• 한국식품과학회지
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• 제19권2호
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• pp.81-88
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• 1987

동결속도를 달리하여 제조한 2종의 동결건조 분말고추장 재수화 현탁액의 리올리지 특성을 원료고추장을 대조구로 온도 $25{\sim}60^{\circ}C$, 고형물 함량 $47{\sim}56^{\circ}C$, 전단속도 $0.1965{\sim}1.9650\;sec^{-1}$의 범위에서 Brookfield 단 원통 회전점도계로 측정하였다. 급속동결 분말고추장 및 완만동결 분말고추장의 재수화 현탁액과 원료고추장은 모두 항복치를 지닌 의가소성을 나타내고. 전단초기 20분까지 Tiu의 모델에 따라 2차 반응속도식으로 붕괴되는 thixotropic거동을 보여주였으며. 분말고추장 현탁액의 구조붕괴 속도가 원료고추장 보다 빨랐다. 평형구조변수는 전단속도에 크게 영향받지 않았으며 그 값은 세가지 시료 모두 비슷하였다. 급속동결분말고추장 및 완만동결 분말고추장의 재수화 현탁액과 원료고추장의 곁보기점도의 온도 의존성은 Arrhenius식과 일치하였으며. 활성화 에너지의 값은 가각 2.21, 2.18, $2.32\;Kcal/g{\cdot}mole $이었다. 세가지 시료의 점조도지수는 온도의 증가에 따라 감소하었으며, 고형물 함량의 증가에 따라 증가하였으나, 유동거동지수는 온두 및 고형물 함량에 거의 영향을 받지 않았다. 급속동결 분말고추장과 완만동결 분말고추장의 러올로지 성질은 큰 차이가 없었다.

• 한국식품과학회지
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• 제27권4호
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• pp.576-581
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• 1995

피부조직에서 추출한 콜라겐의 유동특성을 검토하여 콜라겐을 효율적으로 활용할 수 있는 기초자료를 얻고자 하였다. 콜라겐의 점도는 동물의 나이와 성(sex), 콜라겐 종류에 따라 차이를 보였다. 즉, 주령에 따라서는 콜라겐의 종류에 관계없이 $6{\sim}12$주령의 것이 비교적 높게 나타났으며, 동일 주령에서는 수컷의 점도보다 암컷의 점도가, 그리고 불용성 콜라겐의 점도보다 산가용성 콜라겐의 점도가 높게 나타났다. 콜라겐 용액은 Bingham plastic 및 thixotropic 유체의 특성을 나타냈으며, 온도, pH, 에탄올 농도 및 콜라겐 농도에 따라 점도 변화가 뚜렷하게 나타났다. 즉, 콜라겐 농도를 6%까지 높일 경우 콜라겐 용액의 점조도는 직선적으로 증가하는 경향(산가용성 콜라겐 r=0.972, 불용성 콜라겐 r=0.957)을 나타냈는데, 산가용성 콜라겐의 증가속도가 불용성 콜라겐의 경우보다 높게 나타났다. 온도 증가에 따라 콜라겐 용액의 점조도는 감소하였으며 특히, 산가용성 콜라겐에서는 $30{\sim}40^{\circ}C$ 온도구간에서 점조도가 급격히 감소하였다. pH에 따라 산가용성 콜라겐의 점조도는 pH 6에서 최대치를 보였고, pH 10 부근에서 다시 증가하는 biphasic 현상을 나타냈으나, 불용성 콜라겐의 경우는 pH에 큰 영향을 받지 않았다. 에탄올 농도에 따른 산가용성 콜라겐과 불용성 콜라겐의 점조도는 에탄올 농도 $40{\sim}60%$ 수준에서 높게 나타났다.

• 농업과학연구
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• 제22권1호
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• pp.103-109
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• 1995

