• Journal of Astronomy and Space Sciences
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• v.16 no.1
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• pp.31-40
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• 1999

With a total 761 contact binary systems in Svechnikov & Kuznetsova(1990)'s catalogue, their physical properties by the mass ratio are investigated - for the early CE type with a common radiative envelope and the late CW type with a common convective envelope. It is found that the early CE type shows a higher temperature difference($\mid$$DeltaT$$\mid$) between the primary and secondary components, and also longer period, than the late CW type. The mass ratio of the CW type are distributed in period, than the late CW type. The mass ratio of the CW type are distributed in smaller ranges, from 0.3 to 0.7, than the CE type. Further, the relation between mass ratio and luminosity for the CW type shows a well-defined linear relation, such as ratio and luminosity for the CW type shows a well-defined linear relation, such as $L_2/L_1$ = 0.01 = 0.89q. In the mass ratio-radii relation, it is confirmed that the physical difference of the CE and CW types is a result of the secondary radius. A new mass ratio-radii relation for the CW type is suggested for both the total radius $({gamma}_1/{gamma}_2$ and the radius ratio $({gamma}_2/{gamma}_1$, respectively.

• Korean Journal of Environment and Ecology
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• v.28 no.6
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• pp.715-724
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• 2014

Tongdosa, which is located in Gajisan(Mt.) Provincial Park of Yangsan City, is one of three representative temple in Korea. The purpose of this study was to investigate a relation between plants community and environmental factors in Tongdosa(Temple) District of Gajisan(Mt.) Provincial Park. In order to find out vegetation structure of Gajisan(Mt.) Provincial Park, thirty one plots(unit size: $200{\sim}300m^2$) were set up and surveyed. For environmental factors, it were surveyed and analyzed physical factors such as altitude, aspect etc. and soil characteristics such pH, organic content, total nitrogen content, exchangeable cation and so on. Using DCCA technique, a relation between plants community and environmental factors were analyzed. The surveyed plots were divided into five groups which are Pinus densiflora - Quercus aliena, Carpinus tschonoskii - Q. spp., P. densiflora - C. tschonoskii, P. densiflora - Q. variabilis, and Q. variabilis - Q. mongolica community. Vegetation succession was progressed from Pinus densiflora toward Carpinus tschonoskii and Quercus spp. It was found out that the distribution of vegetation was affected by altitude. Pinus densiflora - Quercus aliena community is located lower altitude and Q. variabilis - Q. mongolica community is located higher area.

• Korean Journal of Environment and Ecology
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• v.23 no.5
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• pp.471-484
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• 2009

This study was carried out to classify vegetation structure on the deciduous forest at Namdeogyu area in Deogyusan National Park from May 2007 to September 2008 using the gradient analyses and phytosociological method. The vegetation was classified into Quercus mongolica community(Typical subcommunity, Rhododendron sehlippenbaehii-Q. mongolica subcommunity, Carex lanceolata-Q. mongolica subcommunity), Q. Serrata community(Typical subcommunity, Q. variabilis -Q. serrata subcommunity, Carpinus laxiflora - Q. serrata subcommunity), C. laxiflora community, Fraxinus mandshurica community and Corn us controversa community. Ecological characteristics such as species composition, layer structure, vegetation ratio, and the distribution of individual trees by DBH(diameter at breast height) were significantly different among communities. The order of important value of the forest community with DBH 2cm above plants was Q. mongolica(67.8), F. mandshurica(44.8), Q. serrata(27.5), Acer pseudo-sieboldianum(17.0), C. controversa(l5.9), F. sieboldiana(l1.5), R. schlippenbachii(11.0), C. cordata(11.0), Styrax obassia(10.9), Magnolia sieboldii(10.4) and C. laxiflora(9.8). Distribution of DBH of Q. mongolica had a formality distribution, suggesting a continuous domination of these species over the other species for the time being. In contrast, F. mandshurica appeared limited to the valley of the sheet and a higher frequency of young individuals, suggesting a continuous domination of these species the development of a climax forest terrain. Q. serrata had a higher frequency of young individuals and middle individuals, suggesting a continuous domination of these species over the other species for the time being in contrast. This study examined the correlation between each community and the environment according to DCCA ordination. The Q. mongolica community predominated in the highest elevation habitats which had many C.E.C and T-N. F. mandshurica community predominated in the highest elevation habitats which had many Moisture and EX-Cation. The Q. serrata community and C. laxiflora community mainly occurred in the low elevation habitats which had few C.E.C and T-N. The C. controversa community appeared on the park in the middle habitats.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.8
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• pp.829-837
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• 2012

