• Korean Journal of Environment and Ecology
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• v.15 no.4
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• pp.354-360
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• 2002

To investigate the structure and the conservation strategy of Natural forest at the ridge from Gittaebong to Cheongoksan area 34 plots(10m$\times$10m) were set up with random sampling method. Three groups(Quercus mongolica community, Quercus mongolica-Tilia amurensis community. Quercus mongolica-Fraxinus rhynchophylla community) were classified by cluster analysis. High positive correlations were proved between Quercus mongolica and Pinus densiflora; Pyrus pyrifolia and Viburnum sargentii, Euonymus sachalinensis; Fraxinus sieboldiana and Rhododendron schlippenbachii, Pinus densiflora; Symplocos chinensis for. Pilosa and corylus sieboldiana var. mandshurica, Rhus trichocarpa Lespedeza bicolor; Rhododendron schlippenbachii and Rhododendron mucronulatum; Weigela subsessilis and Euonymus sachalinensis, Rhus trichocarpa, Lespedeza bicolor; Rhus trichocarpa and Lespedeza bicolor and high negative corrlations were proved between Quercus mongolica and Tilia amurensis, Acer Pseudo-sieboldianum. Species diversity(H') of investigated area was 0.5981~0.8150.

• Particle and aerosol research
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• v.9 no.2
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• pp.89-102
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• 2013

24-hr $PM_{2.5}$ samples were collected from January 19 through February 27, 2009 at an urban site of Gwangju and analyzed to determine the concentrations of organic and elemental carbon(OC and EC), water-soluble OC(WSOC), eight ionic species($Na^+$, $NH^{4+}$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, $Cl^-$, ${NO_3}^-$ and ${SO_4}^{2-}$), and 22 elemental species. Haze phenomena was observed during approximately 29%(10 times) of the whole sampling period(35 days), resulting in highly elevated concentrations of $PM_{2.5}$ and its chemical components. An Asian dust event was also observed, during which $PM_{2.5}$ concentration was 64.5 ${\mu}g/m^2$. Crustal materials during Asian dust event contributed 26.6% to the $PM_{2.5}$, while lowest contribution(5.1%) was from the haze events. OC/EC and WSOC/OC ratios were found to be higher during haze days than during other sampling days, reflecting an enhanced secondary organic aerosol production under the haze conditions. For an Asian dust event, enhanced concentrations of OC and secondary inorganic components were also found, suggesting the further atmospheric processing of precursor gases during transport of air mass to the sampling site. Correlations among WSOC, EC, ${NO_3}^-$, ${SO_4}^{2-}$, and primary and secondary OC fractions, which were predicted from EC tracer method, suggests that the observed WSOC could be formed from similar formation processes as those of secondary organic aerosol, ${NO_3}^-$ and ${SO_4}^{2-}$. Results from principal component analysis indicate also that the observed WSOC was strongly associated with formation routes of the secondary organic and inorganic aerosols.

• Journal of the Korean Wood Science and Technology
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• v.43 no.2
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• pp.168-176
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• 2015

This study was performed to investigate the effects of heat treatment the on mechanical properties of two species of wood under different heating conditions including at $180^{\circ}C$ for 12 h and 24 h, and at $210^{\circ}C$ for 3 h and 6 h. Two species of wood, Pinus densiflora and Larix kaempferi, were exposed to different heat treatments to assess the effects on the volume change, bending properties in static and dynamic mode and compressive strength. The results showed heat treatment caused significant changes in mechanical properties such as the static and dynamic moduli of elasticity ($MOE_d$ and $MOE_s$), and the modulus of rupture (MOR). The volume of the wood after heat treatment decreased as the heating temperature and time were increased. The bending strength performance of the wood after heat treatment decreased as the heating temperature and time were increased. The effect of heat treatment at a high temperature on the bending MOR was greater in both species than that for a long time. However, the compressive strengths of all the heat-treated samples were higher than the control sample. Furthermore, highly significant correlations between $MOE_d$ and MOR, and $MOE_s$ and MOR were found for all heating conditions.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.4
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• pp.1-14
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• 2024