단백질과 전분을 각 성분비로 조합하고, 고형물 함량 8, 9, 10, 11%로 조정한 시료를 $80^{\circ}C$에서 30분간 가열한 후 $25^{\circ}C$로 냉각하여, 온도 $30{\sim}60^{\circ}C$, 0.6 ~ 6 rpm의 범위에서 Brookfield 단원통회전점도계로 리올로지 특성을 측정하였는 바, 아래와 같은 결과를 얻었다. 1. 모델 식품 $P_1S_3$, $P_1S_2$, $P_1S_1$, $P_2S_1$, $P_3S_1$, $P_4S_0$는 모두 의가소성을 나타내고, 항복치를 가지며, 시간 의존성 구조 붕괴를 나타내는 thixotropic 식품이었다. 그러나 $P_0S_4$, 즉 전분의 경우는 8~11% 범위에서 gel의 강도가 크기 때문에 유동성을 보이지 않았다. 2. 각 수분함량에서 모형식품의 단백질 함량에 따른 유통 특성값은 일정한 상관관계를 나타내지 않았다. 3. 전단속도에 대한 전단웅력의 변화는 전분질식품이 ($P_1S_3$, $P_1S_2$) 단백질식품($P_2S_1$, $P_3S_1$)보다 컸으며, 전단초기의 구조붕괴는 Tiu의 모델에 따라 2차 반응식으로 붕괴되었고, 전단속도가 증가 할 수록 구조 붕괴 속도도 빨랐다. 4. $P_1S_2$, $P_2S_1$의 온도의존성은 Arrhenius식에 잘 따랐으며 이때 활성화에너지는 각각 2.35, $1.34Kcal/g{\cdot}mole$이었다.

• 소성∙가공
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• 제15권5호
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• pp.395-401
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• 2006

It is reported that semi-solid forming process takes many advantages over the conventional forming process, such as a long die life, good mechanical properties and energy saves. It is important to predict the deformation behavior for optimization of the forging process with semi-solid materials and to control liquid segregation for mechanical properties of materials. But rheology material has thixotropic, pseudo-plastic and shear-thinning characteristics. So, it is difficult for a numerical simulation of the rheology process to be performed because complicated processes such as the filling to include the state of the free surface and solidification in the phase transformation must be considered. General plastic or fluid dynamic analysis is not suitable for the analysis of the rheology material behavior. Recently, molecular dynamics is used for the behavior analysis of the rheology material and turned out to be suitable among several methods. In this study, molecular dynamics simulation was performed for the control of liquid segregation, forming velocity, and viscosity in compression experiment as a part of study on the analysis of rheology forming process.

• 한국농공학회지
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• 제31권2호
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• pp.43-53
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• 1989

In this research programs, a series test was conducted to show the effects of freeze/thaw process on the various soil properties. The tests were carried out taken from the west sea shore of Korean peninsular and the west sea shore of Scotland, and their results are as follows; 1. There was a positive total heave in a freezing run, although water may he expelled for the sample initially. The water flow must he reverse' from expulsion to intake. 2. The confining pressure had an overriding influence on the heave and frost penetration, a sudden change of the axial strain at failure with strain rate was observed occuring at a strain rate between 10-5 and 10-6, and the initial friction angle of frozen clay was appeared zero. 3. There was shown a significant decrease in liquid limit of soil which was subjected to freeze/thaw process for the initial value of about 20% because of soil particles aggregation. 4. The cyclic freeze/thaw caused a sinificant reduction in shear strength and its thixotropic regain. The frozen/thawed soil exibited negative strength regain, particularly at high freeze/thaw cycles. 5. The freezing temperature greatly influenced on the failure strength of soils and this. Trend was more pronounced the lower the freezing temperature and shown the ductile failure with indistinct peaks.

• Applied Biological Chemistry
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• 제29권4호
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• pp.339-345
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• 1986

발아 옥수수로 부터 분리한 전분의 리올로지 특성을 생옥수수 전분과 비교검토하면서 조사하였다. 발아전분의 유동형태는 생전분과 마찬가지로 빙햄 의가소성 거동을 보였으나 발아전분 호화액의 점조도지수 및 항복응력은 생전분보다 낮은 값을 보였고, 유동거동지수는 비슷한 값을 보였다. 정조도지수의 온도 의존성은 발아전분이 생전분보다 낮았으나 농도 의존성은 변화가 없었다. 발아전분의 시간 의존특성은 생전분과 마찬가지로 틱소트로픽 거동을 보였으나 발아로 인하여 생전분에 비하여 전단하의 구조붕괴가 컸으며 탄성적 성질은 약한 특성을 나타내었다.

