• Journal of the Korean Applied Science and Technology
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• v.28 no.4
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• pp.410-417
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• 2011

Effects of ethylene-propylene diene monomer (EPDM)/polypropylene (PP), zinc oxide, stearic acid, and clay on the combustive properties based on EDPM/PP were investigated. The EDPM/PP/clay nanocomposites was compounded to prepare specimen for combustive analysis by cone calorimeter (ISO 5660-1). It was found that the specific mass loss rate (SMLR) in the nanocomposites decreased due to the fire resistance compared with unfilled EDPM/PP, while the nanocomposites showed the higher total heat release (THR), higher CO production release, and higher specific extinction area (SEA) than those of virgin EPDM/PP. The stearic acid for softening ruber increased the THR and amount of smoke by itself, combustible.

• Nano
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• v.13 no.12
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• pp.1850137.1-1850137.9
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• 2018

A series of silica surface-capped with hexamethyldisilazane (denoted as $H-SiO_2$) were prepared by liquid-phase in-situ surface-modification method. The as-obtained $H-SiO_2$ was incorporated into acrylic amino (AA) baking paint to obtain AA/$H-SiO_2$ composite extinction paints and/or coatings. $N_2$ adsorption-desorption tests were conducted to determine the specific surface area as well as pore size and pore volume of $H-SiO_2$. Moreover, the effects of $H-SiO_2$ matting agents on the physical properties of AA paint as well as the gloss and transmittance of AA-based composite extinction coatings were investigated. Results show that $H-SiO_2$ matting agents possess a large specific surface area and pore volume than previously reported silica obtained by liquid-phase method. Besides, they have better dispersibility in AA baking paint than the unmodified silica. Particularly, $H-SiO_2$ with a silica particle size of $6.7{\mu}m$ and the dosage of 4% (mass fraction) provides an extinction rate of 95.2% and a transmittance of 79.3% for the AA-based composite extinction coating, showing advantages over OK520, a conventional silica matting agent. Along with the increase in the silica particle size, $H-SiO_2$ matting agents cause a certain degree of increase in the viscosity of AA paint as well as a noticeable decrease in the gloss of the AA-based composite extinction coating, but they have insignificant effects on the hardness and adhesion to substrate of the AA-based composite coatings. This means that $H-SiO_2$ matting agents could be well applicable to preparing low-viscosity and low-gloss AA-based matte coatings.

• Journal of Ecology and Environment
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• v.32 no.2
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• pp.103-107
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• 2009

We investigated colonization and extinction patterns in a meta population of the gold-spotted pond frog (Rana planeyi ehoseniea) near the Korea National University of Education, Chungbuk, Korea, by surveying the frogs in the nine occupied habitat patches in the study area four times per breeding season for three years (2006$\sim$2008) and recording whether the patches were occupied by frogs as well as how many frogs were calling in the patches. We then developed five a priori year-specific models using the Akaike Information Criterion (AIC). The models predicted that: 1) probabilities of colonization and local extinction of the frogs were better explained by year-dependent models than by constant models, 2) there are high local extinction and low colonization probabilities, 3) approximately 31% number of patches will be occupied at equilibrium, and 4) that considerable variation in occupation rate should occur over a 30-year period, due to demographic stochasticity (in our model, the occupation rate ranged from 0.222 to 0.889). Our results suggest that colonization is important in this metapopulation system, which is governed by mainly stochastic components, and that more constructive conservation effects are needed to increase local colonization rates.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.768-776
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• 2015

This study was performed to understand combustion properties four major Indonesian wood species such as Albizia, Gmelina, Mangium and Mindi were investigated by cone-calorimeter for better utilization of theses wood species. Heat release rate (HRR), total heat release (TSR), specific mass loss rate (SMLR), effective heat of combustion (EHC), time to ignition (TTI), flame time (FT), specific extinction area (SEA), smoke production rate (SPR) and CO compound production rate were measured. HRR, THR and FT were proportional to the density of woods. Albizia showed the highest HRR, while Mindi had the lowest HRR. For SPR, Albizia showed the highest value due to its higher SEA. On the other hand, Mindi had the lowest SPR due to a lower SEA value. The highest smoke emission was for Albizia at the beginning of combustion. After 300 seconds, smoke emission of Gmleina and Mangium was increased greatly. Mangium and Mindi showed the highest total carbon dioxide emission. Expecially, Gmelina released the highest carbon monoxide during the combustion period and presented three times higher $CO/CO_2$ ratio than those of other species due to incomplete combustion.

