• 설비공학논문집
• /
• 제12권6호
• /
• pp.599-608
• /
• 2000

One dimensional numerical modeling was carried out for the melting behavior of dry snow and the unsaturated flow when heat was supplied from the bottom surface. Discrepancy between the previous experimental data and the present numerical results is substantially reduced by considering the density change of water permeation layer due to the infiltration of meltwater. In the parametric study for effective thermal conductivity, it was found that the effect of this parameter to the behavior of snow melting is minor. Sensitivity analysis showed that the melting time is most sensitive to changes in supplied heat flux, snow temperature, and bulk density, whereas snow bulk density and residual saturation have a significant effect on the height of water permeation layer in snow.

• 멤브레인
• /
• 제23권6호
• /
• pp.409-417
• /
• 2013

이산화탄소의 효과적인 분리 및 포집을 위해서 등방성 다공성 구조의 폴리프로필렌(pp) 격자의 내부에 제올라이트 입자들이 표면 덮임 없이 균일하게 분포되어 있는 흡착투과중공사막(APM: adsorptive permeation hollow fiber membrane)을 개발하였다. 본 연구에서는 이산화탄소/질소 혼합물을 모사 기체혼합물로 사용하였는데, 공급되는 기체혼합물 모두가 APM을 투과하면서 이산화탄소는 APM 내 분포되어 있는 흡착제에 흡착되고 질소는 투과하여 배출된다. APM이 장착된 모듈을 제조하여 이에 대한 흡착투과실험을 수행하여 흡착투과 성능을 분석하였고 또한 포화 흡착된 APM을 진공압에서 탈착 재생하여 그 결과를 재생효율과 에너지소모 관점에서 고찰하였다.

• 폴리머
• /
• 제36권6호
• /
• pp.705-711
• /
• 2012

본 연구에서는 일반 리포좀의 단점을 보완하기 위하여 인지질(PC)과 계면활성제($Tego^{(R)}$ care 450)로 구성된 탄성 리포좀을 제조하였다. 탄성 리포좀의 유효성분으로 천연 항산화제로 알려진 쿼세틴을 담지하였고, 탄성 리포좀의 입자크기 및 가변형성과 쿼세틴의 포집 효율, 안정성, in vitro 피부투과를 평가하였다. 쿼세틴을 담지한 탄성 리포좀의 평균 입자크기는 208.2~303.4 nm이였고, 포집효율은 64.1~87.5%로 측정되었다. 0.1% 쿼세틴을 담지한 탄성리포좀 중에서 인지질과 계면활성제 비율이 90 : 10인 경우가 가장 높은 포집효율(87.5%)과 가변형성 지수(28.3)를 나타내었다. 이 제형을 대상으로 피부 투과 실험을 진행하였다. 그 결과 대조군으로 사용된 일반 리포좀($114.8{\mu}g/cm^2$)과 1,3-butylene glycol($75.1{\mu}g/cm^2$) 용액보다 탄성 리포좀의 피부 투과능($164.6{\mu}g/cm^2$)이 훨씬 더 크게 나타났다. 이러한 결과들로 미루어 보아 $Tego^{(R)}$ care 450을 이용한 탄성 리포좀이 피부를 통한 유효성분 전달에 유용하게 이용될 수 있음을 확인하였다.

• Corrosion Science and Technology
• /
• 제5권4호
• /
• pp.117-122
• /
• 2006

Hydrogen permeation measurements have been carried out on API X65 grade linepipe steel. In order to study the effect of steel microstructure on hydrogen diffusion behavior in linepipe steel, the accelerated cooling condition was applied and then three different kinds of microstructures were obtained. Hydrogen permeation measurement has been performed in reference to modified ISO17081 (2004) and ZIS Z3113 method. Hydrogen trapping parameters in these steels were evaluated in terms of the effective diffusivity ($D_{eff}$), permeability ($J_{ss}L$) and the amount of diffusible hydrogen. In this study, microstructures which affect both hydrogen trapping and diffusion were degenerated pearlite (DP), acicular ferrite (AF), bainite and martensite/austenite constituents (MA). The low $D_{eff}$ and $J_{ss}L$ mean that more hydrogen can be trapped reversibly or irreversibly and the corresponding steel microstructure is dominant hydrogen trapping site. The large amount of diffusible hydrogen means that corresponding steel microstructure is predominantly reversible. The results of this study suggest that the hydrogen trapping efficiency increases in the order of DP, bainite and AF, while AF is the most efficient reversible trap.

