• Fire Science and Engineering
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• v.23 no.4
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• pp.25-31
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• 2009

With rapid growths of economy and technology, structures and forms of buildings have been diversified and complicated. Buildings also have become higher and larger than ever before. As a result, more people use a building and more combustibles exist in the building. Without understanding of combustion characteristics and the establishment of a fire safety plan in case of a residential fire, it is expected great loss of lives and properties. In this study, experiments were carried out to promote an understanding of the combustion characteristics of combustibles in the building. Sofa and bed were used as combustibles in the experiment. Heat release rate of the sofa was about 1.9MW. Heat release rate of the bed was approximately 650kW.

• Archives of Pharmacal Research
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• v.28 no.8
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• pp.983-987
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• 2005

Hydrogels composed of glycidyl methacrylate dextran (GMD) and poly(acrylic acid, PM) were prepared by UV irradiation method for colon-specific drug delivery. GMD was synthesized by coupling of glycidyl methacrylate to dextran in the presence of 4-(N,N-dimethylamino)pyridine. GMD was photo-polymerized by ammonium peroxydisulfate as initiating system in phosphate­buffered solution (0.1 M, pH 7.4). And then, acrylic acid monomer was added and subsequently heat-polymerized by 2,2'-azobisisobutyronitrile as an initiator. The hydrogels exhibited high swelling ratio (about 20) at $37^{\circ}C$, and showed a pH-dependent swelling behavior. In addition, the swelling ratio of the hydrogel was remarkably enhanced to about 45 times in the presence of dextranase at pH 7.4. The swelling-deswelling behavior proceeded reversibly for the GMD/PM hydrogels between pH 2 and pH 7.4. Release of 5-aminosalicylic acid from the GMD/PAA hydrogels was evaluated in simulated gastrointestinal pH fluids in the absence or presence of dextranase. We concluded that the hydrogels prepared could be used as a dual-sensitive drug carrier for sequential release in gastrointestinal tract.

• Nuclear Engineering and Technology
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• v.28 no.3
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• pp.229-246
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• 1996

A mechanistic model has been developed to predict the release behavior of fission gas during steady-state irradiation of LWR UO$_2$ fuel. Under the assumption that UO$_2$ grain surface is composed of fourteen identical circular faces and grain edge bubble can be represented by a triangulated tube around the circumference of three circular grain faces, it introduces the concept of continuous formation of open grain edges tunnels that is proportional to grain edge swelling. In addition, it takes into account the interaction between the gas release from matrix to grain boundary and the reintroduction of gas atoms into the matrix by the irradiation-induced re-solution of grain face bubbles. It also treats analytically the behavior of intragranular, intergranular, and grain edge bubbles under the assumption that both intragranular and intergranular bubbles are uniform in both radius and number density. Comparison of the present model with experimental data shows that the model's prediction produces reasonable agreement for fuel with centerline temperatures of 1000 to 140$0^{\circ}C$, wide scatter band for fuel with centerline temperatures lower than 100$0^{\circ}C$, and underprediction for fuel with centerline temperatures higher than 140$0^{\circ}C$.

• Journal of the Korean Society of Safety
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• v.34 no.3
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• pp.1-7
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• 2019

A variety of composite materials are applied to industries for the realization of light weight and high strength. Fiber-reinforced composites have different strength and range of application depending on the weaving method. The mechanical performance of CFRP(Carbon Fiber Reinforced Plastic) in many areas has already been demonstrated. Recently, the application of hybridization has been increasing in order to give a compensation for brittleness of CFRP. Target materials are UHMWPE (Ultra High Molecular Weight Polyethylene), which has excellent cutting and chemical resistance, so it is applied not only to industrial safety products but also to places that lining performance is expected for household appliances. In this study, the CFRP and UHMWPE of plain weave, which are highly applicable to curved products, were molded into laminated hybrid composite materials by autoclave method. The mechanical properties and the mode I failure behavior between the layers were evaluated. The energy release rate G has decreased as the initial crack length ratio increased.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.353-363
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• 2019

This paper presents a comprehensive simulation and assessment of gas dispersion above sea from a subsea release using a Computational Fluid Dynamics (CFD) approach. A 3D CFD model is established to evaluate the behavior of flammable gas above sea, and a jack-up drilling platform is included to illustrate the effect of flammable gas cloud on surface vessels. The simulations include a matrix of scenarios for different surface release rates, distances between surface gas pool and offshore platform, and wind speeds. Based on the established model, the development process of flammable gas cloud above sea is predicted, and the dangerous area generated on offshore platform is assessed. Additionally, the effect of some critical factors on flammable gas dispersion behavior is analyzed. The simulations produce some useful outputs including the detailed parameters of flammable gas cloud and the dangerous area on offshore platform, which are expected to give an educational reference for conducting a prior risk assessment and contingency planning.

