• Journal of Korean Society of Forest Science
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• v.74 no.1
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• pp.67-81
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• 1986

To investigate the stand structure of the stocked broad-leaved forests in Korea, 1,000 plots, allocated by systematic sampling method, were interpreted on the aerial photographs accompanied with ground survey. Total area of the stocked broad-leaved forests except Jeju island was 818,286ha and the percentage to total forest area was 12.7%. Total stock volume of the stocked broad-leaved forests was $38,890,779m^3$ and the percentage to total stocked forest volume was 27.4%. Mean number of trees per ha was 947 trees/ha, basal area was $11.17m^3/ha$, DBH was 11.30cm, tree height was 7.65m, stock volume was $44.96m^3/ha$, and current annual volume increment was $3.64m^3/ha$ in total land. The 64.7, 79.8 and 52.7 percent of the stocked broad-leaved forest area were distributed at elevations of 300-900m, in slope degree of above 25, and in northern aspect, respectively. Standfactors were apt to get better with the increase of distance from the car road way and the village, and with the increase of elevation belt.

• Korean Journal of Agricultural Science
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• v.5 no.1
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• pp.15-28
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• 1978

It has been known that the shear strength of soil is an important design parameter for the foundation of structures, the retaining walls, the slope failures and so forth. In this study, the shear test was performed by using the direct shear apparatus under various degree of the moisture content and the density of the sample soils. The results of the study were summarized as follows; 1. The shear strength of soil increased with increase in the dry density of soil, and at the same level of density of the sample the shear strength of soil showed large values on a good grading of the sample. 2. The cohesion of the soil varied directly with the dry density of it, however the internal friction angle of soil was not affected by the dry density of tile sample. 3. The shear strength of sample varied inversly with the moisture content of it, and this phenomenon was apparent on a good grad ing of sample. 4. The cohesion of soil showed maximum value when the moisture content of the soil reached optimum level and the internal friction angle decreased with increase in the moisture content of it. These phenomena were very obvious on a good grading sample, SDC-1. 5. The cohesion of the soil decreased with increase in void ratio of the sample, but the internal friction angle of the sample didn't show such tendency.

• Korean Journal of Plant Taxonomy
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• v.46 no.2
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• pp.213-246
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• 2016

Algific talus slopes tend to occur on steep north-facing slopes with bedrock that retains ice and emits cold air throughout the growing season. Algific talus slopes provide a suitable microclimate for disjunct or relict populations of northern plant species at low altitude habitats in temperate zones. The purpose of this study is to suggest a strategy for the comprehensive conservation of the vegetation of algific talus slopes through studies of the floristics and plant species compositions and threat factors at present and in the future of 15 major algific talus slopes in Korea. As a result, the vascular plants surveyed on 15 major algific talus slopes were recorded, with a total of 587 taxa, 109 families, 323 genera, 531 species, 7 subspecies, 47 varieties 1 form and 1 hybrid. Of them, endemic plants numbered 26 taxa, and threatened species according to the IUCN valuation basis numbered 8 taxa. Fourth (IV) and fifth (V) degree indicator species as specified by floristic subregions numbered 31 taxa. Peculiarly, several subalpine-native plant species, in this case Cystopteris fragilis, Gymnocarpium dryopteris, Huperzia selago, Rosa koreana, Vaccinium vitis-idaea and Woodsia hancockii, were distributed on algific talus slopes at 100-600 m above sea level. Numerous and diverse biological resources native to algific talus slopes in Korea have been consistently disturbed or damaged by human activities without some form of protection. An all-taxa biodiversity inventory should be surveyed to provide more information about all biological species living on algific talus slopes. In addition, conservation strategies to ensure biodiversity and effective management of algific talus slopes are discussed in detail.