• 공업화학
• /
• 제24권2호
• /
• pp.190-195
• /
• 2013

이전 연구에서 저자들은 사자발쑥 추출물의 항산화, 항노화 및 항균활성에 대한 결과를 보고한 바 있다. 본 연구에서는 사자발쑥 추출물의 피부 전달시스템으로 에토좀을 제조하고 입자크기, 포집효율 및 피부 투과를 평가하였다. 0.06% 사자발쑥 추출물의 에틸아세테이트 분획을 담지한 에토좀은 3주 동안 보다 더 안정하였고 일정한 입자크기를 유지하였다. 0.06% 에틸아세테이트 분획을 함유한 에토좀의 입자 크기는 $287.05{\pm}0.25nm$, 포집효율은 $51.96{\pm}0.01%$였다. 피부 투과 실험 결과, 에토좀 제형은 일반 리포좀이나 20% 에탄올 용액에서 보다 큰 피부 투과능을 보여주었다.

• KSBB Journal
• /
• 제16권3호
• /
• pp.253-258
• /
• 2001

항고지단백혈증제제를 이용한 경펴투과제제흘 제조하고자 기 재로서 xathan gum을 사용하여 약물의 함량 및 투과 촉전제에 따라서 경피투과체제를 제조하고 경피투과 항고지단백혈증제의 가능성 등을 연구하였다. 기재로 사용한 xanthan gum의 체 타전위를륜 측정하여 응결, 침전이 나타나는 등천점으로부터 제타전위 값의 차이가 나타나 있으므로 피부와 접촉시 연고제제외 석출 가능성이 없다는 것을 확인할 수 있었다. 각각의 지용성과 수용성 항고지단백혈증제제를 함유한 정피투과제제를 사용하여 진행된 투과 실험에서는 자용성인 clofibrat$\xi$의 투파속도가 현저하게 빠르게 나타났는데 이는 지용성인 피부 각질과의 친화 즉 lipophilicity를 증가시킴으로써 지용성인 clofibrate의 경피투과를 촉진시키는 것이라 생각된다. 지용성 경피투과제제에 투과촉진제를 첨가했을 경우, 그렇지 않은 경우에 비해 lag time파 투과속도가 빠르게 나타냈다. 특히 PEG 600을 사용했윤 경우가 가장 빠른 투과속도흘 나타냈고 글리세린, 올레산의 순오로 투과속도의 증가를 나타냈다. PEG 600븐 다른 투과촉진제보다 지용성 약물인 clofibrate에 대해 피부내의 지방과 단백겔의 유동성(fluidity) 과 피부 각질의 lipophilicity를 증가시컴으로서 각질로의 약물분배를 촉진한다고 생각된다.

• Bulletin of the Korean Chemical Society
• /
• 제31권5호
• /
• pp.1143-1148
• /
• 2010

We investigated the separation of nitrogen heterocyclic compound (NHC) contained in a model coal tar fraction comprising four kinds of NHC [indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine (Qu)], three kinds of bicyclic aromatic compound (BAC) [1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN) mixture with ten structural isomers (DMNs; regarded as one component)], biphenyl (Bp) and phenyl ether (Pe) by liquid membrane permeation (LMP). A batch-stirred tank was used as the permeation unit. An aqueous solution of saponin and n-hexane were used as the liquid membrane and the outer oil phase, respectively. Yield and selectivity of individual NHC was much larger than that of BAC, Bp and Pe. Increasing the initial mass fraction of the saponin to the membrane solution ($C_{sap,0}$) and the initial volume fraction of O/W emulsion to total liquid in a stirred tank (${\phi}_{OW,0}$) resulted in deteriorating the yield of individual NHC, but increasing the stirring speed (N) resulted in improving the yield of each NHC. With increasing $C_{sap,0}$, the selectivity of each NHC based on DMNs increased. Increasing ${\phi}_{OW,0}$ and N resulted in decreasing the selectivity of individual NHC based on DMNs. At an experimental condition fixed, the sequence of the yield and selectivity in reference to DMNs for each NHC was Q > Qu = iQ > In. Furthermore, we compared LPM method with methanol extraction method in view of the separation efficiency (yield, selectivity) of NHC.

