• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.623-627
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• 2014

Emulsions are a class of disperse systems consisting of two immiscible liquids. Emulsions are affected by the size of oil drop, the type of continuous and disperse phase, the ratio of continuous and disperse phase, the type of emulsifies and emulsification devices. This study is to observe the viscosity of emulsions with oil polarities and interpret the results by organic conceptual diagram. The emulsions were made with hydrocarbon, ester and silicone oils and then the viscosity of emulsions was measured. As the oil polarity was increased, the viscosity of emulsion was decreased by reducing the amount of emulsifies and emulsion stabilizers arranged at interface. Organic conceptual diagram was used to compare the polarities among oils numerically. The interpretation of organic conceptual diagram and the results of experimental measurement were corresponded except emulsion made with silicone oil.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.91-97
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• 2022

The wettability and rheological properties of solder paste with the size of the solder powder were evaluated. To formulate the solder paste, three types of solder powder were used: T4 (20~28 ㎛), T5 (15~25 ㎛), and T6 (5~15 ㎛). The viscosities of the T4, T5, and T6 solder pastes at 10 RPM were 155, 263, and 418 Pa·s, respectively. After 7 days, the viscosity of the T4 solder paste slightly increased by 2.6% and that of T5 was increased by 20.6%. The viscosity of the T6 solder paste after 7 days could not be measured due to high viscosity. The viscosity variation with solder particle size also affected on the printability of the solder. In the case of the T4 solder paste, printability, slump, bridging, and soldering properties were excellent. On the other hand, T5 showed slight dewetting and solder ball defects. Especially, T6, which the smallest powder size, showed poor printability and dewetting at the edge of solder.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2000.06a
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• pp.115-115
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• 2000

• Korean Journal of Food Science and Technology
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• v.47 no.3
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• pp.293-298
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• 2015

This study aimed at characterizing the rheological properties and molecular weight of tara gum fractionated with ammonium sulfate. Tara gum was separated into six fractions (F1-F6) at different concentrations of ammonium sulfate, ranging from 12.21 to 28.67% (w/w). The yield of the tara gum fractions ranged between 4.98 and 17.47%, and their intrinsic viscosity ranged from 9.38 to 12.44 dL/g. The highest values of Huggins coefficient (k') and viscosity-molecular mass were observed in fraction F3. The shear viscosity of the tara gum fractions was measured by a cone-plate viscometer, clearly showing shear thinning behavior. Size-exclusion chromatography results showed that the molecular weight ranged between 635.42 and 776.71 kg/mol, and the F3 fraction exhibited higher values of molecular weight.

• Korean Journal of Human Ecology
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• v.3 no.1
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• pp.88-99
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• 2000

This study was perfomed to search for how properties of the starch viscosity appear in different qualities, when acetic acid is added. For this study, corn starch which belongs to A-type. Potato starch to B-type. and sweet potato starch to C-type were chosen as an experimental material. which was added to acetic acid controlled as pH 4.0, 4.5, and 5.0 at the time of before and after heating. After that, the viscosity properties of each starch was analyzed using Amylogram and Brookfield viscometer. As a result. the viscosity was shown high in an order of potato. sweet potato, and corn starch. According to addition of acetic acid. tile viscosity appeared to be low. The viscosity differences of before and after heating when the acid is added were shown as follows : Amylogram shows that the lower the pH is. the lower the viscosity is when the acid is added before-heating. In case the acid is added before-heating, gelatinization temperature, consistency and setback was increased. but breakdown decreased. In case the acid is added after-heating, the viscosity goes down at soon as it is added meanwhile consistency and setback was decreased. but breakdown increased. Such properties of the viscosity show a conspicuous variation in an order of potato. sweet Potato. and corn starch. Brookrield viscometer shows that the lower the apparent viscosity is. the lower pH is at the time of before-heating when the acid is added. In case of after-heating, when the acid is added. the apparent viscosity shows a higher inclination than that of before-heating in corn starch and sweet potato starch.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.28-33
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• 1999

Introducing boric acid to the polyviny alcohol(PVA) solutions has a profound effect on the rheological properties through crosslinking between hydroxyl groups of PVA. This study investigates the effect of boric acid on the rheological properties of polyvinyl alcohol(PVA)/dimethyl sulfoxide(DMSO)/water systems in the absence of cations. The viscosity of PVA/ DMSO/water systems containing 1 wt.% boric acid was decreased with increasing water content. PVA/DMSO systems containing 1 wt.% boric acid exhibited rheological properties similar to elastic gels by forming crosslinked structures. On the other hand, PVA/water systems containing 1 wt.% boric acid exhibited rheological properties typical of viscous materials. In-corporation of boric acid into PVA/DMSO system caused a notable change in the viscosity of the system, whereas boric acid had little effect on the viscosity of PVA/water system. PVA/DMSO/boric acid system gave the greatest storage modulus among the PVA solution systems. Increasing water level in the mixed solvent of DMSO and water diminished the storage modulus of the systems.

