• 폴리머
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• 제28권4호
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• pp.335-343
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• 2004

카뮤스틴 (1,3-bis(2-chloroethy1-nitrosourea, BICNU)은 뇌종양 치료를 위하여 임상적으로 사용되는 약물로 짧은 생물학적 반감기를 가지고 있어 장기방출에 적합하지 않다. 하지만, poly(D,L-lactide-co-glycolide) (PLGA)는 벌크 분해 특성으로 인해 약물의 장기방출에 유용하며, PLGA의 유도체인 글리콜라이드 단량체는 독성이 없고 PLGA와 유사한 생분해성을 가지고 있어 BICNU의 방출조절에 이용된다. 이 실험에서 BICNU를 함유한 PLGA 웨이퍼는 일반적인 직접압축법에 의해 제조한 후 BICNU의 방출거동과 웨이펴의 분해속도를 전자주사현미경, 핵자기공명장치 그리고 젤투과크로마토그래피를 통해 관찰하였다. 또한, 글리콜라이드 단량체의 함량변화에 따른 다중층 웨이퍼를 제조하여 단일층 웨이퍼와의 방출거동을 비교하였다. 이러한 결과들로부터 BICNU를 함유한 PLGA 웨이퍼의 약물방출은 BICNU와 글리콜라이드 단량체의 함량이 증가할수록 증가하였고, 다중층 웨이퍼에서 외부층의 글리콜라이드 단량체와 BICNU가 약물방출 거동과 분해속도에 영향을 미친다는 것을 확인하였다.

• 소성∙가공
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• 제31권1호
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• pp.29-38
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• 2022

Recently, the composite material market is gradually growing. Various composite forming processes have been developed in order to reduce the production cost of the composite material. Unlike the conventional forming process, the microwave composite forming process has the advantage of reducing the processing time because the composite material is heated directly or indirectly at the same time. Due to this advantage, in this study, a double cantilever beam test was conducted with specimens manufactured by the microwave composite forming process. The purpose of this study was to compare mode-I energy release rate for specimens manufactured by prepreg compression forming and microwave composite forming processes. First, a microwave oven was proposed to conduct the microwave composite forming process. Double cantilever beam specimens were manufactured. After that, the double cantilever beam test was conducted to obtain the mode-I energy release rate. Mode-I energy release rates of specimens manufactured by the microwave composite forming and prepreg compression forming processes were then compared. As a result, mode-I energy release rates of specimens fabricated by the microwave composite forming process were similar to those fabricated with the prepreg compression forming process with a relatively reduced process time.

• Carbon letters
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• 제10권1호
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• pp.33-37
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• 2009

Activated carbon (AC) is one of the most effective adsorbents for organic compounds because of their extended surface area, high adsorption capacity, microporous structure and special surface reactivity. The composites of pH-sensitive hydrogel and activated carbon were prepared in order to improve the loading capacity of drug. The pH-sensitive hydrogel matrix swelled well in the basic condition to release the drug loaded in AC. The release of drug was controlled depending on both the pH due to the ionization of the carboxylic acid group and the AC due to the surface properties.

• Parasites, Hosts and Diseases
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• 제38권2호
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• pp.99-102
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• 2000

In order to observe the cytotoxicity of Acanthamoeba spp., which were isolated from contact lens containers as ethiological agents for the probable amoebic keratitis in Korea, the crystal violet staining method and LDH release assay were carried out. In the crystal violet staining method, among eight contact lens container isolates, isolate 3 (Acanthauloeba KA/LS5) showed 83.6% and 81.8% of cytotoxicity, and isolate 7 (Acanthamoeba KA/LS37) showed 28.2% and 25.1% of cytotoxicity, in 1 mg/ml and 0.5 mg/ml Iysate treatments, respectively. Acanthamoeba cutbertsoni and A. healyi showed 84.0% and 82.8% of cytotoxicity. Similar results were observed in A. costellunii and A. hafchefti which showed 83.6% and 75.5% or cytotoxicity. Acanthamoeba roureba and A. polyphaga showed 9.0% and 1.7% of cytotoxicity. In the LDH release assay, isolate 3 (20.4%) showed higher cytotoxicity than other isolates in 1 mg/ml Iysate treatment. The results provide that at least isolate 3 has the cytotoxic effect against CHO cells and seems to be the pathogenic strain.

• Journal of Pharmaceutical Investigation
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• 제41권5호
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• pp.279-288
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• 2011

The Dexamethasone (DEX) loaded chitosan microspheres were prepared by thermal denaturation and chemical cross-linking method using a dierent concentration of glutaraldehyde as chemical cross-linking agent. The prepared microspheres were evaluated for the percentage of Drug Loading (DL), Encapsulation Efficiency (EE) and surface morphology by Scanning Electron Microscopy (SEM). DL and EE were found to be maximum range of 10.0 to 10.79 % and 58.19 to 64.73 % respectively. The SEM Photographs of the resultant microspheres exhibited fairly smooth surfaces and predominantly spherical in appearance. In addition, Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) shown that there was no interaction between the drug and polymer. In vitro and in vivo release studies revealed that the release of dexamethasone was sustained and extended up to 63 days and effectively controlled by the extent of cross-linking agent. Non-clinical parameters such as paw volume, hematological parameters like Erythrocyte Sedimentation Rate (ESR), Paced Cell Volume (PCV), Total Leucocytes Count (TLC), Hemoglobin (Hb), Differential Cell Count (DCC) were investigated in Fruend's Complete Adjuvant (FCA) induced arthritic rats. Radiology and histopathological studies were also performed in order to evaluate the therapeutic efficacy of the DEX-loaded microspheres in extenuating the rat arthritic model.

