• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.160-165
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• 1999

Osmotic pressure induced by semi-permeability of hardened cement pasts and cement mortar was studied, which was considered to be a cause of failure such as separation and blistering of floor coatings or wall coatings from the concrete substrate. The specimens with a water cement ratio of 45, 60 and 75% were installed between the solution of sodium chloride and distilled water. First, we measured water flux from distilled water to sodium chloride and the ion flux of Na+ and Cl- through the specimens. Then, we measured osmotic pressure induced by semi-permeability of the specimens using an apparatus which was specially developed for this study. It was made clear that hardened cement paste and cement mortar have properties of semipermeability, and the osmotic pressure is closely related to their water cement ratio. Finally, we calculated the osmotic pressure according to Staverman's equation, which was obtained for organic membranes, and tried to explain quantitatively the observed pressure.

• 멤브레인
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• 제12권2호
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• pp.90-96
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• 2002

멤브레인 여과 실험에서 얻어진 데이터 처리에 간단한 수치해석을 적용하여 삼투압(osmotic pressure) 과 구배확산계수(gradient diffusion coefficient)를 도출하는 새로운 방법론을 제시하였다. 삼투압과 구배확산계수는 이론 및 실험적으로 쉽게 구할 수 없는 물리적 특성치로서 멤브레인 여과의 특성 규명에 중요하다. 모델 라텍스 콜로이드의 여과시간에 따른 투과플럭스(permeate flux) 값과 이에 대한 수치적분과 수치미분 데이터로부터 분산된 입자농도의 함수인 삼투압 관계식을 구했다. 이로부터 계산된 열역학적 계수(thermodynamic coefficient)는 입자농도가 증가할수록 감소하는 거동을 보였고, 여기에 기존에 제시되어 있는 수력학적 계수(hydrodynamic coefficient)를 도입하여 구배확산계수를 산출하였다. 아울러, 본 연구에서 계산된 입자농도에 따른 구배확산계수의 결과와 동일한 멤브레인과 라텍스 콜로이드의 여과에 대해서 기존에 통계역학적 시뮬레이션으로 예측한 결과를 비교하였다.

• 한국미생물·생명공학회지
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• 제27권2호
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• pp.91-95
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• 1999

To investigate the effect of salts on the production of erythritol by Torula sp., cells were grown on the media containing various concentrations of KCl or NaCl. Cell growth and glucose consumption rates decreased when KCl or NaCl concentration increased from 0.0 to 0.5M. The production of erythritol, however, was maximal at 0.3M aCl. The erythritol concentration of 54.3g/l in the medium containing 0.3M NaCl and 200g/l glucose was obtained after 120h. The production of erythritol decreased in cultures above 0.3M NaCl or 0.4M KCl due to the inhibition of cell growth. To elucidate the effect of salts more quantitatively, KCl and NaCl concentrations were converted to osmotic pressure. As the osmotic pressure increased, the yield of erythritol from glucose increased regardless of the kinds of salts and the yield of erythritol was approximately 49% at the osmolality of 2.4Os/kg. When the osmotic pressure increased to 2.5Os/kg, the specific growth rate of cells decreased but the production rate of erythritol increased. For the effective production of erythritol, osmotic pressure must be adjusted not to inhibit markedly the growth rate of cells and to stimulate the production rate of erythritol by supplementing salt.

• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.1056-1069
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• 2015

Osmotic pressure is a critical factor for erythritol production with osmophilic yeast. Protein expression patterns of an erythritol-producing yeast, Yarrowia lipolytica, were analyzed to identify differentially-expressed proteins in response to osmotic pressure. In order to analyze intracellular protein levels quantitatively, two-dimensional gel electrophoresis was performed to separate and visualize the differential expression of the intracellular proteins extracted from Y. lipolytica cultured under low (3.17 osmol/kg) and high (4.21 osmol/kg) osmotic pressures. Proteomic analyses allowed identification of 54 differentially-expressed proteins among the proteins distributed in the range of pI 3-10 and 14.4-97.4 kDa molecular mass between the osmotic stress conditions. Remarkably, the main proteins were involved in the pathway of energy, metabolism, cell rescue, and stress response. The expression of such enzymes related to protein and nucleotide biosynthesis was inhibited drastically, reflecting the growth arrest of Y. lipolytica under hyperosmotic stress. The improvement of erythritol production under high osmotic stress was due to the significant induction of a range of crucial enzymes related to polyols biosynthesis, such as transketolase and triosephosphate isomerase, and the osmotic stress responsive proteins like pyridoxine-4-dehydrogenase and the AKRs family. The polyols biosynthesis was really related to an osmotic response and a protection mechanism against hyperosmotic stress in Y. lipolytica. Additionally, the high osmotic stress could also induce other cell stress responses as with heat shock and oxidation stress responses, and these responsive proteins, such as the HSPs family, catalase T, and superoxide dismutase, also had drastically increased expression levels under hyperosmotic pressure.