• Journal of Plant Biology
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• v.28 no.1
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• pp.1-8
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• 1985

To verify the cause of high productivity in Typha stand, leaf area index(LAI), leaf orientation and inclination, specific leaf area (SLA), and radiation interception profiles were determined in a natural Typha$\times$glauca stand. Throughout the growing season, the leaf inclination has been kept at near-right angle and leaf orientation has been random. These chracteristics were responsible for an uniform spatial arrangement of the leaves within the canopy and could be explained by the SLA value, which increased in their higher strata. The extinction coefficient (K) of the canopy, 0.12 to 0.20, was one of the smallest value out of terrestrial plant communities. At least more than 25% of full radiation penetrated into the lowest stratum of the canopy. High productivity of the Typha would be attributed to efficient penetration of the radiation in virtue of the stiff and straight leaves even though rather small LAI.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.413-418
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• 2018

Cypress woods treated individually with boric acid (BA4), ammonium pentaborate (APB4), or BA4/APB4 additives were examined for combustion gases. Each of the specimens was painted with a 4 wt% solution of boron compounds three times. Dried at room temperature, the combustion gas was analyzed using a cone calorimeter (ISO 5660-1). Consequently, the second maximum oxygen consumption rate of the specimen treated with boron compounds was 0.1067 to 0.1246 g/s, which was 5.3 to 18.9%, respectively lower than that of the blank specimen. The specific extinction area of specimens treated with BA4 and APB4 was also 2.0 to 19.0% lower, respectively. However, treated with BA4/APB4 showed 21.2% higher than that of the blank specimen. The maximum carbon monoxide concentration of the specimens with boron compounds was reduced by 0 to 25%. It was estimated to be 1.6 to 2.2 times higher than the permissible exposure limits by Occupational Safety and Health Administration (OSHA), indicating a fatal toxicity. The boron compounds were effective in reducing carbon monoxide, but didn't meet the OSHA limit. The boron compound inhibited the burning behavior of the cypress wood, which suppressed the second maximum oxygen consumption rate by 5.3 to 18.9% and the maximum carbon monoxide generation by 0 to 25%.

• Journal of Ecology and Environment
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• v.46 no.4
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• pp.316-323
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• 2022

Background: We developed a habitat suitability index (HSI) model for Pedicularis hallaisanensis, a Grade II Endangered Species in South Korea. To determine the habitat variables, we conducted a literature review on P. hallaisanensis with a specific focus on the associated spatial factors, climate, topography, threats, and soil factors to derive five environmental factors that influence P. hallaisanensis habitats. The specific variables were defined based on the collected data and consultations with experts in the field, with the validity of each variable tested through field studies. Results: Mt. Seorak had a suitable habitat area of 2.48 km² for sites with a score of 1 (0.62% of total area) and 0.01 km² for sites with a score of 0.9. Mt. Bangtae had a suitable habitat area of 0.03 km² for sites with a score of 1 (0.02% of total area) and 0 km² for sites with a score of 0.9. Mt. Gaya showed 0.13 km² of suitable habitat for sites with a score of 1 (0.17% of total area) and 0 km² for sites with a score of 0.9. Lastly, Mt. Halla showed 3.12 km² of suitable habitat related to sites with a score of 1 (2.04% of total area) and 4.08 km² of sites with a score of 0.9 (2.66% of total area). Mt. Halla accounts for 73.1% of the total core habitat area. Considering the climatic, soil, and forest conditions together with standardized collection sites, our results indicate that Mt. Halla should be viewed as a core habitat of P. hallaisanensis. Conclusions: The findings in this study provide useful data for the identification of core habitat areas and potential alternative habitats to prevent the extinction of the endangered species, P. hallaisanensis. Furthermore, the developed HSI model allows for the prediction of suitable habitats based on the ecological niche of a given species to identify its unique distribution and causal factors.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.3
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• pp.190-198
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• 2006