• 약학회지
• /
• 제42권1호
• /
• pp.59-69
• /
• 1998

To increase the solubility of quercetin, which is a practically insoluble flavonoid of Ginkgo biloba leaf, the effects of nonaqueous vehicles. Their cosolvents, water-sol uble polymers and modified cyclodextrins (CDs) were observed. Polyethylene glycols, diethyleneglycol monoethyl ether, and their cosolvents with water showed a good solvency toward quercetin. Also the aqueous solutions of povidone, copolyvidone and Cremophor RH 40 was effective in solubilizing quercetin. Complex formation of quercetin with ${\beta}$-cyclodextrin (${\beta}$-CD), dimethyl-${\beta}$-cyclodextiin (DMCD), 2-hydroxypropyl-${\beta}$-cyclodextrin (HPCD) and ${\beta}$-cyclodextrin sulfobutyl ether (SBCD) in water was investigated by solubility method at $37^{\circ}C$. The addition of CDs in water markedly increased the solubility of quercetin with increasing the concentration. AL type phase solubility diagrams were obtained with CDs studied. Solubilizaton efficiency by CDs was in the order of SBCD >> DMCD > HPCD > ${\beta}$-CD. The dissolution rates of quercetin from solid dispersions with copolyvidone, povidone and HPCD were much faster than those of drug alone and corresponding physical mixtures, and exceeded the equilibrium solubility (3.03${\pm}1.72{\mu}$g/ml). The permeation of quercetin through duodenal mucosa did not occur even in the presence of enhancers such as bile salts, but the permeation was observed when the mucus layer was scraped off. This was due to the fact that quercetin had a strong binding to mucin ($58.5{\mu}$g/mg mucin). However rutin was permeable to the duodenal mucosa. The addition of enhancer significantly increased the permeation of rutin in the order of sodium glycocholate.

• Archives of Pharmacal Research
• /
• 제27권3호
• /
• pp.351-356
• /
• 2004

A transdermal preparation containing diclofenac diethylammonium (DDA) was developed using an O/W microemulsion system. Of the oils tested, lauryl alcohol was chosen as the oil phase of the microemulsion, as it showed a good solubilizing capacity and excellent skin permeation rate of the drug. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant and cosurfactant for microemulsion formation, and the effect of these additives on skin permeation of DDA was evaluated with excised rat skins. The optimum formulation of the microemulsion consisted of 1.16% of DDA, 5% of lauryl alcohol, 60% of water in combination with the 34.54% of Labrasol (surfactant)/ethanol (cosurfactant) (1:2). The efficiency of formulation in the percutaneous absorption of DDA was dependent upon the contents of water and lauryl alcohol as well as Labrasol: ethanol mixing ratio. It was concluded that the percutaneous absorption of DDA from microemulsions was enhanced with increasing the lauryl alcohol and water contents, and with decreasing the Labrasol:ethanol mixing ratio in the formulation.

• International Journal of Vascular Biomedical Engineering
• /
• 제4권2호
• /
• pp.13-18
• /
• 2006

Direct injection of a fibrinolytic agent to the intra-arterial thrombosis may increase the effectiveness of thrombolysis by enhancing the permeation of thrombolytic agents into the blood clot. Permeation of fibrinolytic agents into a clot is influenced by the surface pressure, which is determined by the injection velocity of fibrinolytic agents. Computational fluid dynamic methods were used in order to predict clot lysis for different jet velocities and nozzle arrangements. Firstly, thrombolysis of a clot was mathematically modeled based on the pressure and lysis front velocity relationship. Direct injection of a thrombolytic agent increased the speed of thrombolysis significantly and the effectiveness was increased as the ejecting velocity increased. The nine nozzles model showed about 20% increase of the lysed volume, and the one and seventeen nozzles models did not show significant differences. Secondly, thrombolysis was modeled based on the enzyme transport and the fluid flow equations, and quasi steady numerical analysis was performed. Clot lysis efficiency was also increased as injection velocity increased.