• Archives of Pharmacal Research
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• v.16 no.1
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• pp.43-49
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• 1993

The polyvinyl alcohol (PVA) hydrogel containing 1-methy-2-pymolidinone (MP) and sorbitol was preapred by the freeze and thaw method. The release rate of indomethacin from PVA hydrogel was used as a criterion for deciding the optimum formula of hydrogel using the computer optimization technique. The hydrogel of optimum formula was composed of PVA (10 w/v%), MP (0 w/v%) and sorbitol (40 w/v%) and the release rate of indomethacin was 1.981$\mu$g/ml$\cdot{min}^{1/2}$.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.193-200
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• 2003

The energy release rate for an interface crack in pseudo-isotropic dissimilar materials was obtained by the eigenfunction expansion method using the two-term William's type complex stress function. The complex stress function for pseudo-isotropic materials must be different from that for anisotropic materials. The energy release rate for an interface crack in pseudo-isotropic dissimilar materials was analyzed numerically by RWCIM. The results obtained were verified by comparing the other worker's results and discussed.

• Fire Science and Engineering
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• v.22 no.2
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• pp.104-107
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• 2008

Heat release rates of main combustibles in residence area were measured by a calorimeter using oxygen consumption method. It was found that the peak heat release rates of the combustibles were 1.0MW for a refrigerator, 0.8MW for a desk, 4.2MW for a wardrobe and 0.4MW for a bed. Especially, the refrigerator and wardrobe were found to be very hazardous because of their fast fire growth rate.

• Journal of Pharmaceutical Investigation
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• v.26 no.1
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• pp.13-22
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• 1996

Poly(D,L-lactic acid) (PLA) microspheres containing alprazolam(APZ) were prepared by a solvent-emulsion evaporation method and their release patterns were investigated in vitro. Various batches of microspheres with different size and drug content were obtained by changing the ratio of APZ to PLA, PLA concentration in the dispersed phase and stirring rate. Rod-like APZ crystals on microsphere surface, which were released rapidly and could act as a loading dose, were observed with increasing drug content. The release rate was increased with increase in drug contents and decrease in the molecular weight of PLA. The release rate of APZ for long-acting injectable delivery system in vitro, which would aid in predicting in vitro release profile, could be controlled by properly optimizing various factors affecting characteristics of microspheres.

• Archives of Pharmacal Research
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• v.19 no.1
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• pp.1-5
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• 1996

Laminated films composed of drug-containing reservoir layer and drug-free membrane were prepared. Zero-order drug release with lag time was achieved by laminating drug-free film onto the reservoir layer, while burst effect was observed on cast-on film. The rate controlling membrane was either attached to or cast directly into the reservoir. The release rate was independent on the reservoir composition but dependent on the composition of rate-controlling membrane. In growth inhibitory test of cephalexin from Eudragit RS film to Streptococcus Mutans, the disk even after release test for 72 hours showed more bacterial growth inhibition than that of control. Permeation of drug through rat skin was proportional to the HPC fraction in the film. We could control the release of cephalexin from the film by changing the fraction of Eudragit RS, HPC and DEP content. Consequently, Eudragit RS/HPC film was found to be very effective system for local delivery of drugs.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.701-709
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• 1998

