• 한국결정성장학회지
• /
• 제16권3호
• /
• pp.95-100
• /
• 2006

수열법을 이용하여 비팽윤성 운모의 합성을 행하였다. 인위적인 이온의 확산을 유도시키기 위하여 수열참치에 회전장치를 부착하고 0.7mm 크기의 지르콘 비드를 첨가시킴으로써 저온영역에서 비팽윤성 운모를 합성할 수 있었다. 비팽윤성 운모를 제조하기 위한 수열조건은 다음과 같다. 즉, 출발원료: $1K_2O,\;1Al(OH)_3,\;4Mg(OH)_2$ 및 $6SiO_2$, 수열용매: 8M-KOH, 반응온도: $260^{\circ}C$, 반응시간 72시간이었다. 이와 같은 조건에서 얻어진 운모는 $2.89{\mu}m$ 크기의 판상형 이었으며 97% 이상의 백색도를 나타내었다. 그리고 $3700cm^{-1}$ 부근에서 $Mg_3OH$ 진동에 의한 흡수피크를 나타내었기 때문에 $KMg_3AlSi_3O_{10}(OH)_2$의 화학조성을 나타내는 비팽윤성의 금운모임을 FT-IR분석을 통하여 알 수 있었다. 이 결과는 O (41.34%), Mg (3.88%) Al (11.45%), Si (17.62%) 및 K (25.71%)의 원소가 검출된 EDS 분석결과와 잘 일치하였다.

• 한국결정성장학회지
• /
• 제18권3호
• /
• pp.131-135
• /
• 2008

본 연구에서는 합성운모에 대한 코팅기술을 확립한 뒤, 비수성을 나타내는 합성운모를 제조하였다. 합성운모의 표면코팅은 고속교반기를 사용하여 행하였으며, 스테아린산으로 코팅된 합성운모의 특성은 침적실험, XRD 및 SEM을 이용하여 분석하였다. 본 연구 결과, 교반기의 내부온도는 $70^{\circ}C$를 유지하고, 10분 동안 1600 rpm/min을 행함으로써 운모 표면에 스테아린산의 코팅이 가능하였다. 또한 SEM 관찰결과로부터, 스테아린산과 운모의 혼합비율, 교반기 내부온도, 회전속도에 의해 특성이 변화하는 반면 코팅처리시간과는 무관함을 알 수 있었다.

• Geomechanics and Engineering
• /
• 제29권1호
• /
• pp.91-97
• /
• 2022

The cohesive non-swelling soil (CNS) cushion technology has been widely applied in the subgrade and slope improvement at expansive soil regions. However, the mechanism of the inhibition effect of the CNS layer on expansive soil (ES) has not been fully understood. We performed four outdoor model tests to further understand the inhibition effect, including different kinds of upper layer and thickness, under the unidirectional seepage condition. The swelling deformation, soil pressure, and electrical resistivity were constantly monitored during the saturation process. It is found that when a CNS layer covered the ES layer, the swelling deformation and electrical resistivity of the ES layer decreased significantly, especially the upper part. The inhibition effect of the CNS layer increases with the increase of CNS thickness. The distribution of vertical and lateral soil pressure also changed with the covering of a CNS layer. The electrical resistivity can be an effective index to describe the swelling deformation of ES layer and analyze the inhibition effect of the CNS layer. Overall, the CNS deadweight and the ion migration are the major factors that inhibit the swelling deformation of expansive soil.

• Geomechanics and Engineering
• /
• 제22권3호
• /
• pp.227-236
• /
• 2020

Expansive soils are renowned for their swelling-shrinkage property and these volumetric changes resultantly cause huge damage to civil infrastructures. Likewise, subgrades consisting of expansive soils instigate serviceability failures in pavements across various regions of Pakistan and worldwide. This study presents the use of polypropylene fibers to improve the engineering properties of a local swelling soil. The moisture-density relationship, unconfined compressive strength (UCS) and elastic modulus (E₅₀), California bearing ratio (CBR) and one-dimensional consolidation behavior of the soil treated with 0, 0.2, 0.4, 0.6 and 0.8% fibers have been investigated in this study. It is found that the maximum dry density of reinforced soil slightly decreased by 2.8% due to replacement of heavier soil particles by light-weight fibers and the optimum moisture content remained almost unaffected due to non-absorbent nature of the fibers. A significant improvement has been observed in UCS (an increase of 279%), E₅₀ (an increase of 113.6%) and CBR value (an increase of 94.4% under unsoaked and an increase of 55.6% under soaked conditions) of the soil reinforced with 0.4% fibers, thereby providing a better quality subgrade for the construction of pavements on such soils. Free swell and swell pressure of the soil also significantly reduced (94.4% and 87.9%, respectively) with the addition of 0.8% fibers and eventually converting the medium swelling soil to a low swelling class. Similarly, the compression and rebound indices also reduced by 69.9% and 88%, respectively with fiber inclusion of 0.8%. From the experimental evaluations, it emerges that polypropylene fiber has great potential as a low cost and sustainable stabilizing material for widespread swelling soils.