Direct numerical simulations were carried out for turbulent channel flows with $Re_{\tau}$ = 180, 395 and 590 to investigate the turbulent flow structure related to the Reynolds shear stress. By examining the probability density function, the second quadrant (Q2) events with the largest contribution to the mean Reynolds shear stress were identified. The change in the inclination angle of Q2 events varies with wall units in $y^+<50$ and with the channel half height in y/h > 0.5. Conditionally averaged flow fields for the Q2 event show that the flow structures associated with Reynolds shear stress are a quasi-streamwise vortex in the buffer layer and a hairpin-shaped vortex in the outer layer. Three-dimensional visualization of the distribution of high Reynolds shear stress reveals that the organization of hairpin vortices in the outer layer having a size of 1.5~3 h is associated with large-scale motions with high Reynolds shear stress in the outer layer.

• Membrane Journal
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• v.12 no.1
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• pp.21-27
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• 2002

The formation of soluble microbial products(SMP) and molecular weight distribution on loading rate were observed in batch-type culture medium, which phenol was fed as a substrate. The molecular weight destribution was obtained by using 30K, 100K dalton and $0.45{\mu}$ membrane filters. When the phenol concentrationas a substrate was 120, 230 and 440 mg/L , the specific substrate utilization rate(q) showed 0.639, 1.281 and 1.744 mgTOC/mgMLSS/day, respectively. The endogenous biomass decay rate constant($K_d$) at each substrate concentration was 0.00536, 0.0661 and 0.0749($day^1$), respectively. The $SMP_e$ product rate constant($k_{SMP}_ e$) showed 0.006, 0.0058 and 0.0057($day^1$), respectively. The initial influent substrate during the course of time degraded and produced $SMP_s$. The $SMP_s$ was converted to the $SMP_{nd}$ and endogenous phase converted to the $SMP_e$ ingredients. The molecula weight distribution on loading rate was converted to a higher MW during the course of time.

• Journal of Korean Society of Forest Science
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• v.88 no.2
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• pp.149-156
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• 1999

This research was carried out to investigate the effects of the different tree species(Q. spp., L. leptolepis and P. koraiensis) about the chemical properties of throughfall and stemflow, to purify the acid rain at Kyung Hee Univ. experimental forest, Gwangju-gun, Kyunggi-do. The water quality of the precipitation, throughfall and stemflow in each forest stands were analyzed chemically. The throughfall pH ranges were Q. spp.(pH 4.96-6.34), L. leptolepis(pH 3.96-6.41) and P. koraiensis(pH 4.11-6.36), and the stemflow pH ranged Q. spp.(pH 4.33-6.05), L. leptolepis(pH 3.59-6.09) and P. koraiensis(pH 3.60-6.13). pH values of throughfall and stemflow to the precipitation were Q. spp. higer than L. leptolepis and P. koraiensis, while distribution range was small. Therefore, buffering capacity about the precipitation in the tree species trended Q. spp. bigger than L. leptolepis and P. koraiensis. Nearly all concentration of dissolved elements were precipitation${\leq}$throughfall${\leq}$stemflow. The cation ($Ca^{2+}$, $Mg^{2+}$, $K^+$ and $NH_4{^+}$), and anion($Cl^-$ and $NO_3{^-}$) were increased. Especially the concentration of $Mg^{2+}$, $K^+$, $NH_4{^+}$ and $Cl^-$ were noticeable. In comparing concentration of dissolved elements of throughfall with each tree species, $Ca^{2+}$ concentration was Q. spp.$NH_4{^+}$ was Q. spp.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.2
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• pp.37-59
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• 2017

The Korean peninsula belongs to the temperate forest biome dominated by many deciduous oaks. We quantitatively and qualitatively studied vertical and horizontal distributions and habitat characteristics on the major oak species such as Quercus mongolica, Q. serrata, Q. variabilis, Q. dentata, Q. aliena and Q. acutissima. A total of 5,278 samples were analyzed with a species coverage and 6 principal environmental variables extracted from public database of nationwide natural environment survey. Correlation analysis was accomplished by the CANOCO using Canonical Correspondence Analysis and the Pearson correlation coefficient using PASW Statistics. The hierarchical distribution tendency of six oaks was finalized using the Goodman-Kruskal lambda coefficient of non-metric multidimensional scaling by SYN-TAX 2000. The utmost factor on the distributional segregation of oak species was the elevation, i.e. temperature. Q. serrata and Q. mongolica show clearly a diametrical distribution patterns with zonal distribution. Q. variabilis was determined as a thermophilic and xerophilous species that is a component of not only natural pseudo-climax forest but also secondary forest. The highest frequency of the dominant forest was found Q. mongolica. Whereas, Q. serrata showed the highest frequency of individual tree but the relatively lower frequency of dominant forest, which is resulted from the original habitat loss. By the benefit of the traditional Soopjeong-E, Q. acutissima dominant forests were remained rather largely. Individuals of Q. dentata occurred horizontally nationwide, but its dominant forest was the poorest. Dominant forest of Q. aliena, which is a natural vegetation, was the most rare due to a limited potential habitat.