Otters, designated as Class I endangered wildlife due to population declines resulting from urban development and stream burial, have seen increased appearances in freshwater environments since the nationwide ban on stream filling in 2020 and the implementation of urban stream restoration projects. There is a pressing need for scientific and strategic conservation measures for otters, an umbrella and vulnerable species in aquatic ecosystems. Therefore, this study predicts potential otter habitats using the species distribution model MaxEnt, focusing on Hwangguji Stream in Suwon, and proposes conservation strategies. Otter signs were surveyed over three years from 2019 to 2021 with citizen scientists, serving as presence data for the model. The model's outcomes were enhanced by analyzing 'river nature map' as a boundary. MaxEnt compared the performance of 60 combinations of feature classes and regularization multipliers to prevent model complexity and overfitting. Additionally, unmanned sensor cameras observed otter density for model validation, confirming correlations with the species distribution model results. The 'LQ-5.0' parameter combination showed the highest explanatory power with an AUC of 0.853. The model indicated that the 'adjacent land use' variable accounted for 31.5% of the explanation, with a preference for areas around cultivated lands. Otters were found to prefer shelter rates of 10-30% in riparian forests within 2 km of bridges. Higher otter densities observed by unmanned sensors correlated with increasing model values. Based on these results, the study suggests three conservation strategies: establishing stable buffer zones to enhance ecological connectivity, improving water quality against non-point source pollution, and raising public awareness. The study provides a scientific basis for potential otter habitat management, effective conservation through governance linking local governments, sustainable biodiversity goals, and civil organizations.

• Korean Journal of Environment and Ecology
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• v.18 no.2
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• pp.124-130
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• 2004

The valley forests at Songgyesa-Motbong-Wolhatan Area in Deogyusan National Park were studied to investigate forest structure in relation to aspect and altitude of the slope. Density, mean DBH, mean height and basal area of the tree and subtree layers in the north-facing slope were greater than those in the south-facing slope. The impotance percentage of Fraxinus mandshurica and Carpinus cordata increased with increasing elevation while those of Quercus serrata and Quercus aliena decreased. Species diversity of the north-facing slope was 1.362 and that of the south-facing slope was 1.242. There was a tendency that number of species and species diversity decreased with increasing elevation. The result of cluster analysis for the tree and sub-tree layer indicated that the studied forests were classified into broad-leaved tree species community at the low and middle elevation belts of the south-facing slope and the north-facing slope, Fraxinus mandshurica-Quercus mongolica community at the high elevation belts of the south-facing slope and the north-facing slope and Quercus mongolica community at the top area. There were significantly positive correlations in the importance percentages among Quercus serrata, Betuzo davurica and Tilia amurensis. Carpinus laxiflora was significantly correlated with Cornus controversa, Tilia amurensis and Lindera obtusiloba. There was significantly negative correlation between Fraxinus mandshurica and Pinus densiflora.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.191-199
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• 2003

This study was conducted to investigate a seasonal variation of phytoplankton communities at 6 stations in the Hantan River from November, 2001 to August, 2002. Electric conductivity gradually increased from the upper reaches to the down reaches. DO differed not much from the upper reaches to down reaches, but it decreased at the station where the pollutants inflowed. T-N and T-P concentrations were high at station 4${\sim}$6. Chlorophyll-a concentration gradually increased at the mid and down reaches. It was high in May but decreased in August by the heavy rains. Phytoplankton communities were identified a total 354 taxa composed of 99 genus, 320species, 19 varieties, 3 forma and 12 unidentified species. There were 135 taxa of Chlorophyceae, 134 taxa of Bacillariophyceae, and the other taxa were Euglenophyceae, Cyanophyceae, Xanthophycaea, Chrysophyceae and Dinophyceae. Standing crops ranged from 8,600 to 337,100 cells/mL and it was lower in August than May by the rains. Dominant species included Achnanthes alteragracillima, Achnanthes convergens, Achnanthes minutissima and Cymbella minuta var. silesiaca which were the saproxenous species at the reaches, and were Cyclotella meneghiniana, Chlamydomonas pseudopertyi and Nitzschia which were saprophilous and eutrophic species at the down reaches. The correlation coefficients between phytoplankton standing crops and EC, BOD and T-N, T-P was 0.68, 0.60, 0.60 and 0.70, respectively. All correlation coefficients between Chlorophyceae and EC, BOD and T-P were higher than 0.6. A. convergens were negative correlations with EC and BOD, but N. palea were positive with EC, BOD, T-N and T-P.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.285-294
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• 2003

