigation, it was found that the use of Group III and IV base oils in ATF has several benefits in low temperature viscosity. oxidation stability and SAE No.2 friction characteristics.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.1162-1167
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• 2006

Because the mixing efficiency is influenced remarkably by varying the geometrical configurations, the study of flow characteristics inside the agitator is very important. The draught tube in the agitator makes intermixing between the screw and tube by interrupting radial flow, and the helical screw agitator with a draught tube (HSA) is proved more efficient to mix than the others. Consequently, the shapes of helical screw and number of pitches are the main parameters for improving the performance of HSA. In this study, numerical analyses were carried out, using a commercial CFD code, Fluent, to obtain the velocity and pressure distributions under steady, laminar flow and no-slip condition. Results are graphically depicted with various parameters.

• 한국분무공학회지
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• 제24권1호
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• pp.15-20
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• 2019

The agitator is an important industrial instrument widely used for mixing various solutions in the industrial field. In this study, the optimized design of the helical ribbon type impeller, which is mainly used for the stirring of the high viscosity solution, is carried out by CFD analysis. For this purpose, an index for evaluating the agitation performance is newly defined and an optimization design process is performed through a multiphase computational fluid dynamic analysis. From these results, it is understood that the stirring performance is maximized in the case of the helical ribbon impeller under given operating conditions when the width is 7.5 mm, the height is 160 mm and the turn is 1.

• 한국미생물·생명공학회지
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• 제17권4호
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• pp.397-402
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• 1989

Methylobacterium organophilum 이 탄소원과 에너지원으로서 메탄올로부터 생성하는 새로운 다당류계 생물고분자의 화학적 성질과 물성학적 성질을 관찰하였다. 분리정제한 다당류의 분자량은 약 4-5$\times$$10^6$ dalton 정도로 고분자량을 지니고 있다. 다당류의 화학적 조성은 건조중량의 66%가 탄수화물로 구성되어 있으며 이들의 88%가 환원당으로 구성되어 있다. 특이하게 본 고분자는 건조중량의 4.7%가 단백질로 구성되어 있다. 다당류는 glucose, galactose, 그리고 mannose을 몰비로 2:3:2 함유하고 있으며 탄수화물 이외에도 pyruvic acid, uronic acid, acetic acid 등을 함유하고 있다. 정제된 다당류를 증류수에 용해시켜 농도별로 점도를 측정한 결과 비뉴톤성 성질 중 pseudoplastic 성질을 보였으며 농도가 증가함에 따라서 겉보기점도 증가가 월등히 높았다. 동일한 1% 용액의 경우 K(consistency index)값을 비교하면 xanthan gum에 비해 약 10배정도 높은 18,000 cp 값을 나타내었다.

• 한국식품과학회지
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• 제22권7호
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• pp.852-857
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• 1990

대체감미료로 사용되고 있는 당유도체들 fructo-oligo당, HMS, sorbitol 및 maltitol의 유동특성과 식품기능성을 설탕과 비교하였다. 시험된 모든 당유도체 용액은 농도범위 10%에서 원액에 이르기까지 뉴우턴성 유체특성을 나타내었으며 HMS의 점도가 가장 높고 fructo-oligo 당, maltitol, 설탕, sorbitol, 포도당 순으로 점도가 낮아졌다. 용액의 점도가 평균분자량과 직선적 상관관계 (r=0.8038)를 보였다. 농도증가에 따라 점도는 지수적 증가추세를 나타내었으며 농도의존성지수는 당알콜류가 HMS나 fructo-oligo 당 보다 낮았다. 온도증가에 따라 당용액의 점도는 지수적 감소경향을 보여 Arrhenius식을 따랐으며 유동활성화에너지는 sorbitol과 HMS가 설탕보다 큰 반면 fructo-oligo 당과 maltitol은 설탕보다 작았다. Fructo-oligo 당을 사과잼에 설탕 대용으로 사용하였을 경우에는 조직감에 영향을 미치지 않았으나 팥양갱에서는 견고성, 부착성, 탄력성, 응집성을 모두 크게 저하시켰다. HMS는 사과잼과 팥양갱에 설탕 대용으로 전량 대체할 경우 큰 조직감 변화를 가져오지 않으나 설탕과 50%씩 혼용할 경우 견고성이 크게 저하되었다. 반면 당알콜류를 설탕대용으로 잼이나 양갱에 사용할 경우 견고성, 부착성, 탄력성을 저하시켰다. Fructo-oligo 당과 HMS를 설탕에 첨가할 경우 캔디의 고화속도에 큰 변화가 없으나 sorbitol은 고화속도를 크게 저하시켰다.