• 한국세라믹학회지
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• 제50권1호
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• pp.25-30
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• 2013

The pore volume of hardened cement with waterproofing materials is lower compared to that of hardened cement without waterproofing materials. Thus, fewer gaps will appear by means of chemical reactions between $Ca^{2+}$ ions in hardened cement and water, solutes, and other ions. Due to the selective permeability, the osmotic pressure of hardened cement can change due to physical effects such as the reduction of the pore volume and the reduction in the number of pores, as well as by the electrochemical reaction between water, solutes, other ions and $Ca^{2+}$ ions in hardened cement. Of course, these factors do not have independent effects but instead a combined complex effect. Accordingly, we studied changes in the osmotic pressure due to the difference in the pore structure of hardened cement. A pore size smaller than 1 nm in hardened cement had only a slight effect on the osmotic pressure, whereas a pore size larger than 1 nm had a direct effect on the osmotic pressure.

• 대한기계학회논문집B
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• 제39권6호
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• pp.471-475
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• 2015

점차 수요가 증가하는 소형의 약물주입펌프의 개발을 위하여 삼투압을 이용한 약물주입펌프를 제작하고 그 성능을 입증하고자 한다. 삼투압을 이용한 약물주입펌프는 상용화된 전기-기계식 펌프에 비해 무거운 배터리와 액추에이터가 필요 없기 때문에 작고 가볍게 만들 수 있으며, 탄성체 약물주입펌프와 달리 지속적인 압력을 발생할 수 있는 장점이 있다. 제안한 삼투압 약물주입펌프는 약물주머니, 삼투압 발생부, 용매 저장부, 반투막으로 구성되어있다. 약물주입펌프의 성능을 평가하기 위하여 약물의 유량을 측정하고 압력을 측정할 수 있도록 체외 실험기구를 구성하였다. 측정결과 약물주입펌프는 20ml의 약물을 20 시간에 걸쳐 일정하게 공급할 수 있으며, 약물의 최대 압력은 400mmHg 이상이므로 위치변화 또는 환자의 자세변화로 인하여 약물이 역류하는 위험을 원천적으로 예방할 수 있다.

• Journal of Pharmaceutical Investigation
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• 제32권4호
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• pp.241-258
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• 2002

Such osmotic drug delivery systems are based on osmosis, the diffusion of water transversely from a medium with a low osmotic pressure to a medium with a high osmotic pressure for the controlled delivery of active agents. In this review, U.S. Patents on osmotic drug delivery analyze 261 patents until December 2001. These devices form now a major market of drug delivery products. Because of their advantage and innovate idea, it appears that the future of oral drug delivery mark,εt in Korea is promising.

• 한국작물학회지
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• 제28권1호
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• pp.128-132
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• 1983

Pressure chamber(DIC-PC-40형) technique에 의한 대두재배품종 Williams와 금강대립의 경엽에 대한 수분특성의 결과는 다음과 같다. 1. 최대포수시의 삼투압$(\Pi_p)$은 Williams 9.0bar, 금강대립은 10.4bar였다. 3. 초기원형질분리점에서의 상대함수율$(PWC^*)4은 금강대립이 86.0%, Williams가 92.6%였다. 4. 삼투수의 총량에 대한 원형질분리점에서의 침출량비$(V_p/V_o)$는 Williams가 94.0%, 금강대립이 83.4%였다. 5. 최대함수량에 대한 삼투수의 총량의 비$(V_p/w_5)$는 금강대립이 84.3%, Williams가 77.5%였다. 7. 탄성계수는 금강대립이 $1.6\times10^5bar$ 이었으며 Williams는 $8.5$\times$10^2$bar로 현저한 차이를 보였다.

• Membrane and Water Treatment
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• 제1권4호
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• pp.253-271
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• 2010

A theoretical study for the flux enhancement by pulsation of transmembrane pressure is presented for osmotic pressure controlled ultrafiltration under laminar flow regime. The transient velocity profile is solved analytically using Green's function method. Time dependent convective diffusive equation is solved to quantify the membrane surface concentration and the permeate flux, numerically. The effects of the amplitude and frequency of pulsation on flux, surface concentration and observed retention are studied.

• 폴리머
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• 제32권4호
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• pp.328-333
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• 2008

삼투압을 이용한 약물전달시스템은 소화관내의 물이 다공성막을 통하여 시스템 내부로 침투하면 시스템 내부에 있던 삼투압물질과 섞여 삼투압을 발생시키고, 이 삼투압의 힘으로 시스템 내부에 있는 약물을 시스템 외부로 일정한 속도로 방출하는 제제기술이다. 이러한 삼투압을 이용하여 상용화된 대표적인 제품으로 니페디핀을 모델약물로 한 타블렛제형인 Procadia $XL^{(R)}$(Pfizer)과 $Adalat^{(R)}$(Bayer)가 널리 상용화되어 있다. 이번 연구에서는 타블렛 형태의 삼투압정을 유동층코팅 기술을 이용하여 삼투성펠렛으로 제조하였다. 삼투성펠렛은 수팽윤성 고분자와 삼투염을 포함한 시드층, 모델약물인 니페디핀을 포함하는 약물층 그리고 약물의 방출을 조절할 수 있는 다공성막으로 구성되어 있다. 본 연구에서는 다공성막으로 사용되는 초산셀룰로오스(CA)와 $Eudragit^{(R)}$ RS의 구성비와 코팅두께에 따른 약물방출 거동을 확인하였으며, 다공성막의 구성물질인 CA의 비가 증가할수록 또한 다공성막의 코팅두께가 증가할수록 같은 측정시간 때에 약물의 방출이 낮게 나타남을 확인하였다. 약물방출 전후의 펠렛의 형태를 확인하기 위하여 SEM을 측정하였다.