• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2574-2577
• /
• 2008

The screw-feeders are used at gathering the minerals at the seafloor, transportation of the sewage, and at the beverage industry. This study was carried out to study solid-liquid mixture hydraulic transport of solid particles in a horizontal and inclined screw-feeders with rotating. This study is about the amount of the alteration amount of the material transportation for regular transportation. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Relates to the angle, rpm and ratio of pitch ; finding the optimum condition and knowing about designing the screw feeders shape. As a result, we found the suitable rpm and a suitable angle. According to the experiment, the best rpm and angle are 100-200rpm and $10^{\circ}$, respectively.

• 대한기계학회논문집B
• /
• 제22권2호
• /
• pp.184-192
• /
• 1998

This paper deals with an extended analytical solution for the mixture solidification problem, in which temperature is inherently coupled with the solute transport due to the presence of volume contraction induced flow. A new exact solution to the energy equation accounting for the convection effect in the melt is successfully derived, which allows the present analysis to cover a high initial superheating. Difference in properties between the solid and liquid phases is rigorously incorporated into the model equations in the solid fraction weighted form. Taking advantage of linearized correction factors, a systematic and easy-to-implement algorithm for determining the solidus and liquidus positions is introduced, which proves not only to converge stably but also to be very efficient. For a specific case, the present results show excellent agreements with the existing solution. The effect of convection in the melt becomes appreciable with increasing the initial superheating. It is revealed that variable properties in the mushy region significantly affect the solidification behaviors. The present study is also capable of resolving the interaction between microsegregation and macrosegregation.

• 설비공학논문집
• /
• 제18권6호
• /
• pp.518-525
• /
• 2006

The present experiments have been performed for obtaining the melting heat transfer characteristics of micro-encapsulated solid-liquid phase-change material and water mixture slurry flow in a circular tube heated with constant wall heat flux. The phase change material having a low melting point was selected for a domestic cooling system in the present study. The governing parameters were found to be latent heat material concentration, heat flux, and the slurry velocity. The experimental results revealed that the increase of tube wall temperature of latent microcapsule slurry was lower than that of water caused by the heat absorption of fusion.

• 대한화학회지
• /
• 제15권4호
• /
• pp.177-181
• /
• 1971

Free radicals of lysozyme produced by $Ti-H_2O_2$ system were studied in aqueous solution at room temperature using ESR with a continuous flow-mixing. The spectra, each consisting of a doublet with 5.5 G splitting and a broad resonance covering 80 G splitting are closely similar in shape to that for solid irradiated in vacuum at $77^{\circ}K$ and observed at room temperature immediately on warming. The result is assumed to indicate that the secondary protein radical components formed within 0.01 second, dead time of the mixing chamber, and initiated by hydrogen atom abstraction at ${\alpha}$-carbon atom of peptide chain in liquid solution at room temperature are identical to those resulting from the initial formation of a mixture of positive holes and negative ions by ionization processes as well as radical fragments by the rupture of chemical bonds in the solid during similar time at the same temperature. A broad resonance is observed with considerable amplitude on the high field side of the doublet, which is quite dissimilar to the spectra of irradiated solid lysozyme. This resonance was tentatively attributed to the polypeptide free radical in which unpaired electrons are localized on side chain.

• 한국추진공학회지
• /
• 제19권2호
• /
• pp.29-37
• /
• 2015

본 연구는 케로신 연료를 사용하는 액체로켓엔진에서 발생할 수 있는 연소불안정으로 인하여 파괴될 수 있는 연소기의 손상을 수치적으로 모사하는 해석 모델의 기초연구이다. 연소불안정으로부터 야기 될 수 있는 케로신의 데토네이션은 1단계 아레니우스 식의 화학 반응식을 이용하였고, 구조체는 Johnson-Cook 강성모델을 활용하여 데토네이션으로 인한 금속관의 소성 변형을 모델링하였다. 금속관의 소성 변형에 의해 변화하는 유동장과 구조체의 스트레스를 노즐 형상과 관의 두께변화에 따라 해석하였다.

