• 설비공학논문집
• /
• 제11권4호
• /
• pp.549-559
• /
• 1999

An experimental study was peformed to measure the viscosity of microencapsulated PCM slurries as the functions of its concentration and temperature, and also influence to its fluid dynamics. For the viscosity measurement, a rotary type viscometer, which was equipped with temperature control system, was adopted. The slurry was mixed with water and Sodium Lauryl Sulphate as a surfactant by which its suspended particles were dispersed well without the segregation of particles during the experiment. The viscosity was increased as the concentration of MicroPCM particle added. The surfactant increased 5% of the viscosity over the working fluid without particles. Experiments were proceeded by changing parameters such as PCM particles'concentration as well as the temperature of working fluid. As a result, a model to the functions of temperature for the working fluid and its particle concentration is proposed. The proposed model, for which its standard deviation shows 0.8068, is agreed well with the reference's data. The pressure drop was measured by U-tube manometer, and then the friction factor was obtained. It was noted that the pressure drop was not influenced by the state of PCM phase, that is solid or liquid in its core materials at their same concentration. On the other hand, it was described that the pressure drop of the slurry was much increased over the working fluid without particles. A friction factor was placed on a straight line in all working fluids of the laminar flow regardless of existing particles as we expected.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
• /
• pp.543-544
• /
• 2009

고강도콘크리트의 내화성능 증진에 효과적인 것으로 알려진 섬유(NY, PP)는 섬유의 길이조합과 혼입율에 따라 유동성에 차이가 있다. 본 논문에서는 섬유의 길이조합과 혼입율이 고강도콘크리트의 유동성과 레올로지 특성에 미치는 영향을 분석하기 위하여 몰탈시험체를 대상으로 미니 슬럼프 플로우(Mini slump-flow), 간이 V-lot 및 회전점도계에 의한 점도측정을 수행하였다. 실험결과, 섬유의 길이 조합에 따른 유동특성은 큰 차이가 없으나 섬유혼입률이 증가할수록 점도는 큰 것으로 나타났다.

• Fibers and Polymers
• /
• 제5권2호
• /
• pp.122-127
• /
• 2004

In this study, we evaluated the effect of the molecular weight of the polymer on electrospun poly(ethylene terephthalate) (PET) nonwovens, and their mechanical properties as a function of the linear velocity of drum surface. Polymer solutions and electrospun PET nonwovens were characterized by means of viscometer, tensiometer, scanning electron microscope(SEM), wide angle X-ray diffraction measurement (WAXD) and universal testing machine (UTM). By keeping the uniform solution viscosity, regardless of molecular weight differences, electrospun PET nonwovens with similar average diameter could be obtained. In addition, the mechanical properties of the electrospun PET nonwovens were strongly dependent on the linear velocity of drum surface. From the results of the WAXD scan, it was found that the polymer took on a particular molecular orientation when the linear velocity of drum surface was increased. The peaks became more definite and apparent, evolving from an amorphous pattern at 0 m/min to peaks and signifying the presence of crystallinity at 45 m/min.

• 한국세라믹학회지
• /
• 제44권8호
• /
• pp.430-436
• /
• 2007

Rheological properties of cement paste containing ultrafine blastfurnace slag (UBS, $9600cm^2/g$) were investigated by mini-slump test, pH meter, conduction calorimeter and coaxial cylinder viscometer. In order to improve rheological properties of the cement paste, granulated blastfurnace slag (GBS, $3500cm^2/g$) and polycarboxylate type superplasticizer (PC) were also used in this experiment. The fluidity of cement paste containing UBS was decreased. The yield stress and plastic viscosity of cement paste was increased with increasing UBS. But the rheological properties were improved when GBS and PC were added to UBS blended cement paste. In the relationship between the yield stress and the plastic viscosity or the mini-slump value, the yield stress of the cement paste was proportional to the plastic viscosity of it. However the cement paste mini-slump value was in inverse proportional to the yield stress.

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

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제27권1호
• /
• pp.9-15
• /
• 2005

The objective of this study is screening the shear stress related proteins in chondrocytes using twodimensional electrophresis and MALDI-TOF. C-28/I2 cell line were grown. The fluid-induced shear stress(FISS) was applied using a cone viscometer at a rotational velocity of 80rpm for periods of 12 hours. Control cultures were tested under identical conditions without mechanical load application. Collected samples were used for the two-dimensional electrophoresis and MALDI-TOF. The identified proteins were calcyclin, RPE-spondin, interleukin-2, extracellular signal regulated kinase (ERK), lamin B2, porA protein, and RET-ELE1 protein. All of them showed a decreased expression. In conclusion, seven proteins were identified as a shear stress related proteins in chondrocytes. As the destruction of articular cartilage is one of main pathogenesis of TMJ internal derangement, this study will give useful information for the understanding of the molecular aspect of TMJ disease.