Radiation use efficiency (RUE), the amount of biomass produced per unit intercepted photosynthetically active radiation (PAR), constitutes a main part of crop growth simulation models. The objective of the present study was to evaluate the variation of RUE of rice plants under various nitrogen nutritive conditions. from 1998 to 2000, shoot dry weight (DW), intercepted PAR of rice canopies, and nitrogen nutritive status were measured in various nitrogen fertilization regimes using japonica and Tongil-type varieties. These data were used for estimating the average RUEs before heading and the relationship between RUE and the nitrogen nutritive status. The canopy extinction coefficient (K) increased with the growth of rice until maximum tillering stage and maintained constant at about 0.4 from maximum tillering to heading stage, rapidly increasing again after heading stage. The DW growth revealed significant linear correlation with the cumulative PAR interception of the canopy, enabling the estimation of the average RUE before heading with the slopes of the regression lines. Average RUE tended to increase with the increased level of nitrogen fertilization. RUE increased approaching maximum as the nitrogen nutrition index (NNI) calculated by the ratio of actual shoot N concentration to the critical N concentration for the maximum growth at any growth stage and the specific leaf nitrogen $(SLN;\;g/m^2\;leaf\;area)$ increased. This relationship between RUE (g/MJ of PAR) and N nutritive status was expressed well by the following exponential functions: $$RUE=3.13\{1-exp(-4.33NNNI+1.26)\}$$ $$RUE=3.17\{1-exp(-1.33SLN+0.04)\}$$ The above equations explained, respectively, about 80% and 75% of the average RUE variation due to varying nitrogen nutritive status of rice plants. However, these equations would have some limitations if incorporated as a component model to simulate the rice growth as they are based on relationships averaged over the entire growth period before heading.

• Korean Journal of Environment and Ecology
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• v.36 no.2
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• pp.177-201
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• 2022

Following the adoption of the global plant conservation strategies at the Conference of the Parties for Biodiversity Conservation, diligent actions to achieve each targets are actively carried out. In particular, the need for ecological conservation research to achieve targets 2 and 7 of GSPC-2020 has increased. The priority taxa to accomplish the objectives of GSPC-2020 are rare and endemic plants. In particular, endemic plants with limited distribution in specific regions are evaluated to face a high risk of extinction. To address the necessity to preserve endemic plants, we investigated the distribution of Prunus choreiana H. T. Im, a Korean endemic plant. After that, we examined the vegetational environment of the habitat of P. choreiana and evaluated its population structure. The productivity of its fruits and the effects of pollinators on fruit production were evaluated as well. The fruiting ratio was calculated based on the number of flowers produced. Lastly, we observed the annual growth characteristics of P. choreiana. The habitats of P. choreiana did not show a specific type of vegetation. All of them were located in a limestone area of Gangwon-do in the central Korean Peninsula and occupied a site where the coverage of the tree layer and the sub-tree layer was not high or did not exist. The population structure of P. choreiana contained a high proportion of mature plants capable of producing fruits and a low proportion of seedlings and Juvenile plants. We found that the production of fruits required pollinators and was affected by the performance of each plant. Although P. choreiana produces many flowers, only a maximum of 20% and only 2-6% on average bear fruits. These flowering characteristics may be due to pollinators' low abundance and activity during the flowering season (between mid-March and early April), suggesting that many flowers are needed to attract more pollinators. We rarely observed the re-establishment of seedlings in the population of P. choreiana. Despite that, we predict the population to persist owing to its long lifespan and periodic production of numerous fruits. However, if the tree layer and sub-tree layer in competing status with P. choreiana increase their crown density, they are expected to inhibit the growth of P. choreiana and affect the risk of its extinction. Therefore, the current changes in the vegetational environment of the habitats are expected to decrease the number and extent of P. choreiana in the long term. The results of this study may serve as primary and important data necessary for the achievement of GSPC-2020 objectives.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.45-53
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• 2008

The burning behaviors of board for flooring materials were investigated using cone calorimetry at an incident heat flux of $50kWm^{-2}$. Seven domestic flooring materials were used to observe the burning behavior of maximum heat release rate, total heat release and average heat release rate. The experimental data indicated that the medium density fiberboard (MDF) flooring had higher release rate than the other flooring materials. Also, the mass loss of MDF flooring was higher than the other floors. When measuring the smoke production from burning, PE fiberboard flooring and PVC Plastic Resin Sheet showed higher carbon monoxide and carbon dioxide yield than the others. The average smoke release of both carbon dioxide and carbon monoxide through specific extinction area was similar. Toxic smoke measurement from flooring materials were determined by the mouse stop motion, and the results indicated that MDF flooring contains more toxic material than the other flooring materials.