• 폴리머
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• 제36권2호
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• pp.202-207
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• 2012

슈도모나스를 함유하는 poly(${\varepsilon}$-caprolactone)(PCL) 마이크로캡슐은 다중에멀젼 시스템에 의하여 제조하였고, 제조조건에 따른 마이크로캡슐의 특성과 방출거동에 대하여 조사하였다. 마이크로캡슐의 형태와 입도분포는 주사전자현미경과 입도분석기를 이용하여 관찰하였고, 방출거동은 액체배양법을 통하여 확인하였다. 다양한 제조조건에 따라 제조된 마이크로캡슐은 10~60 ${\mu}m$의 입자크기와 표면이 매끈하고 균일한 구형의 마이크로캡슐이 형성됨을 확인하였다. 열분석 결과, 마이크로캡슐은 약 $58^{\circ}C$에서 용융피크를 나타내었고 벽재물질의 함량 증가에 따라 용융열이 증가함으로써 벽재의 두께는 PCL 함량에 비례함을 확인할 수 있었다. 또한 슈도모나스의 방출속도는 유화제 함량, 교반속도, PCL 함량에 따라 조절이 가능하며 이는 유화제 함량과 교반속도 증가에 따른 입자 크기의 감소에 의한 비표면적 증가와 벽재물질의 두께 증가에 인한 방출속도의 감소에 의한 것으로 판단된다.

• 대한기계학회논문집B
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• 제32권6호
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• pp.413-420
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• 2008

The unsteady heat release characteristics play a significant role in combustion instabilities observed in low emissions gas turbine combustors. Such combustion instabilities are often caused by coupling mechanisms between unsteady heat release rates and acoustic perturbations. A generalized model of the turbulent flame response to acoustic perturbations is analytically formulated by considering a distributed heat release along a curved mean flame front and using the flame's kinematic model that incorporates the turbulent flame development. The effects of the development of flame speed on the flame transfer functions are examined by calculating the transfer functions with a constant or developing flame speed. The flame transfer function due to velocity fluctuation shows that, when a developing flame speed is used, the transfer function magnitude decreases faster with Strouhal number than the results with a constant flame speed at low Strouhal numbers. The flame transfer function due to mixture ratio fluctuation, however, exhibits the opposite results: the transfer function magnitude with a developing flame speed increases faster than that with a constant flame speed at low Strouhal numbers. Oscillatory behaviors of both transfer function magnitudes are shown to be damped when a developing flame speed is used. Both transfer functions also show similar behaviors in the phase characteristics: The phases of both transfer functions with a developing flame speed increase more rapidly than those with a constant flame speed.

• 폴리머
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• 제28권2호
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• pp.103-110
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• 2004

토코페롤을 함유하는 폴리($\varepsilon$-카프로락톤)(PCL) 마이크로캡슐은 액중건조법에 의하여 제조하였고, 제조 조건에 따른 마이크로캡슐의 특성과 PCL 필름을 사용하여 PCL의 분해거동을 측정하였다 제조된 마이크로캡슐의 크기 및 형태와 구조적 특성은 각각 SEM과 XRD를 이용하여 관찰하였다. 또한, 접촉각 측정을 통하여 심물질의 농도에 따른 마이크로캡슐의 표면자유에너지를 측정하였다. 실험결과, 마이크로캡슐은 유화제로 폴리(비닐 알코올)을 사용한 경우 안정된 구형의 마이크로캡슐이 형성되었고, 마이크로캡슐의 표면자유에너지와 PCL의 결정성은 감소하고, PCL 필름은 악 21일 후 분해가 시작되었다. 토코페롤의 방출특성은 UV/vis.에 의하여 측정하였으며, 마이크로캡슐의 방출속도는 교반속도의 증가와 함께 증가하였다. 이는 교반속도의 증가와 함께 감소된 마이크로캡슐 입자 크기에 의한 방출용액과 마이크로캡슐 사이의 계면의 증가에 의한 것으로 판단된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.206-212
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• 2009

Chemical behaviors of each surface material for interior facilities affect to fire initiation and growth in general fire situation. These chemical behaviors were characterized by thermal properties (Heat release rate, Pyrolysis rate, specific heat, etc) which could be derived from experimental test. Especially, Heat release rate which indicates aspect of fire size is one of the most important property to asses fire hazard and protection needs. The cone calorimeter test (ISO 5660) has recently assumed to a dominant role in bench scale fire testing to obtain the Heat release rate of materials. This value could be calculated by the 'Oxygen Consumption Method' under various producing irradiances to each surface of materials. In this study, Process of the cone calorimeter test was simulated by Pyrolysis model of FDS (Fire Dynamics Simulator by NIST) base on the ISO 5660 international standard. Then, we could estimate the simulation method of FDS in case of single materials through the comparative study with test results.