• 생명과학회지
• /
• 제8권5호
• /
• pp.526-531
• /
• 1998

In this study, the composition and characteristics of poly-$\beta$-hydroxybutyrate (PHB) biosynthesized by Actinobacillus sp. EL-9 are investigated. PHB produced by Actinobacillus sp. EL-9 was identified as the homopolymer of 3-hydroxy-butyric acid (PHB) by infrared spectroscopy and nuclear magnetic resonance spectroscopy analysis. The melting tem-perature (T$_{m}$), and crystallization temperature(T$_{c}$) of PHB was 169.7$^{\circ}C$ and 69.13$^{\circ}C$, respectively. The viscosity on he basis of Brookfield viscometer was 6.01 ㎗/g. The viscosity-average molecular weight estimated by Mark-Ho-wink-Sakurada equation was 1.08$\times$10$^{6}$ ($\pm$3,000).00).

• 약학회지
• /
• 제35권4호
• /
• pp.319-325
• /
• 1991

Aluminum phosphate gel was synthesized by reacting aluminum sulfate as a soluble aluminum salt to tribasic sodium phosphate in this study. The optimal synthesis conditions based on the yield of product were investigated by applying Box-Wilson experimental design. It was found that optimal synthesis conditions were as follows: Reaction temperature; $61~71^{\circ}C$, concentration of two reactants; 12.27~13.83%, concentration ratio of two reactants; [AI$_{2}$(SO$_{4}$)$_{3}$]/[Na$_{3}$PO$_{4}$]= 0.5, reaction time; 10.9~12.1 minutes, drying temperature of product; $60~72^{\circ}C$. Aluminum phosphate gel prepared by the optimal synthesis conditions was suspended with four types of natural and synthetic gums at the concentration of 0.375~1.5wv%. Their Theological properties of aluminum phosphate gels were examined with Haake-Rotovisco RV 20 rotational viscometer. It showed that the higher concentration of suspending agents and lower temperature, the higher viscosity. Aluminum phosphate gel suspended by pectin and agar showed plastic flow with rheopexy, and their gels suspended by sodium alginate and sod. CMC showed plastic flow with thixotropy.

• 대한화장품학회지
• /
• 제37권1호
• /
• pp.37-42
• /
• 2011

본 연구에서는 수용액상에서 스클레로글루칸의 레올로지 성질을 0.1 ~ 2 wt.%의 농도에서 레오미터와 점도계를 이용하여 측정하였다. 스클레로글루칸 겔은 다양한 염과 pH에서 강한 점증력을 보이며, 식물성 스쿠알란을 함유한 고분자 분산계에서 스클레로글루칸은 강한 오일 분산성질을 보인다. 또한 스클레로글루칸과 로커스트빈검 혼합물의 시너지효과를 관찰하였으며, 스클레로글루칸과 로커스트빈검의 혼합비율이 5 : 5일 때 가장 높은 점증 효과를 나타냈다.이들 연구결과는 다양한 화장품 제형을 위한 점증제로써 스클레로글루칸의 가능성을 보여줄 것이다

• 한국식품저장유통학회지
• /
• 제8권1호
• /
• pp.102-108
• /
• 2001

자색고구마 색소 농축액의 유동특성을 원뿔형 회전점도계를 사용하여 가용성 고형분의 농도 25-65% 및 온도 20-6$0^{\circ}C$의 범위에서 조사하였다. 자색고구마 색소 농축액은 뉴톤성유체의 특성을 나타냈다. 자색고구마 색소 농축액의 점도의 온도에 대한 영향은 Arrhenius 식을 따랐으며, 활성화에너지는 14.23-43.00 kJ/mol로서 농도가 증가함에 따라 직선적으로 증가하였다. 자색고구마 색소 농축액의 점도와 온도 및 농도에 대한 관계를 조사한 바, 일정한 온도에서 용액의 점도는 농도가 증가함에 따라 지수함수적으로 증가하였으며, 그 증가 정도는 온도가 낮을수록 증가하였다.