• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.850-853
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• 2000

It is well-known that Electro-rheological(ER) fluid is a material(suspension) which shows the dramatic change of rheological properties under an electric field. Using these properties, the concept that variable apparent viscosity of ER fluid could be applicable to the polishing for micro parts was introduced. It was investigated that how it works for polishing and how it affects ER effect when abrasives were mixed with an ER fluid. Therefore a few structures for polishing using ER fluid was suggested and evaluated by means of experiments. In this paper, fundamental mechanism and experimental results are described.

• International Journal of Vascular Biomedical Engineering
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• v.4 no.2
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• pp.7-12
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• 2006

The present study investigated the effects of the osmotic environment on the rheological properties of erythrocytes and their suspensions. In an iso-osmotic medium, erythrocytes forming a biconcave discocyte under resting conditions, exhibited high deformability. In a low-osmotic medium, the deformability of erythrocytes, which swelled and exhibited a spherical shape, significantly decreased at a high shear stress and the high-shear viscosity of the cell suspension was slightly higher than that of normal blood. Hyper-osmotic stress, however, which caused to form echinocytes, decreased cell deformability but exhibited smaller viscosity in low shear rates than iso-osmotic blood viscosity. These results showed a close relation with the aggregability measurements, in that hypertonic blood showed lower aggregability than the hypotonic and isotonic RBC suspensions. These findings indicate that the physicochemical environment has a strong influence on the rheological properties of the erythrocyte and its suspensions.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.271-276
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• 2003

This study is about the rheological properties of cement slurry using admixtures. The variables are the type of cement(Type I, II, IV, V) and the substitution ratio of admixtures such as fly ash and slag. As a result of measuring the fluidity of various types of cement slurry at the early stage, type 2, type 4 and type 5 showed the similar property. The fluidity of type 1 and ternary blended cement was low. it is thought that it is because of the high $C_3$A content. The cement slurries containing mineral admixtures were superior in the property of fluidity retention.

• Journal of the Korean Ceramic Society
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• v.38 no.2
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• pp.152-157
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• 2001

본 연구에서는 고유동, 저발열 및 고강도 특성을 발현하는 belite-rich cement(BRC)에 있어서 카르복실산계 유기혼화제를 사용했을 때 가용성 알칼리의 함량 변화에 따른 흡착거동과 유동특성에 미치는 영향성에 대해 검토하였다. BRC에서 알칼리 0.1~0.2 wt% 및 알칼리 설페이트 0.3~0.5 wt% 첨가시 슬럼프가 증가하거나 손실이 거의 없었으며, 그 이상의 함량을 첨가하였을 때 다시 유동서 저하를 가져왔다. 그러나, 보통 포틀랜드 시멘트(OPC)의 슬럼프 유지능력은 알칼리 및 알칼리 설페이트를 첨가할수록 감소되었다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.3
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• pp.369-374
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• 2000

메밀가루를 이용한 빵을 만들기 위하여 밀가루에 메밀가루를 10,20,30%를 혼합한 반죽과 30% 메밀복합분에 글루텐, ascorbic acid 및 HPMC를 혼합한 반죽들의 amylogram, farinogram 및 extensogram의 특성을 측정하였으며 SEM을 이용한 반죽의 구조도 관찰하였다. Amylograph에 의한 호화개시온도, 최고점도 및 최고점도시의 글루텐, ascorbic acid 및 HPMC의 의해 감소하는 경향이었다. Farinograph에 의한 흡수량은 메밀가루의 참가량이 많을수록 약간씩 감소하였고, 글루텐을 첨가하였을 경우에는 증가하였으나 HPMC에 의해서는 오히려 감소하였다. 반죽형성시간은 메밀가루의 혼합비율이 높을수록 점차 짧아졌고 첨가제에 의해서는 증가하였다. Extensograph에 의한 발효특성은 메밀가루의 첨가량이 많을수록 신장도와 신장에 대한 저항도는 감소하였으나 첨가제사용에 의해 증가하였으며 특히 글루템에 의해 신장저항도와 반죽의 강도가 높게 나타났다. 또한 SEM에 으한 반죽의 구조는 메밀가루의 혼합비율이 높아질수록 규칙적인 protein matrix를 형성하지 못하고 구형의 큰 전분입자와 작은 전분입자들이 엉겨서 덩어리진 상태로 혼합되어 있었으며 첨가제에 의해 전분입자와 단백질matrix 상호간에 결합상태가 개선되었으며 특히 첨가제 중 글루템은 밀가루 반죽과 유사하였으므로 빵의 부피 및 제빵성을 향상시켜 줄 것으로 생각된다.