Many dental composites are Bis-GMA based resin which diluted with the more fluid monomer triethylenglycol dimethacrylate(TEGDMA). TEGDMA is often present in exess so that some quantity remains unreacted following photo-initiated polymerization. TEGDMA is a component of some resin composites which contributes to their cytotoxicity. The presence of dentin between resin composite and pulp space reduce the cytotoxicity in vitro. The root system from extrcted human third molar was removed and then a circular occlusal cavity 4mm in diameter was prepared, leaving a remaining dentinal thickness to the roof of the pulpal chamber within the range 1.0-1.5mm. Dentine was treated with 37% phosphoric acid prior to Z 100 placement without using bonding resin(group 1). In group 2, SMP(Scotchbond Multi Purpose) primer, bonding resin prior to Z 100 placement were applied sequently. In group 3, moulds with internal dimensions 4mm diameter by 2mm depth were used to contain the composite alone with an equvalent mass on tooth model, and then they were immersed directly into water. The purpose of this study is to evaluate the release rate and quantity of TEGDMA with or without the application of bonding resin. Both release rate and total cumulative amount of TEGDMA for the three groups were determined using reversed-phase HPLC at times up to 10 days. The results were as follows: 1. All experimental groups showed the highest rate of release was in the first sample period(0-4.32 min) and the rate of release declined exponentially thereafter. 2. The maximum release rate and total cumulative account of TEGDMA in the tooth model of group 1 and group 2 with the use of SMP bonding resin were reduced however ther were no significant differences between these groups(P>0.05). 3. In the first sample period(0-4.32 min), the rate of release of TEGDMA from composite resin in group 3 immersed directly into water was significantly higher than that in group 1 and group 2 of tooth model(P<0.05). Conclusively, TEGDMA diffusion from Z 100 resin was not effectively prevented by the presence of dentin in spite of using the SMP bonding resin.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.349-356
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• 2020

The heat release rate (HRR) and fire growth rate of fire for the solid combustibles consisting of multi-materials was measured through the ISO 9705 room corner test, and the computational analysis in a closed compartment was performed to simulate a fire using the heat release rate prediction model provided by a Fire Dynamics Simulator (FDS). The method of predicting the heat release rate provided by the FDS was divided into a simple model and a pyrolysis model. Each model was applied and computational analysis was performed under the same conditions. As the solid combustible consisting of multi-materials, a cinema chair composed mostly of PU foam, PP, and steel was selected. The simple model was over-predicted compared to the predicted heat release rate and fire growth rate using the pyrolysis model in a closed compartment.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.213-219
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• 2006

Modified singular fracture process zone(S-FPZ) model is proposed in this paper to determine a fracture criterion for continuous crack propagation in concrete. The investigated fracture properties of the proposed fracture model are strain energy release rate at a micro-crack tip and the relationship between crack closure stress(CCS) and crack opening displacement(COD) in the FPZ. The proposed model can simulate the actual fracture energy of experimental results fairly well. The results of the experimental data analysis show that specimen geometry and loading condition did not affect the CCS-COD relation. However, the strain energy release rate is a function of not only specimen geometry but also crack extension. The strain energy release rate remained constantly at the minimum value up to the crack extension of 25 mm, and then it increased linearly to the maximum value. The maximum fracture criterion occurred at the peak load for specimens of large size. The fracture criterion remained at the maximum value after the peak load. The variation of the fracture criterion is caused by micro-cracking and micro-crack localization. The fracture criterion of strain energy release rate can simply be the size effect of concrete fracture, and it can be used to quantify the micro-cracking and micro-crack localizing behavior of concrete.

• Journal of Pharmaceutical Investigation
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• v.16 no.1
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• pp.12-17
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• 1986

Etilefrine hydrochloride was microencapsulated with ethylcellulose by phase separation method to develop a sustained release dosage form. The results of dissolution test carried out with various microcapsules showed that the drug release was decreased with increasing the particle size of microcapsules at a constant core to wall ratio, and with decreasing the core to wall ratio. Also ethylcellulose 50 cps and fast stirring rate (900 rpm) was better in decreasing the drug release than ethylcellulose 22 cps and slow stirring rate (300 rpm), respectively.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.405-410
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• 1996

New methodology for mass and energy release assessment in LBLOCA post blowdown is needed and, first of all, the phenomenologically improved and quantitative assessments through experiment are essential. For tile experiment of a hot leg break LBLOCA in post blowdown, the test facility was set and its feature is that tile broken hot leg has two broken sections in the tore side and in the SG side respectively and a separation valve between the two in order to measure the release rate dividedly. Specially it was focused on whether the mass release through the SG side broken section happened or not. The mass release through the core side broken section is dependent on tile safety injection flow and that through the SG side broken section varies depending on several factors. The principal factor is the primary system pressure and the subfactors such as SI flow rate, SI temperature and initial primary pressure, may contribute, too.