• Journal of Computational Design and Engineering
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• 제3권1호
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• pp.37-52
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• 2016

To injection mould polymers, designing mould is a key task involving several critical decisions with direct implications to yield quality, productivity and frugality. One prominent decision among them is specifying sprue-bush conduit expansion as it significantly influences overall injection moulding; abstruseness anguish in its design criteria deceives direct determination. Intuitively designers decide it wisely and then exasperate by optimising or manipulating processing parameters. To overwhelm that anomaly this research aims at proposing an ideal design criteria holistically for all polymeric materials also tend as a functional assessment metric towards perfection i.e., criteria to specify sprue conduit size before mould development. Accordingly, a priori analytical criterion was deduced quantitatively as expansion ratio from ubiquitous empirical relationships specifically a.k.a an exclusive expansion angle imperatively configured for injectant properties. Its computational intelligence advantage was leveraged to augment functionality of perfectly injecting into an impression gap, while synchronising both injector capacity and desired moulding features. For comprehensiveness, it was continuously sensitised over infinite scale as an explicit factor dependent on in-situ spatio-temporal injectant state perplexity with discrete slope and altitude for each polymeric character. In which congregant ranges of apparent viscosity and shear thinning index were conceived to characteristically assort most thermoplastics. Thereon results accorded aggressive conduit expansion widening for viscous incrust, while a very aggressive narrowing for shear thinning encrust; among them apparent viscosity had relative dominance. This important rationale would certainly form a priori design basis as well diagnose filling issues causing several defects. Like this the proposed generic design criteria, being simple would immensely benefit mould designers besides serve as an inexpensive preventive cliché to moulders. Its adaption ease to practice manifests a hope of injection moulding extremely alluring polymers. Therefore, we concluded that appreciating injectant's polymeric character to design exclusive sprue bush offers a definite a priori advantage.

• 한국식품과학회지
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• 제27권2호
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• pp.246-250
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• 1995

구약감자(Amorphophallus konjac)로부터 glucomannan 현탁액을 제조하고 그 유동특성을 구명하였다. 구약감자 glucomannan 현탁액은 항복응력이 없는 비뉴우톤성유체의 거동을 보여주었으며 다른 다당류 현탁액보다 일정 전단속도에서의 전단응력이 대체적으로 높게 나타났다. n값의 변화로 보아 구약감자분말 현탁액은 팽창유체의 경향을 약간 보인 반면 예비정제 구약감자분말 및 정제 glucomannan 현탁액의 경우는 의가소성유체의 거동을 보여주었다. 온도가 높아짐에 따라 구약감자 glucomannan 현탁액은 일정 전단속도에서의 전단응력의 크기가 감소하는 경향을 보여주었으나 그 감소정도는 비교적 균일하였다. 구약감자 glucomannan 현탁액은 pH 7에서 가장 점성이 높았으며 pH가 이보다 높아지거나 낮아지면 점성이 약간씩 감소하였다. 또한 1%까지의 식염첨가에 의해서는 점성변화가 거의 나타나지 않는 반면 10%까지의 설탕첨가에 의해서는 점성이 감소하다 그후 증가하는 양상을 보여주었다.

• 한국식품과학회지
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• 제21권6호
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• pp.815-819
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• 1989

밤전분 현탁액(3% 및 4%)의 유동특성을 모세관 점도계로 분석하였을 때 $30-65^{\circ}C$에서 항복응력이 존재하지 않는 딜라탄트유체의 거동을 보였다. 그러나 3% 전분 현탁액은 $70^{\circ}C$에서, 4% 전분현탁\액은 $65^{\circ}C$ 이상에서 의가소성 유체의 거동을 보였다. 밤전분 현탁액의 점조도지수의 활성화에너지는 $50^{\circ}C$이하에서는 0.56kcal/mole, $60-70^{\circ}C$에서는 51.9-80.8 kcal/mole 이었다. 전분 호화액(4%)의 유동특성을 회전점도계로 측정하였을 때 가열온도 및 시간에 관계없이 겉보기 점도는 지수적으로 감소하여 의가소성을 나타내었다. 밤전분 호화액을$65-80^{\circ}C$로 가열했을 때의 겉보기 점도의 대수값은 동일온도에서의 전분의 팽화력과 밀접한 관계를 보였다. 가열온도 $70-80^{\circ}C$에서의 겉보기 점도의 활성화 에너지 값은 13.9kcal/mole이었다. 상압$(90^{\circ}C)$ 및 가압$(121^{\circ}C)$ 호화액은 측정온도의 증가에 따라 겉보기 점도가 감소하였으나, 가압호화액은 측정온도의 증가에 따라 겉보기 점도가 감소하였으나, 가압호화액의 겉보기 점도는 동일온도에서 상압호화액의 겉보기 점도보다 높은 값을 보였다.

• 대한화학회지
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• 제15권6호
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• pp.303-312
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• 1971

Dependence of the flow behavior of aqueous suspension of Black Hills bentonite on the concentration and the types of electrolytes was stydied. The flow properties were measured with a Couette-type totational viscometer. On addition of monovalent cations, the apparent viscosity determined from the reproducible flow curves (shear rate vs. shear stress) decreased followed by a rise as the ionic concentration further increased. Addition of multivalent cations (di- and tri-) resulted in the viscosity which increased to a maximum then decreased to a constant value. Anions of different chatges produced essentially the same relationship between viscosity and electrolyte concentration. The flow behavior of the electrolyte-containing suspensions was rationalized in terms of the Derjaguin-Landau-Verwey-Overbeek theory of colloidal stability and the generalized theory of viscosity.

