• Journal of The Korean Association For Science Education
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• v.22 no.3
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• pp.444-454
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• 2002

In this study, we analyzed the explanation of the concepts related to osmotic pressure and semipermeable membrane that were represented in chemistry and biology textbooks of high school and general course of college. There were 4 types of explanation in osmotic pressure and 3 types of semipermeable membrane concept. Students can understand the concepts with different meaning because there are different viewpoints on the explanations of the concepts. We must consider the various types of explanation when we design science textbooks because these confusions disturb students' understanding of the concepts.

• Polymer(Korea)
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• v.32 no.2
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• pp.103-108
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• 2008

Osmotic pellet, which consisted of water-swellable seed layer, drug layer, and porous membrane layer, has been widely utilized in oral drug delivery system. In this work, we describe the preparation of osmotic pellet with nifedipine as model drug and a mixture of cellulose acetate (CA) and Eudragit RS as membrane layer, and then examined the drug release behavior on the variation of the thickness change of membrane layer (CA and Eudragit RS) and release media. Furthermore, we examined the nifedipine release behavior using sodium alginate as a potential membrane candidate. Osmotic pellet was obtained in the quantitative yield by fluidized bed coater. Osmotic pellet exhibited the round morphology and the size ranging $1500{\sim}1700{\mu}m$ in SEM. The nifedipine release decreased as the thickness of membrane layer (CA and Eudragit RS) increased. In addition, it observed that there is difference of release amount in between intestinal juice (pH 6.8) and gastric juice (pH 1.2). In the case of osmotic pellet coated with sodium alginate, nifedipine release behavior depended on the crosslinking of sodium alginate layer. In conclusion, we found that various membrane layers could control the release amount of nifedipine.

• Polymer(Korea)
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• v.29 no.3
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• pp.288-293
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• 2005

Osmotic granule system which is one of the drug delivery systems has been developed to improve manufacturing process and other problems of tablet osmotic systems. It consists of water swellable seed layer, nifedipine drug layer, and drug release controlled membrane layer and manufactured by fluidized bed coater. The granule size and mombrane thickness can be controlled by various amounts of seed and coating solution, respectively. It could be observed that the morphology of osmotic granule was different at each coating step as well as type of coating solution. The bigger the size of granule, the slower the release rate was observed due to decreasing the total specific surface wed of granule. Also, it was observed that the increase of membrane thickness was caused to retard the dissolution of nifedipine due to decreasing the water absorption rate. The drug solubility for dissolution media is greatly affected to nifedipine release. From these results, we assured that osmotic granule can be fabricated by fluidized bed coating methods, and the appropriate release profile could be controlled by the controlling of bead size, membrane thickness and dissolution media.

• Polymer(Korea)
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• v.31 no.4
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• pp.329-334
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• 2007

Osmotic pellet system, which is one of the oral drug delivery systems, has been developed to improve manufacturing process, reduce product cost and other problems of osmotic tablet systems. Osmotic pellet is consisted of water swellable seed layer, drug layer, and membrane layer. Among them, the membrane layer plays an important role in a control of the drug release. In this work, we examined the effect of ratio for Eudragit RL and RS on the drug release behavior. Osmotic pellet with nifedipine as a model drug was easily obtained in a good yield by fluidized bed coater. Osmotic pellet showed round morphology with a range of size $1300{\sim}1500\;{\mu}m$. In the experiment of nifedipine release, the release amount increased with the increase of the ratio of Eudragit. This is due to the fact that Eudragit RL contains more hydrophilic quaternary ammonium group than Eudragit RS. Additionally, the release amount was retarded with increasing the membrane thickness. There are no differences in the release amount measured at the different pH 1.2, 6.5, 6.8, and 7.2. In conclusion, it was found that the drug release from osmotic pellets depended on the composition ratio and coating thickness of membrane layer.

• Polymer(Korea)
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• v.30 no.2
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• pp.112-117
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• 2006

To improve the type error of osmotic tablet which is one of the drug delivery system, osmotic granule could be manufactured by fluidized bed coating. It has drug layer containing different amount of osmogant and is coated with membrane including different types of binder. We confirmed that the morphology of osmotic granule was different at each coating step. The more mont of osmotic agent, the faster drug release was observed due to increasing the driving force for drug release from osmotic granule. And drug release from osmotic granule coated with membrane using different types of binder was differed by solubility of binders to water. The formation of pore in membrane was confirmed by SEM and DSC Membrane using water soluble binder released more amount of drug. From these results, we assured that difference of osmotic pressure between the inside and the outside of granule and porosity of membrane have an effect on drug release from osmotic granule.

• 베이커리
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• no.11 s.364
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• pp.160-160
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• 1998

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.63-67
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• 1989

In order to examine the suppressive effect of dietary fiber toward the intestinal absorption of lead, an in vitro absorption test using a semipermeable membrane was undertaken. Among dietary fiber components, cellulose showed no suppressive effect, guar gum and carboxymethyl-cellulose, a slight effect whereas citrus pectin and sodium alginate exhibited a remarkable effect. Among fibrous foods tested, rice bran, wheat bran, Chinese cabbage, radish and tangle had a higher suppressive effect while mandarin orange, apple and laver showed a lower effect.

• Journal of the Korean Chemical Society
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• v.20 no.6
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• pp.448-452
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• 1976

A simplified statistical mechanical method was developed for the calculation of the dehydration fraction, activation free energy of dehydration, and the relaxation times of hydrated ions. The model used includes the equilibrium constant between hydrated and dehydrated water, a water-ion interaction potential energy term, and a mixing factor for the species present. The agreement between theory and experiment is good. The pressure dependence of ion dehydration is also discussed.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.06a
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• pp.159-174
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• 1997

삼투현상이란 반투막을 사이에 두소 저농도의 용매가 고농도의 용액으로 이동하는 현상으로 막양측 용매의 화학포텐셜이 같아지게 되면 용매의 이동은 정지되고 수두차 만큼의 삼투압차가 발생한다. 이 때 고농도 용액측에 삼투압차 이상의 압력을 가하게 되면 삼투현상과는 반대로 고농도 용액측의 용매가 저농도의 용액측으로 역류하는데 이를 역삼투현상이라 한다. 역삼투현상을 이용하여 물질을 분리하는 역삼투 공정은 막의 물리화학적 특성, 분리대상물질의 물리화학적 특성, 그리고 압력차를 추진력으로 하는 세가지 요소의 조합에 의해 행하여 진다. 역삼투는 분자크기에 따른 분리조작이 아니므로 정밀여과나 한외여과에서와 같은 유기물질의 침착현상이 적으며 결과적으로 막의 수명도 길어진다. 역삼투막은 용존염을 분리제거할 뿐만 아니라 분자량이 적은 유기물 및 Aromatic hydrocarbon 등의 분리조작에도 그 이용가능성이 고조되고 있다.

• Korean Journal of Optics and Photonics
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• v.30 no.4
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• pp.142-145
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• 2019

Normally, a corner cube retroreflector (CCRR) sheet is used as a retroreflective mirror array (RRMA) in a volumetric display. Each CCRR unit reflects light in the retroreflective direction, which is parallel to the incident light, and it makes a blurred image, as it shifts the position of light within its dimensions. Adopting a "curved planar wall" and "parabolic focusing" (x-axis), a hybrid-t(transverse direction)-RRMA is proposed, to improve the image quality and brightness. The improvement of image contrast is achieved by tuning a "linear v-shaped groove" structure to a "parabolic v-shaped groove". Also, the system has been simplified and the brightness enhanced 4 times by removing the half mirror.