• Elastomers and Composites
• /
• 제41권4호
• /
• pp.223-230
• /
• 2006

고무복합체는 높은 점탄성 성질을 보이는데 압출성형 시 이 점탄성 성질 때문에 압출물이 팽창하게 된다. 그리고 팽윤양은 공정 조건에 따라서 변한다. 점탄성 성질에서 탄성 부분은 압출물의 팽창에 있어서 중요한 역할을 한다. 본 논문은 모세관 다이에서 여러 가지 고무복합체에 따른 다이팽윤을 알아보기 위해 상용 CFD 프로그램인 Polyflow를 사용하여 해석을 수행하였다. 컴퓨터 모사에서는 비선형 미분 점탄성 모델인 Phan-Thien-Tanner(PTT) 모델을 사용하였고 온도를 고러하여 해석하였다. 해석을 통해서 레저버와 모세관 다이에서 압출물의 압력, 속도, 그리고 온도 분포 등을 예측하였다. 여러 가지 고무 복합체의 다이 팽윤양을 알아보기 위해서 유량과 모세관 다이의 지름을 변경하면서 연구하였다. 본 연구를 통해서 PPT 모델은 고무 복합체에 대한 점탄성 거동을 잘 표현하고 있음을 확인할 수 있었다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2007년도 춘계학술대회 논문집
• /
• pp.209-212
• /
• 2007

Rubber compounds have high viscoelastic property. One of the viscoelastic behaviors during profile extrusion is the swelling of extrudate. In this study, die swell of rubber compounds at the capillary die have been investigated through an experiment and computer simulation. They have been performed using fluidity tester in experiment and commercial CFD code, Polyflow in computer simulation. Die swell of rubber compounds for relaxation time at several modes under same conditions with the experiment were predicted using non-linear differential viscoelastic model, Phan-Thien-Tanner (PTT) model. The simulation was analyzed compared with the experiment. Viscoelastic behaviors for pressure, velocity and shear rate distribution were analyzed at the capillary die. It is concluded that the PTT model successfully represented the amount of the optimal die swell of rubber compounds for relaxation time at different modes.

• 소성∙가공
• /
• 제16권4호
• /
• pp.260-265
• /
• 2007

Rubber compounds have high viscoelastic property. One of the viscoelastic behaviors during profile extrusion is the swelling of extrudate. In this study, die swells of rubber compounds at the capillary die have been investigated through experiment and computer simulation. Experiments and simulations have been performed using fluidity tester and commercial CFD code, Polyflow respectively. Die swells of rubber compounds in a capillary die were predicted using non-linear differential viscoelastic model, Phan-Thien-Tanner(PTT) model for various relaxation times and relaxation modes. The results of simulation were compared with the experiments. Pressure and velocity distribution, and circulation flows at the comer of capillary die have been investigated through computer simulation. It is concluded that the PTT model successfully represented the amount of the die swell of rubber compounds for various relaxation times at different modes.

• 한국식품과학회지
• /
• 제25권4호
• /
• pp.355-359
• /
• 1993

명반이 멥쌀과 찹쌀전분의 이화학적 성질에 미치는 영향을 조사하였다. 멥쌀 및 찹쌀전분의 팽윤력은 두 전분 모두 대조구보다 명반 $0.05{\sim}1.0%(w/w)$ 첨가구에서 증가하였으며, 이 농도 이상에서는 완만하게 감소하는 경향을 나타내었다. 용해도는 멥쌀전분의 경우 명반 $0.05{\sim}1.0%(w/w)$ 첨가구에서는 온도증가에 따라 점차 증가한 반면, 찹쌀전분의 경우는 온도에 관계없이 감소하였으며, 이농도 이상에서는 두 전분 모두 거의 변화를 보이지 않았다. Blue value값은 명반농도가 증가할수록 멥쌀전분의 경우는 증가한 반면, 찹쌀전분에서는 감소하였다. Amylography에 의한 호화양상에 있어서는 명반 1.0%(w/w) 첨가가 멥쌀 및 찹쌀전분의 호화개시 온도와 breakdown값을 증가시켰고 setback값은 감소시켰다.

• 대한한의학회지
• /
• 제29권2호
• /
• pp.32-40
• /
• 2008

Background: Angelica dahurica has been used in various clinical cases. Its taste is hot and its property is warm, dry and nonpoisonous. Its efficacy is to remove wind-damp, cure swelling and edema, exhaust pus, stop itching, rhinitis and leukorrhea. Object: To test through experiment Angelica dahurica's analgesic and anti-inflammatory efficacy. Method: Inject acetic acid as a pain-inducing substance to the mice and measure visceral pain bywrithing reflex. Inject carrageenan that is an edema-inducing substance to the rat's paw and measure volume of edema. Take thermal pain to mice with plantar test and measure paw withdrawal latency. Normal group is non Angelica dahurica-treated group and treated group is Angelica dahurica-treated group. Results: In acetic acid-induced visceral model, treatment with Angelica dahurica suppressed writhing reflex significantlyand dose-dependently. In carrageenan-induced paw edema model, treatment with Angelica dahurica suppressed carrageenan-induced paw edema. In plantar test model, no significant effect on the withdrawal latency of thermal stimulation-induced nociception was observed. Conclusion: Angelica dahurica has analgesic and anti-inflammatory efficacy.

• Archives of Pharmacal Research
• /
• 제14권1호
• /
• pp.12-18
• /
• 1991

The effect of urea and urea derivatives on the percutaneous absorption of salicylic acid and sodium salicylate through the skin of rabbit from petrolatum ointment was investigated. It was found that addition of urea or urea derivatives to the ointment base significantly increased the percutaneous absorption of the drugs in proportion to the concentratoin of the additive. The percutaneous absorptoin-enhancing activities of these compounds were that urea derivatives with the more and longer alkyl substituents showed the stronger activities. These activities of urea and urea derivatives were ascribed to the binding of these compounds with the lipids and proteins of the stratum corneum of the skin and the swelling of the tissues, which leads to the reduction of the barrier property of the layer. The preliminary skin irritation test showed that urea and urea derivatives were quite non-irritating to the skin. These results suggest that urea derivatives have a strong possibility to be developed as a percutaneous absorption enhancer.