• 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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.70-73
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• 2002

Using a simple compression test, the viscosity measurement experiment is carried out with the grain-refined Al-Si alloy(A356). The measured rheological data are expressed with power-law(Ostwald-de Waele) model and using commercial package, MAGMAsoft, coefficients of Ostwald-de Waele model and Carreau-Yasuda model are calculated. To verify the viscosity data, the die is designed to be applicable to the semi-solid die casting of automotive component and filling test is carried out. The filling test and the simulation result are compared and in good agreement. Hereafter, these data are considered to be usefully allied other product in the semi-solid die casting.

• 한국식품영양과학회지
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• 제15권2호
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• pp.119-127
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• 1986

본(本) 연구(硏究)에서는 마요네즈의 유동특성(流動特性)과 각(各) 성분(成分)의 배합비(配合比)가 점도(粘度)에 미치는 영향을 연구(硏究), 검토(檢討)하였던 바 그 결과(結果)를 요약(要約)하면 다음과 같다. 1. 마요네즈는 강복응력(降伏應力)을 갖는 시간의존적(時間依存的)인 Thixotropic 유체(流體)의 거동(擧動)을 나타내었다. 2. 전단시간(剪斷時間)의 초기(初期)에 마요네즈의 구조는 응력(應力)에 의(依)해 2차(次) 속도식(速度式)에 따라 파괴되었다. 3. 마요네즈 점도(粘度)의 온도의존성(溫度依存性)은 Arrhenius식(式)으로 나타낼 수 있었으며 시제품(試製品)에 대(對)해서는 다음의 식(式)이 성립하였다. In $${\eta}=-0.3+3.527{\times}10^3l/T$$ 4. 난황(卵黃)의 농도(濃度)가 증가(增加)할수록 마요네즈의 점도(粘度)는 높게 나타났으며 안정성(安定性)은 12%에서 가장 높았다. 5. oil의 농도(濃度)가 $65{\sim}75%$ 범위에서는 농도(濃度)가 증가(增加)함에 따라 마요네즈의 점도(粘度)도 높아져 75%에서 최고값을 나타내었으며 그 이상(以上)의 농도(濃度)에서는 오히려 감소(減少)하였다. 한편 현미경 관찰결과 oil농도(濃度)가 높을수록 oil입자(粒子)의 직경(直徑)은 작게 나타났으며 안정성(安定性)은 75%에서 가장 높았다. 6. $2{\sim}8%$ 범위에서 수분함량(水分含量)이 증가(增加)할수록 마요네즈의 점도(粘度)가 높아지는 반면(反面)에 식초함량(食酢含量)이 증가(增加)할수록 점도(粘度)는 낮게 나타났다.

• Carbon letters
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• 제14권1호
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• pp.45-50
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• 2013

Polyacrylonitrile (PAN) copolymers of different molecular weights were synthesized by a suspension polymerization and precipitation polymerization method. The rheology behaviors of the synthesized PAN copolymers were investigated in relation to their molecular weight, solid content and melting temperature. The influence of "historical effects" on the spinning solution of PAN was studied by analyzing the laws of viscosity considering the diversification time and temperature. The viscosity disciplines of each spinning solution conformed well to the rheological universal laws in a comparison of the suspension polymerization product with that of precipitation polymerization. Viscosity changes in the swelling process of dissolution were gentler in the suspension polymerization product; a small amount of water will quickly debase the solution viscosity, and high-speed mixing can greatly shorten the time required by the spinning solution to reach the final viscosity.

• Applied Biological Chemistry
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• 제38권4호
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• pp.353-358
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• 1995

옥수수 전분(초기 수분함량 11.4%)을 $130{\sim}220^{\circ}C$에서 건열처리하여 DSC로 열분석한 결과 $190^{\circ}C$이상에서 호화엔탈피는 감소하였고 알칼리호화시 열처리온도가 상승할수록 점도가 증가하였다. $170^{\circ}C$이상에서 열처리 온도가 높아질수록 원료전분에 비하여 최고점도를 포함한 아밀로그램상의 모든 값들, 전분호화액의 전단응력과 겉보기점도, 점조도지수 및 항복응력은 감소하였다. $90^{\circ}C$에서 호화진행에 따라 모든 시료들의 겉보기 점도와 항복응력은 상당히 증가하였으며 $190^{\circ}C$시료는 특히 초기에 급증하였으나, 점조도지수는 약간 증가한 반면에, 유동거동지수값들은 큰 차이를 보이지않았다. 그러나 $220^{\circ}C$의 경우 모든 값들이 다른 시료들에 비하여 크게 낮았다.

• Korea-Australia Rheology Journal
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• 제16권1호
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• pp.47-54
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• 2004

Low Reynolds number, dilute, and surfactant-free bubble suspensions are prepared by mechanical mixing after introducing carbon dioxide bubbles into a Newtonian liquid, polyol. The apparent shear viscosity is measured with a wide-gap parallel plate rheometer by imposing a simple shear flow of capillary numbers(Ca) of the order of $10^{-2}$ ~ $10^{-1}$ and for various gas volume fractions ($\phi$). Effects of capillary numbers and gas volume fractions on the viscosity of polyol foam are investigated. At high capillary number, viscosity of the suspension increases as the gas volume fraction increases, while at low capillary number, the viscosity decreases as the gas volume fraction increases. An empirical constitutive equation that is similar to the Frankel and Acrivos equation is proposed by fitting experimental data. A numerical simulation for deformation of a single bubble suspended in a Newtonian fluid is conducted by using a newly developed two-dimensional numerical code using a finite volume method (FVM). Although the bubble is treated by a circular cylinder in the two dimensional analysis, numerical results are in good agreement with experimental results.