• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.752-754
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• 1997

The stress intensity factor for an interface crack in dissimilar materials has been obtained by many researchers. But research of the energy release rate for an interface crack in pseudo-isotropic dissimilar materials is insufficient yet. In this paper, the energy release rate for cracks in pseudo-isotropic dissimilar materials was obtained using eigenfunction expansion method and also analyzed numerically using the reciprocal work contour integral method. The results were verified by comparing with other worker's results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2174-2183
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• 2000

In this paper, the evaluation method of interfacial fracture toughness to apply the fracture toughness was investigated in adhesively bonded joints of AI/Ced./A1. Four types of adhesively bonded double-cantilever beam(DCB) joints with the interface crack were prepared for the test of interfacial fracture toughness. The experiments to measure the interfacial fracture toughness were performed under the various mixed-mode conditions. The critical energy release rate, Gc, was obtained by the experimental measurement of compliances. From the experimental results, the interfacial fracture toughness for the mixed-mode specimens is well characterized by the energy release rate, and the method of strength evaluation by the interfacial fracture toughness was discussed in adhesively bonded joints.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.171-178
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• 1996

DCB(pure mode I) and CLS(mixed mode) tests were performed to investigate the effect of fracture mode on the interlaminar fracture of composite laminate. Mode I critical strain energy release rate was found to be $133J/m^2$ from the DCB test and total strain energy release rate decreased from $1, 270J/m^2$ as thickness ratio(tl/t) varied from 0.333 to 0.667 from the crease from the CLS test. Crack length had no effect on the total strain energy release rate and load was almost constant during the crack growth of the specimen which had the specific thickness ratio. Crack initiated when the stress of the strap ply reached constant stress $42kgf/mm^2$ which was found to be independent of the thickness ratio.

• Macromolecular Research
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• v.11 no.4
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• pp.273-282
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• 2003

A hydrophilic macromolecular network containing hydrophobic moieties has been prepared by free radical copolymerization of acrylamide and styrene in the presence of poly(vinyl alcohol) (PVA) and its potential as controlled drug delivery carrier was evaluated with tetracycline as a model antibiotic drug. The amount of drug was assayed spectrophotometrically. The network was characterized by optical microscopy, infra-red spectroscopy and structural parameters such as average molecular weight between cross1inks ($M_c$), cross1ink density (q) and number of elastically effective chains ($V_e$) were evaluated. It was found that with increasing concentration of PVA, ST and MBA in the hydrogel, the release rate initially increases but after definite concentrations of the above components the release rate falls. In the case of AM, release rate constantly decreases with increasing AM concentration in the hydrogel.

• Fire Science and Engineering
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• v.12 no.3
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• pp.31-37
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• 1998

The heat release rate of liquid fuels is estimated by oxygen consumption technique. This method is based on the generalization that the heat release rate of combustion per unit of oxygen consumed are approximately the same for most fuels commonly encountered in fires. The oxygen concentration is measured by analyzer of paramagnetic type. The concentrations of CO2 and CO gas are measured by analyzed of Infra-Rad type. Time delays of analyzers are ignored. Results acqired from measuring techniques of exhaust gas concentrations are compared with each other.

• Advances in materials Research
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• v.11 no.1
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• pp.41-57
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• 2022

This paper is focused on delamination analysis of a multilayered inhomogeneous viscoelastic beam subjected to linear creep under constant applied stress. The viscoelastic model that is used to treat the creep consists of consecutively connected units. Each unit consists of one spring and two dashpots. The number of units in the model is arbitrary. The modulus of elasticity of the spring in each unit changes with time. Besides, the modulii of elasticity and the coefficients of viscosity change continuously along the thickness, width and length in each layer since the material is continuously inhomogeneous in each layer of the beam. A time-dependent solution to the strain energy release rate for the delamination is derived. A time-dependent solution to the J-integral is derived too. A parametric analysis of the strain energy release rate is carried-out by applying the solution derived. The influence of various factors such as creep, material inhomogeneity, the change of the modulii of elasticity with time and the number of units in the viscoelastic model on the strain energy release rate are clarified.

• Korean Journal of Clinical Pharmacy
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• v.21 no.4
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• pp.347-352
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• 2011

Health insurance review & Assessment service (HIRA) has enforced cutting the drug costs when physicians prescribe split extended release drugs, starting from December, 2010. The objective of this study is to analyze extended release and enteric coated drugs on pharmaceutical reimbursement list in Korea, and to investigate the impact and barriers of the health insurance review on splitting extended-release formulation drugs. By using the ingredient code, extended release and enteric coated formulations make up 7.8% of all drugs in April, 2011. The most frequently used drugs are agent affecting circulatory and digestive system. From the extended release and enteric coated formulations (n=112), 34.8% (n=39) were not available in other dosage forms. According to questionnaire survey for 169 pharmacists (response rate: 73.8%), the rate of splitting and crushing of extended release and enteric coated drugs decreased. When pharmacists correct physician's prescription errors, the biggest problem was lack of other dosage forms. So it is necessary to develop variety of other dosage forms, and computerized checking system for splitting extended-release drugs. It is also important to inform physicians and patients in regard to the problems of split prescription of extended release and enteric coated drugs.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.213-214
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• 2008

• The Korean Journal of Pharmacology
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• v.31 no.2
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• pp.145-152
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• 1995

The effects and interactions of $4{\beta}-phorbol$ 12,13-dibutyrate(PDB) and polymyxin B(PMB) with adenosine on the electrically-evoked norepinephrine (NE) release were studied in the rat hippocampus. Slices from the rat hippocampus were equilibrated with $^3H-noradrenaline$ and the release of the labelled product, $^3H-NE$, which evoked by electrical stimulation$(3\;Hz,\;2\;ms,\;5\;VCm^{-1},\;rectangular\;pulses)$ was measured. PDB$(0.3{\sim}10\;{\mu}M)$, a selective protein kinase C(PKC) activator, increased the evoked NE release in a dose related fashion while increasing the basal rate of release. And the effects of $1\;{\mu}M$ PDB were significantly inhibited by $0.3\;{\mu}M$ tetrodotoxin(TTX) pretreatment or $Ca^{++}-free$ medium. $PMB(0.03{\sim}1\;mg)$, a specific PKC inhibitor, decreased the NE release in a dose dependent manner while increasing the basal rate of release. Adenosine $(1{\sim}10\;{\mu}M)$ decreased the NE release without changing the basal rate of release, and this effect was significantly inhibited by 8-cyclopentyl-1,3-dipropylxanthine$(2\;{\mu}M)$, a selective $A_1-receptor$ antagonist, treatment. Also, adenosine effects were significantly inhibited by PDB-and PMB-pretreatment. These results suggest that the PKC plays a role in the NE release in the rat hippocampus and might be participated in a post-receptor mechanism of the $A_1-adenosine$ receptor.

• Fire Science and Engineering
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• v.17 no.1
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• pp.76-84
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• 2003

This study was designed to investigate fire characteristics of the plastics insulating materials such as a polystyrene foam, polyurethane foam, and polyethylene foam, which is used an insulating materials i3t workplace. The fire characteristics of plastic insulating materials were carried out from the Cone Calorimeter test according to ISO 5660. The experimental materials used were commercial plastic insulating materials by products and their composition is not disclosed by the manufacturer. As the results of this study; the heat release rate of plastic insulating materials was increased with increasing density and heat flux. The peak heat release rate and the average heat release rate for the polyethylene foam in insulating materials were showed the highest, and the peak heat release rate for the polyethylene foam was the highest. The standard of heat release rate with a kind of products and heat flux of irradiance to prevent fire by plastic insulating materials was suggested.