• Journal of the Korean Geographical Society
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• v.30 no.2
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• pp.103-119
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• 1995

This Paper aims to compare the lower marine terraces distributed from Muckho to Gangneung in the mid-eastern coast of Korean peninsula by the geomorphic method of using characteristies of terrace features and terrace deposits, paleosol, and fossil cryogenic structures, and to estimate the age of the lower marine terraces on the basis of the comparisons of those with the characteristics of thalassostatic terrace in adjacent rivers. The 1ower marine terraces in this area can be classified into two levels, i.e., lower marine terrace I and II surfaces, in desending order, according to the difference of former shoreline altitude. The former shoreline heights of the lowerm marine terrace I and II surfaces are 18m and 10m, respectiveiy. The width of the I surface is broader and distributed more continuousiy than that of II surface. Daejin I surface in Muckho coast, and Myeongju and Anin terrace in Gangneung coast could be classified into the lower marine terrace I surface, and Daejin II surfaCe into II surface. The Surface of ancient shore platform of the lower marine terrace I and II surfaces were weathered, and the color of the terrace deposit ranges from red to reddish brown. And this terrace deposit is covered with slope deposit of Last Glacial or fossil periglacial structures (platy structure and vecicle) of Last Glacial are formed in terrace deposit. These facts indicate that the lower marine terrace I and II surfaces had been formed before the Last Glacial, and then affected by chemical weathering under warm environment, finally followed by cold period. But the deposit of the lower marine terrace I surface is more weathered than that of II surface. And pseudogleyed red soil, which is developed in I but not in II surface, could be judged to have been formed in the Last Interglacial culmination stage (Oxygen isotope stage 5e). Therefore, in terms of the degree of weathering of the terrace deposit and the existence of pseudogleyed red soil, the age of both terrace is thought to be a little different. And the characteristics of the above mentioned II surface are accord with those of thalassostatic terrace formed in middle or late period of the Last Interglacial (5e or 5a). Thus on the basis of above all points, the lower marine terrace I and II surfaces in this area could be seen to have formed in the Last Interglacial culmination stage and middle or late period of the Last Interglacial, respectively. Because the lower mamine terrace I surface is broadry distributed in the eastern coast of Korea nPeninsula, the surface could be used to be a key surface in studying Quaternary marine terraces.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.61-72
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• 2001

A barrier liner system is placed at the bottom and side slope in landfill to protect a leaking of leachate that the hydraulic conductivity of this system should be less than It 107cm/sec. In this study, the soil-bentonite mixture for the bottom liner system was evaluated in two point of views : changing characteristics of the hydraulic conductivity according to the different mixing ratio of soil-bentonite with the effect of bentonite swelling and the difference method (A & D type) of compaction on the hydraulic conductivity. As the results, maximum dry density (${\gamma}$$_{dmax}$) of SC group mixture was higher than of CL group mixture. However, the result of optimum moisture contents(OMC) of both groups were the contrary. In case of ${\gamma}$$_{dmax}$ by different compaction method, D type was higher than A. But the OMC were the contrary. The difference of ${\gamma}$$_{dmax}$ according to the Compaction energy, “SC” group mixture W3S higher than the “CL” group. In case of OMC of “CL” group was higher than “SC” group. The effecting of swelling was a little bit different on the two factors. According to the result of compaction test, the use of site soil only could not meet the criteria on hydraulic conductivity, but could find a solution for the mixing ratio of bentonite mixture were satisfied to the standard of barriation. The increased in bentonite mixing ratio and degree of swelling, the values of hydraulic conductivity were decreased. Especially the “CL” group with “D” type compaction measured the lowest value with the same conditions. Also, the bentonite mixing ratio has more influenced on the hydraulic conductivity compare with swelling effect. The “SC” group mixture with “A” typo compaction got a big difference from others. The evaluation of economic for the construction cost on the two cases, the lower bentonite mixing ratio of soil-bentonite mixed soil is more economically because of bentonite cost.

