• Fire Science and Engineering
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• v.31 no.5
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• pp.19-27
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• 2017

The effects of changes in area and location of fire source, fire growth rate, and volume of compartment on the major fire characteristics, including heat release rate, in closed compartment fires were examined. To this end, a fire simulation using Fire Dynamics Simulator (FDS) was performed for ISO 9705 room with a closed opening. As main result, it was found that the changes in the area and location of fire source did not significantly affect the thermal and chemical characteristics inside the compartment, such as maximum heat release rate, total heat release, maximum temperature at upper layeras well as species concentrations. However, increasinthe fire growth rate and volume of compartment resulted in increase of the maximum heat release rate and total heat release, decrease in the limiting oxygen concentration and increase in the maximum CO concentration. Finally, a methodology for the application of fire growth curves to closed compartment fires was proposed by deriving the correlation of the maximum heat release rate expressed as a function of the fire growth rate and the volume ratio of compartment based on the ISO 9705 room.

• Journal of Pharmaceutical Investigation
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• v.20 no.2
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• pp.89-95
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• 1990

Ethylcellulose-PEG 4000 film coated on core tablets was investigated as a potential drug delivery system for the controlled release of chlorpheniramine maleate (CPM). The kinetic analysis of the release data indicated that CPM release followed a diffusion-controlled model, where the quantity released per unit area is proportional to the square root of time. The effect of the film composition, CPM concentration, plasticizer concentration and CPM solubility on the release characteristics were examined. The release rate constant increased as CPM concentration increased. It also increased as the PEG 4000 content in the film increased above 10%(w/w), however, it decreased as the PEG 4000 content increased in the concentration range below 10%(w/w). The release rate constant was not affected by the coated weight on the core tablet. The film-coated tablets which contain CPM only in the coated film layer seemed to be a potential oral drug delivery system for the controlled release of CPM.

• Journal of the Korean Society of Safety
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• v.24 no.4
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• pp.96-103
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• 2009

This study was fulfilled to investigate the forest fire risk of forest fuels based on the combustion characteristics of living leaves of coniferous trees and broadleaf trees naturally growing in Youngdong areas of Gangwon Province by using cone calorimeter and smoke density chamber. According to the result, Pinus densiflora and Pinus rigida among coniferous trees released a greater amount of heat release than other kinds. The total smoke release varied depending on the species, whereas Pinus koraiensis showed the largest amount of smoke release. With regard to maximum smoke density, it was much higher in coniferous trees than in broadleaf trees. With regard to smoke temperature, Pinus densiflora showed the lowest compared to other kinds up until 200s from the ignition, but all most trees uniformly maintained constant temperature of about $70^{\circ}C$ after 200s. The concentrations of CO and $CO_2$ release were drastically increased at about 150s and then gradually decreased thereafter. Pinus densiflora showed a bit higher CO release than broadleaf trees, but there was no distinct difference in $CO_2$ release among tress.

• Archives of Pharmacal Research
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• v.13 no.4
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• pp.293-297
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• 1990

Sustained release microspheres containing phenylpropanolamine HCI (PPA) were prepared with acrylic polymer (Eudragit RL/RS) sand hydroxypropylmethylcellulose phthalate (HPMCP) using a emulsion-solvent evaporation method. Magnesium strate was used a smoothing agent for preparation of microspheres. The microspheres obtained were very spherical and free-flowing particles. Scanning electron microscopy showed that microspheres have a smooth surface and a sponage-like internal structure. The dissolution rate of PPA from the microspheres was dependent on the pH of dissolution media. PPA showed faster relase in hP 1. 2 solution than in pH 7.4 solution due to the solubility of PPA. Therefore we prepared new microspheres containing 5% (w/v) HPMCP in order to control the release of PPA. The release rate of PPA from these new microspheres was similar in pH 1.2 and pH 7.4 solution.

• Nuclear Engineering and Technology
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• v.33 no.6
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• pp.557-565
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• 2001

Variations in the number of early health effects resulting from the severe accidents of the YGN 3&4 nuclear power plants were examined for different combinations of release parameters and meteorological data . The release parameters and meteorological data were selected in combination to define a limited number of basic spectra characterized by release height, heat content, release time, warning time, wind speed, rainfall rate, and atmospheric stability class. Variant seasonal spectra were also defined in order to estimate the potential significance of seasonal variations as a factor determining the incidence or number of early health effects. The results show that there are large differences in consequences from spectrum to spectrum, although an equal amount and mix of radioactive material is released to the atmosphere in each case. Also, there are large differences in the estimated number of health effects from season to season due to distinct seasonal variations in meteorological combinations in Korea. Therefore, it is necessary to consider seasonal characteristics in developing optimum emergency response strategies.

