• 대한기계학회논문집A
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• 제21권9호
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• pp.1400-1413
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• 1997

Semi-solid forging(SSF) process of A356 aluminium alloy has been studied to assess the effect of process variables on the component integrity. Semi-solid material(SSM) was fabricated by mechanical and electro-magnetic stirring process. The fabricated SSM by using mechanical stirring process has been carried out on cooling rate of 0.022.deg. C/sec 0.0094.deg. C/sec and stirring speed n=600, 1000 rpm, respectively. The fabricated SSM by using electro-magnetic stirring process is supplied by Pechiney. The holding time and temperature in the semi-solid state before forging also affects the globular microstructure of alloy. Therefore, the influence of these two parameters is discussed in terms of the microstructure of alloy. The SSF process has been conducted with three different die temperatures($T_{die}$=250.deg. C, 300.deg. C, 350.deg. C) and two kinds of gate types(straight gate and orifice gate). This paper is to investigate the influence of gate shapes of die on filling phenomena in SSF process more deeply. The mechanical properties of forged components were also investigated for variation of process conditions such as die temperature, gate shape and SSM.

• Membrane and Water Treatment
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• 제3권4호
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• pp.243-252
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• 2012

Tri-n-butyl phosphate (TBP) was used as carrier for the transport of Golden yellow and Cibacron LSG dyes through a hexane bulk liquid membrane. The transport efficiency of dyes by TBP was investigated under various experimental conditions such as pH of the feed phase (dyes solution), concentration of the receiving phase (NaOH solution), concentration of TBP in membrane, rate of stirring, effect of transport time, type of solvent, dye concentration in feed phase, effect of temperature.. The maximum transport dyes occurs at ratio of 1:1 TBP-hexane At pH 3.0 0.1 (feed phase) the transport dyes decreased. At high stirring speed (300 rpm) the dyes transport from the feed phase to the strip phase was completed within 60 minutes at $27^{\circ}C$. Under optimum conditions: Feed phase 100 mg/L dyes solution at pH 1.0 0.1, receiving phase 0.1 mol/L NaOH solution, membrane phase 1:1 TBP-hexane , Stirring speed 300 rpm and temperature $27^{\circ}C$, the proposed liquid membrane was applied to recover the textile effluent.

• 소성∙가공
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• 제9권5호
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• pp.494-503
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• 2000

The electro-magnetic stirring and mechanical process were applied to fabricate particulate metal matrix composites(PMMCs) with various particle size. The mechanical test on PMMCs was carried out in order to clarify the effect of 76 heat treatment on tensile behaviors. In order to study the thixoforming of PMMCs, fabricated billet are reheated by using the coil designed as a function of length between PMMC billet and coil surface, coil diameter and billet length. The effect of reinforcement distribution on billet temperature variation has been investigated with the calculated solid fraction theory based on a function of matrix alloy and volume fraction of reinforcement.

• Composites Research
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• 제14권5호
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• pp.1-11
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• 2001

본 논문은 금속복합재료를 반용융상태로 재가열하여 Thixoforming을 하는데 필요한 소재를 제공하기 위한 장비 설계와 제조방법 등에 관한 내용을 소개하고 있다. 장비 설계에서 기지재내에 강화재가 균일하게 분산되도록 하기 위하여 강화재의 연속주입 방법과 강화재의 온도를 제어하는 방법을 소개하고 있다. 일정한 양의 강화재를 기지재료 내에 분산시키는 것은 균일 혼합을 위하여 필요한 기술이다. 또한 분산시 강화재의 수분제거를 위하여 강화재의 온도를 제어하면서 연속적으로 강제분산시키는 것은 균일분산을 위하여 필요하다. 기지재의 초정 $\alpha$의 크기가 강화재의 분산성에 크게 영향을 미치기 때문에 기지재의 초기 온도가 초정$\alpha$의 크기에 미치는 영향 등을 검토하여 복합재료 빌렛트의 제조조건에 이용하였다.