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.234-246
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• 1998

The objective of this study is to investigate the correlation between steady shear flow (nonlinear behavior) and dynamic viscoelastic (linear behavior) properties for concentrated polymer solutions. Using both an Advanced Rheometic Expansion System(ARES) and a Rheometics Fluids Spectrometer (RFS II), the steady shear flow viscosity and the dynamic viscoelastic properties of concentrated poly(ethylene oxide)(PEO), polyisobutylene(PIB), and polyacrylamide(PAAm) solutions have been measured over a wide range of shear rates and angular frequencies. The validity of some previously proposed relationships was compared with experimentally measured data. In addition, the effect of solution concentration on the applicability of the Cox-Merz rule was examined by comparing the steady flow viscosity and the magnitude of the complex viscosity Finally, the applicability of the Cox-Merz rule was theoretically discussed by introducing a nonlinear strain measure. Main results obtained from this study can be summarized as follows : (1) Among the previously proposed relationships dealt with in this study, the Cox-Merz rule implying the equivalence between the steady flow viscosity and the magnitude of the complex viscosity has the best validity. (2) For polymer solutions with relatively lower concentration, the steady flow viscosity is higher than the complex viscosity. However, such a relation between the two viscosities is reversed for highly concentrated polymer solutions. (3) A nonlinear strain measure is decreased with increasing stran magnitude, after reaching the maximum value in small strain range. This behavior is different from the theoretical prediction demonstrating the shape of a damped oscillatory function. (4) The applicability of the Cox-Merz rule is influenced by the $\beta$ value, which indicates the slope of a nonlinear stain measure (namely, the degree of nonlinearity) at large shear deformations. The Cox-Merz rule shows better applicability as the $\beta$ value becomes smaller.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1331-1343
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• 2000

Through the integration of USLE and GIS, the methodology to estimate the soil loss was developed, and applicated to the Sacheon river in Gangrung. Using GIS, spatial analysis such as watershed boundary determination, flow routing. slope steepness calculation was done. Spatial information from the GIS application was given for each grid. With soil and land use map, information about soil classification and land use was given for each grid too. Based upon these data, thematic maps about the factors of USLE were made. We estimated the soil loss by overlaying the thematic maps. In this manner, we can assess the degree of soil loss for each grid using GIS. Annual average soil loss of Sacheon river watershed is 1.36 ton/ha/yr. Soil loss in forest, dry field, and paddy field is 0.15 ton/ha/yr, 27.04 ton/ha/yr, 0.78 ton/ha/yr respectively. The area of dry field, which is 4% of total area, is $2.4km^2$. But total soil loss of dry field is 6561 ton/yr, and it occupies 84.9 % of total soil loss eroded in Sacheon river watershed. Comparing with the 11.2 ton/ha/yr of an average soil loss tolerance for cropland, provision for the soil loss in dry field is necessary. Run-off and water quality of Sacheon river were measured two times in flood season: from July 24, 1998 to July 28 and from September 29 to October 1. As the run-off of the river increased, SS, TN, TP concentrations and pollutant loadings increased. SS, TN, TP loads of Sacheon river discharged during the 2 heavy rains were 21%, 39%, and 19% of the total pollutant loadings generated in the Sacheon river watershed for one year. We can see that much pollutants are discharged in short period of flood season.

• Korean Journal of Plant Resources
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• v.33 no.1
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• pp.15-23
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• 2020

There is high vulnerability of soil loss in sloping and highland used for agricultural production due to the low surface covering in summer rainy season. This study evaluated the surface-covering rate of landscape crop in reducing soil loss in the highland. The experiment was conducted in a 55% sloped lysimeter with three treatments of planting density using Korean native chrysanthemum, and investigated the soil coverage rate, run-off water, and soil erosion. The three treatments according to the degree of soil covering are bare soil as the control treatment TC, coverage rate of 43-59% for treatment T1, and, coverage rate of 63-81% for treatment T1, and T2. During the cultivation period, the average reduction of run-off water was 71% for treatment T1 and 76% for treatment T2, which are better, compared with the control. The reduction in eroded soil was 84% in treatment T1 and 98% for treatment T2, which is also better than the control treatment. Therefore, it is possible to alleviate the soil loss in sloping lands by planting chrysanthemum, which is superior among the perennial plant species and considered as a crop with economic value.