• The Korean Journal of Rheology
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• v.9 no.1
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• pp.1-5
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• 1997

새로이 합성한 계면확성제와 대표적 분산용 계면활성제의 분산효과를 상호 비교해 보기 위하여 고농도 석탄-물 슬러리계에 대한 유변학ㅈ거 성질을 측정하였다. 0~$25^{\circ}C$ 온도 범위에서 얻어진 유동곡선으로부터 여러 가지 유동 파라미터를 구한 결과, PS가 상대적으로 structure factor, C2와 shear modulus, $\chi$2/$\alpha$2 값에 있어서 큰 감소를 보여 주엇으며 특히 shear modulus는 계면활성제의 종류에 따라 큰차이를 보여주었다. 이러한 현상을 PS가 다 가음이곤 고분자 전해질과 유사한 구조를 갖고있어서 석탄 입자에 흡착시 입자간 정전기적 반발과 입체장애를 초래하여 슬러리의 유동성을 향상시킨데 따른 결과로 해석된다.

• Korea-Australia Rheology Journal
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• v.19 no.1
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• pp.1-5
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• 2007

By combining ultrasonic energy which is essential for the chain scission of polymer molecules and a multifunctional agent (MFA) having double bonds at its ends, we were able to modify the molecular structure of polycarbonate (PC) from linear to a branched structure during melt processing. The three double bonds in chain ends of MFA were expected to act as sites for trapping macroradicals of PC during the course of ultrasound-assisted mixing process. The transformation of molecular structure of PC was confirmed by the measurements of rheological properties of the modified PC. After the ultrasonic irradiation of PC together with MFA, increase in complex viscosities and shear-thinning behavior were observed. The Cole-Cole plot and measurement of extensional viscosities revealed the characteristic features of branched structure with well-defined extensional behavior which is comparable to that of a commercial branched PC.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.69-77
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• 1995

This paper presents performance investigation of a continuously variable ER(Electro-Rheological) damper for passenger vehicles. A dynamic model of the damper is formulated by incorporating electric field-dependent Bingham properties of the ER fluid. The Bingham properties are experimentally obtained through Couette type electroviscous measurement with respect to two different particle concentrations. The governing equation of the hydraulic model treating three components of fluid resistances;electrode duct flow, check valve flow and piston gap flow, is achieved via the bond graph method. A prototype ER damper is then designed and manufactured on the basis of parameter analysis. The damping forces of the system are experimentally evaluated by changing the intensity of the electric field, the particle concentration and the electrode gap.

• Journal of the Korean Graphic Arts Communication Society
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• v.28 no.2
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• pp.45-56
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• 2010

The computer simulation is presented of gravure ink transferring behavior and penetration to the paper when an gravure roller is used to transfer a printing ink onto a substrate. The three dimensional unsteady ink motion is simulated by Polyflow package software and experimented by IGT gravure printing test machine. The simulation is performed where the flow domain is bounded above by a stress free surface and bounded below by a moving substrate. Specific predictions are made for particular pattern of cells and substrates. Cell size and ink rheological properties are found to be the principal determination of transferring behavior. Simulation is currently restricted to the flow domain beneath the receding meniscus. Both Newtonian and shear thinning inks are considered.

• YAKHAK HOEJI
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• v.21 no.2
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• pp.87-94
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• 1977

The rheological properties of some honey-ginseng powder mixturs, used as pharmaceutical pills, were studied extensively by employing five kinds of honey, acacia, chestnut, buckwheat, green perilla and bush clover. Relation between the viscosity of the sample mixtures and the concentrations of ginseng powder and the temperature effect on the internal change of the structure were studied. The results obtained are as follows: 1) A complete gel formation of honey-ginseng mixtures was observed when about 50 days have passed after the sample preparation. 2) The viscosity of honey-ginseng powder mixtures was related with the concentration of ginseng powder, the temperature and the period of time required in gel formation as shown in the following equation. n=noexp$[{\kappa}_{1}c^{n1}+{\kappa}_{2}(T-273)^{-n2}+{\kappa}_{3} t^{n3}]$