• Journal of the Korean Wood Science and Technology
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• v.30 no.3
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• pp.18-25
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• 2002

Research to discuss the fire performance of materials requires tools for measuring their burning characteristics and validated fire growth models to predict fire behavior of the materials under specific tire scenarios using the measured properties as input for the models. In this study, burning characteristics such as time to ignition, weight loss rate, flame spread, heat release rate, total heat evolved, and effective heat of combustion for four types of wood-based materials were evaluated using the cone calorimeter and inclined panel tests. Time to ignition was affected by not only surface condition and specific gravity of the tested materials but also the type and magnitude of heat source. Results of weight loss rate, measured by inclined panel tests, indicated that heat transfer from the contacted flame used as the heat source into the inner part of the specimen was inversely proportional to specific gravity of material. Flame spread was closely related with ignition time at the near part of burning zone. Under constant and severe external heat flux, there was little difference in weight loss rate and total heat evolved between four types of wood-based panels. More applied heat flux caused by longer ignition time induced a higher first peak value of heat release rate. Burning characteristics data measured in this study can be used effectively as input for fire growth models to predict the fire behavior of materials under specific fire scenarios.

• Macromolecular Research
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• v.11 no.3
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• pp.183-188
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• 2003

The controlled delivery of anticancer agents using biodegradable polymeric implant has been developed to solve the problem of penetration of blood brain barrier and severe systemic toxicity. This study was performed to prepare 5-FU-loaded poly (L-lactide-co-glycolide) (PLGA) wafer fabricated microparticles prepared by two different method and to evaluate their release profile for the application of the treatment of brain tumor. 5-FU-loaded PLGA microparticles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and differential scanning calorimetry (DSC). SEM observation of the 5-FU-loaded PLGA microparticles prepared by rotary solvent evaporation method showed that 5-FU was almost surrounded by PLGA and significant reduction of crystallinity of 5-FU was confirmed by XRD. In case of release profile of 5-FU from 5-FU-loaded PLGA wafer fabricated microparticles prepared by mechanical mixing, the release profile of 5-FU followed near first order release kinetics. In contrast to the above result, release profile of 5-FU from 5-FU-loaded PLGA wafer fabricated microparticles prepared by rotary solvent evaporation method followed near zero order release kinetics. These results indicate that preparation method of the 5-FU-loaded PLGA microparticles to fabricate into wafers was contributed to drug release profile.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7549-7554
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• 2015

The aim of this study was to develop gastric retentive bi-layered tablet using floating drug delivery technique. Metformin was selected as a model drug due to its narrow absorption window as well as very highly water solubility. These properties of metformin led to be difficult controlling the drug release. The bi-layered tablet was prepared with bi-layered compression machine to minimize interference between floating part and controlling part. The tablet weight, appearance and hardness were evaluated after compression process. The times of 'time to floating' and 'Floating duration' were tested for floating ability and drug release study was also carried out to understand drug release behavior. Furthermore, the drug release of bi-layered tablet was compared with marketed metformin tablet with sustained release pattern (Glucopharge XR$^{(R)}$).The floating ability and drug release behaviors were well controlled by changing amounts of $NaHCO_3$ (floating substance) and hydroxypropyl methylcellulose (HPMC; release control material). Bi-layered tablet had 13s of time to float, over 10h of floating duration and very similar drug release behavior compared with Glucopharge XR$^{(R)}$($f_2$: 89.6). Consequently, the bi-layered tablet with floating ability was successfully prepared and these properties can maximize the efficacy of metformin.

• Carbon letters
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• v.10 no.3
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• pp.208-212
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• 2009

Alginate-chitosan blend containing coconut-based activated carbon was prepared as a drug delivery carrier in order to improve the loading and releasing capacity of the drug. The activated carbon was incorporated as effective adsorbent for drug due to the extremely high surface area and pore volume, high adsorption capacity, micro porous structure and specific surface activity. Alginate-chitosan blend containing coconut-based activated carbon showed the sustained release for a longer period. Alginate-chitosan blend showed higher release of drug as the pH increased and higher release of drug as the content of chitosan decreased due to the pH-dependent solubility of blend components.

• Carbon letters
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• v.11 no.2
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• pp.122-126
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• 2010

The alginate-based hydrogel was prepared as a pH-sensitive drug delivery system. To enhance the drug loading capacity, activated carbon was introduced as a drug absorbent. The iron oxide was incorporated into the alginate matrix for the magnetic transferring to the target organ. The activated carbon and iron-oxide were dispersed uniformly in the alginate hydrogel. The drug release from the alginate/activated carbon composite hydrogel was carried out in various pH conditions with vitamin B12 and Lactobacillus lamnosers as model drugs. The fast and sustainable release of drug was observed in the basic condition due to the pH-sensitive solubility of alginate. The novel drug delivery system having pH-sensitive release property and magnetic movement to target place was developed by using the alginate/activated carbon composite magnetic hydrogels.