• 한국주조공학회지
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• 제25권4호
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• pp.156-160
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• 2005

There are many factors that influence solidification behavior during continuous casting, e.g. include superheat, casting speed, cooling rate and holding time. However, when melt is stirred by electromagnetic force, there would be some changes in its solidification behavior compared to that of the ordinary casting process. In this study, the billets of A356 alloy with a diameter of 3 inch were fabricated with electromagnetic stirring under various conditions of superheat, casting speed and input voltage of electro magnetic stirring (EMS) device. The microstructure was also investigated under the various casting conditions and electromagnetic input voltages. When increase in input voltage, the microstructure was changed from dendritic to rosette type and finally to spheroidal. With pouring temperature, casting speed and electromagnetic input voltage were $650^{\circ}C$, 100 mm/min and 140 V, respectively, the billet with a diameter of 3 inch, which has a uniform dispersed spheroidal particles in the whole area of billet except for the surface area, was manufactured.

• 한국식품저장유통학회지
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• 제3권2호
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• pp.121-129
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• 1996

Plum highlighted as a health food is needed to diversify the processed products because labor storage is big problem since the fruit was producted massively in June. The Plum was extracted by the pressing type extractor after washing, drying and removing the seed by seed separator. The crude extract was concentrated with stainless steel vessel at different temperature and stirring speed. This study was obtained as follows. The sugar content of fresh plum concentrated extract was 55.3~58.3$^{\circ}$Brix, and of the freezing plum concentrated extract was 75.5~70.3$^{\circ}$Brix. In color difference, the freezing plum concentrated extract was more deep black than fresh plum. In change patten of pH, it was decreased as concentration was proceed. The final pH was 2.3~2.2 in fresh plum, and 1.8~2.2 in freezing plum. The total acid content of fresh plum concentrated extract and the freezing plum was 45.4~47.8, 60.3~60.9%, respectively. The content of evaporation at 85$\pm$5$^{\circ}C$ was constant irrespective of stirring speed. The yield of extraction of fresh plum was higher than freezing plum. According to this results, the use of stainless vessel, 50rpm, which gave a highly qualified plum concentrated extract.

• Journal of Pharmaceutical Investigation
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• 제13권3호
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• pp.89-99
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• 1983

Nylon microcapsules containing acetaminophen could be obtained by interfacial polymerization between sebacoyl chloride and 1, 6-hexamethylenediamine. Methylcellulose affected the micromeritic properties and dissolution characteristics of microcapsules. The particle size distribution was affected by the stirring speed and viscosity grade of methylcellulose. The surface observed by the scanning electron microscopy was affected by the methylcellulose. Nylon microcapsules produced in above method containing acetaminophen exhibited the retarded dissolution in comparison with uncoated acetaminophen. Release of acetaminophen from microcapsules decreased with decreasing pH of medium and with increasing the viscosity grade of methylcellulose and stirring speed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.660-663
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• 2004

Recently in the automotive industries, light and high quality material is strongly required because of emissions regulation issues. In the electromagnetic stirring process, it has many merits that are the exact control ability about material processing and a good point of the protection of environment. In this paper, the morphology of the change of primary Al phase in A356 alloy by electro magnetic stirrer was investigated to obtain the globular structure. The parameters are the current, stirring time, pouring temperature and cooling rate of different wall thickness; 5mm, 15mm, 25mm respectively. By proper selection of the processing parameters, globular primary particles can be obtained by electromagnetic stirrer.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.431-432
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• 2006

In this study, the effect of the temperature of magnesium slurry was investigated by mechanical stirring method. The evaluations of rheological behavior of AM50A magnesium alloy were measuring of viscosity and microstructures in the semisolid state. The apparent viscosity was investigated at continuous cooling rate using a concentric cylinder viscometer. Measurement of viscosity measures torque that act to stirrer rotating in slurry doing continuous cooling using torque-meter and expressed by POWER-LAW. Microstructures were observed after mechanical stirring that enforce time at steady state temperature of solid fraction.

• The Korean Journal of Ceramics
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• 제6권3호
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• pp.229-235
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• 2000

The spherical silica powder was synthesized by varying the kinds of solvent and mixing energy in emulsion method. The stirring speed varied from 500 to 1000 r.p.m. at 5$0^{\circ}C$ for 2h. Toluene in benzyl groups and a series of alkanes were used as dispersant. The average size of spherical silica particles decreased with increasing the stirring speed and the chain length o solvents used in this work. The average size was controlled in the range of 134~28$\mu\textrm{m}$ by selecting a proper solvent and stirring speed. The optimum processing parameters were described in details.