To select an appropriate sampler for the environmental monitoring survey in coastal waters of Saemangeum, Jeollabuk-do, a macrobenthic sampling was conducted in April 2002. Employed samplers were dredge (type Charcot), a semi-quantitative sampler and Smith-McIntyre (SM) and van Veen grab (VV) as quantitative ones. One haul was tried for dredge and 3 replicates (0.1 ㎡${\times}$3) for SM and W at each of 11 stations. Comparisons of sediment volume in sampler bucket and of precision of biological parameters (i.e., density, biomass, species number and diversity index, H') were made between SM and VV. Sediment volume was significantly different (SM > VV) at p-value of 0.0050 (paired t-test) and, in average, 3 replicate samples of SM and VV satisfied a precision level of 0.2 by applying 4th root transformation. Patterns of observed and expected species numbers and H' were compared. Dredge-VV samples showed higher affinity than any other pair. Several dominant species in the area were underestimated in dredge samples (e.g., polychaete Heteromastus filiformis. Aricidea assimilis etc.). Quantifying the agreement pattern of multi-species responses was accomplished by estimating correlations between similarity matrices. Correlation between dredge and VV was slightly higher, but near-per-fect matches were found in general. Different ranks and composition among principal species lists were presumably linked to the effect of penetration depth that differs among samplers. Lower level of some species' abundance in VV samples (ca. 50％ compared with those of SM) was explained in this context. It seem appropriate to regard the effect as a probable cause of relatively higher correlations in dredge-VV, Overall bio-logica1 features indicated that a better choice could be SM in situations of requiring high data quality. The others work well, however, on observing and defining faunal characteristics and their capability cannot be questionted if we do not expect a first-order quality.

• Journal of Environmental Science International
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• v.11 no.8
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• pp.811-818
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• 2002

The concentration levels of monoterpenes, including ${\alpha}$- and ${\beta}$-pinene, were measured in a pine forest in Florida, USA, over about one year. Based on this measurement data, the current study then investigated the factors affecting the environmental behavior of monoterpenes. Despite a moderately weak temperature variability in the study area, the temperature dependence of the concentration variations was still evident. The concentrations of the two pinenes were significantly affected by changes in the air temperature, as indicated by strong correlations with temperature. A close relation among the measured parameters was also found between the ${\beta}$-pinene and ozone concentrations, which is also in line with previous findings from other studies. In addition, it was interesting to note that the ${\beta}$/${\alpha}$ pinene concentration ratio exhibited a strong inverse correlation to temperature, with the seasonal mean ranging from 0.51(summer) to 0.93(winter). Accordingly, the current results indicate that, in a forest environment, the major terpene species concentrations are affected by both meteorological conditions and chemical reactions.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1448-1451
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• 2008

In this paper we investigate, on the basis of experimental data, the correlations between contamination issues occurring during production process steps and final PDP operational parameters: these reciprocal relations are the result of dynamic equilibria established within the PDP system, amongst residual gases and sorbed species interacting with heat, ions and photons.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.141-144
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• 2004

An analysis procedure for the MCFC channel flow has been developed to predict the fuel cell performance. The channel formed by the uniformly distributed trapezoidal supports is approximated by the porous medium that yields the equivalent pressure drop. The Wavier-Stokes, energy, and species equations are solved to obtain the velocity, temperature and concentration fields for a local current density which is computed from electrochemical correlations. The fuel cell characteristics, such as the temperature, pressure, mole concentration, voltage and current density distributions, are presented and discussed.