• The Korean Journal of Rheology
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• v.2 no.1
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• pp.67-78
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• 1990

세라믹 분말의 사출성형성을 평가하기 위하여 다양한 혼합체 시스템에 대한 혼합도 와 유변학적 성질을 질화규소 미세분말의 부피비를 변화시키면서 조사하였다. 열가소성 결 합체 시스템은 폴리에틸린 폴리에틸렌 왁스 그리고 미소량의 첨가제를 혼합하여 사용하였 다. 혼합성능을 평가하기 위하여 비분산혼합에서는 총접촉면적비를 그리고 분산혼합에서는 총파괴표면적비를 혼합척도로서 사용하여 정성적으로 모형화하였다. 사용된 혼합기내의 유 동장을 해석하기 위하여 뉴우톤유체를 가정하여 유동해석을 수행하였다. 혼합물의 혼합도는 각각 5분 30분 동안 혼합된 시편을 주사전자현미경 사진에 의해 관찰하여 평가하였다. 또한 혼합물의 사출성형성 그리고 혼합질 점도 토우크 곡선 사이의 관계를 규명하기 위하여 전단 변형를 속도를 따른 점도를 모세관 점도계를 사용하여 측정하였으며 질화규소의 부피비가 60%일 때까지는 만족할 만한 성형성과 혼합질을 가짐을 알 수 있었다.

• Geotechnical Engineering
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• v.13 no.5
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• pp.125-132
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• 1997

It is observed that debris mitred with a wide range of soil particles and water moves downwards like viscous fluid soon after a landslide has triggered. An Assumption can be made from the field observation that the debris flow behaves as a kind of non(non-Newtoniron) Newtonian fluid which has non linear viscosity. In this study, a series of viscosity tests are carried out to measure rheological properties of debris by using a viscometer with semples taken from a landslide site. It is proved that debris flows behave as Bingham plastic mod el of non-Newtonian fluid. This model can be used predict the movement of debris flows.

• The Korean Journal of Rheology
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• v.10 no.3
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• pp.152-159
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• 1998

폴리카보네이트와 스티렌-아크릴로니트릴 공중합체의 블렌드를 이축 압출기에서 용 융혼련할 경우의 분산혼련 작용기구를 연구하였다. 분산상 형성에 관계되는 지배적인 과정 은 sheet, lace 및 ligament 생성에 이어 Rayleigh 형태의 불안정성에 기인한 구형의 분산상 (droplet) 형성으로 확인되었다. 분산상과 연속상의 점도비와 분산상의 크기에 대한 상관관 계의 조사에서는 주어진 점도비의 범위에서 점도비 약 70인 경우를 제외하고는 거의 무관한 관계를 나타내었으며 이는 이축 압출기의 강력한 혼련요소인 kneading 부위에서 주어지는 연신 흐름장에 의한 영향을 반영한 것으로 해석되었다. 분산상의 최종크기는 오히려 분산상 들간의 coales-cence 정도에 크게 영향을 받았으며 연속상의 점도가 상대적으로 낮은 경우 에 동일한 분산상에 대한 coalescence 정도가 심화되어 분산상의 크기가 증가되었다.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.16-21
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• 1999

Recently, the rheology on the fluidity of materials has been progressed remarkably. Viscosity measurement for precision-accuracy has needed very important to measure the rheological properties of materials in the field of chemistry-fiber, paint, printing-ink, plastics, rubber, foodstuff-industry, etc. And many methods of measurement have been developed lately. So in this experimental study, small capacity torque transducer with type of strain gage, different method against other existing viscometers, measured viscosity about a liquid that has flowing characteristics of newtonian liquid. Using the assumed computational equation of viscosity, it has same value of viscosity in each different radius of rotating cylinder. In the result, this equipment will be used in the viscosity measurement of a liquid taking flowing characteristics of newtonian liquid.