• Journal of the Korean Society for Railway
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• v.7 no.1
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• pp.55-59
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• 2004

Composite materials were used widely due to merit of light weight, low maintenance cost and easy installation. But it is the cause of enormous casualties to men and properties because of weak about the fire. Particularly, it is more serious in case of subway train installed composite materials. For this reason, experimental comparison has been done fur measuring heat release rate(H.R.R) and smoke production rate(S.P.R) of interior panels of electric motor car using cone calorimeter. A high radiative heat flux of 50kW/㎡ was used to bum out all materials and to simulate the condition of fully developed fire case in the tests. It was observed that Heat Release Rate and Smoke Production Rate curves were dependent on the kinds of the interior materials. From the heat release rate curves, the sustained ignition time, peak heat release rate and total heat release rate were deduced, These data are useful in classifying the materials by calculating two parameters describing the possibility to flashover.

• Journal of the Korean Society of Combustion
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• v.17 no.1
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• pp.30-36
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• 2012

Dynamic characteristics of combustion occurring in various combustion devices have been extensively studied since most of high-performance combustion devices are susceptible to hazardous, unstable combustion that deteriorates combustor's lifetime. One of the most severe unstable combustion phenomena is high-frequency combustion instability in which heat release fluctuations from combustion are coupled to resonant modes of the combustor. Here in this study, characteristics of high-frequency combustion instabilities observed in three different combustion devices have been presented. Lean-premixed combustion instability occurs mainly due to equivalence ratio fluctuations which induce large heat release oscillations at lean conditions. Liquid-fueled combustion also shows high-frequency instability from energy coupling between pressure and heat release oscillations.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.503-512
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• 2012

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan New Port including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. In addition, Yongwon channel is approximately 100 m wide on average and 3,600 m long, and has the highest slenderness ratio (length/width = 36). So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. In this study, the bottom sediment were collected from the 48 points of the Yongwon channel and the long-term leaching characteristics were analyzed. Thus, changes in sediment and water quality were analyzed through the sediment release test to investigate the degree of contamination. The sediment release from the inside region was higher than the outer region, which is due to the pollutant that comes form the downtown area. The results of this study can be used to predict the water quality in the future and prepare the economically optimized countermeasures to improve the water quality of Yongwon channel, Busan New Port.

• The korean journal of orthodontics
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• v.22 no.1
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• pp.273-283
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• 1992

To find out the differences between periodontal ligament cells (PDL cells) and gingival fibroblast cells (GFB cells), alkaline phosphatase, a marker enzyme for osteoblast, was used to measure the activities and $^{45}CaCl_2$ isotope was used to find out cellular and release of $^{45}Ca$, a requisite for bone formation,. PDL cells and GFB cells from 1 to 5 passages were also measured in alkaline phosphatase activity assay. By the use of above methods, followings were concluded that the PDL cells and the GFB cells have characteristics that are different from each other. In that PDL cells showed large amount of calcium uptake and large amount of calcium release in initial stage, they seem to possess characteristics which are similar to osteoblast-like cells. 1. The PDL cells, in contrast to the gingival fibroblast, showed exceedingly high alkaline phosphatase activity which was highest at the second passage, decreasing thereon. But gingival fibroblasts cells showed no distinct differences in alkaline phosphatase activity as the passage were elapsed. 2. For both PDL cells and GF cells, the $^{45}Ca$ uptake was greatest at 2 hours period. The PDL cells showed higher measuring than GFB cells through out the whole time period. 3. Whereas the GFB cells showed slow increase of $^{45}Ca$ release as time relapsed, the PDL cells showed rapid increase of $^{45}Ca$ release.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.21-24
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• 2014

In this study, we have investigated the maximum smoke density and the initial stage smoke density in order to see the characteristics of smoke release of the architectural surface materials and the architectural adhesives, using smoke density chamber. As a result of the study, polyurethane foam showed the highest smoke density index, 206.55 within 10 min. In the case of the other samples, reinforced styrofoam was followed as 39.90, general styrofoam 33.73, and glass fiber 5.40, respectively. In the intial stage of a fire, it is forecasted actually to give hardship at the clear visibility. In the case of architectural adhesives, the highest ranking was those for windows and doors 509.64, stone 275.63, wood 232.25, tile 18.65, and styrofoam 6.44 were followed, respectively. This result is an early research to show characteristics of smoke release through experiment. However, it is meaningful that this study can be used as a basic for further study on architectural fire hazard prediction.