• 한국분무공학회지
• /
• 제1권1호
• /
• pp.55-62
• /
• 1996

In a fuel injection engine, atomization of liquid fuel and mixture formation process has influenced(or affected) directly on the engine performance and pollutant emission. In this study, the characteristics of fuel spray and the behaviors of secondary atomization developed at the downstream of the valves were investigated using an image processing method. Solid and perforated valves are chosen in order to evaluate the valve performance in terns of air flow rate, valve opening angle and valve shape. Experimental results clearly indicate that the spray atomization quality can be improved by increasing the perforated rat io and the blockage rat io in the perforated valve, the characteristics of spray atomization is improved by using the perforated valve with high perforated rat io and blockage ratio.

• 설비공학논문집
• /
• 제4권3호
• /
• pp.175-182
• /
• 1992

Freezing of the binary solution ($H_2O-NaCl$) saturating a packed bed of spheres is investigated experimentally. The system is cooled through its top surface, and the bottom is maintained at a temperature above the liquidus. Experiments are performed on the hypolutectic side, and the cold wall temperature is lower than the eutectic point. The effects of initial mixture concentration, superheat and glass bead diameter on temperature and concentration distributions are investigated. Supercooling was observed only at early times of the freezing process for experiments with 5% initial salt concentration. Flow visualization experiments and mushy-liquid interface position observations revealed natural convection in the liquid region. Remelting phenomena was not observed at both the solid-mushy and mushy-liquid interfaces.

• Journal of Advanced Marine Engineering and Technology
• /
• 제28권8호
• /
• pp.1225-1238
• /
• 2004

The present study has been performed for obtaining the melting heat transfer enhancement characteristics of water mixture slurries of plural microcapsules having different diameters encapsulated with solid-liquid phase change material(PCM) flowing in a pipe heated under a constant wall heat flux condition. In the turbulent flow region, the friction factor of the present PCM slurry was to be lower than that of only water flow due to the drag reducing effect of the PCM slurry. The heat transfer coefficient of the PCM slurry flow in the pipe was increased by both effects of latent heat involved in phase change process and microconvection around plural microcapsules with different diameters. The experimental results revealed that the average heat transfer coefficient of the PCM slurry flow was about 2～2.8 times greater than that of a single phase of water.

• Mass Spectrometry Letters
• /
• 제2권4호
• /
• pp.88-91
• /
• 2011

The pharmacokinetic properties of S-amlodipine were studied using racemic amlodipine and single S-enantiomer (SK310) administration to rats. Plasma levels of the drug were determined using chiral liquid chromatography coupled with tandem mass spectrometry following solid phase extraction. The stereospecific analysis of amlodipine was performed on an ${\alpha}$-acid glycoprotein (AGP) column using a mobile phase comprising 10 mM ammonium acetate (pH 4.0) and propanol at a flow rate of 0.2 mL/min. This method was used to perform a comparative study of the pharmacokinetics of amlodipine and SK310. The results revealed that the pharmacokinetic profile of S-amlodipine after the administration of SK310 was comparable to that following the administration of the racemic mixture.

• Bulletin of the Korean Chemical Society
• /
• 제30권7호
• /
• pp.1563-1566
• /
• 2009

One-dimensional aluminum nitride (AlN) nanostructures were synthesized by calcining an Al(OH)(succinate) complex, which contained a very small amount of iron as a catalyst, under a mixed gas flow of nitrogen and CO (1 vol%). The complex decomposed into a homogeneous mixture of alumina and carbon at the molecular level, resulting in the lowering of the formation temperature of the AlN nanostructures. The morphology of the nanostructures such as nanocone, nanoneedle, nanowire, and nanobamboo was controlled by varying the reaction conditions, including the reaction atmosphere, reaction temperature, duration time, and ramping rate. Iron droplets were observed on the tips of the AlN nanostructures, strongly supporting that the nanostructures grow through the vapor-liquid-solid mechanism. The variation in the morphology of the nanostructures was well explained in terms of the relationship between the diffusion rate of AlN vapor into the iron droplets and the growth rate of the nanostructures.