• The Korean Journal of Ecology
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• v.22 no.3
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• pp.101-108
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• 1999

This survey was performed from March 1993 to March 1998, in order to clarify the relationships between water quality and topographical factor. The study sites were two reservoir basins; Kaesim and Jangchan in Iwon-myon, Okchon-gun, Chungcho'ngbukdo Province. Basin shape factors of Kaesim reservoir were at 0.030∼0.210 (mean value 0.090), those of Jangchan reservoir were at 0.217∼0.452 (mean value 0.325). The mean basin shape factor of Jangchan reservoir was 3.61 times larger than that of Kaesim reservoir because its stream width was narrower and mean stream length was shorter. In the correlation between distance from the source of stream (L) and basin area (A), Iwonchon basin was calculated as L=1.44A/sup 0.6/. Circularity ratio was 17.114 in Kaesim (22% of Kum River), and 7.444 in Jangchan. Elongation ratio was 0.357 in Kaesim, 0.636 in Jangchan and 0.282 in Kum River. Precipitation summation period of Jangchan was 1.54 times slower than that of Kaesim. Rainfall reaching time in each small basin was 337.53 min. in A'(Jangchan-ri) basin of Jangchan and 49.26 min in H (Iwon-ri) basin of Kaesim. In the relationship between watershed frequency (Df) and drainage density (Dd), the regression equation was Df=0.023Dd² in Kaesim and Df=0.189Dd² in Jangchan reservoir. As slope degree increased, DO became higher (Y/sub DO/=0.19X＋6.5927, r=0.8l), but COD(Y/sub COD/=-0.2092X＋9.7104, r=0.52) became lower. Total nitrogen was increased with the increase of basin shape factor and circularity ratio. Ratio of B/sub OD/ to COD was 1/1.2(Y/sub BOD/ = 1.2984 X/sub COD/-3.2004, r=0.9l).

• Korean Journal of Environment and Ecology
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• v.1 no.1
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• pp.1-23
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• 1987

To investigate the forest structure of Mt. Bukhan. ranging from Seoul to Kyongkido, twenty plots were set up by the vegetation physiognomy and vegetation analysis was carried out. According to the leading dominant tree species in canopy stratum, forest communities were classified into three large groups of natural forest communities, semi-natural forest communities and artificial forest communities, and each of them covered 82.64, 7.03, and 5.71% of Mt. Bukhan area, respectively. Pure or mixed natural forest communities of Pinus densiflora and Quercus mongolica were major forest communities and covered 70.8% of Mt. Bukhan area. The important planted tree species were Robinia pseudoacacia, Pinus rigida, and Alnus birsuta and they were mainly planted at the southern slope and roadside. The degree of human disturbance of vegetation of 8, 7, and 6 area covered 82.64, 0, and 12.74%, respectively. According to forest dimensions, most of forest communities were young aged forests of which mean DBH was 20cm and canopy height below 10m. However, a few mature forest communities of Pinus densiflora or Quercus mongolica were found in the small area. The range of Shannon's species diversity of major natural forest communities, pure or mixed forest communities of Pinus densiflora and Quercus mongolica was 1.085~1.242. According to stand dynamic analysis by DBH class distribution, the present Quercus mongolica communities arid Robinia pseudoacacia communities may last long their present forest structure and most of other communities may be succeeded to Quercus mongolica communities, however, a few communities invaded by Robinia pseudoacacia and Quercus aliena-Quercus acutissima communities may be succeeded to Robinia pseudoacacia communities and Quercus aliena communities, respectively. DCA was the most effective method of this study. DCA ordination were showed that successional trends of tree species seem to be from Pinus densiflora through Quercus serrata. Prunus sargrntii. Sorbus alnifolia to Q. mongolica. Fraxinus mandsburica, F. rhynchophylla in the upper layer and from Zanthoxylum schinifolium, Lespedeza crytobotrya trough Rhus trichocarpa. Rh. verniciflua. Rhododendron mucronulatum. Rh. schlippenbachii to Acer pseudo-sieboldianus. Magnolia sieboldii, Euonymus sieboldianus.