• Journal of Pharmaceutical Investigation
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• 제19권4호
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• pp.179-183
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• 1989

Drug release experiments were performed based on pH-sensitive swelling behaviors of polymethacrylic acid. 5-Fluorouracil as a nonionic model drug revealed release patterns depending solely on pH-dependent swelling kinetics of polymethacrylic acid. In contrast, release of propranolol hydrochloride as a cationic model drug was significantly affected by ionic drug-polymer interaction as well as the swelling kinetics. Accordingly, a zero-order release pattern was obtained at pH 7, which was distinguished from the general matrix type drug release pattern.

• Macromolecular Research
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• 제16권5호
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• pp.429-433
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• 2008

Alginate/carboxymethyl scleroglucan (CMSG) hydrogels were suggested as a novel carrier for the controlled release of protein drugs. The drug release characteristics of alginate hydrogels were improved by CMSG addition. Scleroglucan (Sclg) was carboxymethylated using monochloroacetic acid in aqueous alkaline medium. Alginate/CMSG hydrogels were prepared by dropping the mixture solution of alginate/CMSG into calcium chloride solution. The swelling behaviors and drug release characteristics of the hydrogels were investigated in the buffers of pH 1.2 or 7.4. As the CMSG content increased in the hydrogels, the swelling ratio of the alginate/CMSG hydrogel increased rapidly in the buffer of pH 7.4. At pH 1.2, however, the swelling ratio significantly decreased compared to that at pH 7.4. According to in vitro release tests, only 15% of ovalbumin, investigated as a model protein drug, was released from the alginate/CMSG hydrogels at pH 1.2 within 6 h. At pH 7.4, however, the drug release significantly increased due to the rapid swelling of the hydrogels. The release and swelling behaviors of the hydrogels could be controlled by changing the CMSG content in the hydrogels. These results supported the use of alginate/CMSG hydrogels as a suitable carrier for the controlled release of protein drugs in a pH responsive manner.

• 대한약학회:학술대회논문집
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• 대한약학회 2000년도 NEW STRATEGY FOR DRUG DEVELOPMENT IN POST-GENOMIC ERA(대한약학회)
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• pp.260.1-260.1
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• 2000

• 폴리머
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• 제29권6호
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• pp.593-598
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• 2005

Layer-by-layer(LbL) 자기 조립법에 의한 poly(ethylene-alt-maleic anhydride)(PEMAh)/poly(4-vinyl pyridine)(P4VP) 다층막의 염료 흡착 거동 및 pH 변화에 의한 염료 방출 거동을 Rodamine 6G(R6G)를 지시제로 사용하여 조사하였다. UV-vis 분광 분석을 이용하여 (PEMAh/P4VP)n 다층막의 두께 및 R6G의 흡착 및 방출 거동을 조사하였다. 다층막에 흡착되는 R6G의 흡착량은 필름의 두께 증가에 따라 선형적으로 증가하였다. (PEMAhAh/P4VP)n 다층막의 투과성은 pH 조건에 민감한 거동을 보였으며, 방출액의 pH가 감소할수록 R6G 방출 속도와 방출량은 증가하였다. PEMAh/poly(ethyleneimine)(PEI) capping layer를 (PEMAh/P4VP)n 다층막에 추가로 적층함으로써 흡착된 R6G의 방출 속도를 조절할 수 있었다.

• Nuclear Engineering and Technology
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• 제43권6호
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• pp.499-508
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• 2011

The paper briefs a fuel performance code, COSMOS, which can be utilized for an analysis of the thermal behavior and fission gas release of fuel, up to a high burnup. Of particular concern are the models for the fuel thermal conductivity, the fission gas release, and the cladding corrosion and creep in $UO_2$ fuel. In addition, the code was developed so as to consider the inhomogeneity of MOX fuel, which requires restructuring the thermal conductivity and fission gas release models. These improvements enhanced COSMOS's precision for predicting the in-pile behavior of MOX fuel. The COSMOS code also extends its applicability to the instrumented fuel test in a research reactor. The various in-pile test results were analyzed and compared with the code's prediction. The database consists of the $UO_2$ irradiation test up to an ultra-high burnup, power ramp test of MOX fuel, and instrumented MOX fuel test in a research reactor after base irradiation in a commercial reactor. The comparisons demonstrated that the COSMOS code predicted the in-pile behaviors well, such as the fuel temperature, rod internal pressure, fission gas release, and cladding properties of MOX and $UO_2$ fuel. This sufficient accuracy reveals that the COSMOS can be utilized by both fuel vendors for fuel design, and license organizations for an understanding of fuel in-pile behaviors.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.281-285
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• 1996

Pulsatile swelling behaviors and their application to drug delivery system were studied by using interpenetrating polymer networks(IPN) hydrogels constructed with poly(vinyl alcohol) and poly(acrylic acid). The PVA/PAAc IPNs hydrogels were symthesized by UV irradiation tallowed by repetitive freezing and thawing method. These hydrogels showed pH and temperature sensitive swelling behaviors. From the release experiment, the release amount of model drug incorporated into these hydrogels showed pulsatile patterns. Permeability coefficients obtained by various solutes differed in response to changes of permeation conditions.