• 에너지공학
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• 제12권2호
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• pp.93-100
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• 2003

An estimation methodology of the mass and energy (M/E) release due to the main steam line break (MSLB) has been developed with the RETRAN-3D code. In the case of equipment qualification (EQ), the over-estimated temperature would exceed the design limits of some cables or valves. In order to have a more flexible EQ profiles from the MSLB M/E release, the methodology with the best-estimated code was used. The major conditions affecting the MSLB M/E were found to be the initial SG level, heat transfer between primary and secondary sides, power level, operable protection system, main or auxiliary feedwater availability, and break conditions. The RETRAN-3D models were developed for the Kori unit 1 (KRN-1) which is typical two loop Westinghouse (WH) designed plant. Particularly, a detailed model of the steam generators was developed to estimate a more realistic two-phase heat transfer effect of the steam flow. After the modeling, the methodology has been developed through the sensitivity analyses. The M/E release data generated from the analyses have been used as the input to the inside containment pressure and temperature (P/T) analysis. According to the results at the point of view containment P/T, the Kori unit 1 can have more margin of 5∼15 ㎪ in pressure and 8∼15$^{\circ}C$ in temperature.

• Journal of Pharmaceutical Investigation
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• 제40권5호
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• pp.285-289
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• 2010

Manufacturing a multi-layered tablet such as Xatral XL$^{(R)}$ is more complex and expensive than monolayered tablets, but mono-layered tablets may have less favorable release properties depending on the pharmacodynamics and pharmacokinetics of the active ingredient. We therefore sought to develop a monolayer tablet with a similar dissolution profile to the commercial alfuzosin sustained-release triple layered tablet (Xatral XL$^{(R)}$). We prepared four different mono-layered alfuzosin tablets with different concentrations of hydroxypropyl methycellulose and PVP K-90. Fomulation III with alfuzosion/mg-stearate/ HPMC/ PVP K-90 (10/5/110/95 mg/tab) has a similar dissolution rate to Xatral XL$^{(R)}$, with a similarity factor score of 81.4. However, the swelling and erosion rates of the two formulations were different, and NIR analysis showed differences in the mechanisms of drug release. Thus, although formulation III and Xatral XL$^{(R)}$ show similar dissolution rates, the mechanisms of drug release are different.

• Environmental Engineering Research
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• 제17권1호
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• pp.17-25
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• 2012

Concern about green water problem has surfaced as a serious issue in Korea. In order to solve this problem, it is necessary to research inhibition of green water and corrosion control of copper pipe in water service. This paper discovered that moderate corrosion inhibitors can solve the green water problem and copper corrosion in water service by adding the optimal concentration of corrosion inhibitors based on regulation. Firstly, in the case of phosphate based corrosion inhibitors, as dosage of the corrosion inhibitor increases from 1 mg/L to 5 mg/L, the relative effect of corrosion inhibitor declines rapidly. Secondly, except for 1 mg/L dosage of silicate based inhibitor, relative effects of the inhibitor displays a positive number depending on inhibitor concentration. The most significant result is that the amount of copper release shows a downward trend, whereas the phosphate based inhibitor accelerates copper ion release as the inhibitor dosage increases. Thirdly, as the dosage of mixed inhibitors increases to 10 mg/L, the copper release change shows a similar trend of phosphate based inhibitor. Lastly, according to the Langelier saturation index (LI), silicate based inhibitors have the most non corrosive value. Larson ratio (LR) indicates that phosphate based inhibitors are the least corrosive. Korea water index (KWI) represents that silicate based inhibitors are most effective in controlling copper pipe corrosion.

• 대한의용생체공학회:의공학회지
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• 제34권2호
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• pp.69-72
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• 2013

The goal of this study is to develop test method for evaluating the drug eluting properties of drug eluting stents (DES). PBS and the detergent solutions, presented by each DES manufacturer, were used for drug release of DES coated with paclitaxel, zotarolimus and everolimus. The drugs which are coating DES were not released by PBS but released by the detergent solutions, finally paclitaxel 83.38%, zotarolimus 103.85% and everolimus 115.78%. It seems that the use of the detergents is necessary in order to release the drugs because those drugs are extremely hydrophobic. In conclusion, using of detergent solutions presented by each manufacturer were suitable for evaluating the drug eluting property of drug eluting stent.

• Journal of Pharmaceutical Investigation
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• 제22권3호
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• pp.211-217
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• 1992

Stabilization of liposomes against degradation by bile salts has been investigated in order to develop a liposomal model system for oral drug delivery. Two polysaccharides, amylopectin (AP) and chitin (CT), were employed to coat both empty liposomes and bromthymol blue (BTB)-encapsulated liposomes by adsorption-coating techniques. Turbidity changes and BTB-release characteristics in pH 5.6 buffer solutions with or without bile salts, sodium cholate and sodium glycocholate, were observed to compare the differences between uncoated liposomes and polysaccharide-coated liposomes. Initial turbidities of both uncoated and polysaccharide-coated liposomes in buffer solution were kept constant within 3% range during 4 hours of experiments. But they were decreased in a different manner in bile salts-containing buffer solutions, showing 10% or less decrease for polysaccharide-coated liposomes and 25% or more decrease for uncoated liposomes. BTB release from uncoated liposomes has been greatly increased upto 90% after 4 hours in bile salts-containing buffer solution, which is a clue for breakdown of liposomal vesicles. However, polysaccharide-coated liposomes showed the controlled-release pattern which is proportional to square-root of time, followed by around 50% release for the same time period. Consequently, it is possible to conclude that these polysaccharide-coated liposomes might be an available system for oral delivery of a drug which is unstable in gut environment.