• 한국식품영양과학회지
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• 제28권6호
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• pp.1293-1297
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• 1999

Effect of rice protein and lipid on rheological properties of gelatinized rice flour solutions(4%) with three rice varieties(Dongjin, Jinmi, Tamjin) known for varying taste of cooked rice was investigated with Haake viscometer. The rheological behaviors of all rice flour solutions were illustrated by Herschel Bulkley equation and exhibited pseudoplastic behavior with yield stress. When rice flour solutions treated with protease and dithiothreitol, there was decreased in flow behavior index value. Flow behavior index was decreased by dealbumin and deglutelin rice flour solutions among deprotein groups. The Jinmi rice flour solutions exhibited slightly lower consistency index than Dongjin and Tamjin. Defatted rice flour solutions exhibited lower consistency index than rice flour solutions, while dealbumin, deglutelin rice flour solutions exhibited high consistency index. Protease treated rice flour solutions exhibited increase in Dongjin and Tamjin. The yield stress was increased in sequence eating quality. Yield stress of defatted rice flour solutions was decreased, while deglutelin and rice starch flour solutions was increased. The time dependent charac teristics of all rice flour solutions appeared forming hysteresis loop and thixotropic behavior showed. The time dependent characteristics was appeared in sequence eating quality. Rice starch and deglutelin flour solutions appeared greatly time dependent characteristics, but defatted rice flour solutions appeared very little.

• 마이크로전자및패키징학회지
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• 제10권3호
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• pp.9-17
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• 2003

In this paper, thermo-mechanical and rheological properties of NCPs (Non-Conductive Pastes) depending on silica filler contents and diluent contents were investigated. And then, thermal cycling (T/C) reliability of flip chip assembly using selected NCPs was verified. As the silica filler content increased, thermo-mechanical properties of NCPs were changed. The higher the silica filler content was added, glass transition temperature ($T_g$) and storage modulus at room temperature became higher. While, coefficient of thermal expansion (CTE) decreased. On the other hand, rheological properties of NCPs were significantly affected by diluent content. As the diluent content increased, viscosity of NCP decreased and thixotropic index increased. However, the addition of diluent deteriorated thermo-mechanical properties such as modulus, CTE, and $T_g$. Based on these results, three candidates of NCPs with various silica filler and diluent contents were selected as adhesives for reliability test of flip chip assemblies. T/C reliability test was performed by measuring changes of NCP bump connection resistance. Results showed that flip chip assembly using NCP with lower CTE and higher modulus exhibited better T/C reliability behavior because of reduced shear strain in NCP adhesive layer.

• 펄프종이기술
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• 제47권6호
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• pp.5-21
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• 2015

The common production methods of nanocellulosic (cellulosic nanofibrils, CNF) materials from wood are being reviewed, together with large scale applications and particularly papermaking applications. The high energy demand for producing CNF has been one particular problem, which has been addressed over the years and can now be considered solved. Another problem was the clogging of homogenizers/microfluidizers, and the different routes to decrease the energy demand. The clogging tendency, related to the flocculation tendency of fibres is discussed in some detail. The most common methods to decrease the energy demand are TEMPO-oxidation, carboxymethylation and mechanical/enzymatic pre-treatments in the order of increased energy demand for delamination. The rheology characteristics of CNF materials, i.e. the high shear viscosity, shear thinning and the thixotropic properties are being illuminated. CNF materials are strength adjuvants that enhance the relative bonded area in paper sheets and, hence increase the sheet density and give an increased strength of the paper, particularly for chemical pulps. At the same time papers obtain a lower light scattering, higher hygroexpansion and decreased air permeability, similar to the effects of beating pulps. The negative effects on drainage by CNF materials must be alleviated through the appropriate use of microparticulate drainage aids. The use of CNF in films and coatings is interesting because CNF films and coatings can provide paper/board with good oxygen barrier properties, particularly at low relative humidities. Some other high volume applications such as concrete, oil recovery applications, automotive body applications and plastic packaging are also briefly discussed.

• 소성∙가공
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• 제18권1호
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• pp.26-38
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• 2009

It was reported that the semi-solid forming process has many advantages over the conventional forming process, such as a long die life, good mechanical properties and energy savings. It is very important, however, to control liquid segregation to gain mechanical property improvement of materials. During forming process, rheology material has complex characteristics, thixotropic behavior. Also, difference of velocity between solid and liquid in the semi-solid state material makes a liquid segregation and specific stress variation. Therefore, it is difficult for a numerical simulation of the rheology process to be performed. General plastic or fluid dynamic analysis is not suitable for the behavior of rheology material. The behavior and stress of solid particle in the rheology material during forging process is affected by viscosity, temperature and solid fraction. In this study, compression experiments of aluminum alloy were performed under each other tool shape which is rectangle shape(square array), rectangle shape(hexagonal array), and free shape tool. In addition, the dynamics behavior compare with Okano equation to power law model which is viscosity equation.