• 한국재료학회지
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• 제9권4호
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• pp.392-397
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• 1999

The tensile strength and water resistance of ADC12 alloy matrix composites reinforced with saffil/ceraklwool and saffil/Si particle prepared by squeeze casting have been investigated in room temperature and $250^{\circ}C$. Adhesive and scuffing wear phenomena was studied when load was changed to 10~40N and wear velocity was 2.0m/s at room temperature and $250^{\circ}C$. Generally, the morphology of tensile fractured surface revealed dimple pattern which implies ductile fracture of the composites. However, cleavage fracture was also observed in case of ADC12 alloy based saffil/Si particle composite. The maximum tensile strength of 320MPa was obtained in ADC12 alloy based composites reinforced by saffil/cerakwool(5:5) preformed fibers. In the results of dry wear test, it was observed that scuffing was occurred at 40N in room temperature and 30N for $250^{\circ}C$.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.451-454
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• 2005

Recently, Trouble of sand supply is occurred according to exhaustion of natural sand resources. therefore, various measures are proposed for solution of trouble of sand supply and crushed sand among measures is used as one of most universal measures. but because crushed sand have poor particle shape and plenty of makes micro particle, the quality of concrete using crushed sand deteriorated. Therefore, this study evaluated engineering property of concrete with replacement ratio of crushed sand and applied evaluation result to fundamental data for quality control of concrete using crushed sand. The result of this study have shown that quality of concrete using crushed sand independently is poor against general concrete. but, the concrete mixing crushed sand with general sand can be similar in workability of concrete used general sand and increase compressive strength of concrete as against concrete using general sand.

• 한국식품영양과학회지
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• 제22권1호
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• pp.73-77
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• 1993

This study was intended to investigate the effects of solvents, particle size of a sample, sample to solvent ratio, temperature and time on the extraction of garlic oleoresin. Among eleven solvents used for oleoresin extraction from garlic, the optimal solvent was methyl alcohol. The most appropriate particle size of garlic, extracting temperature and mixing ratio of garlic to methyl alcohol were 20mesh, $25^{\circ}C$ and 1 to 3(w/w), respectively. On the basis of yield in oleoresin extraction, optimum extracting time was about 4 hours. The yield of oleoresin under the above-mentioned conditions was 21.3%. "L" and "b" as color appearance were decreased, whereas "a"was increased slightly during 60 days storage at 5$^{\circ}C$, $25^{\circ}C$ and 4$0^{\circ}C$. Changes in the pyruvate content showed close relation to pH value. During storage pyruvate content of garlic oleoresin was decreased as increasing storage temperature.

• 대한기계학회논문집
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• 제8권2호
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• pp.133-140
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• 1984

본 연구에서는 이러한 2유체방정식모델을 Stokes의 저항력 뿐만 아니라 벽면 의 영향을 함께 노고하여 벤츄리관에서의 정압강하가 공기류량과 고체유량, 그리고 입 자의 크기에 어떻게 의존하는가를 해석하였다. 본 연구의 수치해석결과를 Farbar와 Lee와 Crowe의 실험과 비교하였으며, 만족할 만한 일치를 얻었다.

• 산업기술연구
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• 제16권
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• pp.105-112
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• 1996

This paper presents coal mine waste (CMW) for use in concrete manufacture as a replacement of normal aggregates. The CMW in this study was collected from Sabook, Jungson-kun, Kangwon-do. Fine and coarse asggregates from CMW were prepared by crushing it in a jaw crusher and separating debris with #4 sieve. CMW aggregates showed good physical and mechanical properties with having specific gravity over 2.65, absorption less than 1%, and abration ratio below 20%, but particle shape of CMW was long or flat, which caused a poor workability in mixing. Therefore, to make workability better, a 1/4 of CMW coarse aggregate was replaced with normal aggregate which had a good particle shape, and a superplasticizer was added to the mix. Compressive strength and other mechanical properties of CMW concrete was very good. In conclusion, characteristics of CMW concrete was acceptable for use as a concrete structural material.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.178-183
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• 2000

Electrorheological(ER) effect on the dispersive system of polarizable fine powder/dielectric oil has been investigated. The electrical and rheological properties of zeolite and starch based ER fluid were reported. The ER fluids were constructed by mixing zeolite and starch power with two different dielectric oils. Yield stress of the fluids were measured on the couette cell type rheometer as a function of electric fields, particle concetrations, and temperatures. The electric field is applied by high voltage DC power supply. The outer cup is connected to positive electrode(+) and the bob becomes ground(-). And the temperatures the viscosity(or shear stress) versus shear rates were measured. In this experiment shear rates were increased from 0 to $200s^{-1}$ in 2 minutes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.694-699
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• 2003

Simultaneous measurement with PLIF(Planar Laser-Induced Fluorescence) and Stereo-PIV(Stereoscopic Particle Image Velocimetry) was performed to investigate the structural characteristics of flow field in Rushton Turbine Mixer. Instantaneous 3D velocity fields are measured by two 2K ${\times}$ 2K CCD cameras focused on an object plane with the angular displacement methods while the concentration fields are obtained through the measurement of the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. Finally, the spatial structures of turbulent mixing around Rushton turbine were identified by the calculation of cross-correlation fields between the velocity and concentration field.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.23.2-23.2
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• 2010

Researches on the drying of particle/polymer suspensions receive attentions in technical applications such as manufacturing display and batteries. In this study, the effect of polymers on drying behavior of silica/poly(vinyl alcohol) suspension was investigated in terms of suspension stability and stress development during drying. The effect of polymer adsorption was studied by changing pH. More strongly flocculated suspension with lower pH became more dispersed and close-packed film after drying. Evaluation of potential energy allows us to suggest that the adsorbed polymers which bridge the particles introduce steric repulsion and lead flocculated suspension to dispersed film. When the effect of adsorption kinetics was studied by changing the mixing time, the adsorption amount, characteristic stress and dried film density showed a similar behavior in the form of with a single characteristic time. It implies that the drying process can be determined by simple characteristic equation with a single time constant.

• 한국연소학회지
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• 제14권2호
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• pp.32-41
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• 2009

The transported probability density function model combined with the consistent finite volume (FV) method has been applied to simulate the turbulent bluff-body reacting flows. To realistically account for the non-isotropic turbulence effects on the turbulent bluff-body reacting flows, the present PDF transport approach is based on the joint velocity- turbulent frequency-composition PDF formulation. The evolution of the fluctuating velocity of a particle is modeled by a simplified Langevin equation and the particle turbulence frequency is represented by the modified Jayesh - Pope model. Effects of molecular diffusion are represented by the interaction by exchange with the mean (IEM) mixing model. To validate this hybrid FV/PDF transport model, the numerical results are compared with experimental data for the turbulent bluff-body reacting flows.

• 에너지공학
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• 제1권1호
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• pp.76-86
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• 1992

현존하는 미분탄 연소로의 난류 유동장 및 반응을 해석하는 3차원 모델을 제안하였다. 미분탄 불균일 반응, 휘발, 복사 및 서로 다른 방향에서 유입되는 1차 공기와 2차 공기의 혼합, 열 손실 등의 연소로 내에서 일어날 수 있는 제반 현상을 종합적으로 고려하여 비선형 미분 방정식을 세우고 유한 미분법을 적용하여 연소 현상을 묘사하였다. 본 연구에서 제안한 모델을 이용하여 연소로 내에서의 미분탄 연소 거동을 예측하고 연소 효율에 중요한 영향을 미치는 1차 공기와 2차 공기의 주입 속도와 석탄입자크기가 연소 거동에 미치는 영향을 살펴보았다.