• The Korean Journal of Rheology
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• v.2 no.2
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• pp.19-27
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• 1990

레이저와 타이머장치를 설치한 낙구식 점도계에서 구와 니들이 주어진 구간을 통과 하는 시간을 측정하여 종말속도를 정확히 결정하였고 점성이 작은유체와 낮은 전단률 점성 과 영전단률 점성은 속이 빈 알루미늄 구와 니들이 이용하여 측정하였다. 알루미늄 구와 니 들의 속에 철분을 삽입하여 밀도를 다양하게 변화시켰다. 낙구식 점도계에서 측정한 낮은 전단률 점성과 영 전단률 점성 그리고 모세관점도계에서 측정한 높은전단률 점성과 무한 전 단률 점성을 이용하여 점탄성 유체의 특성이완시간을 결정하였다. 실린더 속의 시험용 유체 를 교란시키지 않고 밑면에 떨어진 구를 회수하는 장치를 설치하였다. 이 장치는 하나의 구 로써 점탄성유체의 특성확산시간을 측정하는데 대단히 효과적이었다. Polyacrylamide Separan AP-273 용액(농도 500-200 wppm)의 특성이안시간과 특성화산시간을 낙구식 점도 계와 모세관 점도계의 실험결과를 이용하여 결정하고 폴리며 용액의 퇴화 현상을 실험적으 로 분석하였다.

• Korean Journal of Food Science and Technology
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• v.51 no.4
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• pp.330-335
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• 2019

The aim of this study was to investigate the rheological properties of arabinogalactans (AGs) solution isolated from moth bean (MB), navy bean (NB), and soybean (SB) including monosaccharide compositions, intrinsic viscosity, steady shear and dynamic shear rheological properties. The major monosaccharides in MB, NB, and SB were arabinose (64.8, 51.4, and 42.6%) and galactose (13.4, 19.6, and 46.2%). The yield stresses for 5% (w/v) NB and 2.5% (w/v) SB solutions were assessed as 2.10 Pa and 1.98 Pa, respectively, but in case of MB solution, it was observed to be negligible. While 5% MB solution showed rheopectic property, 5% NB and SB solutions showed thixotropic properties. As a result of frequency sweep experiment, the G' values in 2.5% MB and NB were larger than the G" value showed but 2.5% SB exhibited G" value greater than G'. These results would be useful for future application as a food additive in the food industry.

• Korean Journal of Food Science and Technology
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• v.29 no.6
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• pp.1089-1093
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• 1997

The physicochemical properties of erythritol were examined by measuring water absorption, solubility, water activity, heat stability, and viscosity compared to those of sucrose, xylitol, sorbitol and fructo-oligosaccharide. Erythritol showed the lowest water absorption and the highest water activity reducing capacity. In the solubility test of sweeteners, the saturation concentration of erythritol at $20^{\circ}C$ was 35.8%, which was the lowest solubility. Caramelization test and Maillard reaction test showed that erythritol was stabler than sucrose in heat treatment, while fructo-oligosaccharide showed the strongest reaction. The viscosity of erythritol was similar to that of other sweeteners at the same concentration (10%, 30% w/w). The viscosity of sweeteners increased exponentially with increasing concentration but decreased with increasing temperature following Arrhenius equation. The activation energy for flow of 30% erythritol solution was estimated to be 10.8 kcal/g mol.

• Polymer(Korea)
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• v.34 no.5
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• pp.415-423
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• 2010

Poly(vinyl alcohol)(PVA) with high degree of hydrolysis of above 98% was dissolved in dimethyl sulfoxide(DMSO), and the shear viscosity was measured up to $C{\simeq}0.14\;g/mL$ in the semi-dilute solution regime. Next, as probe particle, polystyrene(PS) latex was introduced into this matrix system and its delayed diffusion due to polymer concentration was investigated by means of dynamic light scattering. When the solution viscosity of PVA/DMSO was plotted against the reduced concentration $C[{\eta}]$, which is scaled by the intrinsic viscosity, the molecular weight dependence was strongly appeared at C$[{\eta}]$ >2. Some heterogeneties in polymer solution were considered as its source. Contrary, the diffusion of probe particle in the matrix solution was observed as a single mode motion at whole concentration range but its ratio of its diffusion coefficient at solution to that at solvent, D/Do did not show any molecular weight dependence at all. However, the application limit of the stretched exponential function was disclosed at C$[{\eta}]$ >2.5.