• Korean Journal of Environment and Ecology
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• v.25 no.5
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• pp.725-735
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• 2011

This study was carried out to analyze the vegetation properties, soil characteristics, and ordination of Stewartia koreana community of Mt. Jirisan in Korea. The S. koreana community was classified into S. koreana-Quercus mongolica serrata community, S. koreana-Quercus mongolica community, and Typical community. In specific, S. koreana-Q. serrata community was classified into two subgroups such as Carpinus laxiflora subcommunity and typical subcommunity. The S. koreana community was found out to be located at an elevation of 409m to 1,604m. The Results of importance value on the S. koreana community consisted of the following in order: 75.47% of S. koreana, the highest, 21.83% of Q. serrata, 18.65% of Q. mongolica, 18.19% of Acer pseudosieboldianum, 10.56% of Rhododendron schlippenbachii, 10.36% of Styrax japonicus. In the targeted study sites, soil organic matter, total nitrogen, available phosphate, exchangeable potassium, soil moisture and soil pH were 3.15~39.1%, 0.37~11.7%, 0.9~45.4mg/kg, $0.09{\sim}1.48cmol^+/kg$, 19.28~55.47% and 4.08~5.65, respectively. The results of the correlation between communities and soil conditions of S. koreana community by DCCA ordination method are as follows: S. koreana-Q. serrata community was found in the highest elevation and followed in order S. koreana typical community, S. koreana-Q. serrata typical subcommunity, and C. laxiflora subcommunity.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.496-503
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• 2021

Pinus densiflora is an essential tree species native to the Republic of Korea (ROK) and covers most of the total natural forest areas in the ROK. This study was conducted to understand the site characteristics and stand structure of P. densiflora forests distributed at sites where P. densiflora covered over 50% of the stand basal area during the 7th National Forest Inventory (NFI) period from 2016 to 2020. P. densiflora dominated 3,665 circular sample plots (400 m²). P. densiflora forests predominated at elevations less than 600 m above sea level (a.s.l). However, most P. densiflora forests were distributed at the slopes facing south and west over 800 m a.s.l. At altitudes below 800 m, they were distributed at all slopes but dominated at the southern and western slopes. P. densiflora grew mainly in the soils of sandy loam, loam, or silt loam with relative infertility. Dominant tree species distributed with P. densiflora were Quercus mongolica, Q. variabilis, Q. serrata, Prunus serrulata var. pubescens and Castanea crenata by the descending order. P. densiflora, P. thunbergii, and P. rigida were grown in large DBH classes, Quercus species and Fraxinus rhynchophylla in middle DBH classes, while Juniperus rigida and Styrax japonicus in small DBH classes. Dominant tree species distributed mainly at the lower layer of P. densiflora stands were Rhododendron mucronulatum, Q. serrata, Lindera obtusiloba, Fraxinus sieboldiana, Toxicodendron trichocarpum and Rhododendron schlippenbachii by the descending order.

• Korean Journal of Plant Taxonomy
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• v.35 no.1
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• pp.57-80
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• 2005

Morphological variation of Quercus L. subgen. Quercus in Korea was examined by numerical methods including principal components analysis of major morphological characters. Principal components analysis revealed the presence of five major species groups of the subgen. Quercus in Korea; these include 1) a group consisiting of Q. acutissima and Q. variabilis individuals, 2) Q. dentata, 3) Q. aliena, 4) Q. mongolica, and 5) Q. serrata. The putative interspecific hybrid individuals occupied intermediate position between the putative parent species in the PCA plot. The analysis also strongly suggested that size and shape of leaf blade and teeth or lobes, twig diameter, size and shape of nuts, and length and width of scales are very useful in distinguishing the species and the putative hybrids of the subgen. Quercus.