• Proceedings of the Korean Fiber Society Conference
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• 1992.06b
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• pp.106-106
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• 1992

• Journal of the Korean Chemical Society
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• v.13 no.4
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• pp.263-272
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• 1969

액체의 상태합을 유도하여 여러 가지 액체들의 적용하여 열역학적 성질들과 점성도를 계산하여여 측정치와의 좋은 일치를 보았다. 그리고 이 상태합을 써서 여러 성분으로 된 액체 용액의 상태합을 얻었으며 나아가서 액체 용액에서의 화학 반응 속도를 구할 수 있음을 보았다.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.37-41
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• 2003

열화학 기상합성법을 이용한 탄소나노튜브의 성장에서 촉매 금속 층의 형성 공정은 탄소나노튜브의 직경 및 길이를 제어해주는 가장 중요한 요소이다. 탄소나노튜브의 대량합성을 위해 자성유체를 이용한 촉매 금속 층의 손쉬운 형성공정을 개발하였다. 수용성 폴리비닐알코올과 마그네타이트 나노 입자들이 혼합된 자성유체를 다양한 기판에 스핀 코팅하여 촉매 금속 층을 간편하게 형성할 수 있었다. 자성유체 제조 시 혼합된 수용성 폴리비닐알코올은 자성유체용액의 점성을 증가 시켜 주었으며, 이러한 점성의 증가는 스핀 코팅 시 용액과 기판간의 접착력을 증대시켜 주었다. 또한 건조 과정 이후에도 잔류되어 탄소나노튜브 합성 공정 중에 촉매금속이 응집되는 현상을 방지 차여 균일한 입자 크기를 유지하도록 하였다. 이는 고밀도의 수직 배열된 탄소나노튜브의 성장의 직접적인 원인으로 생각된다. 또한 탄소나노 튜브의 대량 합성을 위해서 Si 기판 치에 알루미나와 금속 기판에서도 탄소나노튜브의 성장을 시도하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.241-250
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• 1990

Characteristic relaxation time and characteristic diffusion time of viscoelastic fluids are determined experimentally by measuring the zero-shear-rate viscosity by falling ball viscometer and the infinite-shear-rate viscosity by capillary tube viscometer. Fluids used in experiments are aqueous solutions of polyacrylamide Separan AP-273 and the polymer concentrations range from 300 to 2000 wppm. A newly designed laser beam and timer system is employed to overcome the difficulty in measuring terminal velocities of the low concentration solutions. Ball removal device is prepared to remove the dropped ball from the bottom of cylinder without disturbing the testing fluid. In order to measure the zero-shear-rate viscosity, densities of hollow aluminium balls are adjusted very close to the densities of testing fluids. Characteristic diffusion time, which is ball viscometer. However, terminal velocity of a needle by falling ball viscometer is not affected by the time interval of dropping needles and characteristic diffusion time is not measured with a dropping needle. Powell-Eyring model predicts the highest values of the characteristic relaxation times among models used for heat transfer experimental works for a given polymer solution. As degradation of a polymer solution continues, the zero-shear-rate viscosity decreases more seriously than the infinite-shear-rate viscosity. Characteristic relaxation times of polymer solutions decreases as degradation continues.

• The Korean Journal of Rheology
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• v.1 no.1
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• pp.5-11
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• 1989

슬릿트나 관형의 흐름에서 유체의 유변학적 성질을 측정하기 위해서는 벽면에서의 압력구배를 알아야한다. 벽면에서의 압력측정은 특히 관형의 경우 압력구멍의 존자가 불가 피하다. 압력구멍에 의한 오차에 대한 이론적인 고찰이 있었지만 사용된 몇가지 가정이 실 험적인 과찰과 일치하지 않아 이들 이론에 대한 강한 의문을 제기하고 한다. 한편 실험적인 결과는 묽은 고분자 용액인 경우 측정압력에 대한 상대적인 압력구멍 오차가 무시할 수 없 을 정도로 크다. 압력구멍 오차는 압력구멍의 크기, Reynolds 수 (점성) 및 Weissenberg 수 (탄성)의 함수로 나타나고 있다. 그러나 농도가 비교적 높은 고분자 용액이나 용융체는 상대 적으로 무시할 수 있을 정도의 압력구멍 오차를 나타낸다.

• Journal of the Korean Chemical Society
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• v.42 no.5
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• pp.512-518
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• 1998

In this study, various thermodynamic and hydrodynamic parameters characterizing the solution properties of polyethylene ionomer particles in water were determined at $30^{\circ}C$ by means of light scattering and viscosity measurements. Based on the experimental data, we investigated the solution behavior of three kinds of polyethylene ionomers, which are different in composition of the pendant ionic groups of COOK, COOH and $CONH_{2}$, and characterized their particle properties. Ionomers containing 7.6 mol% potassium salt only behave as flexible coils in a relatively good solvent state. On the other hand, two ionomers containing 3.8 mol% amide group together with potassium salt form the compact particles. In addition, the concentration dependence of the effective diffusion coefficient $(D_{eff})$ and the reduced viscosity of the latter ionomers showed the opposite trend from the former, indicating that the composition of the pendant ionic groups have a great influence on the interparticle interaction of ionomers formed in water.